Noise, Hearing Protector Use, and Hearing Loss in American Workers
SangWoo Tak, ScD, MPH
NIOSH has recently published two studies that estimated the prevalence of hearing difficulty, workplace noise exposure, and non-use of hearing protection device (HPD) among U.S. workers using nationally representative survey data collected from 1997 through 2004. These analyses showed that more than 22 million U.S. workers were exposed to hazardous workplace noise (noise loud enough to require a raised voice to be heard). Over 7 million of these noise-exposed workers (34%) reported that they never used hearing protectors when working in noisy environments. Finally, 12.2 million current U.S. workers (11.4%) have at least some self-reported hearing difficulty. Of these, 3.3 million (24%) are considered to have occupational hearing loss (Tak and Calvert 2008; Tak et al. 2009). Higher prevalence of hearing difficulty was found in several industries, including: mining, manufacturing, construction, agriculture, forestry and fishing, railroads, utilities, trucking service and warehousing, and repair services. Some industry sectors and occupation groups were also found to have significant risk of exposure to hazardous workplace noise. The following statistics are the industry-specific findings from our two studies.
Mining
Workers in the mining industry had the highest prevalence of workplace noise exposure; almost three out of four mining
industry workers are exposed. The mining industry has the second highest prevalence of hearing difficulty among all
industrial sectors. Although few miners reported non-use of HPDs, the high prevalence of hearing difficulty (24%)
suggests that further efforts are needed to protect workers’ hearing in this industry.
Manufacturing
Over one third of all manufacturing workers (5.7 million workers total) reported exposure to loud noise. The manufacturing industry is divided into many subsectors. Most manufacturing industry subsectors had a higher prevalence of loud noise exposure compared to workers in all industry sectors combined. Notably, one in two workers in the lumber and wood product, and rubber, plastics, and leather products manufacturing industries were exposed to hazardous workplace noise. Overall, one in four manufacturing workers exposed to loud noise reported non-use of HPDs. The highest prevalence of hearing difficulty was reported from workers in the primary metal manufacturing industries (22%). Furniture, lumber, and wood manufacturing workers had the second highest prevalence of hearing difficulty.
Construction
Approximately 4.5 million construction workers reported exposure to loud workplace noise. Unfortunately, almost one
in three of these noise exposed construction workers reported that they never use HPDs at work. Hearing difficulty was
reported from one in seven construction workers (15%). About 30% of these construction workers with hearing difficulty are
estimated to have occupational hearing loss.
Transportation
Overall, workers employed in the transportation industries are at a high risk of workplace noise exposure; almost one
out of three workers are exposed. Transportation and material moving occupations (other than motor vehicle operators) in
the transportation, warehousing and utilities industry showed the second highest prevalence of noise exposure (Three in four
workers in these occupations). Over 30% of these exposed workers reported non-use of HPDs. Our findings in the railroad
industry stood out for example; no other industry had a higher prevalence of hearing difficulty than the railroad industry (35%) after adjusting for other individual factors. Motor vehicle operators and material moving equipment operators in other
industry sectors, such as mining, manufacturing, construction, were also among the occupations with the highest prevalence
of hearing difficulty. Noise exposures and hearing loss among rail yard and railway workers have been long understudied. Our
results further justify the need to both confirm the magnitude of noise exposure and prevent hearing loss in the transportation industry, and in railroads in particular.
Agriculture
Workers in agriculture, forestry, and fishing industries also had a high prevalence of exposure to hazardous workplace
noise (43.3%). One in four workers in this industry sector reported non-use of HPDs. While only 11% of farm workers
and agricultural workers reported hearing difficulty, farm operators and managers and forestry and fishing occupations
had the second highest prevalence (22%) of hearing difficulty compared to all other occupational categories. This may be
because farm operators and managers operate or work in proximity to mechanized farm equipment which is likely to be the source of noise exposure in this industry.
Repair and maintenance service
The repair and maintenance service industry is at high risk of workplace noise exposure. Almost one in two workers in this industry reported exposure to loud noise. Over 40% of those who are exposed to loud noise reported non-use of HPDs.
No previous study is available to specifically estimate noise exposure levels among workers employed in this industry. Note
that this industry does not include all establishments that do repair and maintenance, for example, a large amount of repair is done by establishments in the manufacturing, construction and transportation sectors. Mechanics and repairers are also captured as an occupation category (i.e. vehicle and mobile equipment mechanics and repairers). Mechanics and repairers are at high risk of hearing impairment across a variety of industries. For example, over 60% of mechanics and repairers with hearing difficulty in manufacturing, transportation, communication, and public administration industries are considered to have occupational hearing loss. There has been no study addressing noise exposure levels and occupational hearing loss among
those in this occupation. There are possible explanations for the high rates of hearing difficulty among mechanics and
repairers. Mechanics and repairers are potentially exposed to high noise levels due to the nature of their work. Mechanics
in the heavy equipment manufacturing industry, for example, use a variety of pneumatic tools that generate high noise levels.
Because mechanics and repairers often need to hear and detect the unusual noises coming from machinery or equipment to
diagnosis mechanical problems, they may not consistently use hearing protection devices. Further surveillance and intervention efforts should be focused on this industry.
A new NIOSH Surveillance effort
Surveillance of occupational hearing loss and noise exposure is vital to prevention because it can identify the most problematic industries, occupations and work activities, and because it can be used to evaluate the effectiveness of intervention activities. The National Academies Institute of Medicine evaluated the NIOSH Hearing Loss Research
Program in 2005 and concluded that the program could not establish and prioritize research goals due to the lack
of surveillance data on occupational hearing loss and noise exposure for U.S. workers. One of our first responses was to
publish the two articles described in this report. NIOSH is planning to develop and conduct an ongoing surveillance program of occupational hearing loss in collaboration with audiometric services providers. NIOSH will develop a database and protocols to manage and analyze de-identified individual level audiometric data. Data from this surveillance effort will be used in several important ways. It will help to identify emerging hearing loss problems, including those associated with new industries, new technologies, or new pieces of equipment. The analysis of the data will also produce national reference statistics for the incidence (or prevalence) rate of occupational hearing loss across industry and occupations.
NIOSH plans to recruit three providers by October 2009 and, by 2012, plans to have a total of 15 providers participating in this surveillance program. For more information about this surveillance program or if you are interested in participating in the surveillance program, please contact me directly at (513)458-7117 or email: STak@cdc.gov.
References
- Tak, S., Davis, R., & Calvert, G. M. (2009). Exposure to hazardous workplace noise and use of hearing protection devices among US workers—NHANES 1999-2004. American Journal of Industrial Medicine, 52(5), 358-371.
- Tak, S., & Calvert, G. M. (2008). Hearing difficulty attributable to employment by industry and occupation: an analysis of the National Health Interview Survey–United States, 1997-2003. Journal of Occupational and Environmental Medicine, 50(1), 46-56.
SangWoo Tak is an epidemiologist in the Surveillance Branch of the National Institute for Occupational Safety and Health—NIOSH