Statistical Considerations and Comparative Studies of Various Screening Measurements for Indoor Radon

Short term sampling methods for Rn analyses have been considered by many to be unreliable for use in real estate transactions. This opinion has been based upon the recognized tact that Rn may vary with fairly short time periods and that some of these variations may be quite large. However, many of the published data regarding variation of concentration were not taken within the complete confines of the U.S. Environmental Protection Agency (EPA) protocol for screening tests. This paper presents an analysis of data from alpha track detectors, continuous Rn monitors, passive activated charcoal canisters, passive electret detectors, and one hour air samples collected on activated charcoal in two homes where the EPA protocols were strictly followed. These data were used to describe the mean concentration over the period of the test, the variance of the mean, the confidence intervals and the probability of shorter term samples being within an acceptable range of the mean. Field data using one hour active collections of radon on charcoal conditions. By samplimg with both short-term and longterm methods, seasonal and weather variations in indoor Rn air concentrations can be described and the accuracy of the screening methods can be compared for their predictive power. The program was made available for participation by any National AARST member and three companies from other regions have participated coninuously or when feasible. A total of eleven companies have participated so far. This report presents interim results covering the first six months of the comparative measurement program and some of the comparisons may change when a full year of data is available. However, some of the results regarding correlations with sample means will probably remain at similar magnitudes.