Radon peril

Radon accumulations in sealed energy-efficient houses are posing a neglected health risk. The amount of radon gas released to the atmosphere due to the mining of the 40,000 tonnes of uranium produced worldwide in 1981 is insignificant compared to the radon released from the 1.5 billion tonnes of uranium contained in the top metre of the earth's land mass. The concentration of radon is ten times higher indoors than outdoors in North America, and the average exposure to radon is approximately 0.2 working level months (WLM) in one year. In Canada, this exposure will produce about 500 lung cancer fatalities per year. Sealing houses and decreasing ventilation rates may increase the lifetime risk of contracting lung cancer to approximately one percent. Energy conservation by sealing homes has a radiological impact of 150 000 person-rem per GW(e). In the United States proposed standards would limit public exposure from high level radioactive wastes to about 600 person-rem per GW(e), and from reactor operation to 20,000