The Definition of Action Level

Definition of Action Level

An action level is an airborne concentration of a regulated substance, or a noise level, set below the permissible exposure limit (PEL), at which an OSHA health standard requires the employer to start specific protective activities. For most substance-specific standards the action level is half the PEL, measured as an 8-hour time-weighted average. Reaching the action level is not a violation, but it typically triggers periodic exposure monitoring, medical surveillance, training and recordkeeping.

Key Facts About Action Levels

• Lead: action level 30 µg/m³, PEL 50 µg/m³ (1910.1025 and 1926.62).
• Respirable crystalline silica: action level 25 µg/m³, PEL 50 µg/m³ (1910.1053 and 1926.1153).
• Benzene: action level 0.5 ppm, PEL 1 ppm (1910.1028).
• Noise: an 8-hour TWA of 85 dBA triggers a hearing conservation program; the PEL is 90 dBA (1910.95).
• Substances listed only in OSHA's Z-tables generally have PELs but no action level.

Example of an Action Level

Personal air monitoring at a foundry shows a grinder's silica exposure at 32 µg/m³ as an 8-hour TWA. That is below the 50 µg/m³ PEL but above the 25 µg/m³ action level, so the employer schedules repeat monitoring within six months, enrolls the grinder in medical surveillance if they meet the standard's exposure-day criteria, and reviews dust controls at the workstation.

What Happens When Exposure Reaches the Action Level

• Periodic air monitoring on a schedule set by the standard
• Medical surveillance, such as blood lead testing or lung exams
• Hazard-specific training and employee notification of results
• Recordkeeping of monitoring and medical records
• Above the PEL, employers must also implement engineering and work practice controls and provide respirators

Related Terms

• Exposure Limit
• Time-Weighted Average (TWA)
• Occupational Exposure Limit (OEL)
• Blood Lead Level (BLL)

Frequently Asked Questions: Action Level

Is exceeding the action level an OSHA violation?

No. Exceeding the action level means the employer must carry out the monitoring, medical and training duties the standard ties to it. A violation occurs when exposures exceed the PEL without required controls, or when the action level duties are not performed.

Why is the action level usually half the PEL?

Workplace exposures vary from day to day, so a single result at half the PEL suggests a meaningful chance that exposures exceed the PEL on other days. The action level builds in a margin so problems are caught before overexposure occurs.

When can exposure monitoring stop?

It depends on the standard. Under the silica standard, for example, monitoring can stop when two consecutive results taken at least seven days apart fall below the action level, unless processes or controls change.