Radon concentrations in selected residential buildings in the city of Łódź

BACKGROUND: Radon and its decay products in the atmosphere are the most important contributors to human exposure from natural sources. In Poland, the total annual effective dose from indoor radon is 1.36 mSv. MATERIAL AND METHODS: Over the past twenty years, the measurements of radon concentration in the building indoor air were performed three times by the Nofer Institute of Occupational Medicine, Łodź, with the use of track detector CR-39 enclosed in NRPB cassette. Those measurements were taken in the ground floor of each building. RESULTS: The average annual radon concentration was 89 Bq/m3 in 1998/1999; 75 Bq/m3 in 2008/2009; and 52 Bq/m3 in 2005. CONCLUSIONS: Assuming that a human spends at home about 5000 hours per annum and using suitable conversion factors, the dose from radon the inhabitants under study are exposed to varies from 0.9 to 1.1 mSv and it is lower than average dose for the Polish population.