MAMF_with 1-21 Revisions

MAMF/MALB Companion Guidance 2021 Understanding Radon 1 Informational Introduction to Radon A. Radon Facts Radon is a naturally occurring radioactive gas that is a part of the uranium-238 decay chain. The immediate parent of radon-222 is radium-226. Radon comes from the breakdown (radioactive decay) of uranium that is found in soil and rock all over the world. Radon is a component of the air in soil that enters buildings through cracks and other pathways in the foundation. Eventually, it decays into radioactive particles (decay products) that can become trapped in your lungs when you inhale. As these particles decay, they release small bursts of radiation that can damage lung tissue and lead to lung cancer over the course of a lifetime. Studies by the U.S. Environmental Protection Agency (EPA) have found that radon concentrations in outdoor air average about 0.4 pCi/L (picocuries per liter) of air. However, radon can reach much higher concentrations inside a building. Radon gas is colorless, odorless and tasteless. The only way to know whether elevated concentrations of radon are present in any building is to test. B. Radon’s Health Effects Radon is a known human carcinogen. Prolonged exposure to elevated radon concentrations causes an increased risk of lung cancer. Like other environmental pollutants, there is some uncertainty about the magnitude of radon health risks, but EPA calculates that radon may cause 21,000 lung cancer deaths in the United States each year. The U.S. Surgeon General has warned that radon is the leading cause of lung cancer deaths in nonsmokers in the United States. Only smoking causes more lung cancer deaths than radon. Not everyone who breathes radon decay products will develop lung cancer. An individual’s risk of getting lung cancer from radon depends primarily on three factors: the concentration of radon, the duration of exposure and the individual’s smoking habits. In addition, some people are more susceptible to lung cancer than others. Risk increases as an individual is exposed to higher concentrations of radon over a longer period of time. Smoking combined with radon is an especially serious health risk. The risk of dying from lung cancer caused by radon is much greater for smokers than it is for nonsmokers. C. Radon Exposure Because many people spend much of their time at home, the home is likely to be where the most significant radon exposure occurs. According to EPA, nearly one out of every 15 homes in the United States is estimated to have radon concentrations that exceed the EPA action level. For most people, the second largest exposure to radon is likely to be at their school or workplace. Elevated concentrations of radon have been found in homes and other buildings in every U.S. state and similarly throughout the world. According to EPA studies, nearly one out of every five schools in the United States are estimated to have radon concentrations that exceed the EPA action level in at least one frequently occupied ground-contact room. While elevated radon may be more common in some areas, any building can have a problem. It is recommended that ALL buildings be tested regardless of the area of the country and that maps should not be used to determine whether to test. The concentration of radon in the air within a building should be reduced below the federally established radon action level or as established by the state or other local jurisdiction. Action levels, such as 4 pCi/L established in the United States, are based largely on the ability of current mitigation technologies to consistently reduce radon concentrations. Any radon exposure creates some risk; no concentration of radon is safe. Even radon concentrations below the action level pose some risk, and the risk of lung cancer can be reduced by further lowering indoor radon concentrations. Depending on the building characteristics, radon concentrations in some buildings can be reduced well below the action level. In others, reducing radon concentrations below the action level may be more difficult. D. Radon Entry Into Buildings Radon in soil gas is the main source of radon problems. Pathways for radon to enter a building include cracks in the slabs and walls, the expansion joints between floor and walls, porous concrete block walls, open sump pits, crawlspaces and openings around utility penetrations. Some buildings have other pathways for radon to enter a building such as sub-slab utility tunnels and heating, ventilating and air conditioning (HVAC) ducts. Radon gas may also enter buildings in well water. Radon from well water used in a building can off-gas and raise concentrations in the air within the building. For buildings or small communities that use well water, a test of the water