Enforcement criteria for lead monitoring requirements of recirculated air.

OSHA interpretation letter from 1982 responding to an inquiry about monitoring recirculated air under the lead standard 29 CFR 1910.1025(e)(4)(ii)(B). It states that a total dust monitor with an alarm triggering a bypass above e.g. 5 µg/m3 is acceptable, and that the provision is enforced only where employee exposures could exceed the PEL of 50 µg/m3.