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NH Environmental Public Health Tracking Program
Radon and Lung Cancer

Radon is the leading cause of non-smoking related lung cancer in the United States, and smokers living in high radon homes are at greater risk of lung cancer. Thousands of New Hampshire residents are unaware of elevated radon levels in their homes and the silent risk it carries.

Radon is a radioactive gas arising from soil and bedrock that can seep into homes through any openings or cracks in the foundation. Radon may also enter the home through running water used for showering and bathing.  Radon has no color, odor or taste, making it difficult to detect without testing.  Indoor exposure to radon gas is the second leading cause of lung cancer in the US (after tobacco smoking) and is the leading cause of lung cancer among non-smokers [1]. The National Science Foundation estimates that radon accounts for 14 percent of all lung cancer deaths in the United States, or up to 20,000 deaths each year [2].

As the “Granite State,” New Hampshire has an average radon exposure potential that is about 44% higher than the national average due to radioactive gas in the bedrock. In the US, the average level of indoor radon is 1.25 picocuries per liter (pCi/L), but in New Hampshire it is estimated to be 1.8 pCi/L, and many homes have much higher levels still.

Long-term exposure to radon gas in the home leads to an estimated 100 lung-cancer deaths each year in New Hampshire. Although testing for radon is inexpensive and can help prevent these lung cancer deaths an estimated 250,000 New Hampshire homes remain untested, and of these, over 60,000 likely have elevated radon levels.

The US Environmental Protection Agency (EPA) has established 4.0 pCi/L as the level at which action should be taken to reduce radon to under 2.0 pCi/L. Of the 25,000 New Hampshire homes that have been tested through the State radon program, more than 30 percent exhibited radon concentrations that exceeded the action level of 4.0. The map in Figure 1 shows that in general, communities in southeastern and eastern New Hampshire have the highest percentage of homes with elevated radon levels. Rockingham, Carroll and Coos counties have several communities in which more than half of the homes tested had elevated radon.

radon exposure risk by town

Figure 1: Radon Exposure Risk by Town, 1987-2009

An analysis of lung cancer rates, summarized in Figure 2, showed a consistent association between the level of radon risk in New Hampshire towns and the incidence of lung cancer, particularly for females. High-risk towns were defined as those in which at least 40 percent of homes exhibited elevated radon levels, medium-risk towns were between 20 and 40 percent, and low-risk towns were those with fewer than 20 percent of homes with radon levels exceeding the action limit.

lung cancer incidence by radon exposure potential of nh towns

Figure 2: Lung Cancer Incidence (Age 65 and Over) by Radon Exposure Potential of NH Towns

The lung cancer rate for females age 65 and older in high-radon risk towns was 28 percent higher than in low-risk towns, and 12 percent higher than in medium-risk towns. The difference in rates between the low-risk towns and the other two groups was statistically significant. No significant differences were found among the rates for males among the three groups of towns.

According to phone surveys of New Hampshire residents (BRFSS 2008), about 50 percent of homes have been tested for radon. Although the southeastern areas with the highest risk have the highest testing rates, nearly 40% of these homes remain untested. Since about half of the untested homes would be expected to have elevated radon levels, increased radon testing remains a significant environmental health challenge.

Radon causes lung cancer and related deaths in up to 100 New Hampshire residents each year. These deaths are preventable through testing and the mitigating of elevated radon levels.

The New Hampshire Department of Health and Human Services (DHHS) Division of Public Health Services tracks lung cancer cases via the NH Cancer Registry and provides health information on radon at a comprehensive environmental health website. DPHS also has a Tobacco Program to address the important impact of smoking on lung cancer.


1. U.S. Environmental Protection Agency (2009a, November 29). EPA. Radon website,

2. Health Effects of Exposure to Radon: BEIR VI, 1999. U.S. Environmental Protection Agency,,

For information about Radon testing in New Hampshire:

To learn more about Radon

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Environmental Public Health Tracking Program
NH Department of Health and Human Services, Division of Public Health Services
29 Hazen Drive, Concord, NH 03301
Tel: (603) 271-4988 800-852-3345 ext.4988

copyright 2009. State of New Hampshire