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Radon is an invisible, odorless, tasteless, cancer-causing gas that comes from the natural radioactive breakdown of uranium and radium in soil, rock and water. Radon enters buildings through cracks, holes and pipes in the foundation. All buildings contain some radon, but homes are the most concerning since that is where families spend most of their time. Radon is found throughout the United States and is particularly prevalent in Colorado. The United States Environmental Protection Agency (EPA) has ranked Colorado as a Zone 1 area, meaning the average house will exceed the EPA's action level for indoor radon.
Radon is produced as a decay product from uranium and radium. This naturally occurring radioactive gas is found in most soil, rock and ground water. Since radon is a gas, the inert element can easily travel through cracks and pores without being chemically bound or attached to other elements. Voids and porous materials are found under every building, allowing radon easy entry.
Radon is a known human carcinogen. It breaks down into radioactive particles that can damage lung cells and increase the risk of lung cancer. According to the EPA, radon is the leading cause of lung cancer among non-smokers causing an estimated 21,000 lung cancer deaths in the United States each year. The Iowa Radon Lung Cancer Study tracked nearly 1,000 women who had lived in their homes more than 20 years. The results of the case-control study (after adjusting for age, smoking, and other factors) indicated that a 20-year exposure of radon levels at the EPA guideline of 4.0 pCi/L yielded an increased lung cancer risk of 50%. Cigarette smoking and radon exposure produce a synergistic effect. In fact, people who smoke who are exposed to high concentrations of radon, have an estimated 10-15 times greater risk of developing lung cancer than non-smokers. Resources and support for quitting tobacco can be found at www.tobaccofreejeffco.com/thinking-of-quitting.
In 1986, the EPA recommended all homes be tested for radon, and in 1988, the U.S. Congress enacted the Indoor Radon Abatement Act, which set a national goal to reduce radon in buildings to the ambient level of outdoor air. As a result, the EPA set an action level of 4.0 picocuries per liter (pCi/L) for indoor radon. If radon is found above 4.0 pCi/L, the EPA recommends homeowners install mitigation equipment. There is still some risk at levels below 4.0 pCi/L, and the EPA suggests that indoor radon levels are as close to ambient outside air as possible (outside air has approximately 0.4 pCi/L). Radon Entry
Elevated radon levels depend upon the strength of the radon source, how easily radon is delivered into the structure and, to a lesser degree, the structure's ventilation rates. In most buildings, 95 percent of the radon entering the structure comes from the rock and soil underneath. The radon is pulled into the building by air pressure differentials created by natural and mechanical ventilation. Natural ventilation occurs due to stack effect (hot air rising in the home), wind and temperature differences between inside and outside air. Rain and low barometric pressure can also increase radon entry. Exhaust fans in the home, as well as negative pressure relative to the outdoors caused by heating systems, also increase radon entry.
These factors cause radon levels to vary, both daily and seasonally. The highest levels are expected during the winter, and lower concentrations are expected during the summer because windows and doors are typically open. Well water and building materials may cause radon in homes, but these usually account for less than 5 percent of the radon that enters.
Testing for radon is a simple and inexpensive. Any home can have a radon problem including apartments. Jefferson County Public Health (JCPH) offers radon test kits for only $10.00. Call 303-271-5700 or visit JCPH at 645 Parfet Street in Lakewood to get your test kit. Long-term test kits are also available at local hardware stores, supermarkets and other retail outlets. If you have questions or need more information on radon, radon testing, and radon mitigation, contact Mitchell Brown at firstname.lastname@example.org at JCPH Environmental Health Services or Linda Jones, Environmental Health Administrative Assistant at JCPH at 303-271-5756.
High levels of radon can be easily remedied. If your home has elevated levels of radon above the EPA’s recommended action level of 4.0 picocuries of radon per liter of air (pCi/L), a radon mitigation system should be installed. Radon levels less than 4.0 pCi/L still pose a risk, and in many cases can be reduced. Repairs usually cost no more than many other common home repairs (ranging from $800 - $1,200) and will not change the appearance of your home.
Methods of mitigation depend on the type of foundation your home has and differ for basements, crawl spaces, engineered floors, slab on grade, or any combination of these foundations. Radon mitigation can be accomplished by mitigating one or more of the following factors:
Of these, controlling radon transport by pressure driven entry is the most common mitigation technique used in Colorado. This is called Active Soil Depressurization (ASD). This technique creates a suction or area of low pressure beneath the structure that is stronger than the partial vacuum applied to the soil by the building. ASD systems consist of pipes connected to a fan, which draws gasses from under the building. Radon is captured and vented to the outside before it has a chance to enter the home. Several types of ASD systems exist including:
All of these ASD systems require expert installation, additional sealing of openings into the home, and of course, testing to verify that radon levels have been reduced to below 4 pCi/L. If you wish to hire a contractor, use a certified radon mitigation contractor who is listed by the National Environmental Health Association and the National Radon Safety Board and is trained in proper and effective radon mitigation. Tips for Hiring a Contractor include:
If you decide to mitigate yourself, information about mitigation system installation and design is available in the manual “Protecting Your Home from Radon: A Step-by-Step Manual for Radon Reduction” by Douglas L. Kladder and Associates. This manual is available in all Colorado public libraries and is also available at JCPH.
Soil gas is the largest natural source of radon in homes; however, well water can be a significant factor if high concentrations of dissolved radon are found. In 1992, the EPA proposed a maximum contaminant level (MCL) of 300 pCi/L for public water supplies. As a result of these proposed MCLs, radon may become the most common treated-for contaminant in well water. In Colorado, radon in well water averages well above the proposed MCL. High radon levels in water are required to significantly elevate radon in air. The EPA uses a "rule of thumb" of 1:10,000. That is, if you have 10,000 pCi/L of radon in water, indoor radon concentrations might increase by 1 pCi/L. Recent studies indicate that elevated radon levels in water are an inhalation threat and may be an ingestion hazard, increasing the risk of stomach cancer.
There are three recognized treatment methods to remove radon from water:
Storing water until the radon decays is somewhat impractical because it takes 27 days for 99% of the radon to decay. A typical family of four using 300 gallons of water per day would need 8,100 gallons of storage. A tank this large is impractical and expensive.
Aeration is the preferred method for treating radon in water. As the water is aerated, radon is released and piped outside. This method requires another pump to pressurize the pressure tank, a radon fan and biological treatment of the aerated water because it may be contaminated by the air used for aeration.
Granular activated carbon (GAC) removes radon in water by adsorbing the radon onto the carbon; however, gamma radiation results from the radon decay products (RDPs) that accumulate in the filter. To prevent radiation hazards to the occupants, the filter must be shielded or remotely located.
Schools are at risk from radon just like homes. The state of Colorado requires all schools to test for radon and to maintain records of the test results for disclosure upon request. The statute does not require schools to mitigate radon. If radon mitigation is needed, the school district and its constituents must address mitigation issues. For more information, visit:
Jefferson County Environmental Health Services: 303-271-5700 Western Regional Radon Training Center: 1-800-513-8332 Colorado Radon Hot Line: 1-800-846-3986
Environmental Protection Agency Radon Webpage
Colorado Department of Public Health and Environment Radon Webpage
World Health Organization Radon Handbook National Radon Proficiency Program
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