Lead Agency: Norwegian Radiation and Nuclear Safety Authority (DSA). Website: The mandatory regulations exist only for rental accommodations and includes legally binding radon limit values for indoor radon. The limits are 100 Bq/m3 (action level) and 200 Bq/m3 (maximum level). For dwellings in general, there are only recommended guidelines.  <<https://www2.dsa.no/dav/906ecb0b6c.pdf>> (in English, see Section 6 paragraph 6)