Hearing Conservation Program Components and OSHA Requirements
Program triggers and the five pillars
Under 29 CFR 1910.95 a hearing conservation program is required when employee exposure equals or exceeds an 8-hour time-weighted average of 85 dBA - the action level. The permissible exposure limit is 90 dBA TWA. At or above 85 dBA, hearing protectors must be made available at no cost; above 90 dBA they must be worn. Protectors are also required for employees who have not yet had a baseline audiogram, or whose audiogram shows a standard threshold shift.
The program has five pillars: monitoring of exposure, audiometric testing, hearing protection, training, and recordkeeping. Each carries a deadline worth memorizing: baseline audiogram within 6 months of first exposure (extendable to 12 months where a mobile test van is used and the employee wears protectors), annual audiograms thereafter, annual training, noise exposure records retained 2 years, and audiometric records retained for the duration of employment.
Traps
Do not blend 85 and 90, and do not borrow NIOSH's 3 dB exchange rate when the question cites OSHA, which uses 5 dB. The standard does not require bone conduction, does not mandate a particular style of protector, and does not require that an audiologist personally test every employee - a physician, otolaryngologist, licensed or certified audiologist, or a properly certified technician is acceptable.
Rule of thumb: at OSHA's 5 dB exchange rate, a steady 85 dBA for 8 hours is a 50% dose; 90 dBA is 100%; 95 dBA for 8 hours is 200%.