Radon is a naturally occurring radioactive gas. It has no color, odor or taste and is chemically inert. It comes from the breakdown of uranium. As the uranium molecule decays to form stable lead, a process taking many, many years, it changes from one radioactive element to another in a sequence known as the Uranium Decay Cycle. Partway through this cycle, the element radium becomes radon which as a gas moves up through the soil to the atmosphere.
Excessive radon levels have been found in all of the 50 states. In Colorado, approximately 50% of the homes have radon levels in excess of the EPA recommended action level of 4 picoCuries per liter (pCi/L).
Radon is estimated to cause about 21,000 lung cancer deaths per year. The Surgeon General has warned that radon is the second leading cause of lung cancer in the United States today. Only smoking causes more lung cancer deaths.
Radon moves from uranium-bearing granite deposits in the soil to the atmosphere because there is a lower concentration of radon in the atmosphere than in the soil. Your home is sited in its path and because the house is usually warmer than the surrounding soil, the air pressure is less and soil gases, including radon, move into the home. The most common routes are:
Spaces between basement walls and slab
Cracks in foundations and/or walls
Openings around sump pumps and drains
Construction joints and plumbing penetrations
Using well water with high radon concentrations
Environmental Protection Agency (EPA) recommends:
Test your home for radon - it's easy and inexpensive.
Fix your home if your radon level is 4 picocuries per liter, or pCi/L, or higher.
Radon levels less than 4 pCi/L still pose a risk, and in many cases may be reduced.