Above 4.0 pCi/L
A safe level of radon gas is no radon gas. Radon gas is a carcinogen which causes lung cancer. The US EPA has put it plainly, stating, Any radon exposure has some risk of causing lung cancer. The lower the radon level in your home, the lower your family's risk of lung cancer.. The average person receives a higher dose of radiation from the radon levels in their home than from their combined exposure to all other radiation sources, natural or man-made Yet, the average person receives a higher radiation dose from radon at home than from all other natural or man-made sources combined. Outdoor radon levels in the U.S. range from 0.02 to 0.75 pCi/L (picoCuries per liter), averaging 0.4 pCi/L. But homes draw concentrated radon gas from the ground. Because radon is nine times heavier than air, elevated radon levels build up in basements and on lower floors. Nearly 8 million US homes, or 1 out of every 15, have radon levels above the EPA's 4 pCi/L action limit and nearly 1 out of 6 exceed the EPA's 2 pCi/L consider action limit. The cost of a mitigation system may vary according to the home's design, size, foundation, construction materials and the local climate. Radon reduction systems average costs nationally are $1,200 with a range from $800 to $1500 common depending on house and market conditions.  Radon gas is a naturally-occurring byproduct of the radioactive decay of Uranium in the soil. Depending on your geographic location, the radon levels of the air you breathe outside of your home may be as high as 0.75 pCi/L. Radon gas is a carcinogen which causes lung cancer. The US EPA has put it plainly, stating, Any radon exposure has some risk of causing lung cancer. The lower the radon level in your home, the lower your family's risk of lung cancer.. The national average of outside radon levels is 0.4 pCi/L and it is estimated by the National Academy of Sciences that outdoor radon levels cause approximately 800 of the 21,000 radon induced lung cancer deaths in the US each year. Radon gas is a carcinogen which causes lung cancer. The US EPA has put it plainly, stating, Any radon exposure has some risk of causing lung cancer. The lower the radon level in your home, the lower your family's risk of lung cancer.. Short-Term Tests: A single short-term test of 2-7 days in length can be used to indicate the radon level in your home. If a single short-term test reveals levels of 4 pCi/L or more, DEP data indicate that subsequent testing would confirm that levels in the home are 4 pCi/L or more in 80 percent of cases. The radon is vented through the pipe to the outside, where it is quickly diluted. The average price of such a system is around $1,200, although prices can range from $500 to $2,500, depending on characteristics of the home and the underlying soil. According to a national residential radon survey completed in 1991, the average indoor radon level in the United States is 1.3 picocuries per liter (pCi/L). The average outdoor level is about 0.4 pCi/L. Excessive radon levels have been found in all of the 50 states.  If the annual average level of radon in a home is above 4.0 pCi/L, the EPA and MDH recommend that steps be taken to lower it. While it isn't possible to reduce radon to zero, the best approach is to lower the radon level as much as possible. The Environmental Protection Agency and MDH set the recommended action level for radon at 4.0 picocuries/liter(pCi/L). To apply the recommended action level correctly, the results should be based on the annual average level of radon measured in a home. The risk to the average person of dying of radon-caused lung cancer due to a lifetime exposure to 4 pCi/L radon level at home is 2.3 percent. If there are five people in your family, the chances that someone becomes a victim of radon over 10 percent. Nearly 8 million US homes, or 1 out of every 15, have radon levels above the EPA's 4 pCi/L action limit and nearly 1 out of 6 exceed the EPA's 2 pCi/L consider action limit.
http://www.radon.com/radon/radon_levels.html http://www.radonseal.com/radon-level.htm http://sosradon.org/reducing-radon-in-your-home http://www.radon.com/radon/radon_levels.html http://www.radon.com/radon/radon_levels.html http://www.nj.gov/dep/rpp/radon/radontes.htm http://co-radon.info/CO_general.html http://www.health.state.mn.us/divs/eh/indoorair/radon/radontestresults.html http://www.radonseal.com/radon-level.htm
average radon levels in homes