In June 2012, USEPA assessed several homes referred by Navajo Nation EPA for radiation exposure to the residents. During the assessments, radiation surveys were performed at 41 homesites on the Navajo Nation to determine gamma activity exposure rates and gamma activity concentrations in the surface soils of the residences and yards. The 41 homesites that were assessed were selected for assessment by Navajo Nation EPA based on data collected by Navajo Nation EPA in 2010.
Based on USEPA's 2012 assessment, it was determined that 6 residences ( 5 of the yards) 2 Hogans (1 ceremonial and 1 residence), and 5 additional yards exceeded the Action Level of 15mrem/yr above background.
