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Heat Management Strategies for Construction Workers

Permanent Link: http://ufdc.ufl.edu/UFE0022250/00001

Material Information

Title: Heat Management Strategies for Construction Workers
Physical Description: 1 online resource (87 p.)
Language: english
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2008

Subjects

Subjects / Keywords: construction, heat, industry, management, productivity, safety, strategies, worker
Building Construction -- Dissertations, Academic -- UF
Genre: Building Construction thesis, M.S.B.C.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: The construction industry differs from other economic sectors in the fact that little or no control of the climatic conditions on the jobsite is available. The research here seeks to provide both a scientific basis for heat stress management, as well as scientifically-based suggestions for the safeguarding of construction worker health and well being, strategies to mitigate the effects of heat stress on worker productivity, and benefit the construction industry as a whole.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Thesis: Thesis (M.S.B.C.)--University of Florida, 2008.
Local: Adviser: Issa, R. Raymond.
Local: Co-adviser: Olbina, Svetlana.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2008
System ID: UFE0022250:00001

Permanent Link: http://ufdc.ufl.edu/UFE0022250/00001

Material Information

Title: Heat Management Strategies for Construction Workers
Physical Description: 1 online resource (87 p.)
Language: english
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2008

Subjects

Subjects / Keywords: construction, heat, industry, management, productivity, safety, strategies, worker
Building Construction -- Dissertations, Academic -- UF
Genre: Building Construction thesis, M.S.B.C.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: The construction industry differs from other economic sectors in the fact that little or no control of the climatic conditions on the jobsite is available. The research here seeks to provide both a scientific basis for heat stress management, as well as scientifically-based suggestions for the safeguarding of construction worker health and well being, strategies to mitigate the effects of heat stress on worker productivity, and benefit the construction industry as a whole.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Thesis: Thesis (M.S.B.C.)--University of Florida, 2008.
Local: Adviser: Issa, R. Raymond.
Local: Co-adviser: Olbina, Svetlana.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2008
System ID: UFE0022250:00001


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PAGE 1

HEAT MANAGEMENT STRATEGIES FOR CONSTRUCTION WORKERS By IAN BRUCE MILLER A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE RE QUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN BUILDING CONSTRUCTION UNIVERSITY OF FLORIDA 2008 1

PAGE 2

2008 Ian Bruce Miller 2

PAGE 3

To Francis, whose life demonstrates the value inherent to intellectual exercise. 3

PAGE 4

ACKNOWLEDGMENTS I wish first to thank my parents for helping to support m e in my education. I would like also to thank Dr. Francis Hort, for his most ex cellent manner of pushing me and all of my close friends to succeed in life. I would like to say a huge thank you to Breen Halley for her emotional support while writing this paper, as well as the delicious food that came to my door at just the right moments to prevent my starvation. I love you all dearly. 4

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TABLE OF CONTENTS page ACKNOWLEDGMENTS...............................................................................................................4 LIST OF TABLES................................................................................................................. ..........8 LIST OF FIGURES.........................................................................................................................9 CHAPTERS 1 INTRODUCTION................................................................................................................. .11 Brief Introduction to Productiv ity and Managem ent Theory.................................................11 The Construction Environment...............................................................................................11 2 LITERATURE REVIEW.......................................................................................................13 Identification of Generic Productivity Factors.......................................................................13 Data Sources...........................................................................................................................16 U.S. Military/FAA...........................................................................................................17 NIOSH/OSHA.................................................................................................................18 ACGIH............................................................................................................................18 Professional Sports..........................................................................................................19 3 EXPLANATION OF CONCEPT...........................................................................................20 Scenarios for Discussion....................................................................................................... ..20 The Contextual Basis for Further Investigation......................................................................23 4 WHAT WE KNOW................................................................................................................2 5 Physiological/Biochemical Processes of Heat Adaptation in Hum ans and the Effects Thereof....................................................................................................................................25 Drugs.......................................................................................................................................29 Other Facts............................................................................................................. .................30 5 THE CURRENT STATE OF THE INDUSTRY...................................................................31 Indicators and Selected Definitions........................................................................................31 Core Body Temperature..................................................................................................31 Heat Stress and Heat Strain......................................................................................31 Sustained Peak Heart Rate...............................................................................................32 WBGT Screening Criteria and Formulae........................................................................32 Heat Disorders (By increasing order of se verity and health risk) according to NIOSH .........................................................................................................................33 Acclimatization................................................................................................................ .......34 5

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Dehydration.................................................................................................................... ........35 6 EXISTING MODELS FO R HEAT MANAGEMENT..........................................................37 Military Case Study 1: USAF Instruction 48-1, D yess AFB..................................................37 How and Why the U.S. Military Model Fails.................................................................39 Caveats to Interpretation of the Dyess Study..................................................................39 Military Case Study 2: USAF Instruction 48-100 Little Rock AFB......................................40 FAA Case Study: Tolerances to Therma l Extremes in Aerospace Activ ities.....................41 Findings...........................................................................................................................42 Pain-Limited Tolerance: PLT..........................................................................................43 Heat-Loador Heat-Storage -Limited Tolerance: HSLT .................................................44 Systems-Limited Tolerance:............................................................................................45 FAA Study Relevance.....................................................................................................46 Study Conclusions..................................................................................................................47 7 OVERVIEW OF CURRENT GUID ELINES AND ESTABLISHED MODELS ..............49 Current Guidelines..................................................................................................................49 Established Models............................................................................................................. ....50 The CDC Public Model ...................................................................................................50 The OSHA Public/Industry Model..................................................................................51 The NIOSH Public/Industry Model.................................................................................51 8 RESULTS PART 1: REAL SUGGEST IONS FO R HEAT MANAGEMENT AND WORKER SAFETY...............................................................................................................52 Caveats....................................................................................................................................52 Hyponatremia/Hypernatremia.........................................................................................52 Hypernatremia..........................................................................................................52 Hyponatremia...........................................................................................................53 Importance to the Construction Environment.................................................................54 Protective Clothing............................................................................................................ .....55 Heat W aves.............................................................................................................................56 Acclimatization................................................................................................................ .......56 Measurem ent a nd Monitoring.................................................................................................58 9 RESULTS PART 2: THE BASIS FOR A SCIE NTIFIC MANAGEMENT MODEL..........62 The Model...............................................................................................................................62 Formula 1: Heat...............................................................................................................6 3 Form ula 2: Water.............................................................................................................66 Formula 3: Salt................................................................................................................ 67 Form ula 4: Energy...........................................................................................................69 Model Conclusions.................................................................................................................72 6

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10 CONCLUSIONS AND RECOMMENDATIONS.................................................................76 Manager Obligations..............................................................................................................76 Brief Return to Interruptions..................................................................................................78 Accountability................................................................................................................. ........78 Recommendations for Future Research..................................................................................79 APPENDIX COMMON DRUG FAMILIES, CHEM ICAL NAMES AND BRANDINGS ......................81 LIST OF REFERENCES...............................................................................................................83 BIOGRAPHICAL SKETCH.........................................................................................................86 7

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LIST OF TABLES Table page 2-1. Sources and Percentage of Nonproductive Tim e in the Construction Industry. Adapted from Construction Productivity: Measurement and Improvement....................................13 2-2. Reasons for Nonproductive Time in th e Construction Industry. Adapted from Construction Productivity: Measurement and Improvement.............................................14 5-1. WBGT Screening Criteria. Adapted from the ACGIH and converted to Fahrenheit working units.. ...................................................................................................................33 5-2. Water deficit and clinical effects. Adap ted from Hydration during exercise: Effects on therm al and cardiovascular adjustments, by Candas et al..................................................36 6-1. USAF WBGT Addition Schedule Adapted f rom Health Hazard Evaluation Report No. 2000-0065-2899.................................................................................................................41 8

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LIST OF FIGURES Figure page 1-1. Labor Productivity Index for US Construc tion Industry and All Non-Farm Industries from 1964 Through 2003. From Teicholz.........................................................................12 2-1. Productivity effects of Work Interrupti ons. Data Table with Graph. Adapted from Construction Productivity: Measurem ent and Improvement.............................................15 3-1. Productivity Curve Versus Repetition for Different First Com pletion Durations. (Productivity Formula Y=AX-n) from Construction Productivity: Measurement.............21 3-2. Single Plot for 4-minute First Completion T ime Showing Asymptotic Behavior of the Learning Curve..................................................................................................................21 3-3. Productivity Versus Temperature. Ad apted from Construction Productivity: Measurement and Improvement by James J. Adrian.........................................................22 4-1. Psychrometric Chart with Comfort Zone s for Low W ork Levels and the Average Construction Worker..........................................................................................................26 4-2. Physiological and Performance Limits in Hot Environments. Modified from Wing. From FAA AM 70-22........................................................................................................28 6-1. U.S.A.F. Heat management disseminati on hierarchy. A dapted fr om NIOSH Dyess AFB Evaluation HETA 2000-0060-2904...................................................................................38 6-2. Tolerance Times for PLT Exposure and Curve Showing Overlap Between Painand Heat-Storage-Lim ited Tolerance Exposures. From FAA AM 70-22................................43 6-3. Tolerance Times for HSLT E xposures. From FAA AM 70-22.............................................45 6-4. Summary Graph of Tolerance Times for Three Toler ance Limit Categories and the Conditions Necessary to Elicit th e Response. From FAA AM 70-22...............................47 6-5. Mean Tolerance Time Versus Temperatur e in Hum ans. Adapted from FAA AM 70-22......48 8-1. Hyponatremia Diagnostic Schedule. (Source: Modified to .jpg Format from http://en.wikipedia.o rg/w iki/Image:Hyponatraemia_Causes.svg......................................54 8-2.Cumulative Effect of Overtime on Pr oductivity for 50and 60-hour Workweeks. Adapted from Scheduled Overtim e Effects on Construction Projects...............................58 9-1. CBT Rise Over Time for Fullyand NonAcclim atized Workers, Showing Dangerous Heat Loading in Non-Acclimatized Workers....................................................................73 9

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Abstract of Thesis Presen ted to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science in Building Construction HEAT MANAGEMENT STRATEGIES FOR CONS TRUCTION WORKERS By Ian Bruce Miller May 2008 Chair: R. Raymond Issa Cochair: Svetlana Olbina Major: Building Construction The construction industry suffers from a number of problems th at directly or indirectly lead to dismal productivity growth. Depending upon whose numbers you choose to regard as most accurately portraying the real situation, the industry has experi enced either wholly stagnant productivity growth, a slight decr ease in productivity, or a serious drop in productivity increases as compared to all other non-farm sectors. Regard less of the source chosen, the fact remains that as compared to every other non-farm sector in the US economy, construction has made far less progress in increasing labor productivity. One of the most notable researchers in the analysis of construction productivity, Dr. Paul Teicholz, has produced some of the most cited data sets regarding productivity. Dr. Teichol zs analysis shows a compounded rate of decline in labor productivity for the construction industry of approximately -0.59% per year. This would not be so alarming if not for the averaged compounded increasing productivity of all other non-farm industries of +1.77% per year. A problem, or rath er a productivity crisis clearly exists. With nearly all construction taking place outdoors, often in warm and/or humid conditions, construction managers need both scientific and practical strate gies for managing worker heat stress levels. 10

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CHAPTER 1 INTRODUCTION Brief Introduction to Producti vity and Management Theory Anyone versed in management theory or even remotely familiar with any industry process will quickly agree that ex cellence in management of labor has pr oven in all sectors to be the closest to a panacea for productivity issues as can be imagined. In fact, if one imagines a labortechnology complex, it is this complex that most modern management theory now applies to. As a brief technical example, in the late 1990s T oyota ran magazine ads essentially touting how much money Toyota of America spends on wrenches The crux of the ad was that Toyota spends in the neighborhood of $50,000 per wrench, and the wrenches are so advanced that the worker need only place a nut in a receiv er, line up the desired bolt, and press a button. The wrench would tighten the nut while precisely measuring sp eed, temperature, strain, and a variety of other factors to place the nut rapidly and at the optimal torque for each part of the vehicle assembly. While this story appears anecdotal at first glance, one must conced e that a large amount of theory and science lies behind its underlying concept. Instead of the work er having to either look up or remember the torque value for the assemblies delivered to his area of the assembly line, ratcheting away and then carefully tightening or loosening to the co rrect torque value, he simply picks up his high-tech wrench, and it does the work for him wit hout the use of much thought or, eminently more importantly, effort. Thus, the work er is not replaced by a machine as so many workers often fear, he tires less easily, the correct torque values are had in significantly less time, and throughput increases. The Construction Environment The same sorts of productivity improvements ha ve been realized in every part of the hum an-technology interaction complex. The mouse, CAD, and BIM are all notable examples 11

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that deserve no further explanation here. Whereas many industry analysts including Dr. Teicholz have concentrated upon the use of technologica l advances to manage labor, documents, procurement, design, production and many other facets of an industry busin ess as the solution to the proven productivity gap, the following pages will focus on another equally critical factor affecting productivity; environmenta l, or more precisely, heat management. One must remember that (to a certain point) while workers in cold environments can easily don more clothing to protect from cold, and waste heat can be used to warm work spaces, workers in warm/hot environments cannot shed more clothing than protection rules allow, a nd there is no practical thermodynamic possibility for waste cold. Figure 1-1. Labor Productivity Index for U.S Cons truction Industry and Al l Non-Farm Industries from 1964 Through 2003. From Teicholz. (Source: http://www.aecbytes.com/viewpoint/2004/issue_4.html Last accessed April 1, 2008). 12

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CHAPTER 2 LITERATURE REVIEW Identification of Generi c Productivity Facto rs There are a number of factors commonly cited as prim e eff ectors of constr uction industry productivity. For the sake of consistency and brev ity, a series of tables and charts from one notable author, Dr. James J. Adrian, one of th e foremost experts in the analysis of labor productivity, will be presented, wi th analysis directly following. Table 2-1. Sources and Percentage of Nonproductive Time in the Construction Industry. Adapted from Construction Productiv ity: Measurement and Improvement and Improvement by James J. Adrian (2004). Sources of Nonproductive Time Labor 1/3 Management 1/3 Industry 1/3 Time Spent Productive 55% Nonproductive 45% Total 100% 13

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Table 2-2. Reasons for Nonproductive Time in the Construction Industry. Adapted from Construction Productivity: Measurement and Improvement by James J. Adrian (2004). Labor-Related Factors ManagementRelated Fac tors Industry-Related Factors High Percentage of Labor Cost Poor Cost systems and Control Uniqueness of Many Projects Variability of Labor Productivity Poor Project Planning Locations at Which Projects are Built Supply-Demand Characteris tics of Industry Poor Planning for Measuring and Predic ting Productivity Adverse Weather and Climatic Seasonality Little Potential for Labor Learning Dependence on the Economy Risk of Worker Accidents Small Average Firm Size Union Work Rules Lack of R&D Low Worker Motiva tion Restrictive Building Codes Interruptions Government Labor and Environm ental Laws 14

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Type of Work Length of Interruption 0.5 hr. 1 hr. 2 hr. 3 hr. 4 hr. 5 hr. 6 hr. 7 hr. Concrete Forming *6.25 12.5 25 37.5 50 62.5 75 87 Masonry 4 8 14 22 32 44 52 56 Electrical 5 10 17 27 39 52 61 72 *Percentage Loss in Efficiency Interru p tion Time Versus Productivit y Level After Interru p tion for Three 0 20 40 60 80 100 120 00.51 2 3 4 5 6 7 Interruption Period (Hou r Concrete Forming Masonry Electrical Figure 2-1. Productivity Effects of Work Interruptions. Data Table W ith Graph. Adapted from Construction Productivity: Measurement and Improvement by James J. Adrian (2004). Beginning with Table 2-1, we see that labor it self is assigned approxim ately one-third of the responsibility for overall construction productivity. This point is made further poignant by the following data. Adrian estimates that current ly, an average contractor incurs approximately $1 of labor cost for every $1 of material cost. This appears to be in line with the Adrians 1/31/3-1/3 view of the division of responsibility for productivity, since management and industry are both responsible for a portion of labor and ma terial costs. Compare these numbers to the $1 15

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of labor cost per $2 of material for the major manufact uring industries, and it becomes clear that managing labor productivity is even more critical in the constr uction industry (Adrian, 2004). Continuing to Table 2-2, we see a small, concise selection of causes for productivity problems divided amongst the thr ee previously mentioned overall factors: labor, management, and industry. The items in Table 2-2 are all directly or slightly indirectly related to labor; if unclear, this fact will be clarified in short order. The first item under La bor-Related has already been touched upon briefly, while each of th e other items in will become more obvious throughout the discussion. In Figure 2-1, we see that interruptions, ma de purposefully nonspecific to include delays of any sort, lead to varying am ounts of subsequent unproductive time through loss of efficiency. It can be assumed that since interruptions can take any form, any activity other than direct work can b termed an interruption. A list of such activitie s on the construction site can easily be imagined to be hundreds of lines long, but some of the most commonly cited interruptions are change orders, trade stacking, planned breaks, unplanned breaks, meals, weather, accidents/incidents, and exhaustion. Data Sources The majority of thermal management informa tion to the construction industry is sourced from extrapolation of data gath ered under the auspices of the Ce nters for Disease Control (CDC), the US Military and, interestingly enough, the Fe deral Aviation Administration (FAA). The first two sources are quite obvious at first glance, since the link between temperature exposure and disease/illness are fairly well understood as co mmon knowledge, and the military has a vested interest in many hundreds of thousands of pers onnel, regularly engaging in missions in every climate imaginable, from the frozen barrens of th e South Pole to the deserts of the Middle East. Information coming from the FAA, however, might seem surprising at first glance, but one must 16

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consider that the FAA has close association with both the military and with NASA, where human performance takes on relatively extreme qualities. One must only imagine the heat (or lack thereof) endured by pilots in military aircraft or the space shuttle, to realize why the FAA would have valuable thermal management data. U.S. Military/FAA It is a combination of these two data sets th at one would expect to prove most valuable, due to the specific types of workers covered by the data. Inform ation from the US Military may be expected to be predicated upon data concerning a range of activity types, from those of fighter pilots to foot soldiers or infant rymen. The fact of the matter is that the available military data are often concerned primarily with the day-to-day health of the average soldier or sailor rather than any specific recommendations for specialized personnel. In essence, the available military data are more concerned with maintain ing the health of large numbers of troops for long periods of time. The FAA, on the other hand, provides data th at is specifically co ncerned with shorter duration activities those that demand full me ntal concentration, full capacity for tactile movement (and endurance thereof), rather than pure strength. Of course, both cases make perfect sense. The military, in general, must be concerne d with large numbers of men whose jobs are of a less refined nature, very much like the averag e construction worker. At the same time, the fine craftsman is quite like a pilot, who must carefully and adroitly go about his job with full faculties at all times. This is not to suggest that the mistake of a craftsman could have the dire consequences of pilot error, but for all intent s and purposes of comparison, the analogy may be assumed to be valid. Between these two sources of information, nearly all of the construction industry is covered. 17

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NIOSH/OSHA The National Institute for Occupational Safety and Health (NIOSH) is the arm of the CDC that acts in essentially all economic sectors, as well as within the military and in conjunction with the FAA. Most importantly, NIOSH serves as the health information clearinghouse for the construction industry. For the sake of clarity and correctness, it should be noted that the Occupational Safety and Health Administration (OSHA) is the main federal agency charged with the enforcement of safety and health legislation. OS HA does not make recommendations; rather it only enforces legislative statutes-in-place (NIOSH, 2007). NIOS H, on the other hand, as part of the CDC, is responsible for conducting research and making recommendations for the prevention of work-related illness and injuries. In between, is th e United States Congress, which acts to formulate the rules and regulations of law (NIOSH, 2007). Both NIOSH and OSHA were created in via the Occupational Health and Safety Act of 1970, and the proper beaurocratic hierarchies are: US Department of Labor>OSHA US Department of Health and Hum an Se rvices>Centers for Disease Control and Prevention>NIOSH. ACGIH It is also worth mentioning that some of the mo st valuable res earch da ta and most stringent recommendations come from the American Conf erence of Governmental Industrial Hygienists (ACGIH). It is widely remarked that the ACGIH recommendations, thou gh oft cited, are where rules become guidelines due to the strictness of ACGIH criteria. The perceived onerous quality of ACGIH information is precisely what makes it so valid and important when discussing heat stress management. 18

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Professional Sports The last source of note is professional sports In professional sports hygiene, dietetics, nutrition, cu tting edge medicine, a nd engineering all come into pl ay. The inclusion of sports training data, while valuable, is deemed to be ou tside the scope of this investigation due to the sheer volume of money that is invested in performa nce athletes, combined with the fact that most athletes are not in training for e ndurance activities, but rather for short bursts of effort. It is suggested, however, that as a separate avenue of investigation, future res earch should attempt to sift through data concerning profe ssional athletes to find any and all solutions that might yield low cost, ease of implementation, or low cost:b enefit ratios when applie d to the construction environment. 19

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CHAPTER 3 EXPLANATION OF CONCEPT Even when performing repetitive tasks, frami ng a wall for exam ple, the productivity of an average worker can and will vary by up to 34% from one hour to the next. Given Adrians scientific evidence provided in Table 2-1, combin ed with Figure 2-1, it is clear that while nonproductive time (Table 2-1) is, in and of itself, the antithesis of productivity, it has a doubly harmful effect on workers in that the learning cu rve for a given activity is set back each time the worker is interrupted from his task (Figur e 2-1). The following three scenarios must be considered: Scenarios for Discussion Scenario 1: We shall restate the above for further dissection and an alysis. Any generic, average worker is on the jobsite, perf orming average, generic tasks. Because of the work at hand, the worker is constantly changing tasks. Each time the worker changes tasks, his learning curve is reset to the start point. (S ee Figures 3-1 and 3-2 below.) Scenario 2: A highly skilled craftsman is perform ing work on a building assembly, which requires highly repetitive work. If it is assumed that he is allowe d to work freely, with correct construction documents, adequate supplies, comp etent helpers, and a lack of other trades interfering in his work that is, industry and management factors are held constant. Thus, the craftsman is allowed to work al ong his learning/performance curve that is, he will gradually become more adept and faster at the given task ov er time. It is understood as a rule of productive human assets, that the learning curve will hit an asymptotic limit at which the craftsman will be at his maximal productivity with all other factor s held constant. (See Figures 3-1 and 3-2 below.) Every time this craftsman must cease work to drink, take a break, or as part of a work-rest regimen, he incurs the productivity lo ss associated with the break period. 20

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Productivity Curves for Various Activity Durations to Show Asymptotic Behavi o 0 50 100 150 200 250 300 12345678910111213141516171819202122232425262728293031 Activity Repetitions 30 seconds 60 seconds 90 seconds 120 seconds 150 seconds 180 seconds 210 seconds 240 seconds Figure 3-1. Productivity Curve Versus Repetition for Different First Completion Durations. (Productivity Form ula Y=AX-n) from Construction Productivity: Measurement and Improvement by James J. Adrian (2004). Asymptote Beahvior of Learning Curves0 50 100 150 200 250 3000 6 12 1 8 24 3 0 36 4 2 48 5 4 6 0 6 6 72 78 84 90 96 1 0 2 1 0 8 1 1 4 120 12 6 132 138 144 1 5 0 1 5 6Repetitions 240 seconds Figure 3-2. Single Plot for 4-minute First Completi on Time Showing Asymptotic Behavior of the Learning Curve. 21

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Scenario 3: Workers at a jobsite are working on different tasks, in different areas of the site, at different paces, and with varying degr ees of physical, mental, and emotional difficulty. Although seemingly different, these workers are all operating in the same general climatic environment That is, they are all exposed to the w eather, be it hot, col d, dry, humid, or any combination thereof. Theses workers are, each and every one, literally and figuratively, at the mercy of the elements. If not managed correctl y, some of the workers may have lower than expected productivity as time goes on because they are overexposed to heat stresses one or more days and do not adequately recover over the fo llowing days. As temperature exposure goes, the workers will find themselves somewhere on the curve given in figure 3-3. Productivit y Versus Tem p erat u 0 20 40 60 80 100 120 40506070758090100110 Temperature in Degrees Faren h Productivity as a Percentage of Normal o r Average Productivity (Blocks or Bricks Place d Per Hour) Figure 3-3. Productivity Versus Temperature. Adapted from Construction Productivity: Measurement and Improvement by James J. Adrian. 22

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The Contextual Basis for Further Investigation Previous to this point in the introduction, liter ature review, and explan ation of concept, the topic of heat m anagement has not been touche d upon in any specific or concise manner. The purpose behind such a circuitous manner of pr ogression is twofold: Firstly, the topic of productivity in industry is circuitous of its elf; and is further compounded by the number of impinging factors involved in the construction environment. It is precisely this compounding of the issue that is the crux of the second reason fo r such a volume of lead-up information. That is, the issue of productivity in construction must be examined in a specific context, or set of contexts, to be easily understood. Thus, to specif y the context for the remainder of the analysis and discussion, the following statements may be made: The Construction Sector operates under a different set of param e ters as compared to other economic sectors. Construction productivity analysis is, therefore, significantly di fferent than the analysis of productivity in other econom ic sectors. The unique characteristics of the con structi on process are the primary causers for this difference; the most important of these differences are the following: Construction projects are often unique assem blies, designed, engineered, and constructed once, without any rehearsal. Home office management is often di stant from each construction site. Construction projects are assem ble d from many thousands or hundreds of thousands of small piece s, essentially by hand. Buildings are constructed prim arily outdoor s, with full exposure to the elements and little potential for th e mitigation thereof. The construction worker often does not ha ve one designated task that can be continually monitored for production thr oughput, as in m anufacturing. Rather, the construction worker must be monitored pa rtially based on parameters other than simple throughput. It is the intention here to deal with the la st two sub-item s above, while keeping the other issues as contextual elements in the periphery only. The issue of the thermal environment and 23

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thermal management is one that, though resear ched in many other contexts, has not been adequately treated as a topic of investigation in the constr uction industry, nor have many ingenious technical solutions been discovered or innovative, effective management practices formulated. It is with a discussion and analysis of the biological processe s associated with heat adaptation, followed by a survey of the current state of the industry as regards thermal issues that we begin. 24

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CHAPTER 4 WHAT WE KNOW Physiological/Biochemical Processes of Heat Adaptation in Humans and the Effects Thereof The explanations below, adapted from UC Berkeley res earchers, Kan-Rice and Rosenberg, suggestions regarding heat management, neatly summar ize the biological reactions involved in heat adaptation. The parts critical to discussion have been explicitly stated via keywords and discusse d directly after. A body at work generates heat faster than at rest, often m ore than needed. Roughly threefourths of the stored energy the body draws on during activity c onverts to heat rather than motion, and more strenuous activ ity naturally generates more heat. Elevation of core body temperature disturbs functioni ng, so the body protects itself by dissipating excess heat. The mechanisms of vasodilatation and sweating ar e critical to moving heat from a human body to the environment. When the body's core te mperature exceeds its norm (generally 98.6 degrees) [now known to be 98.2 F], veins a nd capillaries expand, the heart beats faster, and blood flow increases to outer layers of skin from which heat is radiated to the cooler exterior environment (Kan-R ice and Rosenberg, 2005, p. 2). Convective heat loss only f unctions correctly when T, the m ean difference between the body and the surrounding environment (air) is advantageous to the body. At positive T that is, when the skin temperature is higher than the ambient air temperature, the body can no longer shed excess heat to the outside environment. This is the basis for psychrometry, the study of the effects of temperature and humidity on the perceived comfort of humans. The typical psychrometric analysis that we encounter, howev er, is designed for the study of air-conditioned environments in homes and factories. The comfort zone typically shown is in no way representative of the environmental conditions th at workers often work in, or even conditions that feasibly can be provided in the construction environmen t. Figure 4-1 shows a standard psychrometric chart marked with comfort zones fo r the sedentary (or nearly so) worker and then for the construction worker. 25

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Figure 4-1. Psychrometric Chart with Comfort Zones for Low Wo rk Levels and the Average Construction W orker. Created from Data in FAA AM 70-22 If, however, the body cannot cool fast enough through this means [The UC Berkeley study mistakenly refers to ra diative losses. While radiative losses from the human body are often negligible, convec tive losses have a great effect.], or when surrounding air is warmer than the skin, the brain signals sweat glands to release sweat to th e skin surface. Evaporation of the sweat carries additional heat from the body. Because high humidity decreases the sweat evaporation rate, it slows cooling. After becoming "acclimatized" to a hot environment over time, people sweat more readily and thus cool more efficiently (Kan-Rice and Rosenburg, 2005, p. 2). The heat of evaporation, or the energy require d to evaporate water, is m uch higher than the energy required to warm air, the human body can expel large quantities of heat via the evaporative process. Unfortunately, the body is not capable of forcing evaporation when the rH 26

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rises In situations of high humi dity, sweating can have essentia lly no net effect other than depleting body weight through moisture loss. The human body has no mechanism for sensing this other than feeling stifled. These cooling mechanisms, however, can impa ir strength and comfort. Increasing blood flow to the shin surface reduces th e volume carrying oxygen to muscles, brain, and other internal organs, which in turn accelerates fatigue and diminishes mental alertness. The loss of water volume through sweating also contribut es to fatigue by increasing blood viscosity, making it more difficult for the heart to pump and reducing the body's capacity for subsequent cooling efficiently (Kan-Rice and Rosenburg, 2005, p. 2). Further, the loss of free water from blood se rum combined with the movement of blood and water into the dermal periphery cause the he art to pump harder and faster to maintain the correct flow rate (Pushing less absolute volume through smaller t ubes requires more effort). Finally, because prolonged sweating depletes no t only heat but also electroly tes that are needed for proper muscle function, it can cause cramping. To maintain comfort and health when working in a hot environment, it is critical for people to repl ace both the water and electrolytes they lose through sweating. If body fl uid is not replenished at the same rate as it is lost, or if replacement lacks electrolytes, the cooling mechanisms lose effectiveness and exposure to heat stress rises efficiently (Kan-Rice and Rosenburg, 2005, p. 2). Furthermore, studies by the FAA suggest that at tem peratures other than optimal ambient temperature, a workers manual dexterity dimi nishes in two ways (Iampietro, 1963). In hotter than optimal conditions, sweating effects the abil ity to grip and perform tasks rapidly. Cramping due to electrolyte loss will also become an impi nging factor when heat loads are allowed to accrue. In the cold, nerve transmission is retarde d, and muscle control diminishes. Shivering will also affect the ability to pe rform fine tasks. According to the FAA study, as the corrected temperature varies farther from optimal, the e ffects worsen at an increasing rate. The more complex the manual actions performed, the more th e effect of temperature variation comes into play (Iampietro, 1963). 27

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Later in the FAA study, mental performance is evaluated. The study shows that at 101.3 F, both speed and accuracy in arithmetic problems deteriorates significantly. Using an indexed effective temperature the authors show that im pairment is significant at an environmental temperature of 89.06 when exposed for only 2 hours (Iampietro, 1963). It must, again, be stressed that participants in FAA studies ar e seminude or lightly clothed and essentially sedentary except for the light effort expended movi ng pegs into patterns or performing arithmetic (the activities performed in the tests). The data directly referenced here are included in Figure 42. Specifically, the arrow pointing to THIS ST UDY shows the mental performance limits, while previous studies investig ated recommended and imminent collapse physiological limits. Figure 4-2. Physiological and Performance Limits in Hot Environments. Modified from Wing. From FAA AM 70-22.. It is obvious that the effect s of tem perature not only act upon overall and immediate health, but also on the ability to perform activities of all types, both manua l and mental. It may safely be assumed that the mental and manual effects can be stacked that is, a cumulative effect may be 28

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seen with a reduction in the ability to perform mental activities a nd a reduction in the ability to perform the concurrent or subsequent manual activit y. When this occurs, the safety of the worker and those around him may be compromised. At the ve ry least, it would seem obvious that, from a productivity standpoint that, delays due to mistak es in the field could presumably be reduced simply by keeping the decision makers cool and co mfortable. From this information it is clear that the biological processes of heat response and adaptation must be carefully managed, not just for the health of workers, but as a matter of safe ty and efficiency as well. Anyone familiar with the manufacturing environment w ill recognize instantly the truth here; the more comfortable your workers are (to a point) the more efficiently they are capable of performing and with fewer mistakes. Drugs Contrary to popular belief the use o f illegal drugs, while ag ainst the law, is a significantly lesser threat to the construction worker than the prescriptions that he or his fellow workers may be taking per physician recommendations. Many ille gal drugs have delete rious effects far too powerful to be ignored by coworkers. The follo wing list briefly presents a few of the most important prescription, over-the-counter, a nd everyday drug groups and their respective generalized clinical reactions See Appendix A for common drug action groups, their chemical names, and the associated brands. -adren ergic receptor blockers and calcium ch annel blockers, used to treat hypertension, limit maximal cardiac output and alter normal vascular distribution of blood flow in response to heat exposure. Diuretics, such as caffeine, can lim it cardiac output and affect heat tolerance and sweating. Phenothiazines and cyclic antidepres sants im pair sweating (NIOSH, 1986). Antihistam ines depress sweating, cause torp or, increase heart rate, and occasionally increase urine retention. 29

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Other Facts The following is a list of additional findi ngs and data pertinent to the discussion. Paul Cox, in his 1998 text entitled Glossary of Mathem atical Mistakes states that while 98.6 F has been the standard for normal body temperature, this temperature was extrapolated from a German study that concl uded that 37 C is normal. What was missed in the interpretation was that 37. has two significant digits, while 98.6 has three. Recent studies have found that the human body is, in fact, normally at a temperature around 36.8 C, which translates to 98.2 F, nearly a ha lf-degree less than previously believed. The implications, given the data presented prev iously, are obvious; m easurement of worker temperature on a scale with 98.6 as the base wi ll incorrectly assume that the worker has heated less than the actual e xperienced temperature rise Commonly cited actors contributin g to a workers ability to cope with thermal stress are the following: Age Weight Degree of physical fitness Degree of acclimatization Metabolism Use of alcohol or drugs, in cluding nicotine and caffeine Medical conditions, such as hypertension and diabetes all affect a persons sensitivity to heat. Prolonged increases in CBT and chronic expos ures to high levels of heat stress are associated w ith disorders such as temporary infertility (male and female), elevated heart rate, sleep disturbance, fatigue, and irritability (ACGIH, 2002). A core body tem perature increase of only 1.8 F above normal encroaches on the brains ability to function (ACGIH, 2001). During the first trim ester of pregnancy, a sustained CBT greater than 102.2 F may endanger the fetus (ACGIH, 2002). One or m ore occurrences of heat-induced il lness in a person predisposes him/her to subsequent injuries and can resu lt in temporary or permanent loss of that persons ability to tolerate heat stress (OSHA, 1999). The level of heat stress at which excessive he a t strain will result is highly individual and depends upon the heat tolerance capabilities of each individual. 30

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CHAPTER 5 THE CURRENT STATE OF THE INDUSTRY Indicators and Selected Definitions There are a number of important definitions u sed within the context of the following discussion, and important to regard as critical knowledge in the construction environment. These definitions are provided here, as has been the format previously, in order to put the discussion in the proper context. Core Body Temperature CBT: Core body temperature as measured with an anal or swallowed thermometer. CBT and skin temperature can and often do vary by up to 3 degrees Fahr enheit (NIOSH, 1986). Heat Stress and Heat Strain NIOSH defines heat stress exposure as th e sum of the heat generated in the body (metabolic heat) plus the heat gained from th e environment (environmental heat) minus the heat lost from the body to the environment, whic h is primarily through evaporation. Many bodily responses to heat stress are desirable and bene ficial because they help regulate internal temperature and, in situations of appropriate repeated exposure, help the body adapt (acclimate) to the work environment. However, at some stage of heat stress, the bodys compensatory measures cannot maintain internal body temperat ure at the level required for normal functioning. As a result, the risk of heat-induced illnesses, di sorders, and accidents s ubstantially increases. Increases in unsafe behavior are also seen as the level of physic al work of the job increases (NIOSH, 1986). NIOSH defines heat strain as the bodys response to heat stress (NIOSH, 1986). Operations involving high air tem p eratures, radiant heat sources, high humidity, direct physical contact with hot objects, and strenuous physical ac tivities have a high pote ntial for inducing heat 31

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strain in employees. Heat strain is highly individual and cannot be predicted based upon environmental heat stress measurements. Phys iological monitoring for heat strain becomes necessary when impermeable clothing is worn, wh en heat stress screening criteria are exceeded, or when data from a detailed analysis (such as the International Standards Organization [ISO] required sweat rate [SRreq]) show s excess heat stress (ACGIH, 2001). Sustained Peak Heart Rate ACGIH Suggests that sustained peak heart rate is the best sign of acute, high-level exposure to heat stress. Decreas es in physical job perform ance have been observed when the average heart rate exceed s 115 bpm over the entire shift. This level is equivalent to working at roughly 35% of maximum aerobic capacity, a le vel sustainable for 8 hours (ACGIH, 2001). WBGT Screening Criteria and Formulae The ACGIH-established Wet Bulb Globe Temp er ature (WBGT) Screening Criteria is the most commonly used method of monitoring for potential heat stress (Spear, 2007). WBGT is determined by a calculation involving only three easily obtained measurements: globe temperature, dry bulb temperature, and natural wet bulb temperatur e. The WBGT is determined by the following equations, depending on if measur ements are taken indo ors (without a solar load) or outdoors (with a solar load) (ACGIH, 2004). Outdoors (w ith solar load): WBGT = 0.7(WT) + 0.2(GT) + 0.1(DT) Indoors (without solar load): W BGT = 0.7(WT) + 0.3(GT) WT = Natural wet bulb tem perature GT = Globe tem perature DT = Air Temperature (dry bulb) Work Pattern Adjustments Resting: S itting quietly, sitting with moderate arm movements, etc. Light: Sitting with m oderate arm and leg movements, standing with light work at machine or bench while using mostly arms using a table saw, standing with light or moderate work at machine or bench and some walking about, etc. 32

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Moderate: Scrubbing in a standing positi on, walking about with moderate lifting or pushing, walking on level at 6 kilometers per hour while carrying a threekilogram weight load, etc. Heavy: Carpenter sawing by hand, s hoveling dry sand, heavy assem bly work on a noncontinuous basis, intermittent heavy lif ting with pushing or pulling, etc. Very heavy: Shoveling wet sand. Clothing Correction: Add to WBGT (The WBGT assumes that th e worker is wearing light clothing) The numbers below match Figure 5-1 and have been converted to Fahrenheit working units for ease of use. Summer work uniform 0 Cloth (woven m aterial) overalls 3.5 Double-cloth overalls 5 Table 5-1. WBGT Screening Crit eria. Adapted from the ACGIH and Converted to Fahrenheit Working Units. (Source: http://www.plantservice s.com /articles/2007/132.html Last Accessed March 1, 2008). WBGT Screening Crite ria (Fahrenheit) Acclimatized Non-Acclimatized Work Demand Level Light Moderate Heavy Very Heavy Light Moderate Heavy Very Heavy Work/Rest Regimen 100% Work 85.1 81.5 77 X 81.5 77 72.5 X 75% Work25% Rest 86.9 83.3 81.5 X 84.2 79.7 76.1 X 50% Work50% Rest 88.7 85.1 83.3 81.5 86 82.4 79.7 77 25% Work75% Rest 90.5 87.8 86 85.1 87.8 84.2 82.4 79.7 Heat Disorders (By increasing order of severi ty and health risk) according to NIOSH: Skin disorders Heat rash Hives Heat syncope (fainting) 33

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Results from blood flow being directed to the skin for cooling, resulting in decreased supply to the brai n. The condition most often strikes workers who stand in place for extended peri ods in hot environments Heat cram ps Caused by sodium -salt depletion due to sw eating; typically occu rs in the muscles employed in strenuous work Heat exhaustion Dehydration Sodium loss Elevated CB T (above 100.4 F) Strikes individuals perform i ng strenuous work in hot c onditions with inadequate water and electrolyte intake Heat strok e (thermal regulatory failure) While heat exhaustion victim s continue to sweat as their bodies struggle to stay cool, heat stroke victims cease to sweat as their bodies fail to maintain an appropriate core temperature Occurs when hard work, hot environm ent, and dehydration overload the bodys capacity to cool its elf Irritability Confusion Nausea Convulsions Unconsciousness Hot dry skin CBT above 106 F Death can result from damage to the brai n, heart, liver, of kidneys (Cohen, 1990). Acclimatization It is a well-established a nd commonly known fac t that the human body will, over time, undergo metabolic changes in response to adve rse or changing environmental or thermal conditions. Upon first exposure to a hot enviro nment, symptoms of distress, discomfort, increased Core Body Temperatures, increased res ting and active heart rates, and nausea and/or headaches may occur. Upon the next exposure, a marked adaptation has begun to occur. Progressively, the body will become more adept at managing electrolyte and free water loss, recovery, and release. Instead of the body allowing heat to build due to convective inefficiency, 34

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sweating begins earlier and is su stained at a higher level. Th is is known as acclimatization (ACGIH, 2001). According to the ACGIH guidelines, acclimatiza tion beg ins with consecutive exposures to working conditions for 2 hours at a time, with a concomitant rise in metabolic rate. This will cause the body to reach 33% of optimum acclim atization by the fourth day of exposure. Cardiovascular stability and surface and internal body temperatures will be lower by day 8 when the body has reached 44% of optimum acclimatization. A decrease in sweat and urine electrolyte concentrations is seen at 65% of optimum (day 10); 93% of optimum is reached by day 18 and 99% by day 21 (ACGIH, 2001). Thus, th e saying, it takes three weeks to form a habit is not so much an old wifes tale as a colloquial expressi on of sound science. As previously stated, the ACGIH guidelines are significantly more stringent than those of OSHA, NIOSH, and the US Military. This difference is caused by the following: At one wee k, the typical time-toacclimatization indicated by the other groups, the worker will be capable of surviving the entire 8-10 hour workday. By the ACGIH criteria, the worker will be capable of effectively and healthfully working the full workday (ACGIH, 2001). Loss of acclimatization begins when the activity under heat stress conditions is discontinued with a noticeable loss occurring af ter four days. This lo ss is usually rapidly recovered, so that by the second consecutive day back on the job, workers who were off on the weekend are as well acclimatized as they were on the preceding Friday. Chronic illness, the use or misuse of pharmacologic agents, a sleep deficit, a suboptimal nutritional state, or a disturbed water and electrolyte balance may reduce wo rkers capacity to acclim atize (ACGIH, 2001). Dehydration When working in hot environments, it is often di f ficult to completely replace lost fluids as the days work proceeds. High sweat rates with excessive loss of body fluids may result in 35

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dehydration and electrolyte imbalances (Saw ka and Neufer, 1993). The following facts are important to bear in mind any time labor and thermal management are discussed. Studies by E kblom et al. have shown that even small water deficits have adverse effects on performance (Ekblom, 1977). Studies by S awka and others suggest that dehydration also negates the advantage granted by high levels of aerobic fitness and heat acclimatization (S awka et al., 1979). Below is a schedule, created as an adaptation of research by Candas et al. (1985) and Adolf EF and Associates (1947 ), showing levels of dehydration and the accompanying clinical effects. Table 5-2. Water Deficit and Accompanying Clini cal Effects. Adapted from Hydration During Exercise: Effects on Thermal and Cardiova scular Adjustments, by Candas et al., (1985). H2O Deficit as % of Body Weight Effects 1% CBT Elevation 0.2 F to 0.4 F (This pattern continues in a linear fashion; for each 1% of body m ass lost, an accompanying 0.2-0.4 F rise is experienced.) 2% Generally accepted as the threshold for thirst stimulation 3% Increase in heart rate, depre ssed sweating sensitivity, and a substantia l decrease in physical work capacity 4-6% Anorexia, impatience, and headache often result 6-10% Vertigo, shortness of breath, cy anosis, and spasticity are experienced 12% Individual will be unable to swallo w and will ne ed assistance with rehydration 15-25% Estimated lethal dehydration level 36

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CHAPTER 6 EXISTING MODELS FOR HEAT MANAGEMENT Military Case Study 1: USAF Instruction 48-1, Dyess AFB As previously discussed, the US Military has a vested interest in the sustained good health of its assets. Since all care for Air Force personnel (as well as the cost thereof) is under the direct contro l of the Air Force, it makes perfect sense th at exacting controls be in place for the careful management of human assets. This assumption does indeed hold true, as each Air Force base has a series of protocols in place for the management of exposure to a large number of natural, environmental, and chemical factors including he at loading of personnel. Among the information contained in the Instruction 48-1 document are basic descriptions symptoms and methods for treatment of heat cramps, heat e xhaustion, and heat stroke. When pe rsonnel arrive at a base, they are highly encouraged to begin an acclimati zation program by beginning moderate physical conditioning outside and gradually increasing the physical activity to a full work schedule. Personnel are cautioned against drinking caffeinated and alcoholic beverages, with the additional advice salt intake should be done by lightly sa lting your meals. (Though it is now established that salt intake from meals-only can hamper performance during long duration activities. This will be discussed shortly.) For the sake of brev ity, a distilled synopsis followed by a flowchart, Figure 6-1, graphically demonstrating the resp onsibilities for monitoring conditions and implementing the 48-1 instruction, will be pr esented below, showing only the pertinent relationships. A. Public health personnel are responsible for training personnel on preven ting and controlling heat-induced illnesses. B. Bioenvironm ental engineering (BEE) personnel ar e responsible for periodically monitoring environmental conditions and measuring the WBGT index when conditions dictate. 37

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C. BEE personnel then forward the measurements to Weather Flight personnel for dissemination, and provide information to group/squadron commanders on the WBGT index and work/rest cycles recommended fo r the current climatic conditions. D. Weather Flight personnel are responsible for disseminating the WBGT index to personnel when the WBGT levels exceed 81F (MOPP level 0), 76 F (MOPP levels 1-2), and 71F (MOPP levels 3-4). E. Group and squadron commanders are responsible for ensuring that all personnel exposed to extrem e environmental conditions are aware of heat stress hazards and prevention methods. Supervisors are to ensure that all personnel assigned to their organization are not exposed to excessive heat, are acclimatized to the loca l conditions, follow the recommended work/rest cycles, and follow the recommended fluid intake schedule of 0.5 liters per hour for category I conditions, to more than 2 liters per hour for category V conditions. (MOPP Categories are similar to the non-military clothing (clo.) units except that clo units are often <1 where MOPP categories are >1.) Figure 6-1. U.S.A.F. Heat Mana gement Dissem ination Hierarc hy. Adapted from NIOSH Dyess AFB Evaluation HETA 2000-0060-2904 (2003). 38

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How and Why the U.S. Military Model Fails The key problem regarding the US Military gui deline s is that they are precisely that; guidelines. As an example, a brief synopsis of a Health Hazard Evaluation Report, number 20000060-2904 (2003) from Dyess Air Force Base in Ab ilene, Texas will now be given. Positioned in one of the hottest areas in the United States, Dyess AFB is the perfect candidate for heat management practices to be tested and proven. Curiously, the data prov ided to the public is in the form of a NIOSH report which clearly states that the heat management practices were examined only as part of a hazardous materials exposure analysis investigating fuel fell maintenance. Buried within the report is a sing le sentence of text st ating that data from only one day of testing were available due to equipment malfunctions. What is made obvious, although in not-soincriminating terms, is that while the recommendations are in place, they are purely discretionary in nature and fully un-policed. Quotes fr om the report document are included below. During the NIOSH evaluation, health hazar ds from environmental conditions and overwork did not exist for fuel cell maintenan ce and other workers. However, five of the six participants who were weighed preand post-shift developed mild dehydration, indicating they were at greater risk for developing heat-related illnesses (NIOSH, 2007, ii). Caveats to Interpretation of the Dyess Study Importantly, the report also makes brief m ention that the workers tested spent approximately 50% of their 8-hour workday di rectly participating in the study (in an airconditioned space). This indica tes the strong possibility that even though the study was conducted with prior notice, allowing for the shoring up of heat management practices, and even though the workers were allowed significantly more break-time than what one might surmise is usual they still s howed an 83% chance of having m ild dehydration. Although overarching conclusions are statistically impossible to make from such a small sample, there exists a high 39

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degree of likelihood that Dyess AFB personnel are regularly exposed to conditions nonconducive to continued good health. The Dyess AFB heat stress instruction specifi es only that the W BGT index be monitored May through October, periodically... when conditions dictate. No other requirements, such as specific work sites, are listed. Th ese measurements may not be sufficient because WBGT data for the immediate work area s hould be available when using NIOSH and ACGIH screening criteria (NIOSH, 2007, 10). Military Case Study 2: USAF In struction 48-1 00 Little Rock AFB In addition to the data gathered at Dyess AFB, one additional Air Force B ase case study will be presented. This is due primarily to two factors. 1. Since the data from the first case study are not statistically significant without corrobora tion, the second case study will either reinforce or negate. 2. CDC/NIOSH studies from military installations are easily obtained and tend to be accurately portrayed, because they are not intended to sell anything. It is worth stating that the two studies were chosen entirely at random a nd with no foreknowledge of the content within. The discussion of the data and findings from LRAFB will be brief, because rehashing the main conceptual bases would be pointlessly redundant. The basis of the two studies was almost pe rfectly analogous: NIOSH wa s called upon to study the effects of jet fuel liquid and vapor on worker health, while at the same time investigating the efficacy of military heat mana gement guidelines. Specifically studied were personnel conducting Fuel Systems Maintenance ( FSM) activities. The H ETA documents used as the basis for the case studies treat only the heat management instructions, with brief, casual mention of the jet fuel exposure part of the study. As mentioned rega rding the Dyess AFB case study, the guidelines are just that; guidelines, and not rules per se. Also of interest, as in the Dyess study, is the fact that although data ar e given on a group of military personnel regarding their health in normal working conditions, th e personnel tested worked no more than 50% of the time that would normally be spent doing th eir respective duties. A ll personnel tested were 40

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fully acclimatized accordi ng to metabolic criteria (VO2 and urine solute) (NIOSH, 2003). The major findings are presented below. Table 6-1 gives insight into why, even under otherwise comfortable conditions, USAF personnel ar e at greater risk of heat stress. The FSM participants were exposed to exce ss heat stress and som e felt tired and dizzy from the heat. Nine of twenty-one FS M participants had hi gh heart rates and/or body temperatures during their shift, which put them at gr eater risk of getting sick from the heat. (Heat strain signs in 43% of subjects) Five of nine FSM participants became at least m ildly dehydrat ed during their shift, and one lost over 1.5% of body weight. Personnel who lo se weight during their shift are more likely to get sick from the heat. (56% lost 1.5% of body mass in water) One of nine participants weighed before a nd af ter work activities was dehydrated (lost enough weight to exceed the ACGIH recomm endation that body weight loss over a shift not exceed 1.5%) (Remembering that this worker only performed 50% or less of a normal workday) Some of those affected did not know they had heat strain and/or dehydration and did not know they were in danger of getting sick from the heat. LRAFB has a heat stress instruction, but it does not teac h employees how to monitor themselves for heat strain (NIOSH, 2003). Table 6-1. USAF WBGT Addition Schedule Adapted from Health Hazard Evaluation Report No. 2000-0065-2899 (2003). Clothing Group *Add to WBGT Ground Crew Ensemble 10 F Firefighting Gear 10 F Restrictive or Impermeable Gear 10 F *Additional Stack for Body Ar mor 5 F Cloth Overalls 3.5 F Double Cloth Overalls 7 F FAA Case Study: Tolerances to Thermal Extremes in Aerospace Activities This investigation, undertaken in late 1970, was conducted by the FAA Civil Aerom edical Institute, under the auspices of the US Department of Trans portation. Though dated, the data and 41

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generalized concepts are widely recognized as th e basis for modern thermal management theory. As opposed to the study conducted at Dyess AFB, th e focus of this particular FAA investigation centers more about space travel. For this reas on, synopses of main points only will be presented. The most important aspect of the FAA study involves the formulation of three basic tolerance typologies with resp ect to therm al management. Th e typologies are: Pain-Limited Tolerance, Heat-Load-Limited Tolerance, and System-Limited Tolerance. A caveat must be stated before any further discussion on the s ubject of these three t ypologies. The 1970 FAA study specifically investigated aerospace conditions. As a result, the three tolerance typologies presented in the study are related specifically to exposure types found in the aerospace environment. A worker in the aerospace environmen t is regularly at risk of exposure to surface temperatures up to 500F, radiation other than in frared, visible, and ultraviolet (i.e. unfiltered gamma rays and X-rays), and is often under life -support conditions. The key point of the study is the division of causality a theme that will be treated in depth in the overall investigation. Findings All test subjects were lightly clothed, to di spens e with Clo. units as a variable in the analysis. Test subjects were also resting or sede ntary. Finally, all of the test subjects were men. Heretofore, information and data presented have suggested that it is only the heat-load capacity of the workers body that ultimately affects the to lerance to thermal conditions that is, when inputs of heat exceed outputs of, or the ability to shed, h eat, the biological system is compromised. This question will be revisited, but for now, the argument will be made that under many normal circumstances, this generalization is not always correct. The format here will be presentation of the FAA findings, followed by a brief retort centered on evaluating the information in the context of the cons truction environment. For reference, 42

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Pain-Limited Tolerance: PLT 212-500 F rH <20 (Low) Mean Tolerance Tim e: <1-15 minutes Figure 6-2. Tolerance Times for PLT Exposure a nd Curve Showing Overlap Between Painand Heat-Storage-Limited Tolerance Exposures. From FAA AM 70-22 (1963). Pain-Limited-Tolerance occurs by exposure of skin to direct radiation of the sun, direct exposure to hot objects, or exposur e to other than solar radia tion (Gamm a-Rays, X-Rays, etc). Pain is the main determiner of tolerance he re, whether caused by high exposure temperature or extremely high heat flux. It is well established th at contact with low-flux objects at 160 F causes 43

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extreme discomfort (Iampietro, 1963). It can easily be assumed that temperat ures slightly higher will cross the pain threshold when sustained for any period. In the construction environment, it can be assumed that except for som e rare cases (previous sunburns, for example) solar radiati on can be ignored. Although in some cases the danger exists (such as in high energy TIG weldi ng), other sources of radiation can effectively be ignored as well. It is, ther efore, solely thermal radiant a nd thermal conductive heat that are critical factors in the construction environmen t. In essence, construction workers must be shielded from hot objects whethe r by protection from direct c ontact with the object, or by shielding to mitigate thermal radiation therefrom. Heat-Loador Heat-Storage -Limited Tolerance: HSLT 130-230 F rH <20 (Low) Mean Tolerance Tim e: 20>140 minutes Heat-Storage-Limited Tolerance is, by far, the most comm only used and commonly understood typology. Whereas Pain Limited Toleran ce exhibits a rapid feedback mechanism the recoiling from an extremely hot surface or area via the induced pain HSLT is more insidious in nature due to the human bodys natu ral tendency to biologically and biochemically damp and adapt to heat loads both internal a nd external. (The human body is incapable of producing temperatures above 113 under normal circumstances, thus no damp/adapt mechanism exists; only the pain-recoil feedback ) (Iampietro et al., 1969). It is this insidious nature that makes heat storage feedback so dangerous to the worker; symptoms accrue gradually and the biological limit can be reached w ith a precipitous drop in ability to cope near the limits. Figure 63 shows the smooth drop-off of mental and physiological capacity. Pu t simply, the true danger to health is the fact that fa ctors of judgment come into play with the HSLT typology. 44

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Figure 6-3. Tolerance Times for HSLT Exposures. From FAA AM 70-22 (1963). For the construction worker, the HSLT t ypology is m ost common and also most dangerous, due to the aforementioned insidious natu re of the associated effects and display of symptoms. This tolerance typology is and has been the major focus of the discussion herein, but cannot be viewed as the singular factor for th ermal management analysis in the construction environment. As the subject has previously been expounded upon, it is worth only noting that control, of heat gain and loss from the human bo dy, should be recognized as the critical factor. Systems-Limited Tolerance: SLT 98-130 F rH 45-70 (High) Mean Tolerance Time: 25>180 minutes 45

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Systems-Limited Tolerance is a seldom resear ched, oft ignored, and data-deficient subject for one primary reason; special environmental cond itions are required and must be maintained to illicit the response (Iampietro et al, 1969). The closed circuit, closed environment of space exploration is highly conducive to th is sort of failure. Thus, a failu re of support serv ices to render an environment conducive to human life will result in a SLT failure. Of primary concern is the removal from or addition to the system of humidity, CO, CO2, O2, and sensible heat. A SLT failure is manifested in three prim ary factors, either singly or in some combination: 1. Excessive heart rate. 2. Extreme Hyperv entilation. 3. Nausea, vomiting, a nd dizziness. Subjects exhibiting SLT do not suffer from other tolerance typologies concurrently; the SLT will manifest before an excessive heat build up, for example. Those who do not respond to the SLT will, however, then incur a HSLT associated with thermal overload. Relative to the construction environment, the Systems-Limited Tolerance concept, with its closed-system analysis would appe ar to not deserve consideration. In som e specialized areas of construction, however, such as asbestos mitigation and abatement, closed-circuit gear is used and must be employed with due care. In such circ umstances, tolerance limits must be known and applied in order to safeguard the health of employees. FAA Study Relevance From the discussion and analysis of the FAA case study, it is obvious that Tolerance lim its are a critical limiting factor in sustained worker health a nd well-being. While Pain-Limited Tolerances are often the most psychologically urgent, they must be recognized as relatively unimportant over the long term, as long as burns are not sustained. Inst ead, it is the insidiousnatured Heat-Storage-Limited Tolerances that are most at play in the construction environment, due to the conditions encountered on a daily basis. This is not to negate the effect of Systems46

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Limited Tolerances, since the closed-loop support systems touched upon in the case study do, in fact, occur regularly in the context of construction. Figure 6-4. Summary Graph of To le rance Times for Three Tolerance Limit Categories and the Conditions Necessary to Elicit the Response. From FAA AM 70-22 (1963). Study Conclusions It is clear from the case studies presented that w hile heat management is absolutely critical in the promotion of long-term health of personne l or workers, and while some strategies and guidelines exist for the purpose of heat manage ment, more must be done. The fact that a case study of any quality or length could not be found from the construction industry speaks volumes to the dire need to develop effective heat management strategies for the construction environment. The FAA study, however, provides insi ght into the limits of physical and mental limits of humans. The results are neatly summar ized in Figures 6-4 and 6-5. The logarithmic 47

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curvature of the approximation curve in Figure 6-5 shows that as equivalent temperature rises, tolerance is reduced at an accelerating rate. Tolerance Duration Versus WD Index Ambient Condity = -41.969Ln(x) + 127.9 6 R2 = 0.9303 0 20 40 60 80 100 120 140 160 98100101102103104105106107108109111115 WD Index Temperatu r Mean Tolerance Time in Minute s Logarithmic Trendline Figure 6-5. Mean Tolerance Time Versus Temp eratu re in Humans. Ad apted from FAA AM 7022 (1963). 48

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CHAPTER 7 OVERVIEW OF CURRENT GUIDELI NES AND ESTABLISHED MODELS Current Guidelines While both agencies operating under the auspices of the OSH act attempt to treat any scenario as best they can, there are certain levels of intentionally drafted grey areas woven into the recommendations and even more so into the legislation-in-place. For example, even though NIOSH defines heat stress exposur e as a hazardous agent, it has no set Prescribed Exposure Limits (PELs), no Short-Term Exposure Limits (STELs), nor prescribed methods for measuring such data in the field. Interesti ngly, the employer is still required to protect their employees from such hazards even when not provided with th e means or know-how to do so (NIOSH, 1986). The following list is a collection of limits and guidelines that have been suggested. It is inadvi sable for CBT to exceed 38 C ( 100.4 F) or for oral temperature to exceed 37.5 C (99.5 F) in prolonged daily exposure to heavy work and/or heat (WHO, 1969). A deep body temperature of 39 C (102.2 F) s hould be considered reason to terminate exposure even when deep body temperature is being monitored (NIOSH, 1986). ACGIH recommends immediate term ination of activities when any of the following scenarios are presented (ACGIH, 2001): Sustained (over several mi nutes) heart ra te is in excess of 180 bpm minus the individuals age in years, (180 bpm age) for those with normal cardiac performance Core body temperature is greater th an 38.0 C (100.4 F) for unselected, unacclimatized personnel and greater than 38.5 C (101.3F) for medically fit, heat-acclimatized personnel; Recovery heart rate at 1 mi nute after a peak work effort exceeds 110 bpm; There are symptoms of sudden and seve re fatigue, nausea, dizziness, or lightheadedness. An individual ma y be at great er risk of heat strain if: Profuse sweating is sust ained over several hours; Weight loss over a shift is great er than 1.5% of body weight; or 24-hour urinary sodium excretion is less than 55 millimoles. 49

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Established Models Now that a suitable industry, theoretical and c linical base has been laid, discussion of the truly important questions can begin, namely the following: a. How are heat effects to b e quantified and measured? b. What can be done to m anage heat effects? c. How are such changes to be instituted ? d. Who should be responsible for m onitoring compliance? To answer these questions, the discussion now turns to the three established public and/or industrial models, as op posed to the military model that has previously been outlined. The CDC Public Model The CDC, as the official health steward of the Am erican public, publis hes a guide entitled Extreme Heat: A Prevention Guide to Promote Your Personal Health and Safety. As the CDC does not directly associate itse lf with industry, the guide is focused upon the average citizen, with facts and figures kept to a minimum. General ideas are pr esented, such as recommendations against sun exposure while on drugs or alcohol, s cary language explaining that heat kills more people than hurricanes, lightning, tornadoes, floods, and earthquakes combined (which is true), and the interesting statement that Air-conditioning is the number one prot ective factor against heat-related illness and death (also quite true). The publication goes on to recommend the use of sunscreens, the drinking of plenty of fluids, and other methods most sensible when work is not involved. Curiously, the publication stresses the identification of heat stroke and methods of treating the condition after medical services ha ve been requested, but fails to mention the possibility of shock that could be caused by the suggested cooling methods (CDC, 2008). For industry, the CDC model is, ultimately, lacking. 50

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The OSHA Public/Industry Model The OSHA model is based upon watered-dow n NIOSH doc uments, with a simple description of the symptoms of heat stress (H eat Stroke, Heat Exhausti on, Heat Cramps, Heat Syncope (Fainting), and Heat Rash) followed by prevention suggestions. While the prevention suggestions are nothing more than vague generalizations regard ing common practices, they are worth reading since they are, w ithout a doubt, the most information most workers have ever been exposed to. The referred document, NIOSH Publication No. 86-112: Working in Hot Environments is available via the Worl d Wide Web at the following address. http://www.osha.gov/SLTC/emergencypreparedness/guides/heat.html. Of course, the document also con tains the following disclaimer, indicati ng that it contains nothi ng really worth paying attention to: This is one of a series of fact sheets highlighting U.S. Department of Labor programs. It is intended as a general descrip tion only and does not ca rry the force of legal opinion. The NIOSH Public/Industry Model To prevent redundancy, the NIOSH model is essen tially the sam e as that of OSHA, all the way down to word-for-word reproductions of documents across the two organizations. It is worth mentioning, however, that NIOSH considers the us e of a mnemonic, SHAFTS in its literature. While such simplistic memory devices are ofte n little more than cheek, the mnemonic neatly summarizes the six key factors of heat management These six factors will appear, in spirit, in the following sections. Sensible (i.e. appropriate) Behavior Hydrated Acclimatized Fit Thin Sober (Avoidance of drugs and alcohol) 51

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CHAPTER 8 RESULTS PART 1: REAL SUGGESTIONS F OR HEAT MANAGEMENT AND WORKER SAFETY The following sections will cover some of the more important, pertinent information regarding heat management facts, theory, and da ta. Much of the material in this section is adapted from the American Conference of Government and Industrial Hygienists (ACGIH) and the US Military. These two sources appear to offer more string ent criteria and limiting factors, along with truly science-based management strategies. Caveats Hyponatremia/Hypernatremia It must be stated that although hydration by concept should onl y be good, there are biochem ical dangers inherent to overzealous hyd ration when high metabolic levels combined with activities involving enduran ce are involved Very much like typical construction jobs. These two sympathetic condi tions must be mentioned for two ve ry important reasons. First, the conditions are easily encountered in high heat, heavy workload acti vities, thus deserving mention by necessity. Second, the relationship between the two conditions becomes biologically complicated when one attempts to correct one or the other without pr oper medical understanding. After defining the terms, this rela tionship will be further explained. Hypernatremia The American Medical Society defines Hype rnatrem ia as an electrolyte disturbance consisting in elevated levels of sodium (also potassium) ion in the blood stream. This condition, contrary to what might initially be assumed, is not the presence of extra sodium in the blood (and the previously increased intake of sodium salt), but rather it is most precisely termed an elevated sodium molality due to a reduction in total free water in the serum volume. (A man would have to consume saltwater of high con centration to artificially cause the condition) The keen reader 52

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will realize that this term sounds like dehydration. Dehydra tion is a collection of symptoms, a syndrome, while hypernatremia is a precise term used to describe increased sodium molality. Without further explanation, the key is that hypernatremia is caused by an inadequate balance of water intake and loss. For a construction work er, profuse sweating while not consuming enough fluids will, undoubtedly, result in hyp ernatremia (Mayo Clinic Staff, 2007). Hyponatremia The American Medical Society defines Hypona trem ia as an electrolyte disturbance consisting in abnormally low concentration of sodium ion in the blood serum. Hyponatremia develops when serum sodium levels drop below 135 milliequivalents per liter (mEq/L) and is a life-threatening condi tion that has been recognized as a potential health consequence of endurance activities conducted in hot environments. Increased wate r intake prior to and during activities in hot environments is highly emphasized to prevent dehydration and heat illness. However, drinking too much water can lead to decreased serum sodium concentrations (water toxicity or hyponatremia), and has been rec ognized as an increasing problem among U.S. military recruits. (Gardner, 2002) The condition is generally caused by hypervolemia (water overload) secondary to extensive over-drinki ng. The majority of those suffering from hyponatremia have increased their total body water by about 1 gallon to achieve such low serum sodium values. (Montain et al., 1999) Most cases of hyponatremia result from an inability of the kidneys to excrete an appropria tely dilute urine. The most significant clinical signs of hyponatremia involve the central nervous system, and symptoms vary from subtle changes in ones ability to think, to decrea ses in energy levels, and finally to severe alterations, such as coma or seizure. The severity of symptoms will generally parallel the rate of development and degree of hyponatremia (Dev ita and Michelis, 1993). 53

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Importance to the Construction Environment A generalized flowchart of sy m ptomatic diagnosis of conditions manifesting hyponatremia is given below, to exemplify the difficult ies associated with treating Hyponatremia. Figure 8-1. Hyponatremia Diagnostic Schedule. (Source: Modified to .Jpg Form at from http://en.wikipedia.org/wiki/Image:Hyponatraemia_Causes.svg Last Accessed April 1, 2008). While hyponatremia is generally associated with fraternity and other hazing activities, the condition has a high propensity for occurrence in the construction environm ent. Contrary to popular belief, the recommendation to drink small quantities of not-t oo-cold water when dehydrated is precisely to avoid hyponatremia not stomach upset The biochemical reaction comes in two classic scenarios. Both scenarios be gin with aerobic exercise of some sort; light to heavy work in the case of a construction worker. Scenario 1. The worker performs light work over a lengthy period of tim e while drinking water at regular intervals. Dehydration begins wi th both the loss of free water and sodium salts 54

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from the blood serum. Due to the loss of both s odium and water through perspiration, the worker is depleting natural his bodys s odium stores. On the long run (perhaps over a few days with inadequate sodium uptake), the worker will beco me sodium deficient to the point of suffering hyponatremia. Scenario 2. The worker is performing heavy to very-heavy labor in high-heat condition. Because of the nature of the work, th e work er sweats profusely, losing both free water and sodium from the blood serum in large quanti ties. Upon becoming aware of the effects of dehydration or hypernatremia, consumes large quantities of water until satiated. Because of the percentage of body weight being replaced by free water in the serum, the workers body is unable to maintain osmotic balan ce that is, the body cannot replace the sodium as rapidly as the free water is absorbed. This leads to a catastroph ic drop in sodium ion molality, and the rapid and dangerous onset of symptoms. This scenario is particularly dangerous because giving large amounts of water is often the natural reaction for anyone not trained in treating the condition. Protective Clothing Clothing inhibits the transfer of heat between the body and the surrounding environm ent. Therefore, in hot jobs where the air temperature is lower than skin temperature, wearing clothing reduces the body's ability to lose heat into the ai r. When air temperatur e is higher than skin temperature, clothing helps to prev ent the transfer of h eat from the air to the body. However, this advantage may be nullified if the clothes interfere with the evaporation of sweat. In dry climates, adequate evaporation of sweat is seldom a problem. In a dry wo rk environment with very high air temperatures, protective clothing could be an advantage to the worker. The proper type of clothing depends on the specific circumstance. Ce rtain work in hot environments may require insulated gloves, insulated suits, reflective clot hing, or infrared reflecting face shields. For extremely hot conditions, thermally conditioned clot hing is available. One such garment carries a 55

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self-contained air conditioner in a backpack, while another is connected to a compressed air source, which feeds cool air into the jacket or coveralls throug h a vortex tube. Another type of garment is a plastic jacket that has pockets that can be filled with dry ice or containers of ice. Heat Waves During unusually hot weather condi tions lasting longer than 2 days, the number of heat illn esses usually increases. This is due to severa l factors, such as progressive body fluid deficit, loss of appetite (and possible salt deficit), build up of heat in living and work areas, and breakdown of air-conditioning equipment when appli cable. Therefore, it is advisable to make a special effort to adhere rigorously to the above preventive measures during these extended hot spells and to avoid any unn ecessary or unusual stressful ac tivity. The following are some recommendations particularly important during heat waves. Sufficient sleep and good nutrition are im portant for maintaining a high level of heat tolerance. Workers who may be at a greater risk of heat illne sses are the obese, the chronically ill, and older individuals. When feasible, the m ost stressful tasks should be performed during the cooler parts of the day (early morning or at night). Double sh ifts and overtime should be avoided whenever possible. Rest periods should be exte nded to alleviate the increas e in the body heat load. The consumption of alcoholic beverages dur ing prolonged periods of heat can cause additional dehydration. Persons taking certain medicati ons (e.g., m edications for blood pr essure control, diuretics, or water pills) should consult their physicians in order to determine if any side effects could occur during excessive heat exposure. Daily fluid intake m ust be sufficient to prev ent significant weight loss during the workday and over the workweek. Acclimatization Acclimatization to the work environment and self-lim itation of heat stress exposure are two important ways to prevent heat-related il lness. Allowing employees to become used to 56

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working in the heat significantly increases their ab ility to do so safely and also decreases their risk of heat-related illnesses and unsafe acts. However, significant loss of heat acclimatization can occur after only 4 days when exposure is di scontinued, and if there is no exposure for a week or so, full acclimatization can require up to 3 weeks of conti nued physical activity under heat stress conditions. A properly de signed and applied heat-acclimatization program is especially important for incoming workers, those on swing shif ts or permanently transferred from nights to days, and those employed in hotter areas than those from which they came. Self-limitation of exposure to the heat is also vital. Allowing personnel to take unscheduled breaks during work in hot weather is an extremely important part of heat strain and illness prevention efforts, and it should be emphasized at every toolbox meeting. Figure 8-2, from the 1980 Business Roundtable investigation of temperature and productivity, is extracted from data from a Pr octer & Gamble project in Green Bay, Wisconsin. Obvious, and also curious in the graph is th e immediate precipitous loss of productivity, followed by a short gain and then a nonstop loss ove r time. This graph is the perfect example of what happens when workers are started in an unacclimatized state and subjected to long workdays. The initial discomfort of the wo rkers bodies slows work. Once acclimatization begins, workers are able to work more efficiently, but this gain is short lived, because of the long hours and, it is argued here, poor management of h eat loading, nutrition, water/electrolyte intake, and other factors. 57

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Figure 8-2.Cumulative Effect of Overtime on Productivity for 50and 60-hour Workweeks. Adapted from Scheduled Overtim e Effects on Construction Projec ts by The Business Roundtable (1980). Measurement and Monitoring All workers should be instructed on monitoring them selves and ot hers for heat strain signs and symptoms. Personal monitoring should be used in addition to environmental and metabolic monitoring, and involves checking th e heart rate, oral temperature, extent of body weight loss, and/or recovery heart rate. Measurements should be taken at appropriate intervals covering a full 2-hour period during the hottest pa rts of the day, and again at the end of the workday to ensure a 58

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return to baseline. Use of any of these techni ques should always includ e the determination of baseline values for deciding whether indivi duals are fit to continue work that day. Institute pre-placem ent and periodic medical examinati ons specifically for persons applying for and working in hot and/or phys ically demanding environments. Because aerobic capacities in the working population va ry greatly, persons being considered for jobs requiring high metabolic demands should be specifically tested. The examination should be performed by a healthcare provider with knowledge of the health effects associated with work in hot and physically strenuous environments. The examinations should be performed to assess the physical, mental, and medical qualifications of the individuals and to exclude those with low heat tolerance and/or physical fitness. The health care provider should also update the infor mation periodically for people working in these environments. Establish a h eat-acclimatization program. On e that is properly designed and applied will dramatically increase the safety of worker s in hot and physically demanding jobs, and will decrease the risk of heat-rel ated illnesses and unsafe acts. Such a program involves having employees work in hot environments for progressively longer periods. NIOSH recommends that workers w ho have had previous experience in jobs where heat levels are high enough to produce heat stress (CBT and heart rate increase but do not exceed recommended levels) should work in th e environment 50% of the shift on day one, 60% on day two, 80% on day three, and 100% on day four. New workers who will be similarly exposed should start with 20% on da y one, with a 20% incr ease in exposure each additional day. Being able to work 100% of the shift does not mean that workers will be fully acclimated after 5 days, but that they can work their entire shift in the work environment in which they were acclimatized. These work ers should not be subjected to maximal physical work output for 21 full days. The bodys acclimatizati on will continue to improve each day in that environment for up to 3 weeks. Monitor environmental heat exposures using a corrected tem perature value, such as WBGT, at or as close as po ssible to the area where the worker is exposed. Corrected temperatures in break areas and other areas the employee may be working that differ in temperature should also be measured and used to calculate total heat expo sure if workers are not individually monitored. 59

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Make, at least hourly, corrected temperature measurements during the hottest part of each shift, during the hottest months of the year a nd when heat waves occur or are predicted to occur. If two sequential measurements exceed the applicable criteria (RAL or REL or ACGIH TLV), then work conditions should be modified until two more sequential corrected temperature measurements are within the exposure limits. Whenever personnel are required to wear ai rand vapor-im permeable protective clothing, monitor the dry bulb or adjusted dry bulb temp eratures, not the corrected temperature, and conduct physiological monitoring. Establish an d maintain accurate records of any heat-related illness events and note the environmental and work conditions at the time of the illness. Such events may include repeated accidents, episodes of heat-related di sorders, or frequent health-related absences. Job-specific clustering of specific events or illnesses should be followed up by industrial hygiene and medical evaluations. Encourage personnel to take unscheduled brea ks if they report feeling weak, nauseated, confused, irritable, and/or excessively fa tigued. These heat strain sym ptoms warrant immediate removal to a cooler location, recumbent rest, and administration of fluids. These and any other signs of overexposure to th e heat should then be reported to the superintendent or project manager for follow-up investigation. Hampered judgment and the inability to think critically, although some of the first symptoms of heat strain, usually go unnoticed by the person inflicted. Ensuring that crewmembers are well hydrated, nourished, prep ared, and not sleep deprived or working too hard are some of the best ways to avoid heat strain, unsafe behavior, and poor job performance. Personnel should drink enough water to stay hyd rated and ideally should not lose any body weight during their shift. Always provide cool (50FF) wate r or any cool liquid (except alcohol and caffeinated beverages) and encourage them to drink small amounts frequently, e.g., one cup every 20 minutes. Dr inking from individual containers improves water intake over the use of drinking fountains. Encourage workers to eat m eals during their brea ks. Minerals and electrolytes lost in sweat are readily replaced with a normal diet Workers should be able to m onitor their weig ht so that they do not become dehydrated during the shift. Provide scales in the break rooms so that wo rkers can monitor their weight during the shift and drink more fl uids if they begin to loose weight. Pre-shift and post-shift weights should be approximately the same. Create a buddy system so that crewmembers can monitor each other for signs of heat illness. A buddy system will help to ensure th at each has had enough water and food and is feeling ok to continue. If a co-worker appears to be disorien ted or confused, or suffers inexplicable irritability, malais e, or flu-like symptoms, the worker should be removed for rest in a cool location with rapidly circul ating air and kept under skilled observation. 60

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Immediate emergency care may be necessary. If sweating stops and the skin becomes hot and dry, immediate emergency care with hospitalization is essential. There is evidence that adding sweeteners to drinks leads to increased consum ption. Glucose-electrolyte solutions ha ve been shown to facilitate sodium and water absorption. The glucose in these solutions has the additional benefit of providing energy for muscular activity in endurance events that require vigorous exercise The temperature of the drink will also influence consumption of fluids. Idea lly, fluids should be ingested at 50FF in small quantities (5 ounces) and at fr equent intervals (every 15 minutes). 61

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CHAPTER 9 RESULTS PART 2: THE BASIS FOR A SCI ENTIFIC MANAGEMENT MODEL However well intentioned, the heat manage m ent models espoused by the two major governmental industry-health organizations are simply not effec tive enough to be of any real worth in this day in time. The now famous mana gement mantra of the early TQM days goes as follows: You cannot manage what you cannot measur e. To this, managers in the construction industry must vehemently reply, of course that is correct. As an industry which is currently making the transition to Parametric Building Information Modeling, the industry can no longer rely upon documents with suggested guidelines to safeguard the health and well being of workers. With the switch from descriptive to performance-based specifications looming, the same rationale can and must be applied to more than construction documents. It is with this in mind, therefore, that the foundations for a new performance-based heat management model are laid out. Quantifiable, scient ific methods must be used. The Model As a beginning foray into a sc ientific m ethod for biological heat, the following formulae can be used regarding homeostasis. 1. Heatbiological + Heatwork + Heatabsorbed-radiative + Heatabsorbed-conductive = Heatconvected + Heatevaporated 2. H2Oconsumed = H2Osweat + H2Obreath + H2Oevacuated 3. Na+ sweat + Na+ evacuated = Na+ consumed + Na+ stored x BRFNa+ 4. Energyexpended-work + Energyexpended-heat = Energyconsumed + Energystored x BRFE Where BRF is the Biological Release Factor, a generic term related to acclimatization, health, metabolic state and use of drugs. BRF is re flects the bodys ability to convert stores into a biologically useful form. 62

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Each formula and its implications will be disc ussed, in order, and with reference to the concepts covered up to this point in the discussion. Formula 1: Heat Heatbiological + Heatwork + Heatabsorbed-radiative + Heatabsorbed-conductive =Heatconvected + Heatevaporated One fact, though not mentioned yet in the analysis, is of great si gnificance regarding overall heat balance; the m ajority of the heat that a construction industry worker will face is generated from his own body. As opposed to worker s in the aerospace indus try as in the FAA study the average construction worker is not pr esented with many extremely hot surfaces, nor will the average worker be confronted with life support systems as his only means to expel moisture and heat. As these are specializes circum stances, we may return to the predication that Heat-Storage-Limited Tolerances are the only tole rance type of conseque nce in the construction industry. Even without the use of different tolerance classes as the FAA study suggests, we must still divide the analysis into part s, as shown in the formula above. Heatbiological is the unavoidable heat generated by th e human metabolic reaction. This is the heat treated as the sedentary baseline in the FAA study. This variable is affected by BMI through the insulative properties of fat tissue. A wo rker with more body fat will not shed heat as easily. His body, therefore, will be forced to work harder to expel the basal energy output. There are no m eans to reduce this variab le except through the improvement of aerobic health and BMI. Heatwork is the heat generated in the performance of manual effort. As effort is expended the body uses up ATP, depleting energy stores and generating waste heat. The waste heat comprises approximately 75% of the total energy used. The body must expel this waste heat as rapidly as possible, as a rise in core body temperature has the previously mentioned effects on biological processes, ability for further effort, and brain function. This variable is one of the most 63

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important factors in the management of heat lo ads and heat storage in workers, as it can be throttled as necessary by the use of effort pacing and work-rest regimens. Ability to th rottle Improved via aerobic health and acclimatization Heatabsorbed-radiative is the gross energy absorbed from heat-producing surroundings in the course of performing work. This vari able is part of a pair of vari ables meant to sum the effects of the atmospheric environment, the sun, and surro unding surfaces. For example, on a cold day, the ambient wet-bulb globe temperature in two locations might be the same. If one location is a parking lot and another is on grass, workers in the grass will be si gnificantly cooler than those in the parking lot due to the heat re-radiated (or not ) from the surface material. The same is true of radiative gain from the sun. Further explanation as to this is unnecessary. This variable can be measured by the use of a blackbody thermometer. Almost fully controllable through active and passive means Use of natural assets such as trees and other buildings Area Shadin g Movable Sh ades Donned heat-shielding fabrics Hard-Hats p rovide effective protection to the scalp. Cost Effective (Shading often pr otects m any workers at once) Heatabsorbed-conductive is the net energy absorbed through cont act with surfaces As a factor, it is almost entirely based upon the heat capacity of the material that is contacted. Insulation from warm, hot, or very cold surfaces is key as regards the construction worker. A keen manager will realize that because this variable is the net of energy lost to or gained from an object, cool objects may be used to the adva ntage of the workers and manage r. Gloves are the most obvious means to protect the worker from conductive heat gain, while insulated pads can protect other parts of the extremities. Almost fully controllable through passive means (insulation) 64

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When properly mitigated, this variable can be negated or selectively used in the negative direction through the use of cool surfaces. Heatconvected Is the quantity of heat, m easured in Met, kJoule, K cal, or BTU given off into the surrounding air column via convection between the skin and the thin layer of air contacting the skin surface. Because the human body is not often hot compared to its surroundings, radiative losses are, for all practical purposes, zero. The hum an bodys first means of ridding itself of heat is through convecti on. This variable is dependant upon T, the difference in absolute temperature between the skin and th e surrounding air, and is mediated by the heat capacities of skin and air. Of prime importance is the movement of air masses; since air has a low heat capacity, large volumes are required fo r a given heat load. At low temperatures, especially combined with rapid air movement, convectiv e heat loss can be gr eat, as indicated by the familiar wind-chill-factor. At high temperatures, however, convective losses are effectively zero and convective gains may begin but are negligible under most circumstances. Air movement is of prime importance, as cooling increases with air speed up to around 30 mph (Parsons, 2003). Cost effective (Air m ovement is often provided by nature, while fans cool many workers at once.) Fans/air m overs need not be permanent; th ey can be use and moved only where workers are located. Convective cooling via CO2 and vortex tubes can be employed under impermeable gear. Heatevaporated is the sum latent heat of evaporation for sweat evaporated from the skin Sweat lost into clothing, towels, or lo st altogether without first evap orating is, in essence, cooling potential lost; it is free water lost from the blood serum and unus ed for the evaporative process. This is why sweating in humid c onditions is so stifling. Free water is lost as sweat, but no latent heat is transferred to vapor because the atmosphere is saturated and sweat simply drips away as salt water. Air movement is not of great im portance except in confin ed spaces, as vapor pressures will equalize rapidly, and water vapor carries large amounts of heat as compared to air. 65

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Still air will be stifli ng, while small amounts of air mass move ment will be quite effective in aiding cooling. Process depends on atm ospheric conditions As air tem perature rises, rate of evap oration rises also (holding rH steady). Efficiency improves greatly with small am ounts of air movement Special fabrics exis t that aid evaporative heat loss by increasing surface area and removing excess moisture from the skin. Excess m oisture, if not removed, can lead to rashes and inability to correctly manipulate objects. Formula 2: Water H2Oconsumed = H2Osweat + H2Obreath + H2Oevacuated Water, the truest elixir of life, is of ab solute im portance to the construction worker. Without water, the metabolic processes of th e human body cannot progress, and the main mode of rejecting waste heat from the body, evaporative heat loss, is negated. H2Oconsumed is the gross quantity of water c onsumed via liquids and foodstuffs. Consumption of water is the only means of obtaining water. By the above equation, water consumed must equal water lost by all other pr ocesses. As previously stated, the feedback mechanism for water deficiency is thirst, and th irst often does not act under working conditions until 1.5 to 2% of body mass is lost and the eff ects of dehydration have already begun. The only way to manage water intake under working conditi ons is do drink on a regular basis without first feeling thirst. This management responsibility must be placed along the entire management chain, up to and including the worker. Water m ust be consumed Thirst is not an ef fective indicator Heart rate in crease may be an indicator of wate r deficit, but evidence to the affirmative is inconclusive. 66

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H2Osweat is the gross volume of water transferred from the blood serum to the sweat glands and should not be confused with the heat lost by evaporation of sweat. The gross volume of sweat-water loss is the 100% potential for cooling, but losses including thermodynamic inefficiencies reduce the realized efficiency. Volum e of sweat is reduced through acclimatization Any tool that increases the efficiency of heat transfer via evaporation or any other heatreje ction pathway will ultimately reduce the volume of water lost to sweat. H2Obreath is the volume of water lost as vapor in the process of breathing. Though this volume is often small, the rate of loss can accelerate in extremely dry climates. Absorptive cloth m asks can aid in moisture retention in dry climates. H2Oevacuated is the volume of water lost to the bodys rejection or evacuatio n of wastes. This variable is critical because it is partially controllable and can be dangerous. Although the body must expel waste products with a certain amount of entrained water or with water as the carrier agent, the absolute volume lost can vary greatly. The use of caffeine, water pills, or other diuretics will purge water from the body at a much higher rate than normal, requiring concomitant replacement at an equally increased rate. Any drugs that modify the dilution of urine must also be regarded with care. Worker s suffering from diarrhea are at great risk of developing dehydration and heat-related illness. Controlled through non-use of drugs Any worker taking diuretics or other kidne y-function altering drugs m ust have an adjustment in workload and water consumption. Workers should be screened for m odified re nal function. Those with deficiencies must make adjustments. Improved through fitnes s and acclimatization Formula 3: Salt Na+ sweat + Na+ evacuated = Na+ consumed + Na+ stored x BRFNa+ 67

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As the primary ion used in the body, sodium sa lts are critical for a variety of metabolic functions. Chief among these is muscle action. Sodium pumping across cell membranes provides the primary means of maintaining osmotic potential in muscle cells. It is estimated that up to 25% of the bodys resting metabolic energy goes to sodium pumping. For the sake of brevity and continuation on topic, sodium deficiency leads to muscle cramping. The degree of symptom manifestation increases as the sodium concentra tion diminishes. The primary loss of sodium is through sweat and urine excretion. Na+ sweat is the amount of sodium lost during stren uous exercise or other situations that cause sweating. At rest, the primary loss of sodi um is through urine, but when working, the primary loss is through sweat. Reducing the heat load and the demand for cooling the body will reduce the amount of sweat produced and, consequently, the salt lost. This variable is difficult to change without m odifying the volu me of water lost to sweating. The best way to im prove salt loss is through improvement of health and acclimatization. As health and acclimatization improve, less salt is lost per unit volume of sweat. Na+ consumed is the quantity, by weight, of salt consumed in food and drink. As salts, by their very nature, are almost always dissolved in water, liquid means of ingesting salt is often the easiest. The concept behind Gatorade and other spor ts drinks is precisely this. The athlete (or worker) will have difficulty eating while engaged in physical activity, thus th e drinking of water, something already necessary during aerobic activit y, with dissolved salts will facilitate rapid uptake and replacement of the needed salt. Furtherm ore, since the loss of water and salt must be matched by the uptake, a metered combinati on during physical activity makes excellent biological and managerial sense. This is not to make a case for any particular brand of sports drink, but the marginal benefit of providing wo rkers with much-needed electrolytes is likely much greater than the cost per unit volume of drink. 68

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Research needs to be made into the margin al benefit curve of electrolyte replacement fluids OSHA and NIOSH recommend th e light salting of food The only m ethod of sodium uptake is via consumption Salt Tablets are NOT recomm ende d, as the uptake at high con centrations is retarded and much of the salt will be passed Electrolyte drinks m ay be an excellent solution Na+ stored is the quantity, by weight, of sodium sa lts stored in the body. Without concurrent sodium uptake, the bodys stores of sodium will gradually diminish until cramping and muscle spasms occur. It is imperative that this variab le remain constant, or nearly so, throughout the workday to prevent the onset of sodium deficiency symptoms. Although the body has certain quantities of sodium stores, they are released gradually, meaning that if a periodic sodium deficiency in the body is reached, the stores in the body will only make up the deficit given enough time. Again, this variable should be maintained at a constant. Research into the non-invasive m easurem ent of sodium concentration should be conducted, such as the total electrical potential across an area of skin. If sodium content in the body can be easily monitored, there will exist the potential for easy monitoring of heat stress. Control through workload throttling is possible depletion of sodium stores is proportional to the workload when no sodium uptake is experienced. BRFNa+ is a factor that relates the relative health and state of acclima tization of a worker. Greater health and acclimatization level will affo rd the body greater control of sodium stores, both in the quantity of stores a nd the efficiency of their use. Improved through conditioning and acclimatization Formula 4: Energy Energyexpended-work + Energyexpended-heat = Energyconsumed + Energystored x BRFE 69

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Over the long run, stores of ATP, ADP, Glucose and Glucagon are the critical limiting factor in the continued ability to perform physical work. This f act is seen more in endurance sports than any other venue, but it holds true fo r construction as well. Ho wever, very seldom in the construction environment are workers under conditions ideal enough for energy stores to be the sole limiter. Instead, energy levels are depleted to a certain point where productivity trails off and the feedback mechanism of fatigue sets in. The facts are clear; hea lthier workers can work longer and harder. Energyexpended-work is the energy output expended in physical activity. According to researchers at UC Berkeley, the average person converts about 25% of the total energy expenditure directly into work, with the balanc e converted into waste heat. The energy expended on work is directly proportional to the amount of work done, thus this variable is throttled via work intensity. Efficiency is increased via accl imatization and overall fitness Energyexpended-heat makes up the other approximately 75% of the total energy expended in physical exercise. This variable, like the energy expended for actual work, is throttled via work intensity and improved via acclima tization and overall fitness. Those with low overall p hysical fitness will produce more waste heat with less effort for any overall energy expenditure. Thos who are fully acclim ated to the envir onment will also produce more waste heat and les effort for any overall energy expenditure. Promotion of good health is of great importance Energyconsumed is the amount of energy that the body is able to absorb from foodstuffs and liquids consumed. This is not to be confused with the total caloric value of food and drink consumed, because the quality of calories will vary grea tly between foods. Thus, this variable is ultimately mediated by the quality of diet For th e sake of conversation here, however, we shall 70

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assume that this variable simply represents the adequate intake of food. In essence, the consumption of enough food is necessary for physic al activity, a fact that all workers can agree upon and that the hunger feedback controls. Enough food-energy m ust be consumed for the daily work Enough food-energy m ust be consumed to replace stores used on a daily basis or a deficit will result, slowing effort and potentially endangering health. Energy can be consum ed in liquid form as sugars and carbohydrates Care m ust be taken to not induce crampi ng by consuming large quantities of food and immediately beginning to work. Food-energy should be consum ed in small qua ntities many times per day, just as water. Measured in calories, kCal, or kJoules Energystored is the quantity of energy that the human body is able to access on a daily basis. This variable depends heavily upon the overall phys ical fitness and level of acclimatization. The generic term stamina is the result of the bodys ability to store and use stored energy. The less the body must use energy stores during physical activity, the less recovery is needed after. Heavily m ediated by overall physical health and level of acclimatization Managem ent of over-effort for many days in succession must occur, as stores will be progressively depleted. As stor ed are depleted, a law of dimi nishing marginal returns sets in; each succeeding quantity of energy is more difficult to obtain. If energy store usage can be held nearly c onstant, worker productivity will also hold stead ier. BRFE is the mediator variable that acts upon the bodys ability to store and subsequently access stored energy when needed. The more ef ficiently the body can access energy stores, the less fatigue will be experienced. Further, the more efficiently the body is able to store energy (or recover stores) the longer a worker will be able to perform labor over an extended period of time. In general, greater health will yield greater ability to use and store energy. 71

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Model Conclusions Each element in the given equations is an area of study all unto itself. Only cursory estim ates of the associated numbers can be given at this time and for only a few of the variables. It is, however, the relationships between the va riables within the equations and between the equations themselves in the meta-sense that are of great importance here. Specifically, if we consider the human worker as a system, to which we feed inputs and from which we receive outputs, modifying part of the ove rall equation [Input = Output] will have effects across some or all of the associated equations. For example, we can assume that the human body has a finite quantity of sodium, water, and en ergy stores. We can also assume that these stores can be accessed at some matrix of rates all with finite maximal values. Finally, from the equations, we realize that energy, ultimately, is converted into work and heat. Conclusions based on the given equations are given below. It should be obvious that the relationship be tween work and heat can be modified through fitness and acclim atization. This re lationship is shown in Figure 9-1. 72

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Tem p erature Rise Versus Time For Full y and Non-Acclimated W 94 95 96 97 98 99 100 101 102 1234567891011121314 Time Non-Acclimated Acclimated Figure 9-1. CBT Rise Over Time for Fullyand Non-Acclimatized W orkers, Showing Dangerous Heat Loading in Non-Acclimatized Workers. Modified from data table. (Source: http://www.universeofsuccess.com/exercise_temperature.html Last accessed Jan 27, 2006). Less obvious, perhaps, is the fact that we can obtain greater quantities of work for every energy input if energy is not wa sted in the processes related to generating or expelling the waste heat. Further, if waste heat is reduced, the input quantities to the system can be reduced. Proper work er acclimatization is of critical importance, as it is a controlling factor in multiple equation variables, across multiple equations, and can be managed fully by the employer with the proper protocols in place. The general physical and cardiov ascular health of construction workers is, likely the m ost important variable of all. Although the employer cannot hope to manage the overall fitness of a worker, the workplace is a strong cont ributory factor. The fo llowing factors may be considered by management: The provision of food and dr ink that is of high quality and designed to m eet the metabolic needs of the workers may prove to have a high marginal benefit relationship to productivity through improving health. 73

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As previously stated, the marginal bene fit of providing worker with fortified fluids containing electrolytes, sugars and other metabolically necessary substances may also prove high. Optimization of work-rest-intensity regime ns via monitoring of employees own bodies can be performed. In the computing age, processing power must be integrated to monitor conditions and provide feedback. Automatic throttling of activity inte nsity or signaling for a rest period may be accomplished via realtime monitoring of heart rate, temperature, sodium stores, or many ot her biological factors. It is known that 180-age is the da nger point for heart rate in BPH It is known that a CBT of 100.4 should not be m aintained for long periods It is known that a CBT of 102.2 is cau se for complete cessation of work The list goes on with m ore factors that ar e known limits or points to begin rest. Much of the information has been provided in earlier sections. Optimization of the human cooling mechanism can be performed. Any aid to cooling is of benefit in two distinct ways: First, the reducti on in cooling load represents additional effort that can be made without adverse effects. Second, The reduction in cooling load is a reduction in the amount of heat the body must work further to rid itself of. Clothing designed to protect the worker from radiant and convective heat gain, while encouraging the efficient and comp lete evaporation of sweat may prove valuable. Many fabrics exist on the market, only needing to be tested for fitness and marginal benefit in the construction industry. One of the newest products, Dryskin Extreme, is one excellent example. Most workers and m anagers do no know how to use clothing to maximum advantage. When skin temperature is lowe r than air temperature, exposure of the skin to the air aids in cooling. When skin temperature is less than air temperature, however, loose clothing that is highly permeable should be used to cover all exposed skin, thus allowing for sweat to evaporate but protecting the skin from convective gains Lastly, com plementary or supplementary augmentation of human systems must be considered. This concept is already in pract ice in construction a nd manufacturing. Often the maxim work smarter, not harder is used to represent the idea of making work easier for humans through technology use. For the construction worker, a short list of im provements types with (examples) is provided below: Wear and tear on the body (protective gloves) Strength (wrenches, power tools, m achines) Stamina (back braces, power tools, ergonomic enhancements) For the m anufacturing worker, a short list of improvements types with (examples) is provided below: 74

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Total effort (assembly line, motion studies) Cooling ability ( air conditioning) Regarding cooling ability, the construction industry has the un ique deficiency m entioned in the introduction; esse ntially all construc tion is conducted outdoors, wi thout the possibility of air conditioning. Heretofore, conductive heat loss es from the worker have been treated only insofar as passive cool objects are concerne d. Technology may yet provide the possibility for other means of using conductive loss to ma nage worker storage and heat load. 75

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CHAPTER 10 CONCLUSIONS AND RECOMMENDATIONS The construction industry is fraught with danger from within and without. The time will soon com e when it is not enough that responsible managers provide fall protection for workers, or can rely upon Business Roundtable charts to prove productivity lost du e to working conditions or schedule compression. Soon, the li ability associated simply with the knowledge that certain working conditions can cause disease, chronic illness or shorten the life of workers may implicate managers and their companies for neglig ence of care for their subordinates. Further, with the knowledge that workers health can be improved, the philosophical and moral cases for the employment of heat management strategies can be made. Manager Obligations The most likely circumstance, however, is that m anagers will realize that they simply must do something proactive about produ ctivity instead of resigning themselves to using 40 year old productivity adjustment charts. Making the ex cuse that heat caused nonproductive time and leaving the matter with no more explanation will no longer suffice. Instead, managers will carefully plan for the heat loads imposed on workers as one more scientific and quantifiable factor to be controlled. The managers will realize that although they manage costs, job progress, and nearly every other aspect of their jobs with sophisticated, quantifiable, scientific data, their workers are managed only through rudimentary guidelines and poorly conceived productivity numbers. A scientific model is needed and the base has been provided here. Significant additional research must be made into the ref ining of the formulas and their constituent parts. It is suggested that the arena of professional spor ts be treated with due attention because much performance data and research ma y be readily available. It is absolutely imperative that any subsequent research inves tigates the cost:benefit ratios of any proposed 76

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solutions, because the construction industry will only be accep ting of solutions that make excellent hard-number business sense. Further, it is suggested that a schedule of constituent factors within the four equations be made, with the practical maximal benefit to be had from optimizing each factor. In this way, further res earch can more easily determine where the most value can be had if research dollars are at stake. We will now return to Table 2-2, from the be ginning of the discuss ion. If we assume that proper and careful management of heat loads on workers can lead to increases in overall productivity and this assumption is not so fa r fetched, given the previous discussion then many of the reasons for low productivity within the construction industry as a whole will either disappear altogether, or be marginalized. Further, if we may go one step further and assume that heat management yields high marginal returns, then the worker as an asset suddenly becomes more valuable, and consequently costs less to employ. High Percentage of Labor Cost begins to fall, making profit margins rise. This in turn lead s to an improvement in Lack of R&D. With the potential for higher margins, more money can be allocated to refining best practices and seeking out new ways to build and potentially new a nd better ways to utilize and manage labor. Perhaps one of the offshoots will be to improve the industry-wide problem of Little Potential for Labor Learning. With more money and a higher va lue placed on workers, education may be the next issue of high marginal return on investment. As the overall health of workers improves, due to the lower heat lo ads placed on them, as well as due to the less stressful working conditi ons themselves, Low Worker Motivation can be expected to improve. More importantly, if mana gement makes a commitment to keeping heat loads within the range that allows for full me ntal concentration, Risk of Worker Accidents 77

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undoubtedly will fall. When the overall EMR of industry firms improves, less money is wasted on insurance and thus even more money is available for research, education, and so on. With the appropriate application of tec hnology, Sm all Average Firm Size will matter less and may actually prove to be an asset, as has been seen in other industries when smaller, more agile firms are able to out compete larger, mo re culture-specific ones. Technology may soon be capable of mitigating the effects of Adverse Weat her and Climatic Seasonality, with the ability to damp temperature variations and keep schedules tighter in sync with actual production. As the Variability of Labor Productivity is better understood a nd m ore effectively managed as it relates to the climate, Interruptions can be more effectively identified and managed as well. Lastly, and admittedly a far fetc hed hope, if labor safety increases, education opportunities improve, and worker motivation rises, Union Work Rules may be reconsidered in areas of the country in which union labor st ill holds sway. Although some of the above assumptions may prove to be wishful thinking, they are all plausibl e and based upon a chain reaction that begins with informed, scientific heat management strategies. Brief Return to Interruptions Continuing to Figure 2-1, if management stra tegies can be employed to keep the worker cooler and h ealthier overall, less break time will be needed throughout the day. This concept applies both to scheduled breaks, unscheduled breaks (which have been shown to be quite important), and work-rest regimens. The keen ma nager will realize the do uble-gain to be had from this concept. Not only is the time taken as a break turned directly into earned-time, but this time period, and the time period directly follo wing it, will be mo re productive overall. Accountability Finally, accountability and monito ring m ust be addressed. It is likely true that if the legal environment in the construction environment becomes tenuous regarding heat management, 78

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firms will adopt ways to self-monitor and properly manage the workers. This is a rather pessimistic view, however and should be viewed as the path of last reso rt. Instead, it should be seen as in the best interest of the construction firm to raise productivity simply for the underlying profit potential. As more and more firms discover that measurement of pe rformance statistics of all productive assets aids in estimating jobs, risk, and profit, then the firms will surely realize that the more is known about worker performance the mo re managers will be able to conform to schedule and budget Supposing that a small number of firms adopt effective heat management strategies and, in turn, become more compe titive due to the increased productivity, reduced insurance costs, reduced turnover, and reduced absenteeism, other firms will be forced to, at the very least, pay attention to why their market share is shrinking. Simple rules instituted by the governing body will m ost likely be re quired to provide an agreed-upon base for measurement and, more im portantly, as the basis for establishment of limits to the permissible heat load on workers. Si gnificantly more research is needed in the area before this will occur, but as worker rights are fleshed out, the call for this research will surely come. Recommendations for Future Research It is clear that there has not been adequate and accurate enough research into the issues of productivity and heat m anagement in the constructi on industry. In fact, the majority of the data available in any context for the analysis of heat management is significantly dated. Therefore, the following recommendations are put forward, using th is investigation as a theoretical basis for continuance. Research into the specific biological proce sses th at affect each of the given formulae and their constituent factors must be made. This is the easiest and also most valuable starting point. 79

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Research should look at ways in which each of the variables might be augmented, minimized, or otherwise modified in order to make workers more healthy, more productive, and safer. Researchers must take into account that cons truction workers are not professional athletes, although the two groups do, in fact, share some co mmon traits, such as performance outdoors. With more knowledge about how the human body can be affected, insight in to which particular variables have the highest inhere nt cost:benefit ratio for research as well as for implementation. It is further suggested here that one excellent ave nue that might be explored is in shortcutting the bodys need to switch from radiant to convective cooling. That is, if th e body does not need to sweat to cool itself, the need for both water a nd electrolyte intake diminishes, as will the necessary breaks. It could also be argued that the f irst stepping stone into further analysis is to investigate the familiar question, where are we now? Specifica lly, the construction industry must be analyzed to glean whir sorts of thermal management st rategies are in place, where they are commonly instituted, and what sorts of companies are on board. In this way, a more refined research may then be made into where do we go now. Surveys and interviews would very likely be the easiest ad most efficient manner in which to obtain such information. 80

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APPENDIX COMMON DRUG FAMILIES, CHEMIC AL NAMES AND B RANDINGS This list is in the following format: Action Group Chemical Name (Common, Non-Generic Brand Name) Beta Blockers: Atenolol (Tenorm in) Metoprolol (Lopressor) Nadolol (Corgard) Propranolol (Inderal) Timolol (Blocadren). Certain other Beta Blockers are also sold in eye drop form for treating Glaucoma. Betaxolol (Betoptic) Cartelol (Ocupress) Timolol (Timoptic). Calcium Channel Blockers: Diltiazem (Cardizem, Dilacor, Tiazac) Amlodipine (Norvasc) Verapam il (Calan, Verelan, Verelan PM, Isoptin, Covera-HS) Nifedipine (Adalat, Ni fedical, and Procardia) Diuretics: Hydrochlorothiazide (Hyd roDiuril, Microzide) Acetazolam ide or (Diamox) furosemide (Lasix) Phenothiazines: Chlorprom azine (Thorazine) Fluphenazine (Duraclon) Mesorid azine (Serentil) Perphenazine (Etrafon and Trilafon) Prochlorperazine (Compazine) Promazine (Robinul and Anectine) Thioridazine (Seroquel) Trifluoperazine (Stelazine) Trifluprom azine (Robinul) Cyclic Antidepressants: Amitriptyline Doxepin Nortrip tyline 81

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Antihistamines: Fexofenadine (Alleg ra) Loratad ine (Claritin) Desloratadine (Clarinex) Diphenhydram ine (Benadryl) Tecastem izole Sepracor (Soltara) Cetirizine (Zyrtec) 82

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LIST OF REFERENCES ACGIH (2001). Heat Stress and Strain: Documentation of T LVs and BEIs, 7th ed ., American Conference of Governmental Indus trial Hygienists, Dayton, Ohio. ACGIH (2002). 2002 TLVs and BEIs: Threshold Limit V a lues for Chemical Substances and Physical Agents & Biological Exposure Indices American Conference of Governmental Industrial Hygienists, Dayton, Ohio. ACGIH (2004). Threshold Limit Values for Chemical Substances and Physical Agents and Biological E xposure Indices, American Conference of Governme ntal Industrial Hygienists, Cincinnati, Ohio. Adolf E.F. and Associates (1947). P hysiology of Man in the Desert, Interscience, New York. Adrian, James J (2004). Construction Productivity: Measurement and Improvement, Stipes, Illinois. Air Force Combat Climatology Center (2003). Climate averages for Dyess AFB, Texas, < https://www.afccc.af.mil/o cds_m il/products.txt > (January 12, 2007). Blockley, W. V. (1963). Heat Storage Rate as a Determ inant of Tolerance Time and Duration of Unimpaired Performance above 1500 F. FED PROG 22:887-890. Blockley, W. V. and Lyman, T. (1950). Studies of Human Toleran ce for Heat III: Mental Performance under Heat Stres s as Indica ted by Addition and Number Checking 'rest, AF 'rech. Rep. No. 6022, U.S. Air Materiel Command, Wright-Patterson AFB, Ohio. Buettner, K. (1950) Effects of Extreme Heat on Man. JAMA 144:732-738. Candas V., Libert J.P., Brandenbe rger G. (1985). Hydration duri ng exercise: Effects on thermal and cardiovascular adjustments. Eur J Appl Physiol, 55:113. Cohen, R. (1990). Injuries due to Physical Hazards. LaDou J, ed Occupational Medicine, Appleton & Lange, East Norwalk, CT. Cox, P. (1998).Glossary of Mathematical Mistakes, http://members.cox.net/math m istakes/glossary1.htm (April 14, 2008). Devita ,M.V., Michelis, M.F. (1993). Perturba tions in sodium balance, hyponatrem ia and hypernatremia. Clinics in Lab Med, 13(1):135. Dewdney, A. K. (1993). 200% of Nothing: An Eye Opening Tour Through the Twists and Turns of Math Abuse and Innumeracy W iley, New York. Ekblom B., Greenleaf J.E., Hermansen L. (1970) Tem perature regulation during exercise dehydration in man. Acta Physiol Scand 79:475. Gardner J.W. (2002). Death by water intoxication. Milita ry Medicine, 167(5):432. 83

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Goldman, R. F., Green E. B., Iampietro P. F. (1965). Tolerance of Hot, Wet Environments by Resting Men. J. Appl. Physiol. 20:271-277. Hardy, J. D. (1964). Physiological Problems in Space Exploration. J. D. Hardy ed. Charles C. Thomas, Springfield, MA, Ch. 1. Iampietro, P. F. (1963). Heat-Induced Tetany. FED PROC p. 884-886. Iampietro, P. F., Chiles W. D., Higgins E. A., and Gibbons H. L. (1969). Com plex Performance During Exposure to High Temperatures. Aerospace Med. 40:1331-1335. Kan-Rice, P., Rosenberg, H. (2005). UC gives tips for coping with heat stress < http://news.ucanr.org/newsstorymain.cfm?story=691 > (February 17, 2007). Mayo Clinic Staff (2007). Diseases and conditions: hyponatremia < http://www.mayoclinic.com/health/hyponatremia/DS00974 > (April 1, 2008). Montain S.J., Latzka W.A., Sawka M.N. ( 1999). Fluid replacem ent recommendations for training in hot weather. Mil Med, 164(7):502. NIOSH (1986). Criteria for a recom mended standar d: occupational exposure to hot environments, rev. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 86-113, Cincinnati, OH. NIOSH (2007). About NIOSH: NIOSH Origins and Mision, < http://www.cdc.gov/niosh/about.html > (March 14, 2007). OSHA (1999). Technical manual, Section III : chapter 4, heat stress, < http://www.oshaslc.gov/d ts/osta/otm/otm_iii/otm_iii_4.html > (November 17, 2007). Parsons, Kenneth C. (2003). Human Thermal Environments: The Effects of Hot, Moderate, and Cold, Taylor and Francis, New York. Rolls B.J., Kim S., Fedoroff I.C. (1990). Effects of drinks sweetened with sucrose or aspartam e on hunger, thirst and food intake in men. Physiol. Behav ,. 48:19. Roetzheim R. (1991). Overhydration. Physician Sports Med, 19:32. Sawka M.N., Knowlton R.G., Critz J.B. (1979). The thermal and circulatory responses to repeated bouts of prolonged running. Med. Sci. Sports, 11:177. Sawka M.N., Neufer P.D. (1993). Interaction of water bioavailabilit y, thermoregulation, and exercise performance, In: Marriott BM, ed, Fluid replacement and heat stress, National Academy Press, Washington DC, p. 85. Szlyk P.C., Sils J.V., Francesconi R.P. (1989). Variability in intake and dehydration in young m en during a simulated desert walk. Aviat Space Environ Med, 60:422. 84

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Spear, Jerome (2007). Heat Stress Management: Assess ment and Control Strategies. < http://www.plantservices.com/articles/2007/132.html > (March 18, 2007). Taylor, C. L. (1946). Human Tolerance for Short Exposures to Heat and Humidity USAF Me mo Report TSEAL 695-56B, Air Materiel Co mmand, Wright-Patterson AFB, Ohio. Taylor, C. L. (1952). Physics and Medicine of the Upper Atmosphere, C. S. White and O. O. Benson, Jr., eds ., University of New Mexico Press, Albuquerque, New Mexico, Ch. 21. Teicholz, Paul (2004). L abor Declines in the Constructi on Industry: Causes and Remedies. Analysis, Research, and Reviews of AEC Technology. < http://www.aecbytes.com/v iewpoint/2004/issu e_4.html> (March 18, 2007). VicConnell, N. J., Houghton F. C., and Yaglou C. P. (1924). Air Motion-High Tem peratures and Humidities: Reaction on Human Beings. ASHVE Trans. 30:167. Webb, P. (1961). Aerospace Medicine, H. G. Ar mstrong, ed., Williams and Wilkins Co., Baltimore, Ch.19. Webb, P. (1963). 'I'emperature, Its Measurement and Cont rol in Science and Industry, (J. D. Hardy, ed.) Reinhold Publishing Corp., New York. WHO (1969). Health factors involved in work ing under conditions of heat stress, Tech nical Report Series No. 412, World Health Organization, Geneva, Switzerland. Wing, J. F. (1965). A Review of the Effects of Hi gh Ambient Temperature on Mental Performance, AMRLTR65-102, Wright-Patterson AFB, Ohio. 85

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BIOGRAPHICAL SKETCH Ian Miller Was born December 2, 1982, in Boca Ra ton, Florida, to Mrs. Marilyn B. and Mr. Bruce K Miller. After moving to Vero Beach for most of elementary and middle schools, Ian attended high school at Sebastian River Hi gh Schools International Baccaleaurate Program in Sebastian, Florida. He received an underg raduate degree in archit ectural design from the School of Design, Construction, and Pl anning at the University of Florida in Gainesville, Florida, in 2006. As an undergraduate, Ian had the opportunity to participate in the Preservation Institute: Nantucket (PI:N) program on Nantucket, MA, as well as the Vicenza Institute of Architecture (VIA) program based out of Vicenza, Italy. Due to graduate with his Master of Science in Building Construction in May, 2008, Ian hopes to gain employment with a construction firm in the South Florida market. 86

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HEAT MANAGEMENT STRATEGIES FOR CONSTRUCTION WORKERS Ian Bruce Miller subsonic@ufl.edu Building Construction R. Raymond Issa M.S.B.C May 2008 The construction industry differs from other econom ic sectors in the fact that little or no control of the climatic conditions on the jobsite is available. The research here seeks to provide both a scientific basis for heat stress management, as well as scientifically-based suggestions for the safeguarding of construction worker health a nd well being, strategies to mitigate the effects of heat stress on worker productivity, and be nefit the construction industry as a whole.