Environmental Health Center
General Questions
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. All rocks contain some uranium, although most contain just a small amount. Certain types of rock, including granites, dark shales, light-colored volcanic rocks, sedimentary rocks containing phosphate, and metamorphic rocks derived from these rocks, have higher than average uranium contents.
High levels of radon have been found in all 50 states.
Indoor radon is the second leading cause of lung cancer after smoking.
How does radon get into my home?
Radon enters homes most commonly through:
Radon is 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.
Nearly 1 in 15 homes in the U.S. is estimated to have elevated radon levels. Elevated levels have been found in every state. While radon problems may be more common in some areas, any home may have a problem. In addition, the level of radon in a nearby home or building cannot be used to predict the level of radon in your home or building. Two adjacent houses may have very different radon levels. EPA recommends that all homes below the third floor be tested for radon and that all schools be tested.
The Surgeon General, the U.S. Environmental Protection Agency, 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.
What health effects are associated with exposure to Radon?
An increased risk of lung cancer is the only known health effect associated with exposures to elevated radon levels. Radon does not cause any short-term health effects, such as shortness of breath, coughing, headaches or fever.
According to the U.S. Environmental Protection Agency (EPA), radon causes an estimated 7,000 to 30,000 lung cancer deaths per year.
Radon gas decays into radioactive particles that can get trapped in your lungs when you breathe. As they break down further, these particles release small bursts of energy. This 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:
Smokers have a higher risk of developing radon-induced lung cancer.
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.
I understand that radon is a concern in some areas but not in others. Does my area have a radon problem?
Elevated indoor radon levels have been found in all areas of the country. Houses next door to each other can have very different levels. Some homes in low radon potential areas have been found to have high levels of radon. Conversely, some homes in high radon potential areas have been found to have low radon levels. The only way to know if your house has an elevated radon level is to test. EPA recommends that all residences below the third floor be tested for radon.
EPA and state agencies have identified areas with greater potential for elevated radon levels -- contact your state radon office for more information.
Is radon a problem in drinking water supplies?
Radon can enter a home through well water. It can be released into residences when the water is used for household purposes such as washing dishes and showering. The risk of radon entering homes through water is small compared with that of radon entering through the soil. On average, radon in water contributes about 5% of the total indoor air concentration in homes served by wells.
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.
Contact your state radon office for information about having your well water tested. For additional water safety information, contact EPA's Safe Drinking Water Hotline, (800) 426-4791.
Testing for Radon
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.) You should only purchase EPA certified radon tests kits. These kits and their providers have met EPA's qualifications for radon measurement.
For 12 hours prior to taking the test, and as much as possible during the test, keep all doors and windows closed. You do not have to vacate your home while testing. EPA recommends placing the radon kit in the lowest lived-in level of the home (for instance the basement if it is frequently used, otherwise the first floor). You should test a room that is used regularly, but not the kitchen or bathroom. For placement, follow the instructions that come with the test kit.
Once the test is complete, reseal the kit and send it to the lab specified on the package.
The quickest way to test is with a short-term test. These devices (charcoal canisters, alpha track, electret ion chamber, continuous monitors or charcoal liquid scintillation) remain in the home for two to 90 days. To make sure of the reading follow-up with another short-term kit and average out the two readings.
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's important because of seasonal and other variations.
You may also hire a company to test your home for you. Make sure the company is listed in EPA's Radon Measurement Proficiency Program or certified by your state. Your state radon contact and the Radon Helpline, (800) 557-2366, can provide a list. Ask to see the professional radon tester's EPA photo I.D. card.
You can also browse the Radon Proficiency Program listing on-line to find a certified contractor in your state.
Test kits are generally available from hardware stores, supermarkets, and other retail outlets, and also through the mail for prices ranging from $10 to $45.
Look for a test kit that is certified by your state or is listed by EPA's Radon Measurement Proficiency Program. It will say "Meets EPA Requirements" on the package.
The Air Quality Program offers low-cost short- and long-term radon test kits to anyone who wants to test their home. For more information about our test kit offer...
My neighbor has tested and found an elevated radon level (or found a very low radon level) does this mean I should (or shouldn't) be concerned?
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 1.3pCi/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 above 4 pCi/L. Most homes today can be reduced to 2 pCi/L or below. There is really no "safe" level. Any level of radon exposure carries some risk.
Are radon testing kits accurate?
Responsible 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 EPA Radon Measurement Proficiency Program are marked "Meets EPA Requirements." Long-term test kits (90 days to 1 year) will give a better indication of annual average radon levels.
When should short-term tests be conducted? Does time of year matter?
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.
Why should I spend more for a long-term test than for a short-term test that gives me quicker results?
The long-term radon test kits take into consideration seasonal variation, which can be substantial and therefore provide a better measure of annual average radon exposures than short-term tests. The less expensive short-term kits provide a good indicator of whether additional testing is warranted. If a short-term test result is greater than 4 pCi/L, EPA recommends following up with a long-term test, or a second short-term test, to confirm the result.
Radon Reduction
I tested my home and found a radon level of just under 4 pCi/l. Is that safe?
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's Citizens Guide to Radon contains some comparisons of risk estimates. The brochure is available from your state radon office, the Helpline (800) 557-2366 and can be viewed at EPA's Radon Publications Web Page
I tested my home and found a radon level higher than 4 pCi/l. What should I do?
If you tested with a short-term kit, EPA recommends either testing again with another short-term kit and averaging the results of the two tests, or conducting a longer-term test to confirm the results.
If the high level is confirmed, you should hire an EPA certified mitigator to reduce the radon level in your home. Contact your state radon office, the Helpline, or browse the Radon Proficiency Program listing on-line, for a list of contractors certified in your state.
What is involved in reducing the radon level in my home? What will it cost?
Several different methods are used to reduce radon levels in homes. The most common are sealing cracks and openings which prevents the radon from getting into the home; and reversing the flow of radon entry by pressurizing the home (called subslab depressurization).
In most cases, elevated radon levels can be reduced to between 2 and 4 pCi/l.
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. For more information, and a free copy of EPA's Consumers Guide to Radon Reduction, contact your state radon office, the Radon Fix-It Hotline (800) 644-6999, or the Radon Helpline (800) 557-2366. The brochure can also be viewed at EPA's Radon Publications Web Page
Should I refuse to buy a house with a radon problem?
Homes with high levels of radon can be fixed. Talk with the seller of the home about having the home mitigated.
Contact your state radon office or the Radon Helpline, (800) 557-2366, for a free copy of EPA's Home Buyers and Sellers Guide to Radon. The brochure can also be viewed at EPA's Radon Publications Web Page .
What about radon in new homes?
If you are building a new home, you can have your builder incorporate radon-resistant construction techniques into your home. The techniques add, on average, less than $500.00 to the cost of the home. Many state and local building codes already require these measures to be taken in all new home construction. For a packet of information, including architectural drawings and instructions to give to your builder, E-mail or call the Radon Helpline at (800) 557-2366.
Is radon a problem in schools?
Schools are at risk from radon just as homes are. EPA recommends that schools nationwide be tested.
For more information about indoor air quality issues in schools, visit EPA's Indoor Air Home Page
For more information, contact a specialist at (800) 557-2366 or send us an E-mail message.
| June 18, 1997 | | Disclaimer/Policy |