Occupational hearing loss is hearing loss that develops slowly over a long period of time (several years) as the result of exposure to continuous or intermittent loud noise at a persons place of employment. The good news is that the risk of occupational hearing loss (OHL) is declining. However while progress has been made, additional efforts are needed within the areas of mining, construction, healthcare and social assistance.
SCOPE OF THE PROBLEM
From the Centers for Disease Control and Prevention (CDC):
In the United States, hearing loss is the third-most common chronic health condition among older adults after hypertension and arthritis.
- Over 11% of the U.S. working population has hearing difficulty.
- About 24% of the hearing difficulty among U.S. workers is caused by occupational exposures.
WHAT CAUSES OCCUPATIONAL HEARING LOSS?
- OHL can occur when workers are exposed to loud noise or ototoxic chemicals.
- Noise is considered loud (hazardous) when it reaches 85 decibels or higher, or if a person has to raise his/her voice to speak with someone 3 feet away (arm’s length).
- Ototoxic (having a damaging effect on the ears or balance system) chemicals (and examples) include:
- organic solvents (styrene, trichloroethylene, mixtures)
- heavy metals (mercury, lead, trimethyltin)
- asphyxiants (carbon monoxide, hyrdrogen cyanide)
HOW MANY WORKERS ARE EXPOSED?
- About 22 million workers are exposed to hazardous noise each year.
- About 10 million workers are exposed to solvents and an unknown number are exposed to other ototoxicants.
A recent study examined results from hearing tests of nearly 2 million noise-exposed workers from 1981 to 2010 and found that the overall prevalence of hearing loss in all industries remained consistent at 20 percent. However, the number of new cases of hearing loss decreased, leading researchers to believe some progress has occurred in preventing occupational hearing loss.
Despite this progress, some industries still present a high risk. Construction had the highest incidence of hearing loss during most of the time periods in the study. Additionally, mining, health care and social assistance were the only industries that did not experience a reduction in the risk of hearing loss during the last five years of the study.
OSHA AND HEARING LOSS
The Occupational Safety & Health Administration (OSHA) sets legal limits on noise exposure in the workplace. These limits are based on a worker’s time weighted average over an 8-hour day. OSHA has recommended that all worker exposures to noise should be controlled below a level equivalent to 85 dBA for eight hours to minimize occupational noise induced hearing loss.
In 1981, OSHA implemented new requirements to protect all workers in general industry. Employers were required to implement a Hearing Conservation Program where workers exposed to a time weighted average noise level of 85 dBA or higher over an 8 hour work shift. These requirements also included
- The measurement of noise levels
- The provision of free annual hearing exams and free hearing protection
- Training on the use of hearing protectors
WHAT CAN BE DONE TO REDUCE THE HAZARD FROM NOISE?
As referenced above, progress has been made, but additional efforts at hearing conservation are needed within several sectors. Those additional efforts can include any or all of the following:
- Engineering controls that reduce sound exposure levels are available and technologically feasible for most noise sources. Engineering controls involve modifying or replacing equipment, or making related physical changes at the noise source or along the transmission path to reduce the noise level at the worker’s ear.
- Administrative controls are changes in the workplace that reduce or eliminate the worker exposure to noise. Examples include, operating noisy machines during shifts when fewer people are exposed or limiting the amount of time a person spends at a noise source.
- Increased use of “hearing protection devices” (HPDs), such as earmuffs and plugs, are considered an acceptable but less desirable option to control exposures to noise and are generally used during the time necessary to implement engineering or administrative controls, when such controls are not feasible, or when worker’s hearing tests indicate significant hearing damage.
It is critical to ensure that workers are being protected where noise levels are sufficiently loud enough to cause occupational hearing loss.