Environmental and indoor study of Radon concentration in San Joaquin area, Queretaro, Mexico, first results

A highly contaminated zone with a maximum over 57,000 Bq/m3 was discovered in a populated community "Agua de Venados" during the 2009e2011 soil Radon survey in San Joaquin, Queretaro State, Mexico. The indoor Radon monitoring accomplished in 2 different époques in a nearby 4 dwellings has shown an increased Radon hazard in 1 of the 4 buildings (about 300 Bq/m3) during a rainy season and highly elevated indoor Radon levels (over 400 Bq/m3) already in 3 buildings during a dry season. The averaged diurnal indoor Radon variations are in a correlation with the atmospheric pressure and the air humidity and are independent on the air temperature. The maximum indoor Radon hazard for dwellings is estimated for the morning interval 5e10 a.m.