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Estimates by the Environmental Protection Agency suggest that a lifetime exposure to a radon concentration of one picoCurie a litre . (pCi/L) approximates the risk of lung cancer associated with smoking one ; cigarette a day. Thus, living with 20 pCi/L has an effect comparable to smoking a pack a day.
Most houses in the country prob., ablywmr have a radon problem, but a few have been found to have very high levels. No one knows, however, which houses have a problem and -..Which don’t. To find out more, the ’■ *'■ EPA is launching a nationwide sur; vey of homes and has started investigations in Pennsylvania and some other states.
Large amounts of radon may be present in soils and rocks containing uranium, granite, shale, phosphate, . and pitchblende. But though homes in such mineral-rich areas are partic. ularly vulnerable, other things need to be considered.
The way a house is built, for example. The National Indoor Envi. ronmental Institute says that newer homes - with better door and window seals to protect against heat loss in winter — are more likely to have high radon levels than older, draftier houses. One solution would be to use air-to-air heat exchangers which can increase ventilation in energy-efficient homes without major increases in heating bills.
The type of soil is also important . — more permeable soils such as sand allow radon to pass through faster ; than others, such as clay. Because little is known about this subject,
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