Radon Risk Assessment Tool
Estimate your home's radon risk based on state, basement, home age, and floor level.
Select your state and home characteristics to assess radon risk.
Understanding Radon and Your Health
Radon is a naturally occurring radioactive gas produced by the decay of uranium in soil, rock, and water. It is colorless, odorless, and tasteless, which makes it impossible to detect without testing. Radon seeps into homes through cracks in foundations, gaps around pipes, and other openings in the building envelope.
According to the EPA, radon is the leading cause of lung cancer among non-smokers and the second leading cause overall, responsible for an estimated 21,000 lung cancer deaths per year in the United States. The risk increases with higher radon concentrations and longer exposure times.
The EPA has established an action level of 4.0 pCi/L (picocuries per liter). If your home tests at or above this level, the EPA strongly recommends installing a radon mitigation system. The World Health Organization recommends an even lower action level of 2.7 pCi/L. There is no known safe level of radon exposure.
The EPA divides the country into three zones based on radon potential. Zone 1 (highest potential) includes states like Iowa, North Dakota, Nebraska, Colorado, Pennsylvania, and Ohio. Zone 3 (lowest potential) includes Florida, Louisiana, Mississippi, Hawaii, and most of the deep South. However, high radon levels have been found in all 50 states, which is why the EPA recommends testing every home regardless of location.
Frequently Asked Questions
How do I test my home for radon?
There are two types of radon tests: short-term (2-7 days) and long-term (90+ days). Short-term test kits are available at hardware stores for $10-$30 and give a quick snapshot. Long-term tests provide a more accurate annual average. For the most reliable results, the EPA recommends starting with a short-term test in the lowest livable area of your home with windows and doors closed. If results are 4.0 pCi/L or higher, follow up with a second test or hire a certified professional.
How does radon mitigation work?
The most common mitigation method is sub-slab depressurization (SSD), where a pipe is installed through the foundation slab and connected to a fan that pulls radon from beneath the house and vents it above the roofline. This typically costs $800-$2,500 depending on your region and home design. Professional installation takes about half a day. Properly installed systems can reduce radon levels by up to 99% and typically require minimal maintenance beyond an annual check of the fan.
What is a safe radon level?
There is no truly "safe" level of radon. The average outdoor level is about 0.4 pCi/L, and the average indoor level in the U.S. is about 1.3 pCi/L. The EPA action level is 4.0 pCi/L, but they note that risk exists below this threshold and recommend considering mitigation even at 2.0-4.0 pCi/L. The World Health Organization recommends action at 2.7 pCi/L. Any reduction in radon levels reduces your cancer risk.
Do basements have higher radon levels?
Yes, basements typically have radon levels 2-3 times higher than upper floors because they are in direct contact with the soil where radon enters. If you use your basement as living space, it is especially important to test and mitigate if needed. Even homes without basements can have elevated radon on the first floor, particularly slab-on-grade construction where the concrete is in direct contact with soil.