Exposure to naturally occurring radon is unavoidable and is second only to smoking as a direct cause of lung cancer in the USA. The literature for existing information on US occupations that are prone to increased radon exposures was reviewed. Current recommendations and applicable protective standards against occupational radon exposure that are applicable to US workers are discussed. Exposure varied widely among several working populations, most of whom were employed in industries that were unrelated to the uranium fuel cycle. Radon protection standards differed among agencies and have not changed since the height of domestic uranium production in the 1970s. In contrast, European countries are adopting recommendations by the International Commission on Radiation Protection to set a reference level near a derived annual exposure of about one working level month, which is 25% of the level currently established for US miners.