The findings of this study—20 years after OSHA implemented hearing conservation regulations—raise serious concerns about the adequacy of contemporary OHL prevention, regulation, and enforcement strategies in the United States. In this broad sample of companies from eight industries with variously high rates of OHL claims, nearly all of the companies had employee exposures that required a hearing conservation programme, and more than half had exposures that required the employer to consider possible noise controls. The percentage of workers with full‐shift exposures over 85 or 90 dBA would have been 1.5–3 times higher if noise measurements had used a 3 dB exchange rate rather than the OSHA 5 dB exchange rate. Although most companies had measured noise levels, few had kept any records on which to base current or future actions, and the possibility of new noise controls generally received low priority. Furthermore, most companies had potentially important shortcomings in their hearing conservation programmes, and each industry included companies where policies and practices were substantially incomplete. Finally, personal hearing protection was commonly under‐used.
Overall, only 62% of interviewed employees said they always (or almost always) used hearing protection when they were exposed to loud noise. This is comparable to what other investigators have found,7,8,9,16
and systematic observations in this study indicated that reported use is a reasonably accurate measure. The percentage of employees who always used protection when exposed differed widely between industries and between companies within the same industry. The frequency of protector use was significantly higher at companies where noise exposures were higher and more common. It is not surprising that workers would be more likely to wear protection in higher noise, if only to reduce ear discomfort from the noise, but perhaps also because hearing conservation programmes tended to be more complete (that is, management interview scores were higher) when noise exposure was more common. Ironically, workers with the greatest risk for OHL may be those employed at companies where a moderate or low percentage of workers are overexposed to noise but use of protection is low, rather than at companies where noise is most prevalent and protector use is higher.
Independent of noise levels, the use of protection was significantly higher at companies with more complete hearing conservation programmes, particularly those where protector use policies were actively promoted or enforced, and use of protection was lower at companies with less complete programmes. Employee awareness of hearing loss prevention efforts in general (that is, employee interview scores) also tended to be higher at companies with more complete programmes. Lusk and co‐workers have identified a variety of cognitive‐perceptual and situational factors that influence reported use of hearing protection.17,18,19
However, innovative efforts to redesign training around that knowledge have had limited impact on protector use.20,21,22,23,24
The findings of the present study emphasise that employee under‐use of protection is, in some substantial part, attributable to incomplete or inadequate company efforts. Interventions to improve use of hearing protection may need to focus on the company as well as workers.
Federal OSHA (but not Washington State OSHA) enforcement policy “allows employers to rely on personal protective equipment and a hearing conservation programme rather than engineering and/or administrative controls...[unless] employee exposure levels border on 100 dBA”.25
Given this tolerance for levels of noise that, without hearing protection, are potentially harmful, the primary reliance on hearing conservation programmes and personal protection can only be effective at preventing OHL if efforts are continually and optimally maintained. The present study did not evaluate the true preventive effectiveness of current workplace efforts; this can only be judged by long term monitoring of worker hearing ability. However, the extent of protector under‐use in this study suggests a substantial fraction of workers in noisy workplaces are at risk for OHL.
It is reassuring that the studied outcomes were highest at companies with the highest commitment to hearing loss prevention, indicating that hearing conservation programmes are probably worth the effort; however, the potential benefit appears proportional to the level of company effort. Unfortunately, programmes were commonly incomplete at companies in all of the studied industries, with the relative exception of lumber milling. Most of the study companies had been inspected by State OSHA at some point in time, but only 9% received a citation related to noise or hearing conservation, and neither a past inspection nor citation was associated with current programme completeness or use of hearing protection. These findings suggest the regulatory priority given to personal protection and hearing conservation programmes needs to be re‐evaluated. There is a need either for increased regulatory enforcement or consultation to make this strategy effective or for greater emphasis on reducing levels of noise.
- Using an exchange rate of 5 decibels instead of 3 decibels to measure full‐shift average noise exposure substantially underestimated the extent of worker overexposure.
- At least in one region of the United States, small and medium sized companies commonly gave limited or no attention to noise controls to reduce worker noise exposure.
- After 20 years of OSHA regulations, hearing conservation programmes were commonly incomplete and hearing protection was often under‐used at small and medium sized companies.
- Use of hearing protection was highest when company hearing loss prevention efforts were most complete and when noise exposure was relatively high or continuous.
There are a number of limitations to the present study. The company and employee samples could reflect a volunteer bias. However, we believe any such bias is predominantly non‐differential relative to the studied exposures and outcomes, and is more likely to diminish rather than inflate or distort study findings relative to the true occurrence in the underlying population. Efforts were made to obtain a population based sample of companies, but only about half of the approached companies participated in the study, and some companies belonged to the same corporation. Recruitment was lowest in the three industries (including pulp and paper production) with highest incidence of hearing loss claims, suggesting participation may have been influenced by claims experience. However, it seems unlikely that otherwise “good” companies with complete hearing conservation programmes would be less willing to participate than companies with incomplete programmes, or that any such bias would differ substantially between industries. Similarly, to minimise interference with production activities and ensure optimal company cooperation, employee recruitment relied primarily on volunteer and company designated employees. However, employee selection was designed to be representative of employees in noise exposed jobs, and the rate of participation by approached employees was high. As with companies, we consider it more likely that employees with good practices would be willing to participate than those whose practices were lacking. The exclusion of workers who did not speak English or Spanish could result in underestimation of the OHL risk for some minority workers if there were differences in either the jobs to which they are usually assigned, their ability to comprehend company training or policies, or the prevalence of pre‐existing hearing problems. However, more complete representation of this small minority would be unlikely to substantially alter the study findings. Finally, it is reassuring that the rates of company and worker participation were comparable to those in a recent Danish study that used a comparable strategy to recruit 91 workplaces in 10 industries with very high incidence rates of suspected OHL.16
The findings of that study were also comparable in that 50% of 830 monitored workers had full‐shift average noise exposures >85 dBA, and 20% had exposures >90 dBA. Overall, about half of workers reported using hearing protection, ranging from 37% of workers in the lowest use industry (furniture production) to 85% in the highest use industry (basic metal manufacturing).
The present study sample primarily consisted of small and medium sized companies and may have limited or no generalisability to larger companies. On the other hand, the needs of smaller and medium companies are generally under‐addressed by OSHA, given the number of such companies. In Washington State, employer businesses with <250 employees account for >99% of establishments and 72% of non‐federal employees.26
The findings of the present study may have limited applicability to companies in other parts of the USA, and even less applicability in other countries where different regulations apply, although this is probably more true for specific findings than for the more general findings and conclusions.
- The regulatory priority given by OSHA to personal protection and hearing conservation programmes, and relative inattention to noise controls, needs to be re‐evaluated.
- Worker under‐use of hearing protection is, in some substantial part, attributable to incomplete or inadequate company efforts. Interventions to improve use of hearing protection may need to focus on the company as well as workers.
- Workers with the greatest risk for hearing loss may be those employed at companies where a moderate or low percentage of workers are overexposed, than at companies where noise is more prevalent.
The present study examined programme completeness and use of hearing protection, which is not equivalent to programme effectiveness. It is not possible to say how much incompleteness is needed before a programme is ineffective, or vice versa; however, the strong association between programme completeness and use of protection indicates the former is at least meaningful on a relative scale. Finally, the study relied primarily on reported outcome measures. The consistency between company and employee responses, as well as the high level of agreement between reported and observed use of protection, provides some reassurance that these measures are meaningful.
The potential implications of this study are broader than just noise exposure and hearing loss. There are fewer gaps in knowledge about OHL than for virtually all other occupational illnesses, and the primary barriers to prevention lie in implementation of that knowledge. If workers cannot be effectively protected against the development of OHL, then one must question how well workers are protected against other, more complex or less well understood hazards.