Radon
What is radon?
Radon is a radioactive gas that is found in the earth's rock and soil. It is formed by the natural breakdown of radium, which is itself a decay product of uranium. As radon decays, it forms radioactive by-products called either "progeny," "decay products" or "daughters" which, if inhaled, can damage lung tissue and cause lung cancer. Invisible and odorless, radon is a health hazard when it accumulates to high levels inside homes or other structures. And it is deadly. Indoor radon exposure is estimated to be the second leading cause of lung cancer deaths each year in the United States. Cigarette smoking is responsible for the large majority (87 percent) of lung cancer deaths.
How does radon get indoors?
Radium, which releases radon, is common in the earth's crust. Soils and rocks containing high levels of uranium, such as granite, phosphate, shale and pitchblende are natural sources of radon. High levels of radon in the soil are primarily responsible for radon problems. The radon gas percolates up through porous soils under the home or building and enters through gaps and cracks in the foundation or in the insulation and through pipes, sumps, drains, walls or other openings. Water is another possible pathway for bringing radon into the home. Water, when in contact with rock containing uranium, absorbs the radon gas.
The radon is then carried into the home and released into the air in household dishwashers, faucets, showers, or washing machines. Water-related radon problems usually involve deep private wells rather than community water supplies. In some unusual situations, radon may be released from home construction materials such as stone used to build fireplaces or solar heating storage systems. Radon is not a problem outdoors because it is quickly diluted to low levels by outdoor air.
HEALTH EFFECTS
Radon is estimated to be the second leading cause of lung cancer in the U.S. today, causing thousands of deaths each year. Cigarette smoking remains the primary cause.
Is radon is a problem in your home?
While an area's geology may indicate the potential for radon problems, human senses cannot pick up any evidence of this odorless, colorless gas.
THE ONLY WAY TO DETERMINE IF THERE IS A PROBLEM IN YOUR HOME OR BUILDING IS BY MEASURING THE RADON LEVEL.
Measuring for radon can be done simply and relatively inexpensively. The American Lung Association as well as the EPA and the Surgeon General recommend testing all homes below the third floor for radon. Testing in schools is also recommended. There are many kinds of low-cost "do it yourself" radon test kits available through the mail and in hardware stores and other retail outlets. Call 1-800-LUNGUSA to find out where to buy a kit. Choose a test kit that has passed EPA's testing program. These kits will usually display the phrase "Meets EPA Requirements."
There are two general ways to test for radon:
1. Short-Term Testing
The quickest way to test is with short-term tests. Short-term tests remain in your home for two days to 90 days, depending on the device. "Charcoal canisters," "alpha track," "electret ion chamber," "continuous monitors," and "charcoal liquid scintillation" detectors are most commonly used for short-term testing. Because radon levels tend to vary from day to day and season to season, a short-term test is less likely than a long-term test to tell you your annual average radon level. If you need results quickly, however, a short-term test followed by a second short-term test may be used to decide whether to fix your home.
2. Long-Term Testing
Long-term tests remain in your home for more than 90 days. "Alpha track" and "electret" detectors are commonly used for this type of testing. A long-term test will give a more accurate annual average radon level than a short-term test for your home. The average indoor level is estimated to be about 1.3 pCi/L; and 0.4 pCi/L of radon is found in the outside air. Action should be taken to reduce levels if the test results indicate an annual average radon level of 4 pCi/L or higher.
Credit: National Institute of Health.