What is the average level of radon found in homes in the U.S.?

Based on a national residential radon survey completed in 1991, the average indoor radon level is about 1.3 picocuries per liter (pCi/L) in air in the United States. The average outdoor level is about 0.4 pCi/L.

Learn more about radon by visiting  Health Risks of Radon and the Radon webpage.