Radon has been found in every state included in Arizona
Homes with high levels of radon have been found in every state. In fact, radon levels can vary greatly from home to home--even levels next door can be very different.
Radon is measured in picocuries per liter of air (pCi/L), a measurement of radioactivity. In the United States, the average indoor radon level is about 1.3 pCi/L. The average outdoor level is about 0.4 pCi/L. The
U.S. Surgeon General and EPA recommend fixing homes with radon levels at or above 4 pCi/L. EPA
also recommends that people think about fixing their homes for radon levels between 2 pCi/L and 4 pCi/L.