(1) Radiation exposure to the public from naturally occurring radioactive materials shall be maintained as low as reasonably achievable. For the purposes of this part, the normal background level of gamma radiation in buildings is 6 microroentgens (1.55 nC/kg) per hour and the normal background radon decay product concentration in buildings is 0.004 Working Level (WL).
    (2) The mean gamma exposure rate in a building shall not exceed 20 microroentgens (5.16 nC/kg) per hour, including background, and the annual average radon decay product concentration shall not exceed 0.02 WL, including background.
Rulemaking Authority 404.051, 404.056 FS. Law Implemented 404.022(2), 404.051(4), 404.056 FS. History-New 2-16-86, Amended 1-3-89, Formerly 10D-91.1104.