OSHA noise limits

OSHA, the US workplace safety regulator, limits noise at work to an average of 90 dBA over an 8-hour day. The allowed time halves with every 5 dB above that, down to 15 minutes at 115 dBA. From an 8-hour average of 85 dBA, the action level, employers must run a hearing conservation programme. The rule is 29 CFR 1910.95 for general industry.

OSHA permissible noise exposure table

This is Table G-16 of 29 CFR 1910.95. Levels are measured in dBA on a sound level meter set to slow response.

Impulse or impact noise, such as a hammer blow or a nail gun, should not exceed 140 dB peak.

Mixed levels. When a working day has periods at different levels, OSHA adds them up as fractions: for each period, divide the time spent by the time allowed at that level. If the fractions add up to more than 1, the exposure is over the limit. For example, 2 hours at 100 dBA (2 / 2 = 1) is a full day's dose on its own, so any further time above 90 dBA puts the worker over.

When workers are exposed above the table, the employer must first use feasible engineering or administrative controls, such as quieter machines, enclosures or shorter shifts in loud areas. If those are not enough, hearing protection must be provided and used.

The 85 dBA action level: what employers must do

From an 8-hour time-weighted average of 85 dBA, OSHA requires a hearing conservation programme:

• Noise monitoring to find out who is exposed at or above 85 dBA, repeated when equipment or processes change.
• Hearing tests (audiograms): a baseline within 6 months of the first exposure at or above the action level, then at least once a year, free to the worker.
• Hearing protection made available to every exposed worker at no cost, with a choice of types. It must be worn above the 90 dBA limit, and from 85 dBA by anyone whose hearing test shows a standard threshold shift.
• Training every year on the effects of noise, the use of hearing protection and the purpose of the hearing tests.
• Records of noise measurements and hearing tests.

OSHA vs NIOSH: why the numbers differ

NIOSH, the US research institute for workplace health, recommends a stricter limit: 85 dBA for 8 hours, with the time halving every 3 dB instead of every 5 dB.

The 3 dB rule matches the physics: 3 dB more is twice the sound energy, so it is twice the dose. OSHA's 5 dB rule allows considerably more noise at high levels. Even at its own stricter limit, NIOSH acknowledges that about 8% of workers could still develop hearing loss; the OSHA limit lets in more noise than that. OSHA's figures are the legal minimum for US employers; for your own hearing, the NIOSH figures are the safer guide. Other countries' workplace limits are on noise limits by country.

Checking noise at work

A phone sound meter app gives a quick estimate of whether an area is near 85 or 90 dBA: measure for several minutes where people work and read the average (LAeq). In SoundSense you can set a threshold of 85 or 90 dBA and see how long each saved check stayed above it. A phone reading is not a compliance measurement: OSHA monitoring needs a sound level meter or noise dosimeter that meets the standard, used by someone trained to measure noise.

Sources

• OSHA, 29 CFR 1910.95 Occupational noise exposure
• NIOSH, Understanding noise exposure limits
• NIOSH, Noise and hearing loss

Updated 23 October 2026 by the SoundSense team at Just IT.