Nationwide Survey of Residential Radon Levels in the US

Abstract

The US Environmental Protection Agency's (EPA) National Residential Radon Survey (NRRS) is the first comprehensive effort to estimate the frequency distribution of average annual radon concentrations in occupied housing units across the 50 United States. A stratified three-stage area probability sample was used to randomly select approximately 11,000 homes from 125 counties nationwide. Two to four alpha track detectors were placed in approximately 7100 eligible homes for a period of 1 year. A 22 page questionnaire gathered information on occupant living patterns, smoking habits, house construction, weather-proofing, heating, ventilation, and air conditioning (HVAC) characteristics. The results indicate that the arithmetical average annual radon concentration in US housing units is 46 � 2 Bq.m-3 (1.25 � 0.06 pCi.1-1) with a median value of 25 Bq.m-3 (0.67 pCi.1-1). Based on the empirical evidence, 6.01 � 0.68% of housing units exceed the US EPA Action Level of 150 Bq.m-3 (4 pCi.1-1). This translates into approximately 6,000,000 US housing units exceeding the Action Level.