Radon is a naturally occurring, radioactive gas that you can't see, taste or smell. It is produced by the breakdown of uranium in soil, rock and water.
High levels of radon have been found in all 50 states.
Indoor radon is the second leading cause of lung cancer after smoking. Radon causes an estimated 7,000 to 30,000 lung cancer deaths each year. A combination of smoking and high levels of radon in your house increases your risk.
Radon enters homes most commonly through:
- cracks in foundations;
- openings around sump pumps and drains;
- construction joints;
- cracks in walls;
- crawl spaces; and
- in some cases from well water.
Radon is usually most concentrated in the lowest level of the home.
Radon may also be present in well water and can be released into the air in your home when water is used for showering and other household uses. Radon entering homes through water may be a small risk compared to radon entering though the soil.
According to the U.S. Environmental Protection Agency (EPA), radon causes an estimated 7,000 to 30,000 lung cancer deaths per year.
The Surgeon General, the EPA, the National Academy of Sciences, the American Medical Association, the World Health Organization and the American Lung Association have all identified indoor radon as a national health problem.
EPA recommends that all homes and apartments below the third floor be tested.
As with all pollutants, there is some uncertainty in estimating health risks associated with radon. Because radon risk estimates are based primarily on scientific studies of humans (mostly miners exposed to different levels of radon in their underground work), scientists are considerably more certain of radon risk estimates than they are of estimates based solely on animal studies.
Smoking increases the risk of exposure to radon, by as much as a ten fold increase.
An increased risk of lung cancer is the only known health effect associated with exposures to elevated radon levels. When radon decays within your lungs it releases energy that can damage lung tissue and lead to lung cancer over the course of your lifetime. Not everyone exposed to elevated levels of radon will develop lung cancer.
Your chances of getting lung cancer from radon depend mostly on:
- How much radon is in your home.
- The amount of time you spend in your home
- Whether you are a smoker or have ever smoked.
Houses next door to each other can have very different levels. The only way to know if your house has an elevated radon level is to test. Therefore, it is recommended that all residences below the third floor be tested for radon.
Radon can enter a home through well water. It can be released into residences when the water is run. Generally, radon is not a concern with public drinking water systems, where the radon likely is released to outdoor air before reaching the home faucets. Compared to radon entering homes through soil, radon entering through water is generally a small source of risk.
Contact EPA's Safe Drinking Water Hotline for additional water safety information 800/426-4791.
Schools are at risk from radon just as homes are.
Virginia statute requires all schools to have tested for radon, and to maintain records of the test results for disclosure on request. The regulation does not require schools that find a problem to mitigate according to a mandated schedule. It is up to the District and its constituents to address mitigation issues.
Further information on radon in schools can be found in the EPA Radon Publication Radon Measurement in Schools.
Radiological Health Hotline:1-800-468-0138
You can also call one of the following EPA numbers:
Safe Drinking Water Hotline:1-800-426-4791
Indoor Air Quality Hotline:1-800-438-4318
Radon Fix-it Hotline: 1-800-644-6999
Testing for radon is simple and inexpensive.
There are many 'do-it-yourself' kits you can buy at retail outlets or through the mail. (See next question for where to get a test kit.) EPA recommends placing the radon kit in the lowest lived-in level of the home. Follow the instructions that come with the test kit. After the test is complete, you send it to the manufacturer for analysis.
The quickest way to test is with a short-term test. These devices remain in the home for two to 90 days.
The EPA recommends that if the initial screening result was from 4.0 pCi/l to 9.9 pCi/l, a second test of long-term duration should be taken and used as the basis for determining mitigation. If the first test was 10.0 pCi/l or above, a second test of short term duration should be taken and the average between the two used as the basis for evaluating the situation.
Virginia recommends long-term testing whenever possible, and when the homeowner is comfortable with long-term testing. A long term device which stays in the home for 90 days to one year (such as a alpha track or electret detectors) will give you a reading that is more likely to tell you the home's year-round average radon level. That is important because of seasonal and other variations.
You may also hire a certified company to test your home for you. Make sure the company's tester is listed with either the National Radon Profiency Program (NRPP) or the The National Radon Safety Board (NRSB). (Note some states license radon testers. Virginia does not.)
Test kits are sometimes available from building supply stores and also directly from radon measurement labs. Look for a test kit that is listed by NRPP or NRSB. (Note some states certify test kits. Virginia does not.)
No. Having a neighbor that has tested high (or low) for radon is no guarantee that your house will test similarly. The only way to know if a house has a high level of radon is to test.
Radon is measured in picocuries per liter of air (pCi/l). The average indoor level is 1.3 pCi/l and about 0.4 pCi/l is normally found in the outside air. EPA recommends that action be taken to reduce the indoor radon levels that are 4.0 pCi/l or above. Most homes today can be reduced to 2 pCi/l or below. Any level of radon exposure carries some risk.
NRPP or NRSB approved test kits, when used as directed, provide reliable indications of radon concentrations over the time the kits are used. Test kits that have successfully passed the NRPP or NRSB requirements.' Long term test kits (90 days to 1 year) are more representative.
Proper test conditions are essential for good measurements. For short term tests, key elements are: 12 hrs. of closed house conditions before beginning the test, and for the duration of a short-term test; an absolute minimum of a 48 hr. test period; placing the test device in the lowest occupied level of the home; placing the device at least 12 inches off the ground, and two feet from the ceiling; and keeping the device away from any heat or humidity source.
Winter readings are typically higher than those taken in summer. During winter, the larger differential between outdoor and indoor pressure is likely to lead to higher entry of radon into a house than would occur in summer. In addition, your home is likely to be less ventilated in the winter. EPA recommends testing in the winter.
The long-term radon test kits take into consideration seasonal variation, which can be substantial and therefore provide a better measure of the true, annual average radon exposures than short-term tests. The short-term kits provide a good indicator of whether additional testing is warranted. If a short-term test result is greater than 4.0 pCi/l or greater, EPA recommends following up with a long-term test, or a second short-term test, to confirm the result.
Four picocuries per liter of air has been identified by EPA as the recommended action level. There is no absolutely safe level; there is some level of risk associated with all levels of radon.
EPA estimates that for an annual average to 4 pCi/l of radon, the risk or lung cancer is 7 per 1,000 persons exposed for non-smokers, and 62 per 1,000 persons exposed for smokers.
The EPA recommends that if the initial screening result was from 4.0 pCi/l to 9.9 pCi/l, a second test of long-term duration should be taken and used as the basis for determining mitigation. If the first test was 10.0 pCi/l or above, a second test of short term duration should be taken and the average between the two used as the basis for evaluating the situation. We recommend long-term testing whenever possible, and when the homeowner is comfortable with long-term testing. (For more information, see EPA's brochure "Consumer"s Guide to Radon Reduction" - also available from the EPA Public Information Center 202/260-2080 (document number 402-k92-003)) or EPA Publication Website
Radon reduction is comparable to other home maintenance efforts. If there is a radon problem in a particular residence, it is fixable and usually for between $500 and $2,500.
There are two basic types of kits: short-term kits (2 to 90 days) and long-term kits (90 days to 1 year), the most common type of short-term kit is the charcoal canister and the most common type of long-term kit is the alpha track detector. See Question 7 (Testing).
Several different methods are used to reduce radon levels in homes. The most common is a combination of sealing cracks and openings which prevents the radon from getting into the home; and reversing the flow of radon entry by pressuring the home (called subslab depressurization). In most cases, elevated radon levels can be reduced to between 2 and 4 pCi/l. See EPA booklet: "Consumer"s Guide to Radon Reduction" - - also available from the EPA Public Information Center 202/260-2080.
The cost can for a professionally installed radon reduction typically range from $500 to $2,500.
Radiological Health Program | James Madison Building, 7th Floor | 109 Governor Street, Room 730 | Richmond, VA 23219 | Telephone (804) 864-8150 | Fax: (804) 864-8155