The Two Numbers That Matter: 85 dBA and 90 dBA

Cal/OSHA’s occupational noise exposure standard sits in Title 8 of the California Code of Regulations, sections 5095 through 5100. These sections apply to general industry; agriculture, construction, and oil and gas have separate noise provisions. The standard mirrors federal OSHA’s 29 CFR 1910.95 in structure but is enforced independently by Cal/OSHA’s Division of Occupational Safety and Health. Two numbers do most of the work:

• 85 dBA TWA (action level). Once an employee’s 8-hour time-weighted average noise exposure reaches or exceeds 85 dBA, the employer must set up a hearing conservation program. This means continued monitoring, annual audiometric testing, employee training, hearing protection at no cost to the employee, and recordkeeping.
• 90 dBA TWA (permissible exposure limit, PEL). This is the legal ceiling for an 8-hour average. Above this level, the employer must use feasible engineering or administrative controls, and use hearing protection to bring exposure below the PEL.

These are averages over time, not peak readings. A short burst at 95 dBA does not automatically put an employee above the action level. The TWA accounts for duration.

Permissible Noise Exposure Table

This is the duration-versus-level breakdown from Cal/OSHA Title 8 §5096 and 29 CFR 1910.95 (Table G-16). It defines how long a worker can be exposed at each sound level before the PEL is exceeded.

Impact and impulse noise must not exceed 140 dB peak under any circumstance.

When real workplace exposures fall between these listed values, exposure is calculated as a dose using the 5 dB exchange rate (each 5 dB increase halves the allowable time). Dosimeters compute this automatically.

When Cal/OSHA Requires Monitoring

Cal/OSHA expects an employer to monitor when there is any reasonable indication that employee exposure equals or exceeds the 85 dBA action level. In practice, the triggers we see in California facilities are:

• An employee complaint about noise or hearing trouble.
• A Cal/OSHA inspection that notes loud operations and asks for monitoring data.
• New equipment, layout changes, or production process changes that may have altered the noise profile.
• An insurance carrier or corporate safety program requiring documentation.
• A facility’s own walkthrough revealing equipment loud enough to warrant baseline measurement.

When we walk a facility for a noise scoping discussion, the first thing we look at is the duty cycle of the loudest equipment and how long workers stand near it. A grinder running 30 seconds out of every hour is a different problem from a packaging line that runs all shift. The TWA, not the peak, drives the regulatory outcome.

What an OSHA-Compliant Noise Survey Has to Do

A noise check using a phone app does not satisfy Cal/OSHA. Defensible monitoring requires calibrated equipment, prescribed settings, and a methodology that produces reproducible results. Specifically:

• Dosimeter settings (per 29 CFR 1910.95 Appendix A and Title 8 §5096 Appendix A): threshold level 80 dB, criterion level 90 dB, exchange rate 5 dB, A-weighting, slow response.
• Calibration before and after each field use with a reference acoustic calibrator (typically 94.0 dB ±0.5).
• Personal dosimetry placed at the employee’s collar near the ear, worn through a representative shift (6 to 8 hours).
• Field notes documenting the operations, tasks performed during the monitoring period, equipment running, and whether the day was typical.
• A written report comparing each TWA against the 85 dBA action level and 90 dBA PEL, with recommendations.

If a Cal/OSHA inspector asks for noise monitoring records and what you have is a screenshot from a phone app, the data does not count. The inspector is looking for calibrated TWA measurements taken with the methodology above.

After Monitoring: What Happens at Each Level

The TWA result determines the obligations:

• Below 85 dBA: No formal program required. Document the monitoring and the result; keep the records.
• 85 dBA or above (but below 90): Hearing conservation program required. Provide audiometric testing, employee training, hearing protection on request, and recordkeeping. Re-monitor whenever conditions change.
• 90 dBA or above: Engineering or administrative controls required to reduce exposure. Hearing protection must be used to bring exposure below the PEL.

For employees identified at or above the action level, see our piece on what to do when your noise survey exceeds 85 dBA, which walks through the steps to building a hearing conservation program.

What a Cal/OSHA Inspector Typically Asks For

When Cal/OSHA enters a facility and notes loud operations, inspectors will usually ask for:

For California facilities that have never measured, the gap usually shows up here. The inspector notes the absence of monitoring data and requires it as part of an abatement plan. It is faster and cheaper to have current data on hand than to scramble to produce it under a deadline.

Where Most California Facilities Get Stuck

The two patterns we see most often:

• Facilities that assume “it’s not that loud.” Without data, neither the employer nor the inspector can determine that. The action level is not intuitive: by the time speech in a normal voice becomes difficult, you are usually already above 85 dBA TWA for that role.
• Facilities relying on outdated monitoring. If the equipment, layout, or production volume has changed since the last survey, the older data does not protect you. Cal/OSHA expects re-monitoring whenever conditions change.

For our noise (sound) monitoring service, the most common engagement is a single-day survey of two to six roles or areas, with personal dosimetry, and a written report comparing the TWAs to the 85 and 90 dBA thresholds.