What is EPA's Action Level for Radon and What Does it Mean?
Radon in air is ubiquitous (existing or being everywhere at the same time). Radon is found in outdoor air and in the indoor air of buildings of all kinds. The EPA recommends homes be fixed if the radon level is 4 pCi/L (picocuries per liter) (150 becquerels per meter cubed (Bq/m3)) or more. Because there is no known safe level of exposure to radon, the EPA also recommends that Americans consider fixing their home for radon levels between 2 pCi/L and 4 pCi/L (75 - 150 Bq/m3) .
The average indoor radon concentration for America’s homes is about 1.3 pCi/L (50 Bq/m3). It is upon this national average indoor level that the EPA based its estimate of 21,000 radon-related lung cancers a year. The average concentration of radon in outdoor air is .4 pCi/L (15 Bq/m3)or 1/10th of EPA's 4 pCi/L (150 Bq/m3)action level.
Note: Countries worldwide have adopted action levels for radon exposures. Most are similar to the 4 pCi/L (150 Bq/m3) action level recommended in the United States. The action level observed should comply with the guidance of the country, state, or other local jurisdiction of authority where the test is being conducted. For more information, review Protocol for Conducting Measurements of Radon and Radon Decay Products in Multifamily, School, Commercial and Mixed-Use Buildings Section 7.1 Action Level Guidance. (ANSI/AARST MA-MFLB-2023)
- Read A Citizen's Guide to Radon. (PDF)
- Read about Radon's Health Risks
- Find out how to test your home
- Find out how to fix your home by reading a "Consumer's Guide to Radon Reduction: How to Fix Your Home." (PDF)