Occupational hearing loss is one of the most common workplace injuries, according to the Centers for Disease Control. The CDC estimates that at least 5 million and as many as 30 million workers in the U.S. are regularly exposed to workplace noise levels that put they at risk for hearing loss. The Occupational Health and Safety Administration sets standards for the levels of acceptable noise in the workplace to prevent employee hearing loss.
OSHA Noise Regulations
Noise induced hearing loss can be prevented, but it cannot be reversed. So, OSHA requires that employers take steps to reduce the noise levels by modifying business practices or implementing engineering solutions. If noise levels cannot be reduced to safe levels, then the employer must provide hearing protection devices and limit workers’ exposure time to loud noises. Simply stated, the louder the noise, the shorter the worker’s permitted exposure to it. Exposure time is the sum of all noise exposure incidents throughout the workday, rather than the time a single incident.
Continuous Noise Limits
Workplace noise is considered continuous if the interval between occurrences of the maximum noise level is one second or less. Continuous noise is measured in decibels, expressed as dBA. OSHA combines the decibel level with the time a worker is exposed to it to determine decibel exposure. For example, a diesel truck produces 84 dBA at a distance of 50 feet and a motorcycle at 25 feet produces 90 dBA. OSHA regulations specify that workers may be exposed to 90 dBA for up to eight hours, 95 dBA for four hours and 115 dBA for 15 minutes of less without hearing protection. According to OSHA, an employer must have a "continuing and effective" hearing conservation program whenever continuous noise exposure exceeds 85 decibels for eight or more hours without hearing protection.
Impact or Impulse Noise Limit
Impact or impulse noise is a loud momentary explosion of sound that lasts a few thousandths of a second and repeats less than once every second. Examples of impact noises are power-driven nail guns, drop hammers, pile drivers, explosions and gun fire. Workers may not be exposed to impact noises in excess of 140 decibels.
Hearing Protection Requirements
Employers must give workers hearing protection equipment when they are exposed to noise in excess of OSHA limits. The noise exposure levels (decibels and time) requiring hearing protection are affected by three factors: workers’ location relative to the sound; whether workers move between work areas with different decibel levels; and whether the sound is generated by a single source or multiple sources. Hearing protectors must reduce a worker’s exposure to acceptable limits as defined by OSHA and may include single-use earplugs; preformed or molded earplugs; or ear muffs that cover the entire ear.
Hearing Conservation Program
OSHA requires that employers implement a hearing conservation program to protect employees at risk for noise induced hearing loss. This program includes noise monitoring, annual employee hearing tests, employee training, hearing protectors and record keeping to document the results of noise level tests, equipment calibrations and employee hearing tests.