OSHA's first line of defense against hazardous noise involves engineering and administrative controls on equipment or manufacturing processes. If these fail, the Occupational Noise Exposure Standard and Hearing Conservation Amendment (29 CFR 1910.95) outlines a rigorous, employee-oriented program to mitigate risks of noise exposure in the workplace.
The standard mandates that personal protective equipment shall be provided and that employers administer a continuing, effective hearing conservation program when employee exposure levels equal or exceed an 8-hour time-weighted average sound level (TWA) of 85 dBA. A common rule of thumb to determine when hearing protection is needed is that if you have to shout over the background noise to communicate with someone an arm's length away, the noise level probably is hazardous. OSHA, however, requires noise monitoring when exposure levels in the workplace “equal or exceed” the 85 dBA action level.
Monitoring
Monitoring requires the use of sound level meters to sample area noise and dosimeters to record an employee's noise exposure. While area sampling provides a good understanding of general noise levels throughout a facility, personal dosimetry documents an employee's complete exposure during the course of his or her workday. As employees move about during the day and are exposed to a variety of noises and noise levels, dosimetry provides the best indication of an individual's TWA.
In-house staff can perform monitoring, as long as the equipment properly is calibrated to ensure accuracy. However, many companies contract with outside surveillance consultants or utilize their own liability insurers to perform this service and make appropriate recommendations.
Noise monitoring must be performed any time there is a noticeable change in machinery or manufacturing processes, whether the noise levels increase or decrease. Posting a “noise map” of the facility in an accessible location gives employees a visual reference of areas where hearing protection devices (HPDs) must be worn, and identifies other areas where it is a good idea to keep HPDs handy. Posting specific decibel levels in work areas also helps employees select the right protector for their application.
Audiometric Testing
According to the OSHA standard, all new employees are required to undergo an audiometric test within 6 months of hire, and all noise-exposed employees must be tested annually. Individual results are compared from year to year to determine if hearing has remained stable or changed.
Audiometric testing must be conducted by a trained professional, and can be done in-house or outsourced to industrial clinics and audiology practices. Many practices offer mobile testing services that suit a wide variety of company sizes and schedules — especially if a company works three shifts — to minimize employee downtime. The National Hearing Conservation Association maintains a list of competent mobile testing services (http://www.hearingconservation.org).
Include the TWA of an employee's noise exposure in his or her job description or employment file. This can help an audiologist better understand an employee's occupational noise history when interpreting audiograms. Make certain your testing service provides the required baseline comparisons, and that the follow-up reports are understandable. You also are required to maintain all documentation, but more on recordkeeping later.
While audiometric technicians can administer an audiogram, only audiologists, otolaryngologists and physicians may interpret the test results. Often, these providers can send out any notifications as required by the OSHA standard. Research shows that when employees receive copies of their audiograms or explanations of the results at the time of testing, rates of noise-induced hearing loss decrease.
Training
To comply with the standard, all employees exposed to the 85 dBA action level must receive annual training, which includes information on the effects of noise exposure; the use, selection and fitting of hearing protectors; and audiometric testing procedures. Traditionally, this has been performed via group sessions, conducted by safety managers, industrial hygienists, occupational health nurses and hearing conservation professionals using videos, posters and other educational and motivational materials. Hearing conservation training helps employees recognize hazardous noise situations at work and at home, and encourages them to protect themselves appropriately.
Recent studies on the real-world attenuation of hearing protectors worn on the job suggest that one-on-one training may be most effective. It long has been recognized that the best time to motivate employees to use hearing protection is immediately after their audiometric tests, when they actually can see the results. A recent study conducted by the Howard Leight Acoustical Labs takes this idea a step further.
The study was conducted with more than 100 employees at eight different facilities. Employees were tested during their standard shifts. They were not pre-screened, and were tested with their own earplugs that they routinely wore on the job, with no modifications. The tested earplugs were from four different manufacturers, and employees received no training or coaching as part of the test. They simply were asked to insert the earplugs as they normally did on the job. No feedback or correction was offered if they fit the earplug incorrectly.
The results (Figures 1 and 2) showed a direct correlation between earplug fit and effective attenuation. One-third of employees achieved attenuation higher than published noise reduction ratings (NRR) for their earplugs. Another third achieved attenuation within 5 dB of those ratings, while only the bottom third had attenuation that was more than 5 dB below published NRRs.
By identifying the factors that contributed to good earplug fit, and hence, good attenuation in use, only one-on-one training had a strong correlation. The more often an employee received individual training in the proper use of hearing protectors, the higher the probability that employee would achieve a good fit.
An effective hearing conservation program should include a high proportion of individual fit training sessions. Group training also should include motivational materials to help make the case that employees are susceptible to noise damage, demonstrate the risk of hearing loss and encourage employees to wear hearing protectors both on and off the job.
In addition to formal training, hang motivational and informational posters in common areas or near hearing protection sources. These can include fitting instructions, noise thermometers and posters visually demonstrating the effects of NIHL. Many HPD manufacturers offer such posters for free or make them available online as PDFs. These can provide additional reinforcement on the importance of hearing protection and conservation.
Hearing Protection
OSHA requires employers to provide employees with a “variety of suitable hearing protectors” — earplugs or earmuffs — whenever noise levels meet or exceed the 85 dBA TWA. Employees with normal hearing are required to wear HPDs when exposure levels reach 90 dBA, while employees with an identified standard threshold shift (STS) must wear HPDs when noise exposure reaches 85 dBA.
While OSHA does not define the term “variety” (but recently has ruled that hearing protectors are to be provided at no cost to employees), it is a good practice to provide a robust selection of HPDs. Everyone's ears are different, and one earplug or earmuff style may not be comfortable for an entire workforce, nor relevant to all jobs or applications.
Another question posed by the study mentioned earlier was whether employees who achieved low attenuation with one type of earplug also would attain low attenuation with all types of earplugs. This was tested by inviting some employees to try a second, different pair of earplugs. Employees who tried a second pair of earplugs often had major leaps in attenuation, bringing them closer to the published NRR.
A wide variety of HPDs are available to meet specific applications or employee preferences, ranging from earplugs packaged in paper bags for process industries, to banded earplugs that can be inserted quickly during intermittent noise, to dielectric and cap-mounted earmuffs. Offer employees several different styles, including single- and multiple-use earplugs, as well as earmuffs. Also, include a group of employees from different areas in the selection process to improve employee buy-in and compliance.
It also is a good idea to make hearing protectors accessible. If employees cannot easily obtain a pair of earplugs or earmuffs, they most likely will go without. Simple actions, such as placing single-use earplug dispensers by main entrances to the job site, by the time clock or in the cafeteria or locker room, or keeping earmuffs at a supervisor's workstation, make access to HPDs more convenient and encourage compliance.
Encourage employees to take extra earplugs home. Noise-induced hearing loss is not solely a workplace issue; it also can occur off the job. Many employees use power tools, attend loud rock concerts or sporting events or participate in shooting sports — all opportunities for exposure to hazardous noise levels. Prevention is the key, on the job and off.
Finally, set a good example. Include all levels of management in the audiometric testing program and make sure managers and supervisors are proactive in wearing protection, even if they only are running out to the shop for a few minutes. When employees see the higher-ups taking their hearing seriously, it sends a positive message throughout the workforce.
Recordkeeping
The final component of OSHA's hearing conservation amendment discusses the employer's responsibility to maintain all records. While tedious, it makes good sense. Without accurate records, you have no way of assessing progress or rectifying problems. Thus, accurate records of noise exposure levels and of all audiometric tests must be kept. Don't forget to post a copy of OSHA's hearing regulations at the worksite. Nearly three-fourths of OSHA's recordkeeping violations in hearing conservation in the past 5 years were for not having a copy of the hearing conservation standard posted in the workplace. (The standard is available from OSHA at http://www.osha.gov, and a workplace poster about noise and hearing conservation is available at http://www.osha.gov/pls/publications/publication.AthruZ?pType=Industry&pID=145.)
The dictates of Occupational Noise Exposure Standard and Hearing Conservation Amendment (29 CFR 1910.95) are rather straightforward: employers who have work areas with noise levels above 85 dBA must implement a hearing conservation program in which employees exposed to those levels must undergo annual audiograms and be provided with hearing protectors and be trained in their use. To increase the effectiveness of an OSHA-approved hearing conservation program, focus on individual training, offer a wide variety of hearing protectors and make them accessible.
Make hearing conservation part of your corporate culture. Make it visible, make it mandatory and set a good example from top management on down.
Renee S. Bessette, COHC, is marketing manager for Sperian Hearing Protection LLC (http://www.sperianprotection.com).