Public Health Assessment for Petitioned Public Health Assessment, OttawaRadiation Areas, Ottawa, LaSalle County, Illinois, Region 5. CERCLIS No. ILD980606750

摘要

During an aerial survey for radiation levels following the cleanup of a radiumdial painting operation, abnormally high levels of gamma radiation were detected at thirteen locations throughout Ottawa, Illinois. Additional ground level measurements helped to localize these and four additional areas within the city with levels of radioactivity elevated above background. Field studies by the U.S. Environmental Protection Agency (EPA) and the Illinois Department of Nuclear Safety have identified the major contaminant at these areas as radium-226 (Ra-226). Additional studies to determine the levels of radon-222 (Rn-222) within many structures have indicated radon concentrations well above the EPA limit of 4 picocuries per liter (pCi/L).