Determination of School Site Radon Potential in Los Angeles County, California

Select communities in Los Angeles County, California that are located on uranium-rich subunits of the Miocene Monterey Formation have been found to exhibit significant indoor radon levels. Since uranium is the source of radon gas, other areas underlain by related sediments may also contain high-risk neighborhoods that may be overlooked due to a lack of data or inaccurate extrapolations. Because radon is a serious health hazard that accounts for approximately 21,000 cancer deaths each year, identification of specific radon-prone neighborhoods and school sites can help to reduce student exposure to this known carcinogen. Current methods for identifying radon-prone areas include the use of indoor radon measurements, geological subunit composition, and aerial radiometric data collected for the National Uranium Resource Evaluation (NURE) Program during the early 1970s. Unfortunately, due to air space restrictions, many densely populated areas where radiometric measurements would be the most beneficial were not surveyed by the NURE effort. The present study suggests that site-specific gamma-ray spectrometry measurements that directly measure surface uranium concentrations can be an accurate and cost-efficient method for assessing the radon potential of specific school sites on the Monterey Formation. Furthermore, comparisons with reference school districts with both classroom radon data and school site uranium measurements can be used to generate more precise risk assessments for the targeted schools.