Oral exposure to radon can occur as a result of radon gas dissolving in water. Inhalation exposure of radon may also result when household appliances are not properly vented to the outside. This is also the case of radon released from water into the air when clothes and dishes are washed, toilets are flushed and water splashes during showering. Indoors, radon infiltration from soil into buildings may result in inhalation exposure. The most important route of exposure to radon is inhalation. Risk of developing disease also involves individual characteristics such as age, genetic factors and health status. Exposure is determined by assessing potential exposure pathways, including potential sources and routes of exposure, and other exposure risk factors, such as being a smoker. These factors can include the extent of exposure, particularly the concentration, duration and frequency of exposure. The toxic effects of radon depend on several factors. However, only those people in environments with increased levels of radon are at a higher risk of potentially developing negative health effects. (EPA 2017)Įveryone is potentially exposed to environmental radon. Surgeon General recommend testing all dwellings below the third floor for radon. The American Cancer Society (2015) estimated that there are 8 million dwellings in the U.S.is estimated to have elevated radon levels at or above EPA’s action level of 4 pCi/L. Nearly one out of every 15 dwellings in the U.S.The action level recommended by the Environmental Protection Agency (EPA 2019) for indoor exposure to radon is 4 pCi/L. Basements and lower levels of the buildings are likely to have higher levels of radon, as it is a heavy gas. This is especially true of newer construction that is more energy-efficient but can increase the levels of radon inside. In indoor locations, such as dwellings, schools, or office buildings, levels of radon are generally higher than outdoor levels. However, the average indoor level in the U.S. They can vary based on location and the geology of the soil. 1996).īackground levels of radon in outdoor air are generally quite low, typically around 0.4 picocuries per liter of air (pCi/L). Locations that are not contaminated, but at which elevated natural radon levels exist, can include utility and subway tunnels, fish hatcheries, natural caverns, and excavation sites (EPA 2007 Field 1999 Fisher et al. Radioactively contaminated sites can include uranium mill sites and associated mill tailing piles, phosphate fertilizer plants, oil refineries, power plants, and natural gas and oil piping facilities. These sources can include underground uranium, hard rock and vanadium mines, and water treatment plants. The radioactive radon attaches to dust particles, smoke, walls, floors, ventilation equipment, and clothing, allowing it to be inhaled into the lungs.Įxposure to high concentrations can occur in any location with geologic radon sources (EPA 2007 Field 1999). Since uranium and thorium are ubiquitous in the earth’s crust, rock and soil will continually release radon in the environment. Radon may also enter dwellings through the water supply and natural gas that had previously been in contact with underground uranium and thorium-bearing rock and soil. The main source of indoor radon gas is from rock and soil underneath buildings where it infiltrates through crawl spaces, cracks in solid floors, construction joints, cracks in walls, gaps in suspended floors, gaps around service pipes, and cavities inside walls. When radon escapes from soil or is discharged from emission stacks to the outdoor air, it is diluted to levels that are normally lower than indoor air. The burning of coal and other fossil fuels also releases radon. It is also present in rock, soil, water, and building materials. Radon is normally found at very low levels in the outdoor air.
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