10 CFR § 835.403
Air monitoring
June 9, 2020
(a) Monitoring of airborne radioactivity shall be performed:
(1) Where an individual is likely to receive an exposure of 40 or more DAC-hours in a year; or
(2) As necessary to characterize the airborne radioactivity hazard where respiratory protective devices for protection against airborne radionuclides have been prescribed.
(b) Real-time air monitoring shall be performed as necessary to detect and provide warning of airborne radioactivity concentrations that warrant immediate action to terminate inhalation of airborne radioactive material.
[63 FR 59683, Nov. 4, 1998]