Radon Basics
General Information
Radon is an odorless, invisible gas known to be a human lung carcinogen. Millions of homes and buildings contain high levels of radon gas. The Environmental Protection Agency’s (EPA) efforts are directed at locating homes with high levels and encouraging mitigation.
As a means of prevention, the EPA and the Office of the Surgeon General recommend that all homes below the third floor be tested for radon. Because radon is invisible, a test is the only way to determine high radon levels. The EPA recommends mitigating homes with high radon levels (e.g., above 4 pCi/l) and there are straight-forward reduction techniques that will work in most any home.
Most houses will not have a radon problem and there is a simple test to find out if you do or do not have high radon levels – The US Environmental Protection Agency’s position on radon
What is radon?
Radon is a colorless, odorless radioactive gas which comes from the natural breakdown (i.e., radioactive decay) of radium, which is a decay product of uranium. Uranium and radium are both common elements in the soil. The Surgeon General has warned that radon is the second leading cause of lung cancer in the U.S. today. Only smoking causes more lung cancer deaths. If you smoke and your home has high radon, your risk of lung cancer is especially high.
Where is radon found?
The major source of high levels of radon in houses is soil surrounding and under the house, particularly soil containing uranium. Radon is found all over the U.S. and the world. Some areas have more radon problems than others because of varying concentrations of radon-producing minerals in the soil, variation of soil types from one place to another and different characteristics found in individual homes. Radon problems have been identified in every state. The EPA estimates that as many as 1 in 15 houses have elevated annual radon levels.
What are the health risks?
Almost all scientists agree that radon is a health hazard to humans and that it causes lung cancer. Risk calculation and the action level usually raise debate. The EPA has declared radon to be a “Class A Carcinogen,” which means that it has been shown to cause cancer in humans.
Radon gas decays into radioactive solid particles that can get trapped in your lungs when you breathe. As the particles break down further, they release small bursts of energy that can damage lung tissue and lead to lung cancer. Not everyone exposed to elevated levels of radon will develop lung cancer. The amount of time between exposure and the onset of disease may be many years. Smoking combined with radon exposure is an especially serious health risk. You can reduce your risk of lung cancer by stopping smoking and lowering the radon level in your house.
What levels are too high?
Radon is measured in picocuries per liter (pCi/L) of air. A pico Curie is a measure of the amount of radioactivity of a particular substance. A liter is about equal to a quart. The level of radon in outdoor air is about 0.4 pCi/L. The average indoor radon level is about 1.3 pCi/L. The EPA has established 4.0 pCi/L as the action level for radon in houses, schools and workplaces. This is a technology-based number, not a health-based level. Current mitigation technology can generally reduce radon levels to 3.9 pCi/L or less. Since radon is a carcinogen, no level is completely risk-free. However, since it is a natural part of the environment there is no such thing as a “0″ level. (Radon is the largest source of exposure to naturally occurring radiation)
What is a pico Curie?
Radioactivity is commonly measured in picocurries (pCi). This unit of measure is named for the French physicist Madam Marie Curie, who was a pioneer in the research of radioactive elements and their decay. One pCi is equal to the decay of about two radioactive atoms per minute. Because the level of radioactivity is directly related to the number and type of radioactive atoms present, radon and all other radioactive elements are measured in pCi. For instance, a house having 4 pCi of radon per liter of air has about 8 or 9 atoms of radon decaying every minute in every liter of air inside the house. A 1,000 square foot house with 4 pCi/L of radon has nearly 2 million radioactive decays in it every minute.
How does radon get into homes?
Radon is a soil gas that typically moves up through the ground to the air above. Air pressure inside a house is usually lower than pressure in the soil around the house’s foundation. Because of the difference in pressure, a house acts like a vacuum, drawing radon in through dirt floors, hollow-block walls, cracks in the foundation floor and walls and openings around floor drains, pipes and sump pumps.
This information was provided courtesy of the Southface Energy Institute. Visit their web site at http://southface.org/web/resources&services/radon/sf_radon-menu.htm for additional information.
