Health Effects of Radon

Radon is the second leading cause of lung cancer after smoking, according to a recent report from the National Academy of Sciences. The United States Environmental Protection Agency (EPA) and the Surgeon General strongly recommend that all homeowners test for radon and, if there is a problem, take action to fix it.

Radon is not an irritant to the eyes or lungs, nor is it an allergen. The only risk from radon in air is lung cancer, after many years of breathing it in.

Four picoCuries per Liter (4 pCi/L) is the US EPA’s action guideline for the radon concentration in the air in occupied spaces of homes. When people are breathing in air with a higher level of radon over a long period of time, action should be taken to reduce the radon level.

Built up over a lifetime (74 years), the risk from breathing an average of 4 pCi/L depends on a person’s smoking history:

RISK ESTIMATES AT 4 pCi/L, long-term exposures:

For people who never smoke:

• 2/1000 (Citizen’s Guide to Radon, US EPA,1992)
• 7/1000 (report from the National Academy of Sciences)

For current smokers:

• 3/100 (EPA 1992 and recent NAS report)

For former smokers:

• Risk is between the risks for smokers and those who have never smoked

When windows are open, radon levels are very low. The estimates above assume one spends 70% of one’s time indoors at home breathing 4 pCi/L. Short times spent in a region with higher radon (a basement) will not be important.

For just one year of exposure, the risk would be about 1/74 as high. If the radon level typically inhaled is higher, the risk is greater. If the average radon inhaled is lower, the risk is less.

At this time, there is not clear evidence on whether children are at greater risk than adults from radon. Because of the time it takes for cancer to develop and the cumulative nature of radon risk through time, there is no chance that someone could get lung cancer from radon before age 35, although exposures before that age contribute to the risk at later ages. The average number of years of life expectancy lost per death from lung cancer is about fifteen.