Occupational health
Noise Exposure & Safe Time Calculator
Evaluate how long you can stay in a noisy environment before risking hearing damage. Enter the A-weighted sound level (dBA), expected exposure duration, and select a guideline (NIOSH or OSHA).
Use a sound meter or manufacturer specifications.
NIOSH (stricter): 85 dBA for 8 hours, 3 dB exchange rate. OSHA: 90 dBA for 8 hours, 5 dB exchange rate.
Recommended max time
47.6 minutes
2857 seconds
Your planned exposure
60 minutes
126% of recommended limit
Exposure exceeds recommended limit. Use hearing protection and reduce duration.
How to Use This Calculator
Measure or estimate the sound level
Use an A-weighted sound meter app/device or documented equipment specifications.
Select appropriate guideline
NIOSH is recommended for occupational health; OSHA represents regulatory compliance thresholds.
Implement controls
Use hearing protection, reduce exposure time, and implement engineering controls to stay within safe limits.
Formula
Recommended time (minutes) = Base time × 2(Reference − Level)/Exchange Rate (if Level ≤ Reference)
Recommended time (minutes) = Base time ÷ 2(Level − Reference)/Exchange Rate (if Level > Reference)
Base time = 480 minutes (8 hours). Exchange rate: NIOSH 3 dB, OSHA 5 dB.
Full Description
Noise-induced hearing loss is cumulative and irreversible. NIOSH recommends limiting exposure to 85 dBA for 8 hours with a 3 dB exchange rate—every 3 dB increase halves the safe exposure time. OSHA uses a less stringent 5 dB exchange rate and 90 dBA reference for regulatory compliance.
Implement engineering controls (enclosures, dampening), administrative controls (scheduling, rotation), and personal protective equipment (earplugs, earmuffs). Monitor exposure regularly and provide audiometric testing for workers in high-noise environments.
Frequently Asked Questions
Does doubling exposure double risk?
Yes. Exposure beyond recommended time dramatically increases risk of permanent hearing damage, especially without protection.
How effective are earplugs?
Properly fitted hearing protection can reduce noise by 15–30 dB. Combine with administrative controls for best results.
Should I use time-weighted averages?
Yes. For multiple noise levels during a shift, calculate dose using cumulative exposure or specialized dosimeters.
Is impulse noise treated differently?
Impulse or impact noise requires additional analysis; peaks above 140 dB can cause immediate damage even with brief exposure.