Radon Exposure
Environmental Risk Factor
Radon is a naturally occurring radioactive gas that seeps from the ground into buildings, particularly through foundation cracks, gaps around pipes, and sump pump openings. It is colorless and odorless, making it undetectable without testing. Radon is the second leading cause of lung cancer in the United States, responsible for approximately 21,000 deaths annually. Every home is potentially at risk, regardless of age or condition, though certain geological formations produce more radon than others. The EPA estimates that nearly 1 in 15 US homes has elevated radon levels above the recommended action level of 4 picocuries per liter (pCi/L).
How It's Measured
Radon is measured using specialized test kits placed in the lowest livable level of a home for a minimum of 48 hours (short-term) or up to 90 days (long-term). Results are reported in picocuries per liter (pCi/L). The EPA recommends action if levels exceed 4 pCi/L but notes there is no truly safe level of radon exposure. Zone designations from the EPA Radon Zone Map classify counties into three zones based on predicted average indoor radon screening levels. Zone 1 counties have the highest predicted potential.
Health Effects
- ⚠️Lung cancer — the primary health risk of radon exposure
- ⚠️Increased lung cancer risk when combined with smoking
- ⚠️Potential contribution to other respiratory diseases
- ⚠️Particularly dangerous for children with developing lungs
- ⚠️Cumulative risk increases with long-term exposure duration
- ⚠️Risk increases proportionally with concentration levels
Data Sources
- 📊EPA Map of Radon Zones
- 📊State radon testing databases and surveys
- 📊USGS geologic radon potential maps
- 📊Indoor radon testing data aggregations
How to Protect Yourself
- ✓Test your home for radon — kits are inexpensive and available at hardware stores
- ✓Test the lowest level of your home where people spend time
- ✓If levels exceed 4 pCi/L, install a radon mitigation system
- ✓Radon mitigation typically costs $800-$1,500 and reduces levels by up to 99%
- ✓Test again after mitigation to verify effectiveness
- ✓Consider radon testing when buying or selling a home