The Measurement of Sound Levels in Construction

Material Information

The Measurement of Sound Levels in Construction
ANDERSON, ERIK WILLIAM ( Author, Primary )
Copyright Date:


Subjects / Keywords:
Acoustic noise ( jstor )
Auditory perception ( jstor )
Ears ( jstor )
Hearing loss ( jstor )
Information retrieval noise ( jstor )
Noise generation ( jstor )
Noise measurement ( jstor )
Noise meters ( jstor )
Noise reduction ( jstor )
Sound ( jstor )

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
Copyright Erik William Anderson. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Embargo Date:
Resource Identifier:
660033964 ( OCLC )


This item is only available as the following downloads:

Full Text




2007 Erik William Anderson 2


ACKNOWLEDGMENTS I would like to convey my appreciation to my committee members, Dr. Jimmie Hinze, Dr. Robert Stroh and Dr. Leon Wetherington for thei r endless patience, support and knowledge. Dr. Hinze provided direction, advice, and suggestions during the entire deve lopment and execution of this research. Dr. Stroh provided guidance throughout the process of data collection and analysis. Dr. Wetherington provide d constant support and advice. I also was fortunate to have Dr. Gary Peigelbeck, a distinguished audiolog ist, provide interest, insight, knowledge and patience from start to finish. In addition, I would like to thank Dottie Be aupied for her tireless administrative assistance and positive attitude. I would like to thank my parents, brothers, sisters and fiance for their continuous support throughout this entire process of this research and my entire education. 3


TABLE OF CONTENTS page ACKNOWLEDGMENTS...............................................................................................................3 LIST OF TABLES................................................................................................................. ..........6 LIST OF FIGURES.........................................................................................................................7 ABSTRACT.....................................................................................................................................8 CHAPTER 1 INTRODUCTION............................................................................................................... .......9 Noise on Construction Sites.................................................................................................... ..9 Properties of Sound...................................................................................................................9 Hearing Protection..................................................................................................................11 Research Objectives............................................................................................................ ....12 2 LITERATURE REVIEW.........................................................................................................13 Noise Levels in Construction..................................................................................................1 3 Hearing Loss in Construction.................................................................................................15 Hearing Conservation........................................................................................................... ..21 3 METHODOLOGY...................................................................................................................31 Introduction................................................................................................................... ..........31 Basis for Research............................................................................................................. .....31 Data Source.............................................................................................................................31 Data Collection Procedure......................................................................................................31 4 RESULTS.................................................................................................................... .............33 Introduction................................................................................................................... ..........33 Noise Levels of Indoor Activities...........................................................................................34 Noise Levels of Outdoor Activities........................................................................................37 Summary.................................................................................................................................44 5 CONCLUSION.........................................................................................................................57 6 RECOMMENDATIONS..........................................................................................................59 The Construction Industry......................................................................................................59 Further Study..........................................................................................................................60 APPENDIX NOISE LEVEL COLLECTION SHEET................................................................61 4


LIST OF REFERENCES...............................................................................................................62 BIOGRAPHICAL SKETCH.........................................................................................................65 5


LIST OF TABLES Table page 2-1 Sound Levels of Comm on Construction Hand Tools............................................................26 2-2 Sound Levels of Comm on Construction Equipment.............................................................27 2-3 Sound Levels of Various Construction Equipment...............................................................28 2-4 Sound Levels of Different Trades in an Eight-Hour Shift.....................................................29 2-5 OSHA Permissible Noise Exposure Limits...........................................................................30 4-1 Noise Levels of Co mmon Construction Activities................................................................47 6


LIST OF FIGURES Figure page 4-1 Noise Levels for Indoor Construction Activities...................................................................48 4-2 Indoor Noise Levels of a Concrete Chipping Hammer.........................................................49 4-3 Indoor Noise Levels of an Electric Grinder on HM Door Frame..........................................50 4-4 Indoor Noise Levels of an Elect ric Grinder on a Concrete Block Wall................................51 4-5 Outdoor Activity Noise Leve ls on Compacted Limerock Ground........................................52 4-6 Noise Levels of Ou tdoor Activities on Grass........................................................................53 4-7 Noise Levels of Outdoor Activities on Concrete Floor.........................................................54 4-8 Noise Levels of Handheld Equipment Outdoors on Dirt Ground.......................................55 4-9 Noise Levels of Heavy M achinery Outdoors on Dirt Ground............................................56 7


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 THE MEASUREMENT OF SOU ND LEVELS IN CONSTRUCTION By Erik William Anderson May 2007 Chair: Jimmie Hinze Cochair: Robert Stroh Major: Building Construction As sound levels become elevated and undesirable, they are typically referred to as noise. The construction industry has many sources of noise. For years, workers have been exposed to these elevated levels and have experienced no ise-induced hearing loss. Usually the hearing impairment in workers is due to prolonged e xposure to hazardous noise levels in conjunction with neglecting to use hearing protection devices. Research has shown that pieces of equipment commonly used in construction produce noise levels that are considered hazardous. My research measured the noise levels on construction site s during common activities and analyzes how the levels diminish with distance. The results s how that many common construction activities are performed at noise levels that will result in hearing loss if hear ing conservation efforts are not implemented. 8


CHAPTER 1 INTRODUCTION Noise on Construction Sites The National Institute for Occupational Safety and Health (NIOSH) estimates that approximately 30 million workers are exposed to hazardous noise on the job. There are many different sound levels that workers are exposed to through the various phases of construction projects. When these sound levels become elev ated for an extended duration, they can cause permanent hearing damage. As sound levels become elevated and undesirable, they are typically referred to as noise. When adequate protection and proper traini ng is not implemented, noise can do significant damage to the human ear resulting in hearing loss. According to the Occupational Safety and Hea lth Administration (OS HA), noise is one of the most common health hazards in the construction industry. This hazard has also been difficult to evaluate and predict because it is often ignored until the damage is done and a person’s hearing is severely impaired or completely lost. The ideal way to prevent the adverse effects of noise exposure is to use engine ering modifications to the nois e source or to the surrounding environment to reduce noise levels. In construc tion, when activities that produce high levels of noise cannot be altered to acceptable lower noise levels, personal hearing protection must be used. Hearing protection such as ear muffs or plugs should be used by all workers during activities that produce noise levels that may damage their hearing. Properties of Sound Sound is generated when a disturbance of the air is created, which sets up a series of pressure waves fluctuating above and below the air's normal atmospheric pressure, much as a stone that falls in water genera tes growing ripples on the surface. However, unlike water, these pressure waves propagate in all directions from the source of the sound. The human ear detects 9


two measures of these pressure waves, the p eak, or amplitude, and the frequency. The human ear senses these pressure fluctuations and converts them to el ectrical impulses, and transmits them to the brain where th ey are interpreted as sound. Air pressure is usually measured in units of Pascals (Pa). Atmospheric pressure is about 100 kilopascals (kPa). Sound pressure is a measure of the fluctuation of the air pressure above and below normal atmospheric pressure as the so und waves are intercepted by the ear. As these fluctuations become larger, the sound becomes loude r or intensifies. The pressure variations in an individual sound wave are much less than the static atmospheric pressure. The faintest sound which the human ear can detect is known as the threshold of hearing. It is generally accepted that the threshold of heari ng is assumed to correspond to pressure fluctuations of 20 microPascals, but this can vary considerably betw een individuals. The threshold of pain in the ear corresponds to pressure fluctuations of a bout 200 Pa. This second value is ten million times the first. Since the range of intensities which the human ear can detect is so great, the scale which is frequently used by physicists to measure intensity is a scal e based on multiples of 10, commonly referred to as a logarithmic scale. This means that as decibel intensity increases by units of 10, each increase is 10 times the lower figur e. Thus, 20 decibels is 10 times the intensity of 10 decibels, and 30 decibels is 100 times as intense as 10 decibels. The scale for measuring sound intensity is known as the decibel scale with each unit being expressed as a number followed by dB. While the intensity of a sound is a precise quantity which can be measured with sensitive instrumentation, the loudness of a sound is more of a subjective response which will fluctuate with a number of factors. Two similar or equa l sounds will not be perceived to have the same loudness to all individuals. Along with hearing impairment from exposure to elevated noise 10


levels, age is also a factor which affects the human ear's response to sound. Furthermore, two sounds with the same intensity but different frequencies will not be perceived to have the same loudness. Because of the human ear's tendency to amplify sounds having frequencies in the range from 1000 Hz to 5000 Hz, sounds with these intensities seem louder to the human ear. Despite the distinction between intensity and loudne ss, it is safe to state that the more intense sounds will be perceived to be the loudest sounds. Sound is known as isotropic which means that it emits radiation equally in all directions. Because of this, the sound level is dependent upo n the distance from the source. As a sound is emitted, it outputs a total power continuously which spreads out passing through the sphere around the source. The equation that relates the power, intensity, a nd distance reveals that if the distance is doubled, then the sound pressure is reduced by a factor of two, and the intensity is reduced by a factor of four. This results in re ducing the sound level by si x decibels. Because the equation is logarithmic, based on factors of 10, if the distance from the source is increased by a factor of 10, the sound level is reduced by 20 dB. Hearing Protection It has been demonstrated that exposure to noise levels at 85 decibels or above for eight or more hours a day is hazardous (Seidman, 1999). It is important to use hearing protection when elevated sound levels are presen t. Hearing protection devices reduce the intensity of sound that reaches the eardrum. Hearing protection device s are available in two forms: earplugs and earmuffs. Earplugs are small inserts that are pl aced into the outer ear canal. They must be snugly sealed so the full circumference of the ear canal is blocked. An improperly fitted, dirty or worn-out plug may not seal and can irritate the ear canal. Earpl ugs are offered in a range of shapes and sizes to fit indivi dual ear canals and can be custom made. For people who have difficulty keeping them in their ears, they can be fitted to a headband. Earmuffs fit over the 11


entire outer ear to form an air seal so the enti re circumference of the ear canal is blocked, and they are held in place by an adjustable ba nd. Earmuffs may have difficulty sealing around eyeglasses or long hair, and the adjustable headba nd tension must be sufficient to hold earmuffs firmly around the ear. These two methods of hearing protection are rendered useless unless used properly. When hearing protectors are properly posi tioned, the user will hear thei r own voice as being louder and deeper. Correctly fitted earplugs or muffs usually reduce noise levels by 15 to 30 dB. The better earplugs and muffs are approximately equal in sound reductions, although earplugs are better for low frequency noise and earmuffs for high frequency noise. Simu ltaneous use of earplugs and muffs usually adds 10 to 15dB of additional protec tion than either used alone. Studies suggest that this combined use should be considered when noise levels exceed 105 dB. Research Objectives To determine where noise can create hearing damage, it is important to understand which construction activities produce thes e elevated sound levels. In addition, it is important to understand the basic principles of sound, what sound levels are considered hazardous, and the various hearing protection options that are available to prevent hearing loss. In my study, the objectives are to measure the noise levels associ ated with different construction activities and phases as well as to determine how these levels diminish with distance under various conditions. 12


CHAPTER 2 LITERATURE REVIEW Noise Levels in Construction The construction of facilities is by no means a quiet process. The activities that take place on construction sites frequently re quire the use of heavy machiner y and other noisy equipment. In addition, the intensity of the sound levels in crease when there are several sources producing noise simultaneously. There have been several studies that have examined the different noise levels generated by different pow er tools and equipment that ar e commonly used on construction sites. One recent study conducted at the University of Florida found that sound from common power tools such as a belt sande r, router, circular saw, and reciprocating saw ranged between 97 and 108 decibels. The study was conducted using these tools in an indoor environment and reading the sound levels at a dist ance of 0.6 meters from the tool, approximately the distance that represents the sound level expe rienced by the tool operator. The study also provided the cumulative effect of having two sources of sound. From the information provided by the study, “it is apparent that the cumula tive effect of having two sound sources with the same sound level will result in an elevation of the sound level by th ree decibels”(Hinze, 2006). Table 2-1 displays the results from a similar study that was conducte d in New Zealand. The table provides both an average sound level range as well as the peak levels for each tool tested. For this table as well as the other subsequent tables, the distance from which the readings were collected is not reported, however it is probably a small distance to represent the noise levels that would be present for the operator. When the tools shown are used inside or in enclosed situations the operator will be exposed to the higher end of the ra nge while when used outside in the open, the exposure will be at the lower end. In addition, the table provides the allowable exposure times based on the upper 13


part of the range. Similar to the United States , New Zealand has an exposure standard for peak noise at 140 decibels. The article states that “a peak level of 140 dB compresses the same amount of sound energy as 85dBA over 8 hours into 0.09 seconds” (OSH, 2002). The Center to Protect Workers’ Rights (CPWR) issued a hazard alert on construction noise about the damage that can result from exposure to noise and provided a basis for estimating the noise levels of common heavy e quipment and tools found on construction sites (Table 2-2). The alert provides several of the OSHA regulations in regards to noise levels and emphasizes that these regulations are only minimums. The alert states that “when the noise is 95 decibels, OSHA says you may work with no hearing protection for onl y 4 hours. Even so, this noise level is not safe; 1 in 5 people exposed regularly to 90 deci bels (as OSHA allows) will lose some hearing. Short, very loud (impact) noises can do th e most harm” (CPWR, 2003). The center recommended five things for workers in orde r to protect them from construction noise. Making the workplace quieter by purchasing and using equipment that has new mufflers and is well maintained. Using plywood or plastic sheeting around noisy equipment and machinery to shield the worker from the noise. Workers reduce the time they spend around loud noises by asking employers to move around from noisy jobs to qui eter jobs if possible. Workers to wear protective equipment along with having their hearing checked annually. Employers conducting a site audit to measure th e noise levels on site to identify the areas that pose the greatest risk of causing hearing damage (CPWR, 2003). The Construction Safety Asso ciation of Ontario provided a similar table in their Construction Health and Safety Manual that consists of common construction equipment and their respective noise levels (see Table 2-3). Fo r this list they recomm ended hearing protection for the common limit of 85 decibels and double protection (use of ear plugs and muffs 14


simultaneously) for levels above 105 decibels. The table shows a few tools or pieces of equipment and their respective average noise levels , some of which were not included in the lists of other noise sources (Sahai, 2006). In addition to the studies conducted related to the noise levels of tools and equipment, there have also been studies of noi se levels associated with differe nt trades. Several studies have been conducted by the University of Washington to record the av erage noise level exposure for different types of trades for a t ypical eight-hour work day. The tr ades that were represented in that study are shown in Table 2-4 along with the corresponding average noise level during a typical eight-hour shift. From the study, the university’s Department of Occupational and Environmental Health Sciences published trad e specific pamphlets for distribution. The pamphlets also included information on what por tion of each trades shift was found to be above or below the safe noise level of 85 decibels. For example, although bricklayers were found to have an average exposure of 83 decibels across a full work shift, the research also found that more than one-quarter of the work shifts were above 85 decibels and almost two-thirds of the work shifts had short periods of sound levels above 115 decibels. In addition, each pamphlet provides information on the common noise source s for that specific trade as well as general information for all trades on hearing conservatio n and the various options available for hearing protection. The trades that were associated with the highest e xposure levels were those that involved the use of pneumatically operated tools and heavy equipment. The pamphlets emphasize that prolonged exposure to noise levels above the 85 decibels, as well as short-term exposure to levels above 95 decibels, can be hazardous (Seixas & Neitzel, 2003). Hearing Loss in Construction With the elevated noise levels being so pr evalent in the constr uction industry and the common lack of hearing protection use, hearing impairment has become a common hazard in the 15


industry. The National Institute for Occupational H ealth and Safety predicts that approximately 30 million United States construction workers are exposed to hazardous noise and over 10 million will damage their hearing as a result. Da mage to hearing in the construction industry is commonly referred to as noise-induced hearing loss (NIHL). “Noise-i nduced hearing loss (NIHL) is defined as loss of hearing seconda ry to over-stimulation by sound energy” (Seidman, 1999). “According to OSHA, occupationally in duced hearing loss is one of the leading occupational illnesses in the U.S. Chronic NIHL is a permanent sensorineural condition and cannot be treated medically” (Dunn, 2001). Workers th at are exposed to elevated noise levels do not realize that noise does more than compromise hearing. “In addition to its effects on hearing, noise interferes with understanding speech, causes stress, interferes with sleep, lowers morale, reduces efficiency, causes annoyance, interferes with concentration and causes fatigue” (Dunn, 2001). Noise can also cause tinnitu s, a constant ringing sound in the ear, as well as increased blood pressure and stress that may l ead to heart disease (CPWR, 2003). There have been a number of studies on NIHL in the construction industry. Several of these studies were conducted to find the various sources of elevated noise levels and the consequences associated with prolonged noise ex posure. Others were conducted to see if the workers were aware of the problem. Each year Porter/Novelli, Inc. conducts a surv ey known as Healthstyles to determine the view of different health-related beliefs, attitudes, and behaviors of American adults. The survey usually includes various issues that the organization feels need to be improved upon or made aware to workers in the cons truction industry. In the 1998 su rvey, NIOSH included several questions concerning noise induced hearing loss. The results of the survey were weighted to compensate for the response rate of 74 percent. “T he preliminary data reveal ed that adults in the 16


United States know that hearing lo ss is a problem and they appear to understand the implications of hearing loss” (NIOSH, 1998). Close to half of the adul ts felt that they had suffered some sort of hearing loss and knew that hearing loss is not ju st a part of growing ol d. Also, over 75 percent of the adults felt that hearing loss can in terfere in a person’s so cial life and personal relationships. Unfortunately, one third of the adults surveyed were not aware of the common household noise sources that may be hazardous, such as lawn mowers, hair dryers, and vacuum cleaners. In addition, over one third of the adults were not regul arly screened for hearing loss and over half felt that they did not have conveni ent access to a hearing test. Surprisingly, only 51 percent of those workers in i ndustrial or noisy occupations be lieved that hearing tests were readily accessible to them (N IOSH, 1998). It was concluded that the overall awareness and education of most aspects of hearing induced hear ing loss in American adults is mediocre and has much need room for improvement. “NIHL is the leading cause of occupationally induced hearing loss in industrialized countries” (Seidman, 1999). Noise that reaches an elevated level of 85 decibels for an extended period of time may cause a person to experien ce a temporary or permanent shift in that individual’s temporary threshol d. A temporary threshold shift (TTS) is a momentary reduction in hearing that typically occurs after a person is exposed to a shor t period of loud noise such as a jet engine or loud music. One may experience a te mporary ring in the ears, but there is usually a full recovery within a few hours. In contra st, a permanent threshold shift (PTS) is an irrecoverable impairment in hearing and occu rs after a longer and higher intensity sound exposure. It is generally accepted that the more intense and greater duration of noise exposure, the greater the hearing loss (Seidman, 1999). 17


After hearing impairment among workers had escalated, the federal government attempted to protect the American public from occupati onally induced hearing loss. “In 1936, the WalshHealy Public Contracts Act was the first regu lation instituted to oversee workplace noise exposure, although it was impeded by a general la ck of enforcement” (Siedman, 1999). Thirtyfour years later, the creation of the Occupational Safety and Health Administration (OSHA) included a mandate for it to observe and cont rol workplace noise exposure. The current guidelines mandated by OHSA to help regulate exposing workers to extended durations of unsafe noise levels are shown in Table 2-5. OSHA’s permissible noise level is 90 dB for eight hours a day. This has been a controversial issue since the 1970s when the guidelines were drafted. This level is five decibels greater than what is advocated by the U.S. E nvironmental Protection Agency (EPA). Most professionals believe that the EPA level is more accurate due to studies that have shown that “sounds of 85 dB or higher cause definite microsc opic changes to the structures of the inner ear in addition to altering blood flow and, ultimately, reducing oxygen delivery to the cochlea” (Seidman, 1999). In addition to the discrepancy between OSHA and the EPA, these laws have been extremely difficult to enforce. “The number of on-the-job (O SHA) inspections has decreased in the past 10 years, and the average fine for a noise level violation was merely $18” (Seidman, 1999). Also, the EPA eliminated thei r Office of Noise Abatement and Control in 1982. The overall degree of damage resulting from NI HL can be determined in several different ways. The primary diagnostic method used is audiometric testing. This is a hearing test that is performed in a soundproof booth in conjunction with testing a person’s speech discrimination and tympanometry. Tympanometry is a test used to detect disorders of the middle ear. Air 18


pressure in the ear canal is varied to test the condition and mobili ty of the ear drum. Asymmetric hearing impairment requires futh er testing with a brainstem aud itory evoked response (BAER) or radiological imaging such as a high resolution CAT scan of the innner ear and internal auditory canal or an MRI. Typically, noise exposure cau ses hearing damage in the higher frequencies (3000-6000 Hz) and one observes he aring loss at 4000 Hz with im provement in hearing at 8000 Hz. However, with age, this improvement at 8000 Hz may be hindered, which causes some difficulties in determining whether the hearing loss was from noise exposure rather than aging or other causes (Seidman, 1999). The frequency of NIHL in construction is comm only related to particul ar trades. The most common trades that experience hearing loss are those which are exposed to the highest noise levels along with those workers experiencing pr olonged exposure at these levels. One study was conducted using 133 construction workers from four construction trad es: carpentry, labor, ironwork, and equipment operation. The carpent ers and laborers accounted for 36.1% and 33.4% of the sample obtained for the study, while ironworkers and operating engineers accounted for 16.3% and 14.2%, respectively. The data were collected using a data logging noise dosimeter. The dosimeter provides a time weighted average (TWA) of noise levels for a worker’s eight-hour shift and can be used in plac e of a sound level meter. The workers from the different trades performed 39 unique tasks and us ed 32 different tools. The study showed that heavy equipment and pneumatically driven tools contributed greatly to elevated noise levels. Furthermore, it suggested that workers in all four examined trades can be exposed at levels that exceed the allowable limits on any site duri ng any stage of construction. However, no significant differences were found between the mean exposure levels for the four trades which showed that a worker’s environment is not an effective predictor of th e risk of exposure to 19


elevated noise levels. The study suggested that overexposures to elevated noise levels are most common during the structural stage of constructio n, at sites using multiple concrete construction techniques and where heavy equi pment operation and pneumatic tool use occurs. “Therefore, focusing attention on these areas may result in exposure reductions, with a commensurate reduction of NIHL in construction workers and in the associated costs” (Neitzel, Seixas, Camp, & Yost, 1999). There have been several noise-r elated studies conducted in c ountries other than the United States. One particular study took place in Siva s, Turkey. Sivas is a growing providence of Turkey and is known for their exquisite handmade carpets. The research consisted of a survey administered to the workers along with noise level readings collected in various popular industrial environments. The noise level readings were taken at concre te traverses, cement plants, iron and steel mills, and textile factories that were lo cated in this region. They determined that the highest noise levels were produced in the cement and concrete traverse factories with readings at 106 dBA and 107 dBA, respectively. The survey was completed by a total of 256 workers representing all of the four industries. The study generated the following findings related to elevated noise levels in the workers’ workplaces: 73.8% of the workers in these industrie s were disturbed by workplace noise 69.0% of the workers experienced problem s of nervousness caused by the noise 30.9% of the workers have ailments as ringing in the ears and hearing loss 85.9% of the workers do not take periodic hearing test Only 32.9% of workers used proper hearing protection From these results the study concluded that th e industries in Sivas have a problem with noise. In addition, the workers in Sivas need to be better educated a bout the possible damage that is caused by exposure to elevated noise levels (Atmaca, Peker, & Altin, 2005). 20


An interesting noise study was conducted in Ku wait. Because of its fast infrastructural growth rate over the last 20-30 years, this coun try in the Persian Gulf Region was selected by researchers to gather informati on pertaining to noise pollution. Research was conducted during a time of increased development in Kuwait to determine the workers’ perceptions and awareness of noise pollution on construction sites. The data consisted of a randomly selected sample of 26 construction projects that were observed for noi se pollution levels. In addition, more than 500 workers at the selected sites were surveyed for their acuity and awarene ss of construction noise. Although the measured noise levels were often si gnificantly above standard outdoor noise levels for most of the monitoring periods, a large percen tage of the surveyed workers realized noise was a nuisance, but were not cons cious of possible negative impacts. The majority of the neglect in the severity of the problem with elevated noise exposure came from laborers and workers with minimal education. It was also documented that for the entire 10 month duration of the study, no worker was equipped with a he aring protection device. The study also found that the noise levels increased as the size of the project increased. The overall mean noise level for the sites that were measured was nearly 80 dBA, with the highest 10 percentile at 85 dBA and impulsive noise frequently exceeding 100 dBA. Most of the workers surveyed perceived noise as a problem, yet very few believed that noise adversel y affected their productiv ity at work and could lead to accidents (Koushki, Kartam, & Al-Mutairi, 2004). Hearing Conservation In construction, workers often are not aware that the elevated noise le vels that they are being exposed to can indeed cause them harm. Their minimal amount of awareness stems from improper training and inadequate methods of h earing protection. First, workers must be conscious of the damage that elevated noise levels can do to their heari ng. Also, they must be aware of which noise levels are considered da ngerous. Once they know that noise exposure 21


causes hearing loss, they must be properly trai ned to use hearing protection and know to avoid prolonged exposure at elevated no ise levels. There have been several approaches to hearing conservation programs that have been used in th e industry. The key to reducing cases of NIHL is to use hearing conservation programs effec tively in conjunction with over-emphasis and education on using hearing protection. “The leading protectiv e strategy for NIHL is avoidance of damaging the acoustic stimuli” (Seidman, 1999). The ideal way to prevent this from occurring is avoidance. In construction, avoidance is commonly not viable and therefore it is imperative to reduce the amount of elevated noise levels that reach the sensitive portions of the ear. This prevention requires the use of either a mechanical device to muffle the noise levels produced by equipment, or to equip workers with hearing protection. The use of earplugs can provide between 10 and 22 decibels of sound attenuation, yet earmuffs can provide protection between 20 and 55 decibels. When both are used simultaneously, the effect is additive but workers commonly will lose the ability to hear their colleagues which may lead to ev en larger problems (Seidman, 1999). To determine areas of constr uction that often produce elevated noise levels, some employers conduct noise audits on th eir sites with the us e of a dosimeter or sound level meter. Each device will determine where noise levels ar e hazardous; however they each have different units of measure, each with their individual adva ntages and disadvantages. Dosimeters A dosimeter provides a time weighted aver age (TWA) or daily dose while a sound level meter provides instantaneous and peak noise levels. The dosimeter is small enough for workers to wear and usually is capable of storing noise levels throughout an extended period of time. Some models may also have mechanisms to aler t a worker if an event has occurred that has 22


produced an unsafe noise level. The advantage of a dosimeter is that it pr ovides the user with an output that is comparable to most governmental regulations and captures all the noise to which a worker is exposed throughout the day. One disadva ntage of a dosimeter is its tendency to over estimate noise levels due to the microphone being attached directly to the worker, leading to increased reflected noise. “The theoretical noise level increase is 3 dB for a microphone placed next to a perfect reflecting plane, and 6 dB in the corner of two reflect ing planes. Although the shirt, skin, or helmet is not a perfect reflecti ng plane, 2-3 dB increases are common” (Kluesener, 2001). The majority of the interfering reflect ion can be eliminated by keeping the microphone pointing away and perpendicular from where it is attached to a worker. Another disadvantage is the difficulty in determining which sources produced the sound levels that were recorded. There are assumptions that are made that a worker is exposed to only certain noise sources when they may be exposed to several different sources simultaneously or a variety of sources (Kluesener, 2001). Sound Level Meters A sound level meter provides the user with an instantaneous sound pressure level (SPL) in decibels. The meter can often be set to read noise levels at a sl ow or fast response as well as provide a peak noise level. Like the dosimeter, this device may al so contain the ability to store the noise levels that are read; however, the sound level meter does not provide a weighted average of the noise levels ove r a certain period of time. Th is meter is often handheld and usually used to measure the noise levels of the specific piece of equipment that may be a source of noise (Kluesener, 2001). Once an employer has determined which activit ies are known sources of elevated noise, a hearing conservation plan can begin to be developed. The plan mu st consist of the obvious use 23


of hearing protection where elev ated noise levels are present, along with other policies that control and ultimately reduce the workers exposure to elevated noise levels. A large aspect of the hearing conservation program should include addressing the noi se levels that are produced from the equipment and machinery that is commonl y used onsite. One recent system that shows strong signs of success is labeling noise sources w ith different colored stickers based upon their level of noise output. This system was develope d by Build It Smart, the Building Trades LaborManagement Organization of Washington State. It consists of four categories that are differentiated using a combination of shapes and co lors. A green circle is considered safe and these labels are placed on equipment producing nois e levels less than 85 dBA. A yellow triangle displays caution and these labels are placed on equipment in the 85 – 95 dBA range. A hazardous condition is indicated by an orange square for levels between 95 and 105 dBA. Finally, a dangerous level is expressed using a re d octagon for levels higher than 105 dBA. The labels are available in three si zes ranging from small decal size to poster size (eLCOSH, 2004). These labels provide workers with a quick and ea sy indication of when hearing protection should be used. In an attempt to enhance the acc eptability of noise controls in the construction industry, the director of Health and Safe ty for Laborers Heath and Safe ty Fund of North America has developed an organization known as the Construc tion Noise Control Partne rship (NCP). This group consists of volunteers from many different areas that are working on promoting awareness of noise control in several ways. They are in the process of creating a noise database that provides noise level information on different types of equipment. The NCP is also distributing informational materials to the industry that cont ain best practice guides for typical construction equipment and common noise expos ure scenarios. Other organizations such as the National 24


Hearing Conservation Association and the National Institute for Deafness and Communication Disorders have also been involved with the NC P to assist in promoting noise control and reducing the amount of hazardous noise level exposu res. “The most effective way to protect workers’ hearing is to prevent noise exposure in the first place; this is exactly what the NCP hopes to accomplish” (Neitzel, 2002). Another program that offers advice and promot es noise control is the German Blue Angel Program. “This program allows manufacturers to voluntarily submit specific equipment for analysis; equipment meeting cert ain criteria, including sound pow er levels, is designated as environmentally friendly” (Neitzel, 2002). If th e equipment manufacturer agrees to execute a four year contract with the German Federal Environmental Agency, their equipment can be marked with the Blue Angel symbol. This pr ogram has been certifying various types of low noise construction equipment since 1988 and has b een considered a strong sales attribute. Nearly 40 manufacturers have marketed over 200 Blue Angel certified pieces of equipment (Neitzel, 2002). The noise controls that are used by an empl oyer must not only be effective, but also practical and affordable. Furthermore, the most effective way to ensure the proper controls are being put in place is education and awareness. The noise control program must also focus on reducing the noise levels produced by the equipm ent that is used by workers. This includes teaching workers which types and which levels of sound are considered hazardous as well as properly training employees how to utilize protective equipment. 25


Table 2-1 Sound levels of common construction hand tools (OSH, 2002) Tools Average (dB) Peak (dB) Longest Exposure Without Hearing Protection (each day) Powder-actuated tool into masonry 107 110 147 0 (based on peak) Powder-actuated tool into timber 100 104 143 0 (based on peak) Paslode nailgun 97 – 104 138 0 (based on peak) Electric grinder (on aluminum) 98 – 102 123 8 minutes Cut-off saw 98 – 102 118 8 minutes Hand-held planer 96 – 100 114 15 minutes Masonry drill (timber then concrete) 96 – 100 111 15 minutes Bench rip saw 95 – 99 116 15 minutes Circular saw 94 – 98 113 15 minutes Hammer on nail into timber 93 – 97 131 0 (based on peak) Bench grinder 92 – 96 113 30 minutes Jigsaw 91 – 95 112 30 minutes Belt Sander 91 – 95 105 30 minutes Router 90 – 94 108 1 hour Electric chainsaw 89 – 93 112 1 hour Electric drill into timber 87 – 91 100 2 hours Electric sander (1/3 sheet) 79 – 83 103 8 hours 26


Table 2-2 Sound levels of common construction equipment (CPWR, 2003) Equipment Sound Level (dB) Pneumatic chip hammer 103 – 113 Jackhammer 102 – 111 Concrete joint cutter 99 – 102 Portable saw 88 – 102 Stud welder 101 Bulldozer 93 – 96 Earth Tamper 90 – 96 Crane 90 – 96 Hammer 87 – 95 Earthmover 87 – 94 Front-end loader 86 – 94 Backhoe 84 93 27


Table 2-3 Sound levels of various construction equipment (Sahai, 2006) Equipment Sound Level (dB) Pile driver 112 Air arcing gouging 110 Impact wrench 108 Bulldozer – no muffler 107 Air grinder 102 – 104 Crane – uninsulated cab 102 Bulldozer – no cab 101 – 103 Concrete chipper 97 Circular saw and hammering 96 Jack hammer 96 Quick-cut saw 96 Masonry saw 95 Compactor – no cab 94 Crane – insulated cab 90 Loader/backhoe – insulated cab 87 Grinder 86 Welding Machine 85 – 90 Bulldozer – insulated cab 85 Speaking voice 60 70 28


Table 2-4 Sound levels of different trades in an eight-hour shift Trade Average Exposure (dB) Portion of Shift >85dB Portion of Shift >115dB Bricklayers 83 1/4 2/3 Carpenters 82 1/2 1/2 Cement masons 79 1/2 1/3 Electricians 80 1/5 1/3 Insulation workers 75 1/5 1/5 Ironworkers 83 1/2 3/4 Laborers 84 1/2 2/3 Masonry restoration workers 83 1/3 1/3 Operating engineers 85 1/2 1/3 Sheet metal workers 79 1/10 1/5 Tilesetters 76 1/5 1/3 29


Table 2-5 OSHA permi ssible noise exposure limits Duration per Day (Hours) Sound Level (dBA) 8 90 6 94 4 95 3 97 2 100 1.5 102 0.5 105 0.25 or less 115 30


CHAPTER 3 METHODOLOGY Introduction This research was conducted to examine sound le vels on construction site s. This research was focused on sources of elevated noise levels, and the rate that the noise levels diminish with distance. The construction activities and e quipment that produce hazardous levels were identified in order to develop a hearing conser vation program that when implemented would help minimize noise induced hearing loss in the industry. Basis for Research The rationale for this research was based on determining the common areas on construction sites where noise is at a hazardous level. The ultimate goal of this research was to identify common activities and equipment that produce high noise levels and determine how these noise levels weaken with respect to distance. Data Source The sample population for this research consis ted of commercial cons truction projects in Gainesville, Florida. A total of seven construction projects were visited to collect the data. The majority of the readings were recorded on construction projects on the University of Florida campus. The size and type of projects ranged from small interior renovati ons to multi-story new construction projects. Most of the projects were studied at varying stag es of construction in order to obtain readings from a variety of equipment and machinery. Data Collection Procedure To obtain realistic data, sound level readings were taken on actual construction sites during various phases of the project. The majority of th e data were collected from activities that were suspected of producing elevated noise levels. The noise level readings were collected and 31


recorded on weekdays during nor mal construction working hours between 7:00 am and 3:30 pm. The data for this research were collected using a digital tape measure and sound level meter. The sound level meter used was a handheld device with a digital display of sound levels in decibels. The sound level meter used for this research was an Extech Instruments model number 407740. The meter is capable of providing both instantaneous as well as peak sound levels. To verify the desired distance from the various sound sources, a Strait-Line Sonic Laser Tape 50 digital tape measure was also used. The sound meter in c onjunction with the tape measure allowed sound levels to be collected at radi al distances around the various sources. The noise levels were collected at radial distances of 2 feet, 8 feet and 16 feet from the source. The data were recorded on the noise level collection sheet shown in Appendix A. For a few selected activities, due to site logistics and safety reasons, readings at the two foot level we re not able to be taken. Where the source of noise was constant or continuous, a slow response, instantaneous setting was used on the sound meter. Short bursts of noise, known as impact noises, were recorded using the peak setting on the meter. In addition to the sound le vel and distance, the activity and equipment used were recorded along with a brief description of the surroundings or envi ronment. Whether the operator was wearing hearing prot ection was also noted. The data collection occurred over two months beginning in January 2007 and ending in February 2007. 32


CHAPTER 4 RESULTS Introduction Data collected on construction site s were used as the basis of an alysis. In order to obtain realistic data, noise level read ings were collected on severa l construction pr ojects during different construction activities. The majority of the readings were taken during activities that use pieces of equipment and machinery that we re noticeably louder than other activities. Twenty-five noise level readings were coll ected and recorded from seven different construction sites. In addition, three separate scenarios were a udited for different sound levels for two different tools under diffe ring site conditions. Table 4-1 shows the composition of all of the individual noise level readings taken from tw enty-five different construction activities. The activity and the piece of equipm ent or machinery being used du ring that activity are shown along with the site conditions and noise level readings for distances of 2-feet, 8-feet and 16-feet from the source. The majority of the activities produced noise levels that were constant or continuous. For these activities, the noise level meter was set on a slow response setting and noise levels were taken at radial distances from the source. The noise level recorded was the level that displayed on the meter most often and was assume d to represent the average noise level for the corresponding radial distance. Some of the activities produced short, loud noises known as impact noises. For these activities, the meter was set on a setting to read the peak noise level. Table 4-1 also notes the activ ities for which the operator was using hearin g protection. For the purpose of analyzing the data, the different activities were separated by their conditions and environment. The majority of th e activities audited were performed outdoors in open areas on dirt ground. Several of the activities were outdoors on other ground types such as grass, concrete or compacted limerock. When pr esenting the information in the figures, each 33


group of data includes the theo retical situation for a hypothetical activity producing a noise level of 100 decibels, which was the average of all the noise readings at a two foot distance. In theory, when the distance from the source is doubled, the noise level decreases by six decibels. This would produce theoretical noise le vels of 88 dB and 82dB for dist ances of 8-feet and 16-feet, respectively. Noise Levels of Indoor Activities The noise readings that were collected fo r specific construction activities performed indoors were limited. The floor conditions for the i ndoor activities that were audited were either dirt or concrete. The noise levels that were produced from the three i ndoor activities are shown in Figure 4-1. The highest noise level in Figure 4-1 was produced by the small hydraulic tractor was 95.2 dB at the two-foot dist ance. The noise level while laying CMU block using a metal trowel was 90.1 dB at the two-foot distance. A noise level for the 16-foot distance was not able to be taken for laying CMU block due to limited space on the construction site. The lowest noise level was produced by the electric shop-style vacuum was 85.8 dB at the two-foot distance. The slope between the three audited activities is less than the theoretical of 12 dB between the twoand eight-foot distances. However, the slope between the 8 and 16-foot distances are quite similar to the theoretical condition. The inconsis tent slope likely occurred from the noise being reflected from the surrounding features such as walls and ceilings in this indoor setting. The majority of the elevated noise levels observed on the various construction sites were produced outdoors during constructi on. For this reason, the number of indoor activities that were able to be studied was minimal. To better understand how noise levels diminish with common indoor obstructions, three differe nt scenarios were audited. Figure 4-2 shows the first scenario which wa s performed during an interior renovation. The scenario consisted of an operator using a c oncrete chipping hammer to chip out a concrete 34


slab in the middle of an interior room. Note that the position of the operator, relative to the tool, is shown in the figure. The noise levels that we re taken inside the room during the activity were considered hazardous. Noise levels were recorded from seven different locations, readings were taken with the door to the room being open and similar readings were taken with the door closed. A total of 14 readings were taken. The highe st noise levels were 104.5 dB (door closed) and 103.9 dB (door open) taken approximately 1 foot fr om to the piece of equipment (location M1). The lowest noise level readings were 91.4 dB (door open) and 83.4 dB (door closed) taken from outside the room in the corridor (location M7). The noise level was shown to reduce between one and two decibels when taken in the corner s of the room that were behind the operator (designated as M4 and M5). The noise levels in side the room were shown to increase an average of 1.84 decibels when the door to the room was cl osed. Two of the readings were taken outside of the room, one each for when the door to the room was open and closed. One reading was taken standing in the doorway (designated as M6) to the room; the other reading was taken outside of the room a few feet down the corridor from the door opening (shown as M7). The highest decrease in noise levels were experienced in the door way. When the door was open, the noise reading was 16.1 decibels greater than wh en the door was closed. The door being placed between the meter and the activity reduced the noise level from an unsafe 101.3 dB to a tolerable 85.2 dB. Another indoor scenario was audited using an electric rotary grinde r under two different site conditions. Figure 4-3 show s an electric grinder being used indoors to grind metal fasteners on a hollow metal door frame. The noise levels were collected from vari ous locations surroundi ng the activity. The activity took place on the inside of a hollow metal door frame located in an eight foot wide, latex 35


painted, concrete block corridor. This area ha d vinyl composite tile flooring and 10-foot high, acoustical tile ceilings. The opera tor (as denoted in th e figure) was standing in the door frame facing the inside of the frame. A total of 11 noise level readings were collected from 11 different locations surrounding the activity. The highest noise level was 95.6 dB which was experienced closest (one-foot distances, loca tion M11) to the activity. The other readings were collected at either a six or eight-foot radius around the noise source. Th e noise levels ranged between 83.1 dB and 88.9 dB at four different points along the si x-foot radius. The lowest noise level on the six-foot radius was at location M1 which was ta ken at a point obstructed by the operator. The highest noise level on the six-foot radius was found at locatio n M3 which provided the noise level meter a direct sight to th e piece of equipment without any obstructions . At the eight-foot radius, the noise levels ranged between 78.3 dB and 87.2 dB. The lowest noise level of 78.3 dB was found at locations M5 and M10. Location M5 was taken from eight feet away behind a column that protruded six inches into the corr idor. Readings at loca tion M10 were taken along the eight-foot radius from inside a door opening in an adjacent room. The readings were found to diminish between 1 and two decibels betwee n the six-foot and eigh t-foot radius. The theoretical reduction in the noise leve l from six to eight feet is 2.5 dB. The final indoor scenario consisted of using th e same electric grinder to cut an expansion joint into a concrete block wa ll. Figure 4-4 shows the noise levels at various locations concentrated along a two-f oot and five-foot radius. A total of 11 readings were taken from th e different locations shown. The area where readings were taken had concrete floors with a 24-foot high, vaulted, wood ceiling. The noise levels ranged between 82.2 dB and 97.3 dB. The highest noise level was 97.3 dB at location M4 which was located along the two-foot radius to the left side of the operator. The noise levels on 36


the two-foot radius decreased almost five decibe ls between locations to the sides of the operator (locations M2 and M4) and the lo cation directly behind the operator (location M3). The lowest noise level was 82.2 dB at location M8 which was located along the five-foot radius and obstructed by a wall that protruded out between the reading location and the activity. The second lowest noise level was 83.1 dB at location M9 which was located only a foot and a half from the activity, but protected by concrete block walls. One surprisingly el evated noise level of 96.2 dB was taken at M1 located in the corner to the right of the operato r and 4.6 feet from the source. Noise Levels of Outdoor Activities The majority of the construction activities that were audited took place outdoors, in open areas, on dirt ground. A few of the outdoor ac tivities took place on gr ass, concrete, or compacted limerock. In order to analyze the data , the outdoor activities we re divided into four different categories based on their ground condi tions. Each category was compared to a theoretical prediction for a 100 dB level which displays a decrease of six decibels for each time the distance from the source is doubled. Figure 4-5 shows two different activities th at were being performed on a compacted limerock ground in an open area. The highest no ise level at the two-f oot distance was 110.2 dB produced by the electric circular saw. The lowe st noise level at the two-foot distance was 76.2 dB from the hand saw. For the electric circular saw cutting wood, the slope differs by less than one decibel from the theoretical situation. The hand saw was one of the few activities that did not produce noise levels above th e hazardous threshold of 85 dB. The readings collected from the hand saw were found to decreas e at a rate considerably less than the theoretical example. Figure 4-6 shows the noise levels that were present when using an electric circular saw to cut concrete blocks on grass. This activity was one of the highest audite d with a noise level of 37


120.1 dB at the two-foot distance. The noise leve ls for this activity are found to decrease at a rate much greater than the theoretical situation. The noise levels between the 8-f oot and 16-foot distances decreased 13.6 dB which is more than double the theoreti cal decrease of six decibels. This large decrease may have been caused by the readings being taken while the operator was moving around the block being cut. This m ovement would place an obstruction between the meter and the piece of equipment which would a ppear to reduce the amount of noise projected from the source. Figure 4-7 shows the noise level readings of ac tivities that took place on a concrete floor. The highest noise level of the entire study wa s taken under these conditions. In addition, the majority of these activities experienced changes in noise levels for the different studied distances that were much different than the theoretical situation. In Figure 4-7, th e highest noise level of 120.7 dB (impact noise) at the two-foot distance was generated by a 0.22 caliber electrical ramset driving fasteners through metal studs into structural steel framing. For this activity, the decrease in noise levels between the two foot and eight foot di stance was 7.1 dB which is close to half of the computed theoretic al decrease of 12 dB. In cont rast, the decrease between the 8foot and 16-foot distances was 9.7 dB which is over 50 percent greater than the theoretical decrease of 6 dB. These readings varying so dr astically from the theoretical situation may have resulted from the obstructions that were present when these reading were taken. This activity was being performed under an entryway soffit which must have reflected most of the sound between the two and eight foot distances and shie lded the sound for the 16 foot distance. One of the other activities involved connecting metal studs to structural steel but used screws with an electric hammer drill. The electric hammer dr ill produced a noise level of 116.7 dB at the two foot distance. This activity experienced decrea ses in noise levels that were closest to the 38


theoretical situati on with a decrease of 13.8 dB (12 dB d ecline is theoretical ) between the twoand eight-foot distances and 4.6 dB (6 dB declin e is theoretical) between the 8 and 16-foot distances. The other activities shown in Fi gure 4-7 also experienced vari ations from the theoretical situation for the 2-foot, 8-foot and 16-foot distances. The activity that involved using an electrical reciprocating saw to cut metal studs produced a noise le vel of 117.5 dB at the two-foot distance, with a decrease of 17.3 dB between the two and eight foot distances which was the greatest decline noted in the en tire study. This activity was pe rformed by a large operator who was able to obstruct the majority of the sound that was being released from the source as the noise levels were being taken. The decrease between the 8 a nd 16-foot distances was 4.1 dB which is almost two decibels less than the theore tical predicted decrease which could have been caused by the saw producing more noise as it made its way through different points of the metal stud. One of the other activities wa s also to cut metal studs, but used an electric miter saw. The electric miter saw cutting me tal studs produced a noise leve l of 109.3 dB at the two-foot distance. This activity experien ced a decrease of 5.2 dB (12 dB decline is theoretical) between the two-foot and eight-foot dist ances and a decrease of 4.1 dB (6 dB decline is theoretical) between the 8-foot and 16-foot distances. This may have been caused by the absence of obstructions and perhaps causing nois e levels to project with greater intensity in all directions from the source. The activities displayed in Figures 4-8 and 4-9 took place outdoors on dirt ground. Due to the large number of activities collected under these conditions, th e activities were divided into handheld equipment and heavy machinery. Figure 4-8 displays the noise levels of handheld 39


pieces of equipment when performing activities. Figure 4-9 shows the noise levels of heavy machinery used to complete tasks. The noise level of the temporary power porta ble gas generator is shown in Figure 4-8. Even though this is not a piece of handheld equipment, it was analyzed with the handheld equipment because it is often used to provide power for handheld equipment. The noise level produced by the generator was 93.5 dB at the two foot distance. The noise level of the portable generator was found to decrease 10 dB between the two and ei ght foot distances and 3.3 dB between the 8 and 16 foot distances. This was less than would be predicted which may have been caused by the fluctuation in the noise out put of the generator as it was placed under different loads by the tools for which it was supplying power. This activity was the only activity where workers had placed a piece of plywood between them and noise sour ce to reduce the noise level. Behind the plywood barri er, the noise level was 85.1 dB at the two foot distance. This noise level was 8.4 dB less than the noise level that was taken without any obstructions at the two foot distance. Figure 4-8 also shows the noise levels that were produced when cutting trees with a gas powered chain saw. The noise readings were taken while the chain saw was cutting and while the saw was idling. The noise level while the ch ain saw was idling was 82.3 dB at the two foot distance. The noise levels of the idling chain saw were found to be below the hazardous level and decreased 3.2 dB between the two and eight f oot distances and two decibels between the 8 and 16 foot distances. The noise level while the chain was cutti ng was 101.9 dB at the two foot distance. The noise levels while the chain saw was cutting where found to decrease 5.8 dB between the two and eight foot di stances and 6.8 dB between the 8 and 16 foot distances. The 40


decrease in noise level being less than the theore tical predicted value may have resulted from the gas motor in the chain saw producing fluctuating noi se levels as the chain cut through the trees. The remaining two activities that are shown in Figure 4-8 also do not experience a noise level decrease that is consistent with theoretic al predictions. The hamme r being used to drive nails into wood experienced a noise level of 89.7 dB at the two foot distance. This activity had a decrease of 3.4 dB from two to eight feet and a decr ease of 4.4 dB from 8 to 16 feet. This activity was taking place on wood formwork being constructed for concrete columns. The worker using the hammer was standing inside the area that was going to be filled with concrete and driving nails through the plywood and into wood framing. The noise produced from the hammer striking the nails was cons idered an impact noise and th e decrease in the noise level with distances was less than predicted, possibly because the plywood reflected or absorbed the sound. The other activity involved an electric co ncrete vibrator which was used to eliminate voids that are created when concrete is poured. The concrete vibrator required two operators. One operator was at the end of th e hose moving the vibrator in and out of the concrete while the other operator held the motor that powered the vibrator. Most of the noise was produced by the motor that drove the vibrator. The noise leve l was 96.1 dB at the two foot distance from the motor. The noise levels were found to decrease 6.9 dB between the two a nd eight foot distances and 6.4 dB between the 8 and 16 foot distances. The decrease of 6.9 dB between the two and eight foot distances is much less than theo retical and may have been caused by the motor fluctuating as the vibrator was placed in and out of the concrete. The activities that are shown in Figure 4-9 are those that took place on dirt ground and involved the use of heavy pieces of machinery. All of these activities produced levels above 90 dB for the two foot distance. In addition, all of these activitie s experienced a decrease in noise 41


levels between the two and eight f oot distances that were less than the theoretical 12 dB. Only a few of these activities experienced a decrease in noise levels near the th eoretical six decibels between the 8 and 16 foot distances. Three different activities are shown in Figur e 4-9 that took place during the process of placing concrete. The concrete tr uck was a typical dies el truck with a 10 yard rotating drum. When the concrete truck was idling, the noise le vel was 90.1 dB at the two foot distance. The noise levels produced by the truc k at the two foot distance were 15.6 dB greater when the truck was “churning.” This process took place when the drum rotated at a greater rate to dispense the concrete from the drum, to the hopper and down th e chute to the pump. The decrease in noise levels between the 2, 8 and 16 foot distances we re much less than the theoretical prediction. This may have resulted from the noise being pr oduced from several different locations on the concrete truck. When the noise levels were taken at different positions around the truck, the levels were different. The front of the truck (103.2 dB), where the engine was located, was much louder than the side (92.1 dB). In addition, the no ise levels over 100 dB at the rear of the truck were most likely a result of the concrete pump and concrete truck running simultaneously. This may have also led to the small decrease of two decibels experi enced by the concrete trailer pump between the two and eight foot distances. Figure 4-9 also shows four diffe rent pieces of heavy machiner y that were used during the initial stages of clearing a constr uction project site. These pieces of machinery were all used to move dirt and clear trees. Of the four pieces of machinery used to move dirt, the highest noise level of 100.6 dB for the two foot distance was produced by the small dozer. The lowest noise level of 96.3 dB for the two foot distance was produ ced by the small skid steer. For all four of the pieces of machinery, the decrease in noise le vels were much less than the theoretical 12 dB 42


between the two and eight foot di stances. The decrease in noise levels between the 8 and 16 foot distances were also less than the theoretical six decibels, but only by one or two decibels. The noise levels decreasing at a rate less than theore tical may have resulted from the orientation of the machinery constantly changing. As the diffe rent activities were performed, the pieces of machinery were moving and rotating in multiple directions which changed the direction of the noise projections while the noise level readings were being r ecorded. All of the activities involved in site clearing were extremely dynamic and difficult to obtain noise level readings consistent with the collection methods on the other activities audited. Two activities shown in Figure 49 involved using machines to lift people and materials. The gas powered scissor lift used to lift worker s while installing ceili ng framing experienced a noise level of 100.2 dB for the two foot distance. This noise level was recorded from the ground level, at the bottom of the machine which was not what the workers being lifted would have experienced. The decrease in noise levels betw een the two and eight foot distances was 3.9 dB which is less than half of the theoretical 12 dB. The decrease in noise levels between the 8 and 16 foot distances was 6.5 dB which is 0.5 dB greater than the theoretical si x decibels. The other piece of equipment used for lifting was a gas powered forklift which produced a noise level of 96.3 dB for the two foot distance. The forklift e xperienced decreases in noise levels similar to the scissor lift. The decrease in noise level between the two and eight foot distance was 3.5 dB which is considerably less than the theoretical 12 dB. The decrease in noise levels between the 8 and 16 foot distances was 5.7 dB which is 0.3 dB less than the theoretical six decibels. The decrease in noise levels between the two and eight foot distances may have been much less than theoretical as a result of the load on the lift be ing moved up or down during the time it was being audited. 43


Summary A few interesting observations we re made on site about the workers and various situations encountered during the data collec tion process. The workers on th e construction sites were often worried about being observed by an unfamiliar pers on. The mere presence of a person collecting and recording data led most workers to beli eve they were doing something wrong and were going to be punished. The majority of the worker s that were violating common construction site safety policies, such as not wearing a hard hat, immediately reacted to an unfamiliar person recording data by complying with the safety po licies. Once the purpose of collecting the noise levels was explained to the workers, most worker s became interested and were very helpful. In addition, it was surprising how rapidly the information traveled between workers and how quickly newly enlightened workers showed signs of relief. The productivity also seemed to increase with an unfamiliar person exploring the pr oject site. It was common to see workers who had been standing idle (not performing any wo rk) suddenly becoming busy when they saw an unfamiliar person. Most of the activities that pr oduced elevated noise levels took place in open areas which provided a more accurate reading by reducing the amount of noise reflection. Activities in open areas also allowed workers that we re not operating the piece of equi pment to keep a safe distance from the noisy operations. For this reason, the majority of the exposure to the elevated noise levels was experienced by the operators. In most cases, the operat ors did not take any precautions to prevent other workers from being exposed to elevated noise levels produced by their task activities. The only piece of equipment that was placed away from workers was a gas powered portable generator. The generator was located approximately 25’ from the workers. The noise levels produced by the generator we re noticeably elevated (above regulatory tolerances) within a few feet. The obvious elevated noise levels compelled one worker to place a 44


piece of plywood near the generator to shield the noise while briefly working near the piece of equipment. Placing the piece of plywood between the worker and the generator was found to reduce the noise level more than 10 decibels an d brought the noise exposur e of the worker to a safe level. The compiled data showed that the noise levels on construction sites are often elevated. The three different interior scenarios displayed that noise levels will decrease when obstructions are present and noise levels may increase when reflected. Each activity experienced a decrease in noise levels when readings were taken from behind the operator. In addition, the noise levels were reduced by other obstructions such as doors or partitions. The noise levels were found to decrease when the distance from the source was increased, but not uniformly at the theoretical rate of 6 decibels each time the distance was doubled. The majority of the individual construction activ ities that were audited were found to have elevated noise levels that exceeded the safe noi se levels. Out of the twenty-five individual activities that were audited, only two were found to produce noise levels below the hazardous level of 85 dB at the two-foot distance. All of the noise levels were shown to decrease as the distance from the source increased, but this reduction was often considerably less than the theoretical decrease of 12 dB between the two and eight-foot distances. The decrease in noise levels between the 8 and 16-foot distances were f ound to be less than the theoretical six decibels, but usually by only one or two decibels. For the twenty-fiv e activities audited, the mean decrease in noise levels was 6.6 dB between the two and eight-foot distances and 5.3 dB between the 8 and 16-foot distances. For a few of the activities audited, the decrease in noise levels were found to be greater than the theoretical predicted decrease. This may have resulted from the initial noise level 45


reading for the two-foot distance being taken at a distance less th an two feet. In theory, this would produce a decrease in noise level greate r than 12 dB between the two and eight-foot distances. For example, if init ial noise level r eading was mistakenly taken at a distance of 1.75 feet, the theoretical decrease in the noise level between 1.75 feet and 8 feet would be 13.2 dB. In addition, if the first noise level r eading for an activity is taken at 1.5 feet, the theoretical decrease in noise level between 1.5 feet and 8 feet would be 14.5 dB. 46


Table 4-1 Noise levels of common construction activities Activity Equipment Environment Conditions** Noise @ 2 ft (dB) Noise @ 8 ft (dB) Noise @ 16 ft (dB) Laying CMU Block Metal Trowl ID Dirt Floor, High Ceilings 90.1 87.7 N/A Cutting CMU Block Elec Handheld Saw OD Grass, Open Area 120.1 105.2 91.6 Small Hydrolic Tractor Kubota ID Concrete floor, Block walls 95.2 90.1 85.3 Cutting Wood Elec Circular Saw OD Limerock ground, Open 110.2 97.8 90.3 Cutting Wood Hand Saw OD Limerock ground, Open 76.2 72.1 70.8 Cutting Metal Studs Elec Reciprocating Saw OD Concrete floor, Open 117.5 100.2 96.1 Fastening Metal to Struct Steel Elec .22 cal Ramset* OD Concrete, Metal deck ceiling 120.7 113.6 103.9 Screwing Metal to Struct Steel Elec Hammer Drill OD Concrete, Metal deck ceiling 116.7 102.9 98.3 Cutting Metal Studs Elec Miter Saw OD Concrete, high ceiling 109.3 104.1 100.0 Installing Ceiling Framing Gas Scissor Lift OD Dirt, Ceiling overhead, Open 100.2 96.3 89.8 Lifting Pallets of CMU Block Gas Forklift / Lull OD Dirt, Open Area 96.3 92.8 87.1 Cutting Trees Gas Chain Saw Cutting OD Dirt, Open Area 101.9 96.1 89.3 Cutting Trees Gas Chain Saw Idling OD Dirt, Open Area 82.3 79.1 77.1 Moving Dirt / Trees Small Diesel, Track Dozer OD Dirt, Open Area 100.6 93.3 88.1 Loading Cut Trees Large Diesel, Track Excav ator OD Dirt, Open Area N/A 91.0 85.2 Placing Concrete Concrete Drum Truck Idle OD Dirt, Open Area 90.1 87.1 83.3 Placing Concrete Concrete Drum Truck Churning OD Dirt, Open Area 105.7 99.8 96.1 Placing Concrete Concrete Trailer Pump Pumping OD Dirt, Open Area 98.3 96.2 90.3 Using Temporary Power Gas Portable Generator OD Dirt, Open Area 93.5 83.5 80.2 Using Temporary Power Gas Portable Generator OD Behind 3' x 8' plywood 85.1 N/A N/A Nailing into Wood Handheld Claw Hammer* OD Dirt, Open Area 89.7 86.3 81.9 Moving Dirt Large Diesel, Rubber Tire, FE Loader OD Dirt, Open Area 96.3 90.1 86.2 Moving Dirt Small Diesel, Rubber Track, Skid Steer OD Di rt, Open Area 92.1 87.8 83.3 Vibrating Concrete Electric Concrete Vibrator OD Dirt, Open Area 96.1 89.2 82.8 Cleaning w/ Vacuum Electric 4hp shop-vac ID Concrete floor, Block walls 85.5 81.2 76.3 *Impact noise Collected with sound meter set on peak (a ll other readings were taken on the slow response) **ID Indoors, OD Outdoors Operator wearing hearing protection 47


70 75 80 85 90 95 100 105 2 ft 8 ft 16 ft Distance from Source (ft)Noise Level (dB) Small Hydraulic Tractor Kubota Cleaning w/ Vacuum Electric 4hp shop vac THEORETICAL Laying CMU Block Metal Trowel Figure 4-1 Noise Levels for Indoor Construction Activities 48


M2 M3 M1 M5 M4 X1 M6 M7General Notes:Concrete Floor Open Ceiling, Steel Deck @ 16' AFF All readings were taken with door open and closed X1 Electric Concrete Chipping Hammer Operator Location Solid Wood Core Door Interior Partitions Uninsula ted, 4" Metal Stud w/Drywall ACTIVITY EQUIPMENTX1 ELECTRIC CONCRETE CHIPPING HAMMERLocation Noise LevelDoor Open (dB) Door Closed (dB)Noise Level Delta (dB)Operator not wearing hearing protectionM1 M2 M3 M4 M5 M6 M7 103.9 101.1 101.3 98.3 99.9 101.3 91.4 104.5 102.3 102.9 101.9 102.1 85.2 83.4 0.6 1.2 1.6 3.6 2.2 16.1 8 Figure 4-2 Indoor Noise Levels of a Concrete Chipping Hammer 49


CORRIDOR (8' WIDE)X2 6' RADIUS 8' RADIUS M1 M2 M3 M4 M9 M8 M7 M6 M5 M10Corridor Walls are Painted CMU X2 Electric Grinder on Metal Door Frame Readings were taken at "M" locations Operator Location General Notes:10' Ceiling Height, Acoustical Ceiling Vinyl Composite Tile FloorM11 ACTIVITY EQUIPMENTX2 ELECTRIC GRINDER ON HOLLOW METAL DOOR FRAMELocation RadialDistance (ft)Noise Level (dB)M1 M2 M3 M4 M5 M6 M7 68 3 . 1 86.8 88.9 85.3 78.3 83.1 85.9Operator not wearing hearing protectionM8 M9 M10 M11 87.2 84.1 78.3 95.6 6 6 6 8 8 8 8 8 8 1 Figure 4-3 Indoor Noise Levels of an Electric Grinder on HM Door Frame 50


Operator Location X3 Electric Grinder on CMU General Notes:CMU Block Walls Wood Vaulted Ceiling @ 24' AFF Concrete Floor X3 5' RADIUS 2' RADIUS M10 M11 M9 M7 M6 M5 M2 M1 M4 M3 M8 Operator not wearing hearing protection ACTIVITY EQUIPMENTX3 ELECTRIC GRINDER ON CMU WALLLocation RadialDistance (ft)Noise Level (dB)M1 M2 M3 M4 M5 M6 M7 4.696.2 97.1 92.3 97.3 88.7 87.3 88.9 M8 M9 M10 M11 82.2 83.1 88.6 86.7 2 2 2 5 5 5 5 2 6.5 13 Figure 4-4 Indoor Noise Levels of an Electric Grinder on a Concrete Block Wall 51


70 75 80 85 90 95 100 105 110 115 2 ft 8 ft 16 ft Distance from Source (ft)Noise Level (dB) Cutting Wood Elec Circular Saw Cutting Wood Hand Saw THEORETICAL Figure 4-5 Outdoor Activity Noise Levels on Compacted Limerock Ground 52


70 75 80 85 90 95 100 105 110 115 120 125 2 ft 8 ft 16 ft Distance from Source (ft)Noise Level (dB) Cutting CMU Block Elec Handheld Saw THEORETICAL Figure 4-6 Noise Levels of Outdoor Activities on Grass 53


70 75 80 85 90 95 100 105 110 115 120 125 2 ft8 ft16 ft Distance from Source (ft)Noise Level (dB) THEORETICAL Cutting Metal Studs Elec Reciprocating Saw Fastening Metal to Structural Steel Elec .22 cal Ramset Screwing Metal Studs to Struct Steel Elec Hammer Drill Cutting Metal Studs Elec Miter Saw Figure 4-7 Noise Levels of Out door Activities on Concrete Floor 54


70 75 80 85 90 95 100 105 2 ft 8 ft 16 ft Distance from Source (ft)Noise Level (dB) THEORETICAL Cutting Trees Gas Chain Saw Cutting Cutting Trees Gas Chain Saw Idling Using Temporary Power Gas Portable Generator Nailing into Wood Handheld Claw Hammer Vibrating Concrete Electric Concrete Vibrator Figure 4-8 Noise Levels of Handheld Equipment Outdoors on Dirt Ground 55


80 85 90 95 100 105 110 2 ft8 ft16 ft Distance from Source (ft)Noise Level (dB) Installing Ceiling Framing Gas Scissor Lift Lifting Pallets of CMU Block Gas Forklift / Lull Moving Dirt / Trees Small Diesel, Track Dozer Loading Cut Trees Large Diesel, Track Excavator Placing Concrete Concrete Drum Truck Idle Placing Concrete Concrete Drum Truck Churning Placing Concrete Concrete Trailer Pump Pumping Moving Dirt Large Diesel, Rubber Tire, FE Loader Moving Dirt Small Diesel, Rubber Track, Skid Steer THEORETICAL Figure 4-9 Noise Levels of Heavy Machinery Outdoors on Dirt Ground 56


CHAPTER 5 CONCLUSION As a construction project is being built, the sound levels are often elev ated. All stages of the project require the use of different tools and equipment th at produce many different noise levels. With various critical project dead lines, several activitie s must be performed simultaneously. The combination of multiple activities taking place elevates the noise levels even further. The elevated sound levels can cr eate problems on constructi on sites that directly affect the workers and the project. When a work er is exposed to unsafe levels, above 90 dB, for an extended period of time, they risk incurring hearing damage. Hearing damage can lead to reduced worker productivity, poor site communicati ons and unsafe site conditions. Since this type of noise-induced hearing loss has become more common, construction companies as well as government agencies are beginning to promote aw areness and using hearing protection devices. The main focus of the research was to de termine noise levels on construction sites; however, whether workers were using hearing protection was also noted dur ing the site visits. The expectation that hearing prot ection was seldom used was indeed correct. The majority of the workers involved in the activities that produced elevated noise levels did not use any hearing protection devices. It was a surpri se to this researcher to see a worker using hearing protection devices when they were being exposed to elevat ed levels. The most common type of hearing protection used was ear muffs. One interest ing observation was made on a site where an operator was using ear muff s while cutting metal studs with a miter saw. When the worker took a break from cutting, he was questioned about w hy he chose to wear hearing protection during this activity. The question was answered wit h, “This thing is loud. I’m young, and do not want to end up deaf like most of these older guys.” It was interesting to see a younger worker taking 57


the necessary precautions to prevent noise-induced hearing loss because he was aware that there were many workers who suffer from hearing impairment. Based on this research, it can be concluded that construction site s experience elevated noise levels. These elevated noise levels were produced by a variety of sources and often were levels that are considered hazardous to workers. In addition, this research showed that the sources of elevated noise levels are found in all stages of a common construction project. The sound levels were found to radiate outward from the source and as the distance between the sound level meter and the source in creased the noise levels decreas ed. The noise levels were always found to diminish in relation to distance, however not in a uniform fashion. The levels were also diminished when obstructions existe d between the source and the sound level meter. The majority of the obstructions separating the source and the meter were the operators of the different hand-held tools. Othe r obstructions ranged from other workers in the area, sheets of plywood, doors, windows, partitions, vehicles and tr ees. In contrast, if the obstruction such as plywood was capable of reflecting the noise, th e noise levels were highest between the obstruction and the source. That is, the noise level might actually be higher at a small distance from the noise source because of the sound being reflected by the obstruction. 58


CHAPTER 6 RECOMMENDATIONS The Construction Industry The issue of elevated noise leve ls on construction projects is ex tremely difficult to resolve. The activities that must take pl ace to complete a construction pr oject often produce considerable noise. The ultimate problem with the elevated nois e levels is the damage it can do to a worker’s hearing. There are two possible so lutions that are available to pr otect workers from experiencing hearing damage from construction noise. The mo st desirable solution is to reduce the amount of noise that is being produced on c onstruction sites. The other and more feasible solution is to increase the worker’s awareness about construc tion noise and make hear ing protection available to all construction workers. The elevated noise levels on construction pr ojects are produced by pieces of equipment and heavy machinery. The elevated noise levels produced from these sources are difficult to reduce, but they are often easy to deflect. The no ise can be deflected using a variety of building materials such as plywood, drywall or sheet metal. These materials can be placed between the source of the noise and other workers to reduce the amount of noise experienced by the worker. This will protect other workers from exposure; however, the operator of the piece of equipment must always use hear ing protection devices. The construction industry must improve its hearing conservation policies. Most construction companies are not aw are of what noise levels are common on their construction projects. In addition, most companies are not aware of the damage that can be done to a worker’s hearing from being exposed to elevated noise levels. If construction companies mandated sound audits of their construction projects and become aware of the noise levels that the workers are being exposed to, th ey would realize the amount of elevated noise levels that are 59


present. Once a company determines whether th eir projects are experiencing elevated noise levels, they can develop a plan to protect their workers from being exposed to these levels. The plans overall focus needs to be to educate worker s of the various activitie s, pieces of equipment, and machinery that are common sources of elevated noise levels. The workers also need to know that activities that produce noise levels above 90 decibels are hazardous a nd require the use of hearing protection devices. The next step is to supply workers with effective hearing protection devices, such as ear plugs or ear muffs, and properly train workers how to use the hearing protection devices. The final step is to enforce the us e of hearing protection devices by all equipment operators and any worker w ithin an unsafe dist ance of the activity. Further Study Although this research has been informative about the common noise levels produced from common activities on construction proj ects; other areas related to this research can be examined further. The opinions of workers and construc tion companies about hearing conservation would be a good area to investigate. This could provide information of what workers are currently experiencing on construction projects and if construction companies are using any type of preventative measures. In addition, a study c ould examine how workers feel about using different hearing protection devi ces and which type of protecti on devices they prefer and why. The overall effectiveness of hearing conser vation awareness on construction projects should be explored. An analysis of construc tion companies that do or do not have hearing conservation plans could be compared to th e number of employees who have experienced hearing loss. This study could al so explore the number of work ers’ compensation cases due to hearing loss. 60


APPENDIX A NOISE LEVEL COLLECTION SHEET 61 # Activity Radial Dist. (ft) Noise Level (dB) Prot. (Y/N) Other/Comments 2 8 1 16 2 8 2 16 2 8 3 16 2 8 4 16 2 8 5 16 2 8 6 16 2 8 7 16 2 8 8 16 2 8 9 16 2 8 10 16 2 8 11 16 2 8 12 16 2 8 13 16 2 8 14 16 2 8 15 16


LIST OF REFERENCES Arezes, P., & Miguel, A. (2005). Individual perception of noise exposure and hearing protection in industry. Human Factors, 47(4), 683-692. Atmaca, E., Peker, I., & Altin, A. (2005). Industrial noise and its effects on humans . Polish Journal of Environmenta l Studies, 14(6), 721-726. Berg, S.Z. (2003). Sound advice – protect your ears in noisy work environments . NIOSH Safety and Health. h/topics/noise/abouthlp/soundadvice.html. Accessed January 2007. Berger, E. (2000). Dual protection. Occupational Health & Safety, 69(10), 98. Canadian Centre for Occupational H ealth and Safety (CCOHS). (2006). Noise – basic information. /phys_agents/noise_basic.html. Accessed January 2007. Center to Protect Workers’ Rights (CPWR). (2003). Hazard alert – construction noise . d0100/d000020/d000020.html. Accessed January 2007. Chang, T., Ruei-Man Jain, G., Wang, C., & Chan, C. (2003). Effects of occupational noise exposure on blood pressure. Journal of Occupational & Environmental Medicine, 45(12), 1289-1296. Daniells, A. (2001). Mitigating noise-induced hearing loss. Occupational Health & Safety, 70(6), 131. Dunn, R. (2001). Understanding industrial noise. Plant Engineering, 55(6), 51. Electric Library of Construction Occupati onal Safety and Health (eLCOSH). (2003, February). OHSA’s approach to noise exposure in construction. d0500/d000573/d000573.html. Accessed January 2007. Electric Library of Construction Occupational Safety and Health (eLCOSH). (2004, June). Colors warn about noise. d000662.html. Accessed January 2007. Eleftheriou, P.C. (2002). Industrial noise and its e ffects on human hearing . Applied Acoustics, 63, 35. Hinze, J. (2005). Noise generated by construction power tools . Third International Conference on Construction in the 21st Century, Advancing Engineering, Management and Technology. Athens, Greece. September 15-17, 2005. 62


Kluesener, M. (2001). Sound level meter or dosim eter? Making the choice. Plant Engineering, 55(2), 94. Koushki, P.A., Kartam, N., & Al-Mutairi, N. (2004, June). Workers’ perceptions and awareness of noise pollution at construction sites in Kuwait . Civil Engineering and Environmental Systems, 21(2), 127-136. National Institute for Occupational Safety and Health (NIOSH). (November, 1998). Noiseinduced hearing loss – attitudes and behaviors of U.S . Adults. niosh/topics/noise/a bouthlp/nihlattitude.html. Accessed January 2007. Neitzel, R. (2002). Construction noise strategies. Occupational Health & Safety, 71(6), 72. Neitzel, R., Seixas, N.S., Camp, J. & Yost, M. (1999). An assessment of occupational noise exposures in four construction trades. American Industrial Hygiene Association Journal (AIHA), 60, 807-817. Occupational Safety and Health Servi ce of New Zealand. (OSH) (November, 2002). Noise levels created by comm on construction tools. Construction Bulletin, 23. OSHA Seeks Input On New Noise Standards for Construction. (2004) . ENR: Engineering News-Record. Ryan, A.F., Bennett, T.M., Woolft, N.K., & Axelsson, A. (1994). Protection from noiseinduced hearing loss by prior exposure to a nontraumatic stimulus: Role of the middle ear muscles. Hearing Research, 72(1-2), 23-28. Sahai, Dru. (2006). How to prevent noise induced hearing loss in construction. Construction Health. hearing.htm. Accessed January 2007. Sataloff, R., & Sataloff, J. (2004, June 1). Occupational hearing loss: An interdisciplinary challenge. ENT: Ear, Nose & Throat Journal, pp. 377,377. Seidman, M.D. (1999). Noise-induced hearing loss (NIHL). Volta Review, 101(1), 29. Seidman, M.D., Kahn, M.J., Bai, U., Sh irwany, N. & Quirk, W. S. (2000). Bilogic activity of mitochondrial metabolites on aging and aged-related hearing loss. American Journal of Otology, 21, 161-167. Seixas, N.S., & Neitzel, R. (2003). Noise on the job can damage your hearing: Bricklayers, carpenters, cement masons, electricians, in sulation workers, ironworkers, laborers, masonry restoration workers, operating engi neers, sheet metal workers, tilesetters . University of Washington, Dept of Envir onmental and Occupational Health Sciences. 63


Stearns, M. (2000). Recognition, evaluation, and control . Occupational Health & Safety, 69(6), 97. Stephenson, C. M. (2003). Choose the hearing protecti on that’s right for you . NIOSH Safety and Health. niosh/topics/noise/abouthlp/ chooseprotection.html. Accessed January 2007. Turney, T. (2006). Sound practice. Occupational Health, 58(4), 13-13. Weisskopf, P., Boone, J., Kopke, R.D., Jackson, R ., Wester, D., Hoffer, M.E., Al ford, K., & Lambert, D. (1999). Reduction of noise-induced hear ing loss using antioxidants. Association for Research in Otolaryngology, St. Petersburg Beach, FL. White, D.R., Boettcher, F.A., Mile s, L.R., & Gratton, M.A. (1998). Effectiveness of intermittent and continuous acoustic stimul ation noise induced hearing and hair cell loss. Journal of the Acoustical Soci ety of America, 103(3), 1566-1572. 64


BIOGRAPHICAL SKETCH Erik W. Anderson was born on March 14, 1984 in Palm Beach Gardens, Florida. He was the first son and second child born to William L. Anderson and Taryn G. Kryzda. He received his high school diploma from Martin County Hi gh School in 2002. That year, he was accepted as a student of the University of Florida and move d to Gainesville, Florid a. In 2006, he received his Bachelor of Science in Building Construction from the M.E. Rinker, Sr., School of Building Construction at the University of Florida. He entered the combined degree program of the M.E. Rinker, Sr., School of Building Construction and received a Master of Science of Building Construction in 2007. 65