Air Monitoring Action Level Calculator

OSHA PEL, NIOSH REL, and IDLH values for 600+ chemicals. Build custom action level tables for HASPs and exposure monitoring programs. Data pulled directly from the NIOSH Pocket Guide to Chemical Hazards.

Build Your Action Level Table

Search and select chemicals present at your site. The tool builds a side-by-side action level table showing OSHA PEL, NIOSH REL, IDLH values, and action thresholds at 50% of the most conservative TWA.

How to Use This Data

Setting action levels for monitoring

OSHA substance-specific standards require monitoring when concentrations reach an action level, typically 50% of the Permissible Exposure Limit. When an 8-hour TWA sample equals or exceeds the action level, additional monitoring, training, or medical surveillance is triggered under the applicable standard (benzene, cadmium, lead, and chromium VI all have specific action level provisions).

Selecting respiratory protection

For exposures below the OSHA PEL, respirators are not required under 29 CFR 1910.1000 (though employers may choose protection for comfort or as a best practice). Between the PEL and IDLH, select respirators using the Assigned Protection Factor method in 29 CFR 1910.134 Appendix A. At or above IDLH, use only pressure-demand SCBA or airline respirator with escape bottle.

When NIOSH REL is more conservative than OSHA PEL

Most OSHA PELs have not been updated since 1971. NIOSH RELs reflect newer toxicology and are often more protective. Industry best practice, and ACGIH guidance, is to design controls around the most conservative exposure limit, which is frequently the NIOSH value. For carcinogens marked "Ca," NIOSH generally recommends reducing exposure to the lowest feasible level regardless of the OSHA PEL.

Limitations of this data

This tool reflects the NIOSH Pocket Guide and OSHA general industry PELs (29 CFR 1910.1000 Tables Z-1, Z-2, Z-3). It does NOT include ACGIH TLVs (copyrighted, purchase separately) or construction and maritime industry PELs, which can differ. Always verify current values against the source regulation before relying on this data for compliance decisions. For state plan programs (California Cal/OSHA, Michigan MIOSHA, Oregon OR-OSHA), some chemicals have more stringent state PELs that override federal values.

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