About these resources
This appendix lists approximately 450 chemicals for which NIOSH adopted RELs on the basis of their comments during the OSHA PEL (permissible exposure limits) Project.
For further information about these chemicals, refer to OSHA's final rule on air contaminants in the Federal Register [54 FR 2641 (1989)].
Content Source
National Institute for Occupational Safety and Health
About This Page
Published: December 17, 2025
Updated: October 9, 2026
This page was last updated on this date. Updates may include minor edits, image changes, or other modifications to page content.
Reviewed: October 9, 2026
The information on this page was last reviewed by subject matter experts to ensure accuracy.