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NC State Extension

Why Should I Worry About the Presence of Radon Inside My Home?

Radon is present inside as well as outside homes in almost all air, and we all breathe it in every day. The amounts present outdoors are however very low and not a cause of worry. Average outdoors radon levels are estimated at 0.4pCi/L (picocuries per liter). Indoors, for an average home, these have been estimated to be 1.3 pCi/L.To protect homeowners from radon exposure and its adverse effects, EPA recommends that the indoor levels to be below 4 pCi/L. Indoors, the levels can get very high either because the soil on which a home is built has high quantities of radioactive uranium (the primary source of radon gas release) or the home is built so tightly that the indoor air does not get replaced sufficiently with the outdoor air (low in radon) and leads to radon build-up indoors. As per EPA, radon exposure at low levels (under 4 pCi/L ) will also have an adverse health effect on occupants of the home. Hence, it recommends that for any home with radon levels between 2 to 4 pCi/L, the homeowner should take measures to reduce the sames (U.S.EPA, n.d.)

Radon is radioactive by nature and decays to form other elements emitting tiny radioactive particles in the process. These particles have high energy levels and penetrate the cells lining our lungs when we breathe-in the radon present in the indoor air. When the indoor radon levels are high and the home occupants are exposed to and breathe-in the radon infested air for a long time, their lungs get damaged and develop cancer over time. There is some inconclusive evidence that radon exposure can lead to higher risk of leukemia too (National Cancer Institute, 2011).

Radon exposure is 2nd largest cause of lung cancer deaths

Radon exposure is the next cause, after smoking, leading to cancer deaths in the U.S. For people who smoke, radon exposure leads to additional higher risk of developing lung cancer. The bar graph below depicts how deaths due to radon exposure are far higher than many other common causes of accidental deaths in the U.S. (U.S. EPA, 2012). Clearly, radon exposure is something that homeowners should pay attention to, especially since it is an easily avoidable risk.

Comparison of death nos

Source: U.S.EPA, 2012

Risk of stomach cancer by using water contaminated with radon 

As we know radon can enter a home through soil as well as the water supply sourced from ground water. When someone drinks or uses water with high radon levels for household chores, the exposure to radon is much lower than from breathing radon which enters a home through soil. Only 1% of cancer cases in U.S. from radon exposure are due to radon infested water. These 1% cases cause 19 deaths annually due to the stomach cancer which develops upon drinking water with high radon levels (National Academy of Sciences, 1999). The remaining 99% radon related deaths are due to breathing indoor air contaminated with radon.

Video: Breathe easier: Test for Radon and Remove it (Developed by Minnesota Department of Health, this video features true story of a young woman who lost her mother to lung cancer from radon, and who now wishes to educate all residents of Minnesota about the harmful effects of exposure to radon).


National Academy of Sciences. (1999). Risk Assessment of Radon in Drinking Water. Retrieved January 20, 2015, from

National Cancer Institute. (2011). Radon and Cancer. National Institute of Health. Retrieved January 20, 2015, from

U.S.EPA. (2012). A Citizen’s Guide to Radon: The Guide to Protecting Yourself and Your Family From Radon. Retrieved January 20, 2015, from

U.S.EPA. (n.d.). Why is radon the public health risk that it is? Retrieved January 20, 2015, from