In the 20-plus years since OSHA implemented detailed noise exposure regulations (29 CFR 1910.95), diligent employers and safety professionals have monitored noise levels, posted warning signs, purchased earplugs and routinely tested employees' hearing. If they've been especially diligent, they've also conducted training programs for new employees, put up posters and established product selection groups to improve employee "buy-in."
Yet, workers continue to suffer noise-induced hearing loss at alarming rates. The cost of noise-induced hearing loss in the United States is now measured in billions (not millions) of dollars annually. What's gone wrong?
Like bringing the proverbial horse to water, setting up a hearing conservation program is the easy part; getting workers to internalize it and act on it is another matter. Nor is the liability for hearing loss just limited to noise levels at the workplace: Risks for noise-induced hearing loss can be just as prevalent off the job as on the job, and are often a lot less noticeable.
Unlike many other occupational hazards (such as chemical or electrical exposures), there are few built-in safeguards or warning signs in off-the-job noise exposures. Lawnmowers, firearms, hobby tools, motor sports and personal music players can contribute to noise-induced hearing loss. At the workplace, the offending noisy equipment is clearly posted with warning signs; but the warnings on consumer products are often tucked away in an obscure, frequently skimmed-over section of the user's manual.
Why should an employer be concerned about an employee's noise exposure off the job? Aside from a healthier worker, liability is one major reason. OSHA-required audiometric testing of exposed workers does not differentiate between occupational and non-occupational noise damage, so employers assume much of the liability for off-the-job noise damage.
A safety manager might have the strictest of enforcement policies for hearing protection for 40 hours each work week, which is just 24 percent of an employee's week. That safety manager has absolutely no control over the remaining 128 hours of that worker's personal life in a world filled with 120 dB concerts and motor sport events, 130 dB chainsaws and gas-powered blowers and 160 dB firearms. The challenge is to instill a culture of hearing conservation that works on the job, but also carries over to the remaining 76 percent of that worker's life spent off the job.
Managers of effective hearing conservation programs recommend the following strategies to bridge that gap from workplace to personal life:
Know Your Decibels
The ear's receptor cells are indiscriminate. A masterpiece recording of a Bach concerto at 92 dB is just as damaging as the bone-rattling buzz of a workplace grinder at 92 dB. According to OSHA regulations, noise sources over 90 dB must be sign-posted at work, but there are no warning signs or safety lines painted on the floor for household or recreational noise.
Teach employees to use hearing protectors for off-the-job exposures (most employers openly encourage their workers to use the company-provided protectors for personal use during noisy off-job activities). Employees should be familiar with the rule of thumb for identifying hazardous noise: if you must shout to be understood by someone standing an arm's length away, then that background noise probably exceeds OSHA's 85 dB hazardous noise limit.
Remind your workers that noise-induced hearing loss is a balance between two quantities of the noise: intensity and duration. OSHA mandates a halving of the allowable exposure time for every 5 dB increase in the noise level: 8 hours for 90 dBA, 4 hours for 95 dBA and so on.
Many noise exposures that we consider loud (the soundtrack at a movie theater or the booming bass from the megawatt-powered sound system of the car next to us at the stoplight) are too short to cause hearing loss. They may be annoying, but not hazardous to us. Single exposures to 90 dB of noise, like a door slam, will generally not harm hearing. But a single unprotected exposure to a 160 dB gunshot can cause instant permanent damage because it can pack the noise equivalent of a 40-hour workweek in one pull of the trigger.
An earplug in an ear canal can offer anywhere between 0 dB and 40 dB of protection. Some of that is determined by the makeup and quality of the earplug, but by far the greatest influence on the protection offered by any earplug is proper fit. The amount of protection achieved is very literally in the hands of the user.
Fortunately, there are several tests to determine whether that earplug is doing its job. An earplug that is clearly visible from the front (looking at yourself in the mirror, or viewing the user face-to-face) is a warning sign of poor insertion. For earplugs with a stem, only the tip of the stem should be visible to someone looking at you from the front. All flanges of a flanged earplug should be well inside the ear canal. For earplugs without stems (most foam earplugs), the end of the earplug should not be visible to someone viewing you from the front.
When it comes to fit training, studies repeatedly confirm the advantage of one-on-one training and personal feedback in preventing hearing loss. The measured rates of proper fit increase with small-group sessions, and are highest with one-on-one fit training.
An ideal time to perform that one-on-one training is in conjunction with annual audiometric testing. But if training must be conducted in small groups, make sure nobody leaves the room without having demonstrated a proper earplug fit (simply observing it on a video doesn't suffice).
One audiologist includes an eye-opening lesson in the hearing conservation training she provides to companies. She requires every attendee in the small-group session to demonstrate a proper earplug fit in their own ear, and then to fit an earplug properly in a co-worker's ear. This allows them to feel a proper fit in their own ear, and to see a good fit in the ears of co-workers.
Include Non-Occupational Examples in Training
A "noise thermometer" is used by many trainers to help employees understand the decibel scale. Include examples of non-occupational noise so workers can relate their workplace noise to their recreational exposures. For example, jackhammers can measure around 130 dB, but so too can peak noise levels at auto racing events. A worker who rides a motorcycle is exposed to the same hazardous noise level as the impact wrench used at work, about 105 dB. And a table saw on the job emits around 95 dB, just like the gas lawnmower at home.
In your training, use non-occupational examples that are customized to your work force or region, examples to which each worker can readily relate. It may be auto racing or chainsaws, rock concerts or monster truck events, dirt biking or firearms, farm equipment or woodshop equipment. But there is no use warning about the dangers of 180 dB rocket launches when the more likely culprit will be a circular saw or personal stereo.
In your periodic noise training, teach the self-help tools that will help workers take responsibility for their own hearing and prevent noise damage at home and at noisy recreational events:
- Where possible, double the distance between you and the noise. This reduces the noise level about 3 dB (a halving of the noise energy).
- Plan ahead to carry hearing protectors for yourself and your family or friends. Don't rely on makeshift earplugs from cotton or tissues, which provide less than 10 dB of protection in critical frequencies. Tie a pair of corded earplugs to the lawnmower handle, or hang an earmuff near the power switch of the garage table saw. Keep a few packs of disposable earplugs in the car or truck toolbox.
- To protect against sudden unexpected noise, close your ears by pushing closed the tragus (that flap at the entrance of your ear canal). This offers around 35 dB of temporary protection.
Selection of Hearing Protectors
Workers who have a good experience using hearing protectors at work are more likely to continue that practice off the job. But some employers doom their chances of success from the very start in their selection of hearing protectors.
Workers will intentionally compromise the fit of earplugs they feel are uncomfortable, or earmuffs they believe will impair their ability to communicate or perform their job. Factors that give hearing protectors their best chance of success are comfort, communication and convenience.
OSHA requires that "employees shall be given the opportunity to select their hearing protectors from a variety of suitable hearing protectors provided by the employer." The term "suitable" has been interpreted by OSHA to mean a protector that will bring noise levels below 90 dBA time-weighted average. In practical terms, this means the employer should provide three, 200-count boxes of different earplugs all three earplug types meeting the noise reduction requirements of the environment rather than one, 600-count box of the same earplug.
By enabling the worker to choose, it becomes his or her hearing protector, not the company's hearing protector.
Some workers may use comfort as the determining factor, while others may focus more on the ability to hear co-workers while wearing protection. Some may value the convenience of a folding earmuff, or a banded earplug for intermittent noise. For others in a tedious job, an earmuff with AM/FM radio will be the best choice. As long as the offered protectors provide adequate protection for the noise levels where they will be used, leaving the final choice to the worker fosters buy-in.
We live, work and play in a noisy world a world that does not suddenly become quiet when we punch out at the time clock. Safety managers can build a culture of hearing conservation that bridges the gap between workplace and home, to foster hearing loss prevention among workers, their peers and family. A worker who knows how to relate occupational and non-occupational noise hazards, and adapt the hearing protection skills learned on the job to home and recreational noise exposures, will have the insight to keep good hearing for life.
Brad Witt, MA, CCC-A, is audiology and regulatory affairs manager, Hearing Safety Group, Bacou-Dalloz.