Radiation in different types of building, human health.

Radon is a radioactive gas permanently produced in rocks, soils, building materials as an indirect decay product of uranium and thorium. According to EPA, radon is the second most frequent cause of lung cancer, after cigarette smoking. The aim of survey was to measure radon levels and ambient gamma dose rates in dwellings in various types of buildings situated on various ground and to evaluate health parameters depended on indoor radiation such as lung cancer risk and total annual effective dose rate. Moreover, we wanted to verify the possibility to predict indoor radon concentration in specific dwelling knowing types of soil, building construction, building materials and floor number. The measurements of radon concentrations were carried out using SSNTDs Kodak LR-115 which were exchanged seasonally. The ambient gamma dose rates were measured using Geiger counter. Radon concentrations in all dwellings were lower than 300 Bq m (recommended by EU action level). In some dwellings during some seasons radon concentrations were above 100 Bq m. Prolonged exposure to indoor radon at the levels of 100 Bq m causes statistically significant increase of lung cancer. The average indoor radon concentration in Wroclaw's dwellings was 46 Bq m. The annual risk of lung cancer was lower than 0.0005%. The total annual effective dose rates ranged from 1.36 mSv y to 3.3 mSv y. We observed seasonal, vertical, spatial variations of radon concentrations. We did not notice significant drop of ambient gamma dose rates between the ground floor and floors 2nd to 5th as we did for radon concentrations. We noticed that indoor radon concentrations differed 4 to 6 times even among dwellings located in these same types of buildings, on these same soil types or these same floors.