Abstract
Results of a survey of 222Rn concentration using direct measurement in 834 Cairo houses are reported. Although the study was not random with respect to population or land area, it was useful in identifying areas at risk and locating several houses having elevated indoor 222Rn air concentrations. Approximately 22% of the houses tested exceeded 37 Bq/m3, with 2.4% exceeding 70 Bq/m3. Several Cairo regions had larger fractions of houses exceeding 49 Bq/m3, such as Madinat Al-Muquattam (44%), Manshiyyat Nasir (31 %), Al-Abbasiyyah (29%) and Hadiak Al-Qubbah (17%), Elevated 222Rn concentrations were measured for a variety of house types having different construction materials. The effect of water was identified as a potentially significant source of 222Rn in Madinat Al-Muquattam homes. This survey is the first by this method in Egypt (a hot region) . The indoor concentration of 222Rn were measured in homes, in different locations within the flat, also the concentration of radon has been shown to decrease with the increase of the distance of room investigated from ground level with different heights in a tall building during the winter and summer seasons. Indoor radon concentration ranged from 6.32 Bq/m3 to 97.68 Bq/m3 and averaged value with standard deviation was 21.77±7.85 Bq/m3. The concentrations of radon in the unoccupied flats were observed to be considerably higher than those occupied one.
