NIOSH REL

A NIOSH REL (Recommended Exposure Limit) is a workplace exposure level recommended by the U.S. National Institute for Occupational Safety and Health to protect workers from a hazardous substance. For asbestos, NIOSH has long recommended a REL of 0.1 fiber per cubic centimeter of air, averaged over an 8-hour workday, and has stated that no safe level of exposure has been established. NIOSH RELs are advisory. They are not themselves legally enforceable, unlike OSHA's Permissible Exposure Limits (PELs).

Origin

NIOSH was created by the Occupational Safety and Health Act of 1970 as the federal research agency tasked with recommending workplace safety standards. NIOSH issued its first Criteria Document recommending an asbestos REL in 1972 and tightened the recommendation in 1976, well before OSHA adopted comparable enforceable limits.

Significance in Asbestos Context

NIOSH RELs matter to patients because they document what the federal government knew, and was telling industry, about safe asbestos levels at specific points in time. If an employer or product manufacturer exposed workers to fiber concentrations above the NIOSH REL after it was published, that is powerful evidence the exposure was both foreseeable and preventable. The gap between the early, protective NIOSH recommendations and the later, weaker OSHA enforceable limits is frequently raised in litigation to show that industry had clear scientific guidance long before it was forced to comply.

Example Sentence

The industrial hygienist's report showed fiber counts in the plaintiff's work area were ten times the NIOSH REL throughout the 1980s, even though the recommendation had been public since 1976.

Related Terms

OSHA PEL, Threshold Limit Value (TLV), Action Level, Criteria Document, State of the Art

Notes

• Ask your legal team to compare the NIOSH REL in effect during each year of your work history to the actual fiber levels (or estimated levels) at your jobsites.
• Preserve any employer air-sampling records, industrial hygiene reports, or union safety files. These often reference NIOSH limits directly.
• If you worked in construction, shipyards, insulation, or auto repair after 1976, the NIOSH REL of 0.1 f/cc is the key benchmark; exposures above it are well-documented as hazardous.
• NIOSH has stated asbestos is a carcinogen with no known safe exposure level, which directly counters defense arguments that low-dose exposures are harmless.