OSHA Noise Dose & 8-Hour TWA Exposure Calculator
Determine daily occupational noise dose (%), 8-hour Time-Weighted Average ($TWA$), and compliance with OSHA 29 CFR 1910.95 and NIOSH standards.
Workplace Exposure Periods (up to 3 tasks)
Occupational Noise Dose & TWA Output
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OSHA 29 CFR 1910.95 Noise Dosimetry
Under federal OSHA safety standards, employee noise exposures must be evaluated on an 8-hour time-weighted average ($TWA$) basis. OSHA employs a $5\text{ dB}$ exchange rate, meaning that every $5\text{ dB}$ increase in sound level cuts the allowable exposure duration by exactly half.
Action Level vs Permissible Exposure Limit (PEL)
The OSHA Action Level is an 8-hour TWA of $85\text{ dBA}$ (a $50\%$ noise dose). Reaching this threshold requires employers to administer a continuing Hearing Conservation Program (HCP), including annual baseline audiometric testing and training. The Permissible Exposure Limit (PEL) is $90\text{ dBA}$ ($100\%$ dose), above which engineering controls and mandatory hearing protection are required.