Enterprise Health
Occupational Health

PELPermissible Exposure Limit

The maximum legal exposure to a hazardous substance an employee may experience, set and enforced by OSHA.

Reviewed June 2026 by Enterprise Health

Key facts

  • OSHA's enforceable exposure limit, usually an 8-hour time-weighted average.
  • Approaching an action level or PEL can trigger monitoring and surveillance.
  • Many PELs are dated; NIOSH RELs and ACGIH TLVs are often stricter.

What it means

PELs are OSHA's enforceable limits, usually expressed as an 8-hour time-weighted average. When exposures approach or exceed an action level or PEL, the relevant standard typically triggers exposure monitoring and medical surveillance. Many PELs date to the 1970s, so employers often also reference the stricter NIOSH RELs and ACGIH TLVs.

Frequently asked

What is a permissible exposure limit?

The maximum legal exposure to a hazardous substance OSHA allows, typically expressed as an 8-hour time-weighted average. Exceeding action levels or PELs usually triggers exposure monitoring and medical surveillance.

Why do employers use TLVs if PELs are the law?

Many PELs date to the 1970s and lag current science, so industrial hygienists often follow the stricter NIOSH RELs and ACGIH TLVs to be more protective.

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