Key OSHA Noise Limits at a Glance
- 90 dBA - Permissible Exposure Limit (PEL) for 8-hour workday
- 85 dBA - Action Level triggering hearing conservation program
- 140 dBA - Maximum impulse/impact noise limit
- 5 dB - Exchange rate (halving of allowed time per 5 dB increase)
Understanding OSHA's Occupational Noise Exposure Standard
The Occupational Safety and Health Administration (OSHA) establishes and enforces workplace noise exposure limits through 29 CFR 1910.95. These regulations protect approximately 22 million American workers exposed to potentially hazardous noise levels each year.
Noise-induced hearing loss (NIHL) is one of the most common occupational health conditions, and it's 100% preventable. Understanding OSHA's noise limits is essential for employers, safety managers, and workers in manufacturing, construction, and other high-noise industries.
The Two Critical Thresholds
Permissible Exposure Limit (PEL)
The PEL is the maximum noise level a worker can be exposed to during an 8-hour work shift. At 90 dBA TWA (Time-Weighted Average), employers must implement engineering or administrative controls to reduce noise, or provide hearing protection.
Violation of PEL: Can result in OSHA citations and fines up to $15,625 per violation (or $156,259 for willful violations).
Action Level
When workers are exposed to 85 dBA TWA or higher, employers must implement a Hearing Conservation Program. This is a proactive threshold designed to prevent hearing loss before it occurs.
Required actions: Noise monitoring, audiometric testing, hearing protection, training, and recordkeeping.
OSHA Noise Exposure Time Limits
OSHA uses a 5 dB exchange rate, meaning for every 5 dB increase in noise level, the allowable exposure time is cut in half. Here's the complete reference table:
| Sound Level (dBA) | Maximum Exposure Time | Common Examples |
|---|---|---|
| 85 | 16 hours | Heavy traffic, noisy restaurant |
| 90 | 8 hours | Lawn mower, shop tools |
| 95 | 4 hours | Motorcycle, power drill |
| 100 | 2 hours | Chainsaw, jackhammer |
| 105 | 1 hour | Rock concert (front row) |
| 110 | 30 minutes | Power saw, symphony orchestra |
| 115 | 15 minutes | Sandblasting, loud sporting event |
Calculating TWA (Time-Weighted Average)
OSHA requires employers to calculate the Time-Weighted Average (TWA) of noise exposure across an entire work shift. The TWA accounts for varying noise levels throughout the day.
TWA Calculation Formula
Dose (%) = 100 × (C₁/T₁ + C₂/T₂ + ... + Cₙ/Tₙ)
Where C = actual exposure time at a given noise level, and T = permissible exposure time at that level
A dose of 100% equals the PEL (90 dBA TWA). A dose of 50% equals the Action Level (85 dBA TWA). Our online decibel meter automatically calculates TWA and dose percentage in real-time.
Hearing Conservation Program Requirements
When employee noise exposure equals or exceeds 85 dBA TWA, OSHA mandates a comprehensive Hearing Conservation Program with these elements:
1. Noise Monitoring
Conduct monitoring to identify employees exposed to 85+ dBA and accurately measure exposure levels
2. Audiometric Testing
Baseline and annual audiograms for all exposed employees to detect hearing loss early
3. Hearing Protection
Provide hearing protectors at no cost; mandatory use above 90 dBA or after significant threshold shift
4. Training & Education
Annual training on noise hazards, hearing protection, and the purpose of audiometric testing
5. Recordkeeping
Maintain noise exposure measurements for 2 years and audiometric test records for duration of employment
6. Program Evaluation
Regularly evaluate effectiveness and update controls as needed
OSHA vs. NIOSH: Understanding the Difference
NIOSH (National Institute for Occupational Safety and Health) recommends stricter limits than OSHA requires:
| Parameter | OSHA (Required) | NIOSH (Recommended) |
|---|---|---|
| Exposure Limit | 90 dBA TWA | 85 dBA TWA |
| Exchange Rate | 5 dB | 3 dB |
| At 100 dBA | 2 hours allowed | 15 minutes allowed |
Best Practice: Many safety professionals recommend following NIOSH guidelines for better hearing protection, even though OSHA standards are the legal minimum.
Industries Most Affected by Noise Regulations
Manufacturing
Stamping, grinding, and assembly operations often exceed 90 dBA
Construction
Power tools, heavy equipment, and demolition create hazardous noise
Aviation
Ground crews and maintenance workers face jet engine noise up to 140 dB
Entertainment
Musicians, sound engineers, and venue staff at concerts and clubs
Automotive & Mining
Heavy machinery and drilling operations in enclosed spaces
Monitor Your Workplace Noise Levels Free
Use DecibelPro to measure sound levels and track OSHA compliance. Our tool calculates TWA, dose percentage, and alerts you when action levels or PEL are exceeded.
Employer Responsibilities Summary
Below 85 dBA TWA: No Action Required
Workers are not at significant risk. Good practice to monitor periodically.
85-89 dBA TWA: Hearing Conservation Program
Implement full program: monitoring, audiograms, protection, training, records.
90+ dBA TWA: Engineering/Administrative Controls + HCP
Must reduce noise through controls. Hearing protection mandatory while implementing controls.
Conclusion
OSHA's noise exposure limits exist to protect the 22 million American workers exposed to hazardous noise each year. The 85 dBA action level triggers preventive measures, while the 90 dBA PEL represents the maximum allowable exposure.
Whether you're a safety manager, HR professional, or worker concerned about your hearing health, regular noise monitoring is essential. Tools like DecibelPro make it easy to measure workplace noise levels, calculate TWA exposure, and maintain OSHA compliance - all for free, right in your browser.