Soil characterization for indoor radon potential at eighteen schools in New York State

Abstract

During the two school years between 1991 and 1993, 60 schools were measured for indoor radon in New York State. Schools were solicited from areas considered to be at risk for above-average indoor radon based on residential indoor radon measurements and on the geology of the area. Eighteen of the sixty schools participating in the New York State study were selected for soil-radon potential characterization. Soils near the perimeter of the school, in the school yard, and in crawl spaces were measured for soil 226Ra concentration, soil-gas 222Rn concentration, and permeability for gas flow. In general, above-average indoor radon concentrations in the schools were found to correlate with highly permeable, gravelly soils. At 10 schools, the average soil permeability for gas flow was greater than 3 × 10 −10m 2 for each school, and 47% of the rooms tested in these 10 schools had long-term indoor radon concentrations greater than 150 Bq/m 3. The soils near the 10 schools were generally glacial outwash gravel deposits containing average concentrations of 226Ra and soil-gas 222Rn.