Construction work has historically been among the most dangerous of occupations, and injury and fatality rates for the construction industry are often several times higher than those of all industries combined (Welch & Hunting, 2003). In the past few decades, however, tremendous progress has been made in construction safety, and injury and accident rates have reduced (Welch & Hunting, 2003). With the reduction in acute hazards on construction sites, the focus of safety and health efforts has shifted towards developing a better understanding of the risk of chronic occupational illnesses often associated with construction, including noise-induced hearing loss (NIHL).
Construction work is dynamic in nature, with constantly changing jobsites and a highly transient workforce. This makes the assessment of occupational noise exposure - and the prevention of subsequent NIHL - difficult in this industry. Until relatively recently, few data were available regarding exposure levels and the prevalence of NIHL in the construction industry. Fortunately, a number of research studies have focused on these issues in recent years. This paper provides an overview of the regulations and recommended standards that pertain to hearing conservation in the construction industry, construction noise exposure levels, use of hearing protection by construction workers, and NIHL among construction workers. Finally, recommendations are made for hearing loss prevention practices for the construction industry.
Construction Noise Regulations and Standards
Occupational health regulations governing the construction industry, including those pertaining to hearing conservation, are generally less comprehensive than those for the general industry. As a result, health surveillance and preventive programs for chronic diseases such as NIHL are limited in the industry. The US Occupational Safety and Health Administration (OSHA) has two regulations pertaining to hearing conservation in the construction industry. The first, 29 CFR 1926.52, sets forth an eight-hour time-weighted average (TWA) permissible exposure limit (PEL) of 90 dBA and requires a hearing conservation program (HCP) for workers whose exposures exceed this level. The second, 29 CFR 1926.101, requires the use of hearing protection devices (HPDs) when noise exposures cannot be reduced below the PEL.
There are two main similarities between construction regulations and the general industry hearing conservation regulations (29 CFR 1910.95). First, they share the same 90 dBA PEL and requirements for HPDs and an HCP for overexposed workers. Second, both the construction and general industry standards use a 5 dB time/intensity trading ratio (also referred to as an exchange rate), meaning that a 5 dB increase or decrease from the 90 dBA PEL requires a halving or doubling, respectively, of the allowable exposure duration (e.g. a 4-hour PEL at 95 dBA, a 2-hour PEL at 100 dBA, a 1-hour PEL at 105 dBA, and so on). From this point, the similarities end. Whereas the general industry regulation specifies five critical HCP components (noise monitoring, audiometric testing, noise controls, employee training, and use of HPDs) (Stewart, 2000), the construction regulation simply requires "a continuing, effective hearing conservation program," and provides no guidance or specifications as to what such a program entails. Additionally, the general industry regulation specifies an 85 dBA action limit (AL);workers with exposures exceeding this level must receive training and be offered HPDs and audiometric testing. The construction industry regulation specifies no AL.
The US National Institute for Occupational Safety and Health (NIOSH) has a recommended standard for all industries, including construction (Centers for Disease Control and Prevention/NIOSH publication 98-126). This standard specifies an 85 dBA recommended exposure limit (REL), and makes specific recommendations on the five key elements of an effective HCP (noise monitoring, audiometric testing, noise controls, employee training, and use of HPDs) (Stewart, 2000). In addition to using a lower exposure limit than OSHA, the NIOSH standard uses a more protective 3 dB exchange rate that results in shorter allowable exposures at high noise levels than those of the OSHA regulation. For example, OSHA permits an exposure to 105 dBA for one hour per day, whereas NIOSH recommends that such an exposure last less than 5 minutes (Figure 1). NIOSH estimates that approximately 1 in 4 workers exposed at the 90 dBA OSHA PEL eight hours per day over a 40 year working lifetime will suffer a compensable hearing loss from noise, compared to only about 1 in 12 workers exposed at the 85 dBA NIOSH REL.
Figure 1. Comparison of OSHA and NIOSH allowable exposure durations at various exposure levels.
Hearing conservationists may be surprised to learn that neither the OSHA nor the NIOSH limit is designed to protect every worker from suffering any NIHL;however, the NIOSH standard is the more health-protective limit of the two and is consistent with the exposure guidelines used by most scientific and regulatory bodies internationally. OSHA has acknowledged the need for a more comprehensive hearing conservation regulation for construction, and the agency began the lengthy process of revising its current standard in 2002 (OSHA, 2002). A new standard from the American National Standards Institute (ANSI), ANSI A10.46-2007 Hearing Loss Prevention for Construction and Demolition Workers, may serve as a useful template for OSHA as it works to revise its existing construction hearing conservation regulations.
Noise Exposures in Construction
The assessment of construction workers' noise exposures is problematic, because workers often do several tasks in a single workshift, and their work activities change from shift to shift. In addition to these worker-specific changes, construction sites evolve radically over time. These factors make the collection of accurate and comprehensive exposure data time-consuming and difficult. There are few historical data available regarding the noise in construction;however, several early studies in the 1960s and 1970s documented high levels of exposure among operating engineers (LaBenz, Cohen, & Pearson, 1967) and sheet metal workers (Kenney & Ayer, 1975). In 1981, the US Environmental Protection Agency (EPA) estimated that 513,000 construction workers were exposed to noise levels over 85 dBA (NIOSH, 1998). Of the approximately 5 million construction workers in the US in 1995, about 754,000 were estimated to have the potential to be exposed over 85 dBA. Concrete work, carpentry, and highway construction were the industry sectors estimated to have the highest percentages of overexposed workers (Suter, 2002).
The University of Washington (UW) has been collecting data on noise exposures in a variety of construction trades since 1997 (Neitzel, Seixas, Camp, & Yost, 1999;Reeb-Whitaker, Seixas, Sheppard, & Neitzel, 2004;Seixas, Ren, Neitzel, Camp, & Yost, 2001). The mean noise exposure level across 557 full-shift noise measurements (measured according to the NIOSH criteria) on nine construction trades was 87.4 dBA, and about two-thirds of all measured construction shifts had full-shift average levels that exceeded the 85 dBA NIOSH REL (Neitzel & Seixas, 2005) (Table 1). Between 15 and 49% of the time in each shift was spent above 85 dBA, indicating that potentially hazardous noise levels occurred during a substantial fraction of each measured workshift. Trades with the highest full-shift exposure levels were ironworkers, carpenters, masonry workers, and operating engineers. Even "quiet" trades that do not regularly work directly with noisy tools or equipment (e.g., electricians) were frequently overexposed to noise, indicating that exposures from nearby work can contribute significantly to workers' exposures. Taken in sum, available data demonstrate a substantial risk of exposure to high levels of noise among workers involved in a wide variety of construction operations and activities.
Table 1. Construction noise exposures and overexposures overall and by trade (Adapted from Neitzel & Seixas, 2005).
Noise-Induced Hearing Loss in Construction
As with information on noise exposures in construction, there are few historical data available on NIHL among construction workers. An early study of Swedish construction workers found that in 1974 only one in five construction workers had hearing within normal limits at age 41 (CPWR, 2002). The Workers Compensation Board of British Columbia (WCB BC) began testing the hearing of construction workers in the 1980s, and initial testing results showed that nearly 50% of 5,000 workers tested had compensable NIHL (Schneider, Johanning, Belard, & Engholm, 1995). Additional tests by the WCB BC in 1989 showed that 22% of tested construction workers had severe to profound hearing loss (Schneider et al., 1995). A more recent survey of more than 3,000 construction workers employed by the US Department of Energy found that about 60% of tested workers had a material hearing impairment (Dement, Ringen, Welch, Bingham, & Quinn, 2005). Researchers at UW have assessed the hearing ability of a prospective cohort of several hundred young construction workers and have found measurable losses of hearing function among workers in their first several years of construction employment (Seixas et al., 2005).
Another group of UW researchers analyzed workers compensation claims for NIHL in the state of Washington from 1984-1998 (Daniell, Fulton-Kehoe, Cohen, Swan, & Franklin, 2002). Over that period, the incidence of hearing loss claims filed by construction workers in any construction sector was between 9 and 13 claims per 1,000 full-time equivalent (FTE) workers per year;however, several construction sectors had claim rates that were greater than 25 per 1,000 FTE-years. For comparison, the incidence rate across all Washington industries was less than 3 claims per 1,000 FTE-years. Construction workers, who represented about 7% of Washington state employees from 1992-1998, filed more than 20% of all NIHL claims during that period. Overall, the available data on NIHL in the construction industry indicate that this completely preventable occupational disease is quite widespread.
Use of Hearing Protection by Construction Workers
Although noise exposure assessment is difficult in the construction industry, many contractors acknowledge the potential for workers to have high noise exposures and make HPDs available to workers. Despite the provision of HPDs on many worksites, however, available data indicate that HPD usage rates remain quite low. In one study, carpenters and plumbers/pipefitters in the US Midwest self-reported use of hearing protection 17% and 38% of the time they spent in high noise at their previous work site, respectively (Lusk, Kerr, & Kauffman, 1998). In their analysis of 557 construction workshifts, UW researchers found that workers spent almost one-third of the time in a shift over 85 dBA on average (Table 1), but HPDs were used less than 20% of the time in noise above 85 dBA (Neitzel & Seixas, 2005). In addition, HPD use was found to vary widely by trade. For example, operating engineers had the highest average full-shift exposure level;however, they also used HPDs most often during high noise. Ironworkers had the second highest average percent of time within each shift spent in levels above 85 dBA, but they had among the lowest HPD usage rates.
As part of the same study, HPD attenuation was tested on a group of construction workers. The average amount of attenuation received by the workers was about 20 dB, which is a substantial fraction of the labeled noise reduction rating (NRR) on the HPDs tested. This indicates that construction workers can receive adequate attenuation from HPDs when protectors are used. However, given the small amount of time that HPDs are actually worn, the study authors estimated that, on average, workers receive only a 3 dB reduction in their full-shift average noise level from their use of HPDs. Trades that wore protectors more often, such as operating engineers and sheet metal workers, had greater estimated reductions in their full-shift exposure levels (11 and 7 dB, respectively). In contrast, trades that wore HPDs less often, such as electricians and insulation workers, had reductions of less than 1 dB. Until usage rates increase, HPDs cannot be relied upon to prevent NIHL in construction workers.
Preventing Hearing Loss In Construction Workers
The data described above demonstrate a clear need for improved hearing loss prevention efforts in the construction industry. To prevent NIHL among construction workers, several critical aspects of hearing loss prevention must be considered. These include development and implementation of noise controls, delivery of hearing conservation training, and proper use of hearing protection. In addition, audiometric surveillance is an important hearing conservation activity;however, the transient nature of the construction workforce makes it very difficult to conduct. It is worthwhile to note that the construction hearing conservation regulation enforced by the WCB BC is widely considered to be the most successful in the world, and it relies on a centralized audiometric testing and data management program coordinated by the provincial government (Suter, 2002). This centralized program is funded by workers compensation premiums paid for by all construction employers. This approach is rather different than that in the US, where individual contractors have to test employees that, in some cases, may only work for them for a few days.
In the US, audiometric testing in construction remains problematic, and information on NIHL prevalence in construction is lacking as a result. However, the absence of audiometric testing in construction hearing conservation programs does not diminish the preventive potential of the programs;rather, it eliminates a potential mechanism to track program effectiveness and manage NIHL claims. Although audiometric testing among US construction workers clearly needs improvement, noise controls, training, and use of hearing protection all play a critical role in reducing NIHL in the construction industry, and the remainder of this report emphasizes these preventive activities.
Noise controls
Noise controls are changes to the workplace or to tools and equipment which result in reductions in workers' exposure levels. These types of controls have not been commonly used in the construction industry due to a perception that they are very costly and difficult to implement at a worksite that is constantly changing;however, there are some noise control techniques which can be inexpensively implemented in construction operations. Noise control techniques are divided into engineering strategies (which alter the workplace or equipment) and administrative approaches (which alter the way in which work is performed).
One available engineering noise control strategy is to modify or retrofit equipment. This can include adding mufflers to unmuffled exhaust systems on heavy equipment and using noise-dampened saw blades on power saws. Loud equipment can also be replaced with quieter equipment as part of a "Buy Quiet" program;as a rule thumb, smaller tools make less noise than larger tools of the same type. Some manufacturers are beginning to make the noise levels associated with their tools available to the public, which can help in the selection of quieter equipment. Barriers or enclosures are another type of control that can be used;for example, heavy equipment should have enclosed cabins to protect the operating engineers running the equipment. In addition, plywood barriers can be built around noisy equipment such as compressors or generators to prevent the equipment noise from traveling throughout the site. Finally, relocating equipment can be a very effective and inexpensive control. Doubling the distance between a worker and a noisy piece of equipment can reduce that worker's exposure level by 3-6 dBA, which is a substantial reduction, given that many overexposure situations in construction work involve levels that are only a few dBA over the allowable limit (Neitzel & Seixas, 2005).
Administrative noise controls involve changes to the way work is conducted in order to reduce associated noise exposure levels. These changes can involve posting signs warning workers to keep out of high noise areas (e.g. parts of a construction site where equipment such as generators or compressors are located) or that HPDs are needed near certain high-noise operations. Another type of administrative control is job rotation, where workers are rotated between jobs involving high and low levels of noise. Workers should take breaks in low-noise areas when possible to avoid unnecessary exposure. Construction activities with very high noise levels (above 105 dBA) and correspondingly low allowable exposure durations may need to have set limits specifying how long that activity can be conducted by an individual worker. Finally, high noise operations can sometimes be scheduled to take place at a time or on a day when the fewest number of workers will be onsite and exposed.
Hearing protection
Although the use of hearing protection among construction workers is currently low, there is research that suggests hearing protection has the potential to effectively reduce construction workers' noise exposures to safe levels. As mentioned previously, research at UW has demonstrated that workers can achieve more than 20 dB of attenuation by wearing earplugs (Neitzel & Seixas, 2005). If workers used HPDs 100% of the time that they are exposed to noise over 85 dBA, this amount of attenuation would be adequate to protect the vast majority of construction workers. Even assuming that workers only achieve half of the labeled NRR of the HPD they use, 95% of all construction workers would be adequately protected from noise with an NRR of 26 dB (Seixas & Neitzel, 2004). Having a selection of HPDs (including formable earplugs, premolded earplugs, earmuffs, and semi-insert ear caps) available to workers is essential, because not all workers will find a single type or model of HPD to be acceptable. In addition, many workers have exposures that are only a few dBA over the allowable exposure limit;therefore, making at least one lower-NRR HPD available will help workers avoid being overprotected (i.e., achieving attenuation that is greater than needed leading to a subsequent reduction in the ability to communicate or hear important sounds).
Training
Although it is often overlooked or given only cursory attention, training is a critical element in any hearing loss prevention program. In addition, a number of studies have demonstrated that training can improve HPD use rates among construction workers. In 1999, Lusk et al. described a theory-based intervention consisting of a video, pamphlets, and a guided practice that significantly increased self-reported use of HPDs among US construction workers. Another study found that a training program consisting of a video, booklet, and group activities also substantially increased the use of HPDs among Australian construction workers (Dineen, Reid, & Livy, 1998). A third study found that the attenuation achieved with two different types of hearing protection was significantly greater after a short multimedia training program (Joseph et al., 2007). Finally, UW researchers developed a live hearing conservation training program for the construction industry (available online at depts.washington.edu/occnoise/hc_training.pdf). The results of a pilot test of this training program on a single site showed a significant increase in the amount of time HPDs were used (Neitzel et al., 2008). A separate study of the training program found it to be equally effective regardless of whether it was delivered by a hearing conservation professional or construction safety personnel (Trabeau, Neitzel, Meischke, Daniell, & Seixas, 2008). All of the successful training programs described above included a trial and fitting of HPDs, and any hearing conservation training program should include these elements to insure that workers are familiar with available protectors and able to wear them properly.
Conclusions
Noise and NIHL represent a serious health hazard in the construction industry. Noise exposure levels are often quite high among construction workers, and few, if any, trades are exempt from the potential for overexposure to noise. NIHL is common in the industry, and the use of hearing protectors, which is the traditional approach to exposure reduction in the industry, is generally low. Efforts to reduce noise and subsequent NIHL in this industry should focus on implementation of noise controls, improved worker training, and proper use of HPDs. Although NIHL is a completely preventable occupational disease, without these efforts the burden of NIHL in this industry will remain high.
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