The hearing conservation section of OSHA's noise exposure standard (29 CFR 1910.95) requires that employers establish "a continuing effective hearing conservation program" if their facility generates high noise levels, that is, levels exceeding 85 decibels (dB) on an eight-hour time-weighted average (TWA). Also, employees must be trained in the potential hazards of noise exposure, and must be offered a choice of hearing protection devices.
It's estimated that more than nine million people are exposed to job-related noise levels above 85 dB, most of whom work in manufacturing and utilities. High noise levels are quite common in many workplaces. When assessing the risk of noise-induced hearing loss, it is essential to consider the exposure duration. Noise levels even as high as 130-140 dB can be harmless if the duration is extremely short and if there are no or few repetitions.