The current issue is regarding the necessity of a hearing conservation program in regards to OSHA 29 CFR 1910.95. The widely recognized regulation as to when the program becomes necessary reads as follows:
The employer shall administer a continuing, effective hearing conservation program, as described in paragraphs (c) through (o) of this section, whenever employee noise exposures equal or exceed an 8 hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or, equivalently, a dose of fifty percent. For purposes of the hearing conservation program, employee noise exposures shall be computed in accordance with appendix A and Table G-16a, and without regard to any attenuation provided by the use of personal protective equipment.
There is also a footnote in the standard that refers to permissible exposure limits for noise that sets the absolute highest level of noise an unprotected employee can be exposure to for instantaneous noises. This reads as follows:
Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level.
The idea behind this quotation is that if there are instantaneous noises of 140 dB of higher, employees must wear hearing protections. Based on this, the question was raised as to whether or not an employee could be in a situation that would require hearing protection, but where he would not fall under the hearing conservation program.
In response to this question, OSHA has determined that the Time-Weighted Average (TWA) of 85 dB over an 8-hour period is the only basis for requiring hearing conservation programs. Any instantaneous noises must be included in the TWA, so as long as they do not bring the average up to or above 85 dB, employees might need hearing protection, but would not fall under a hearing conservation program.
*Unless specific citations are shown, all answers are based on interpretations provided by authorized officials. As such, all information is deemed reliable, but not guaranteed.