Most of the public's exposure to natural radiation comes from radon which can be found in homes, schools, offices, or any other closed-building situations. The EPA estimates that the national average indoor radon level in homes is about 1.3 Pico Curies per liter (1.3 pCi/L) of air, compared to an average outdoor level of 0.5 to 1.0 pCi/L. They also estimate that about 1 in 15 homes nationwide have levels at or above the level of 4 pCi/L, the level at which the EPA recommends taking action to reduce concentrations. Levels greater than 3,000 pCi/L have been measured in some homes.
Radon is also found in the water in homes, in particular, homes that have their own well rather than municipal water. When the water is agitated, as when showering or washing dishes or laundry, radon escapes into the air (10,000 pCi/L in water when agitated produces only about 1.0 pCi/L in the air). However, radon from well water generally contributes only a small proportion - less than 1% - of the total radon in indoor air in most housing. Municipal water systems hold and treat water, which helps to release radon, so that levels are very low by the time the water reaches our homes. There is currently no federally-enforced drinking water standard (acceptable level) for radon, and the EPA does not regulate private wells. Radon is less dangerous when consumed in water, but remains a risk to your health.
You cannot see, feel, smell or taste radon. Testing your home is the only way to know if you and your family are at risk from radon. The EPA and the Surgeon General recommend testing for radon in all homes. The EPA also recommends testing in schools.
The EPA Citizen's Guide to Radon describes commonly available tests for measuring radon concentrations in the home.
Radon testing is inexpensive and easy - it should only take a few minutes of your time. Millions of Americans have already tested their homes for radon. Various low-cost, do-it-yourself test kits are available through the mail and in hardware stores and other retail outlets (error rate of 20 to 40%, frequently requiring multiple test kits). You can also hire a trained contractor to do the testing for you using more accurate testing devices. Electronic CRM monitors (Continuous Radon Monitor) are the most accurate, and typically have less than a 1% error rate.What can I do to protect myself and my family from radon?
The first step is to test your home for radon, and have it mitigated if it is at or above the EPA's Action Level of 4 pCi/L (Pico Curies per liter). You may want to take action if the levels are in the range of 3-4 pCi/L. Generally, levels can be brought down below 2 pCi/L fairly simply.
The best method for reducing radon in your home will depend on how radon enters your home and the design of your home; every home is different. For example, sealing sump pump pits, and cracks in floors and walls may help to reduce radon. There are also systems that remove radon from the crawl space or from beneath the concrete floor or basement slab that are effective at keeping radon from entering your home. These systems are simple and don't require major changes to your home. Other methods may be necessary.Who Discoved Radon?
The German chemist Friedrich E. Dorn discovered radon-222 in 1900, and called it "radium emanation". However, a scarcer isotope, radon-220, was actually observed first, in 1899, by British scientist, R.B. Owens and New Zealand scientist, Ernest Rutherford. The measurement of radon, the Pico Curie, is named for French scientist Marie Curie because of her work in the field of radiation.
The EPA and the medical community nationwide became aware of the possible extent of a radon problem in U.S. homes in 1984. That year a construction worker at a nuclear power plant under construction in Limerick, Pennsylvania set off radiation monitor alarms as he arrived at work. The source of the radiation was determined to be radon decay products from his home. To date, his home has had some of the highest radon levels in the United States, at a level of 2,600 pCi/L.Is there a medical test to determine exposure to radon?
Several decay products can be detected in urine, blood and lung tissue. However, these tests are not generally available through typical medical facilities. Also, they cannot be used to determine accurate exposure levels, since most radon decay products deliver their dose and decay within a few hours. The best way to assess exposure to radon is by measuring concentrations of radon (or radon decay products) in the air you breathe at home.