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OSHA noise exposure limits
OSHA's permissible exposure limit for workplace noise is 90 dBA averaged over 8 hours, with a 5-dB exchange rate that halves the allowed time for every 5 dB above it. The action level that triggers a hearing conservation program is 85 dBA. NIOSH, the research agency, recommends 85 dBA with a 3-dB exchange rate, which is stricter at every level above 85.
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OSHA permissible noise exposures (Table G-16)
From 29 CFR 1910.95, the occupational noise exposure standard for general industry. Duration is per day; the level is the A-weighted slow-response sound level.
| Duration per day (hours) | Sound level (dBA, slow response) |
|---|---|
| 8 | 90 |
| 6 | 92 |
| 4 | 95 |
| 3 | 97 |
| 2 | 100 |
| 1½ | 102 |
| 1 | 105 |
| ½ | 110 |
| ¼ or less | 115 |
Exposures at different levels in one day are combined as a dose: C1/T1 + C2/T2 + … must not exceed 1, where C is the time at a level and T is that level's allowed time. The table ends at 115 dBA for a quarter hour or less, and exposure to impulsive or impact noise should not exceed a 140 dB peak sound pressure level.
The 85 dBA action level
When the 8-hour time-weighted average reaches 85 dBA, before the 90 dBA limit is exceeded, the employer must operate a hearing conservation program under 1910.95(c) through (o): a monitoring program, baseline and annual audiometric testing, hearing protectors made available to every exposed employee, annual training, and records. Protectors become mandatory where exposure exceeds the limit, or at the action level for an employee who has shown a standard threshold shift.
NIOSH recommended exposure limit
NIOSH Publication 98-126 recommends an exposure limit of 85 dBA as an 8-hour time-weighted average with a 3-dB exchange rate. Because sound energy doubles every 3 dB, NIOSH halves the allowed time every 3 dB, where OSHA halves it every 5. The gap widens quickly:
| Level (dBA) | NIOSH maximum per day | OSHA permitted per day |
|---|---|---|
| 85 | 8 hours a day | No limit |
| 88 | 4 hours a day | No limit |
| 91 | 2 hours a day | 6 to 8 hours |
| 94 | 1 hour a day | 4 to 6 hours |
| 97 | 30 minutes a day | 3 hours |
| 100 | 15 minutes a day | 2 hours |
| 103 | 8 minutes a day | 1 to 1.5 hours |
| 106 | 4 minutes a day | 30 min to 1 hour |
| 109 | 2 minutes a day | 30 min to 1 hour |
| 112 | 56 seconds a day | 15 to 30 min |
| 115 | 28 seconds a day | 15 min |
NIOSH also recommends a 140 dBA ceiling for impulsive noise and a hearing loss prevention program at 85 dBA. The NIOSH figures are the ones this site's safe-exposure times use everywhere; see safe decibel levels for the everyday version.
Which limit applies to you
- General industry (factories, warehouses, offices): 29 CFR 1910.95, the tables above.
- Construction: 29 CFR 1926.52, the same 90 dBA limit and duration table, with 1926.101 for hearing protection.
- Mining: MSHA's 30 CFR Part 62 uses the same 90 dBA limit and an 85 dBA action level.
- Not covered by OSHA: the self-employed, most public-sector workers in states without an OSHA-approved plan, and everyone off the job. For those, the NIOSH 85 dBA figure is the number to use.
Related terms
The limits above are in dBA; the dBA vs dBC page explains the weighting and the 140 dB peak rule, sound exposure level covers single events rather than a working day, and the sound distance calculator shows how far from a source the level drops below 85 dB.
Measure the level first
An 8-hour average needs a dosimeter or an integrating sound level meter, and a phone is not a compliance instrument. It is good enough to tell whether a space is anywhere near these numbers: open the free online decibel meter and watch the average, not the peak. Above 85 dBA on the meter, the conversation about protection should already be happening.
What is the OSHA noise limit?
The OSHA permissible exposure limit is 90 dBA as an 8-hour time-weighted average, with a 5-dB exchange rate: every 5 dB above 90 halves the allowed time (95 dBA for 4 hours, 100 dBA for 2 hours). Table G-16 ends at 115 dBA for a quarter hour or less per day, and exposure to impulsive or impact noise should not exceed a 140 dB peak sound pressure level. Source: 29 CFR 1910.95.
What is the OSHA action level for noise?
An 8-hour time-weighted average of 85 dBA. At or above it, the employer must run a hearing conservation program: noise monitoring, baseline and annual audiograms, hearing protectors made available, and annual training. The 85 dBA action level is different from the 90 dBA exposure limit.
How is NIOSH different from OSHA?
OSHA sets the legal limit; NIOSH sets the health-protective recommendation. NIOSH recommends 85 dBA for 8 hours with a 3-dB exchange rate, so its allowed time halves every 3 dB rather than every 5. At 100 dBA that is 15 minutes under NIOSH against 2 hours under OSHA. Employers must meet OSHA; NIOSH is the level researchers consider safe.
Does hearing protection count toward the limit?
Under OSHA, engineering and administrative controls come first when exposures exceed the limit; hearing protectors are required where those controls fail to bring exposure below the limit, and must be made available at the 85 dBA action level. The protector's attenuation, adjusted per Appendix B of the standard, is what reduces the employee's exposure on paper.
What about construction sites?
Construction has its own standard, 29 CFR 1926.52, with the same 90 dBA permissible limit and the same duration table. Its hearing conservation requirements are less detailed than general industry, which is why NIOSH and many contractors apply the 85 dBA recommendation on site.