NIOSH

NIOSH is part of the Centers for Disease Control and Prevention. It was established by the same 1970 law as OSHA but has a different role: research and recommendations rather than enforcement. Its scientists review studies, publish guidance, and develop criteria for safe exposure.

Several NIOSH products show up on safety data sheets. The recommended exposure limit (REL) is NIOSH's own suggested limit. The IDLH value indicates conditions considered immediately dangerous to life or health and is used in choosing respirators. NIOSH also publishes the Pocket Guide to Chemical Hazards, a widely used reference.

NIOSH also certifies respirators. Approval under 42 CFR Part 84 means a respirator model passed required tests, which is why a NIOSH-approved respirator is the standard for workplace use. OSHA's respirator rule at 29 CFR 1910.134 requires employers to use NIOSH-certified equipment.

The RELs are not legally binding. OSHA PELs are the enforceable limits, though some RELs are lower and more protective, reflecting newer science. Employers can use RELs as a target even when they are not required to.

NIOSH also offers health hazard evaluations, which employees, their representatives or employers can request to investigate a suspected workplace problem.