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Radon is a radioactive gas produced from the decay of uranium which is naturally present in rock and soil around the world. Radon is the second leading cause of lung cancer after smoking tobacco and causes an estimated 21,000 deaths per year in the United States. It enters a building through cracks and gaps at the base of the structure due to buildings having lower air pressure than outdoors and can reach very high levels in buildings in some cases. According to the United States Environmental Protection Agency (EPA) outdoor air has a radon concentration of approximately 0.4 pico Curies of radon per liter of air (0.4 pCi/L) on average, and the levels in homes is around 1.3 pCi/L on average. While there is no known "safe" level of radon, the EPA has set an action level at 4.0 pCi/L meaning if the concentration in a building is at or above that level, action should be taken to mitigate it, usually with the installation of a radon mitigation system. The EPA also recommends that homeowners consider installing a mitigation system if the levels are between 2-4pCi/L. 

Colorado counties radon zone map

According to the Colorado Department of Public Health and Environment (CDPHE) every county in Colorado is in Zone 1 which indicated that any given home is at significant risk of elevated indoor radon levels. Radon kills approximately 500 Coloradans per year and nearly 1 in 2 homes in Colorado has radon levels above the EPA action level, so it is extremely important to have your home tested. The EPA recommends that a radon test be performed on every home when it is being purchased, and every 2 years even if the building has a radon mitigation system to ensure it is operating properly and lowering indoor radon to levels below the action level. Radon levels inside a home will vary based on many factors such as soil composition, geological activity in the area, house build quality, and how the home is used. It is not possible to estimate the radon level inside a home, the only way to know if elevated radon is present in a home is to have it tested. If you have a radon test performed before purchasing a house you may be able to negotiate with the sellers to have them install a mitigation system if elevated levels are detected. Visit for more information on radon.

Click here to find out why you should have an advanced radon test performed with a continuous-monitor device rather than with a charcoal canister.

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