The natural decay of radioactive uranium produces radon gas. Radon poses no danger when present in low levels. When the gas accumulates in houses or poorly ventilated areas, however, it may lead to long-term complications. Potentially harmful levels of the colorless and odorless radon gas can be detected only through testing.
Sources
Uranium and radon are natural elements found in the soil, says the Environmental Protection Agency, EPA. As radioactive uranium decays, it releases radon gas. Uranium and radon are found in all types of soil across the United States. Radon may also be found in groundwater.
Penetration
Radon becomes a health risk when it accumulates in homes or enclosed spaces, such as caves, explains the EPA. The gas from the ground enters homes through foundation cracks or other openings. Basements, crawl spaces and first floors of homes tend to have the highest radon levels because the gas seeps up from the ground. Radon levels may be higher in well-sealed homes that trap the gas, according to the National Cancer Institute, NCI. Radon may also enter a home through well water, although that is much less common.
Health Risks
Exposure to high levels of radon leads to lung cancer, says the NCI. The Institute estimates radon accounts for up to 22,000 deaths from lung cancer annually. Radon particles release small amounts of energy as they break down in the lungs, explains the EPA. Over time, these energy bursts damage lung tissue and eventually may lead to cancer. Not everyone who inhales radon gas develops lung cancer, says the EPA, and it may take many years for cancer to develop. People who smoke have a higher risk of developing radon-associated lung cancer.
Safe Levels
Radon is a naturally occurring element and trace amounts are always detectable, according to the EPA. All radon exposure carries a risk and the EPA states no level is completely safe. Radon is measured in units called picocuries per liter of air, or pCi/L. Outdoor radon levels usually hover around 0.4pCi/L. Government guidelines specify indoor levels should be equal to outdoor levels, which may be impossible to achieve in all cases. The EPA maintains indoor radon levels should be less than 4 pCi/L.
Testing
Radon gas is colorless, odorless and tasteless. Testing is the only way to detect and measure radon, and the EPA and Surgeon General recommend testing all homes. Self-administered test kits are available at home improvement stores. The test kits sample air from the lowest level of the house, where radon is more likely to accumulate. Every house must be tested individually, recommends the EPA. Houses next door to each other may have different radon levels depending on insulation, soil variations or other factors. The EPA recommends remediation for homes with radon levels of 4 pCi/L or higher.
When to Test
Residents whose homes have radon levels below 4 pCi/L should retest periodically, advises the EPA. Test basement air if you are planning to spend more time in the area, such as before remodeling the basement into a recreation area. The EPA suggests testing a home before sale and keeping a record of the results for prospective buyers. Some home sales require radon testing, and testing before putting your home on the market allows time to take action to reduce radon levels, if necessary.
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