A SURVEY OF INDOOR RADON POTENTIAL AT SELECTED ELEMENTARY SCHOOLS IN SAN DIEGO COUNTY, CALIFORNIA

The Poway Unified School District in San Diego, California, has a student population of approximately 33,000 children, with twenty-five elementary schools located in four separate zip codes. According to the California Department of Health Services Indoor Radon Levels by Zip Code, three (92127, 92128, 92129) of the four zip codes report no residential indoor radon measurements exceeding the Environmental Protection Agency action limit of 4 pCi/L, while data from the fourth zip code (92064) indicate that more than 10% of homes exceed the action level.

Past studies of other southern California school districts have shown that residential zip code and county radon averages alone may not accurately describe school site radon vulnerability. This is mainly due to the occurrence of localized soil uranium distributions and a variety of factors, including school site construction practices.

In the present study, surface gamma ray spectrometry is used to rapidly assess the indoor radon potential of school sites, based on surficial uranium concentrations and building construction. Site measurements from elementary schools located within the 92064 zip code are compared to those in the low reading areas, in order to determine if the published California Department of Health Services residential radon data correlates with the school site measurements presented in this study. The effect of school building construction is also discussed since it can influence indoor radon levels.