Radon gas builds up in everyone's home as it seeps from the ground. The earth produces the gas as radium, uranium and thorium go through radioactive decay. Because the gas itself is radioactive, it is a contributing risk factor for the development of a number of cancers, most commonly cancer of the lung. You can test your home's radon level with a short-term or long-term test. A long-term radon test will give you the most accurate picture of your home's average radon level.
Why Conduct a Long-Term Test?
You should conduct a long-term radon test only if the results of a short-term test justify it. Short-term tests usually last three days. During a short-term test, you keep all the doors and windows to your home closed as much as possible to see how quickly radon builds up. If the results of a short-term test show a high radon level--greater than 4 pCi/l--the U.S. Environmental Protection Agency recommends you do a long-term test to get a more accurate picture of your home's average radon level. A long-term test lasts a minimum of 91 days and gives you a better idea of the radon level in your home over a long period of time as you and your family go about your regular business.
Who Can Conduct the Test?
You can hire a professional contractor to conduct a long-term radon test in your home, or you can do it yourself. Most states maintain a list of certified radon contractors that will do the testing for you. You can find a link in Resources to a page with contact information for all state radon offices. There are two privately run national radon programs you can contact, as well. You can reach the National Environmental Health Association's National Radon Proficiency Program at 800-269-4174, and the National Radon Safety Board at 866-329-3474.
What Type of Tests to Use for Long-Term Testing
Several types of radon test kits exist. They include charcoal canisters, electret ion chambers, alpha tracks, continuous monitors and charcoal liquid scintillation detectors. You should only use the alpha track or electret ion chambers for long-term testing, according to the Environmental Protection Agency. Your state's radon contact and the national radon agencies can help you get your hands on test kits. Also, you can obtain discounted test kits through the website for the National Radon Program Services at Kansas State University.
Conducting the Test
When you obtain your radon testing kit, follow the laboratory's instructions regarding where to place the testing devices. During the testing period, remember to use your house as you normally would: leave windows open if you like; enter and exit through all doors; run the heating and air conditioning as usual. The point of the test is to determine if radon builds up to dangerous levels in your house; there's no point in creating artificial conditions in your home, because then you'll get artificial results.
Do not disturb the testing devices during testing. Keep all objects four inches or more away from the devices. Keep them out of direct sunlight and away from exposure to excess moisture. When the test period is complete, send the kit back to the laboratory and await your results.
(info from this section from reference 4)
Results and Mitigation
Radon levels are expressed in picoCuries per liter (pCi/l) of air. Indoor environments contain, on average, 1.3 pCi/l of radon, and the outdoor atmosphere contains approximately 0.4 pCi/l. The Environmental Protection Agency set the official radon action level at 4 pCi/l. If your long-term testing reveals a radon level greater than the action level, you should mitigate the problem. Radon mitigation involves having contractors install special ventilation systems that pipe radon gas away from your home, either from under the foundation or directly out of the basement.
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