INDOOR RADON EXPOSURE IN CLUJ-NAPOCA CITY, ROMANIA

Radon and its decay products are the most important sources of natural radiation for the human exposure (UNSCEAR, 2000). As the second cause of lung cancer (after smoking), radon is received indoors, in houses and others buildings by the majority of the population exposed (ICRP, 1993). In the past decades, systematic radon surveys in dwellings were carried out all over the world (UNSCEAR 2000). Almost half of the radioactive dose is due to radon gas. The objective of this present study was to estimate the lung cancer risk induced by exposures to radon for a period of 200-210 days in bedrooms at 1-1.5m distance from the floor. The mean measured radon concentration values were corrected for seasonal variations, depending on the time when detectors were exposed during the course of the year. The radon average concentration in the exanimate places was <C-Rn> = 112Bqm(-3), C-Rnmin = 9 Bqm(-3) and C-Rnmax = 1127Bqm(-3). The geometrical mean of radon, GM, in studied areas were found to be 68Bqm(-3). Distribution of indoor radon concentration in homes was: 32,7% in C-Rn[0-40 Bqm(-3)], 31,5% in C-Rn[41-80 Bqm(-3)], 11% C-Rn[81-120 Bqm(-3)], 6,3% in C-Rn[121-160 Bqm(-3)], and 18,1% in C-Rn[>160 Bqm(-3)].