The recommended exposure limit for occupational noise needs to be revised downwards

Abstract

Noise-induced hearing loss (NIHL) is caused by cumulative occupational and non-occupational noise exposure. The National Institute for Occupational Safety and Health (NIOSH) developed occupational noise exposure recommendations (85 dBA 8-hour time-weighted average) in 1972. Fifty years later, the NIOSH recommended exposure limit (REL) needs to be revised downwards. In its calculations, NIOSH assumed that workers have quiet when not at work, something no longer true. Non-occupational noise exposure begins in childhood and continues during work years and into retirement. Multiple studies document daily non-occupational noise exposures near 75 dB or dBA, exceeding the Environmental Protection Agency's calculated noise exposure level to prevent hearing loss, a time-weighted average of 70 dB for 24 hours (Leq(24)). NIOSH calculations were based on occupational studies of material hearing loss measured by limited frequency pure tone audiometry, an insensitive measure of noise-induced auditory damage. Use of more sensitive measures of auditory damage would show more NIHL after shorter exposure times. Downward revision of the NIOSH REL will protect workers, and may lead to greater public awareness of the dangers of noise, guidance for reduced noise exposure, and regulations for lower ambient noise levels. A quieter world will be a better and healthier world for all.