Radon 222 Concentrations in the United States - Results of Sample Surveys in Five States

Abstract

During the winter of 1986-1987, the United States Environmental Protection Agency (EPA) provided assistance to ten states to begin state-wide radon surveys. This paper presents survey results from the five states that completed a survey using a probability sample of housing units. Radon concentrations in six thousand homes in Alabama, Kentucky, Tennessee, Wisconsin, and Wyoming were measured. The data recorded from detectors placed in those houses have been compiled into the first multi-state survey of radon levels that allows valid extrapolation to the population at large. The target population was ground level, owner occupied residences with listed telephone numbers. Each state was partitioned into strata according to geologic characteristics relevant to radon levels. A systematic random sample of telephone numbers was selected within each stratum, and the telephone numbers together with associated names and addresses were supplied to each state. Charcoal canisters were deployed for a two-day period in each sample home, following the EPA screening measurement protocol. Strict procedures were followed to ensure randomness of the sample and the accuracy of the measurements. The results were analysed to produce estimates of the frequency distribution of radon concentrations throughout each state and for areas within states. A smaller sample of residences which were volunteered by their owners in each state also received detectors. The radon data from these houses were analysed separately. Estimates from the two northern states were significantly higher than those from the more southerly states and estimates for volunteers tended to be higher than the estimates from the random sample of homes. In the former case, the differences were influenced by the proportion of homes with basements.