SEASONAL-VARIATION OF INDOOR RADON LEVELS IN COASTAL KARNATAKA ON THESOUTH-WEST COAST OF INDIA

Indoor radon levels were measured in different seasons throughout 1995 in selected dwellings of coastal Karnataka using LR-115 type II peela ble films. Seasonal variations were studied. The arithmetic mean value of radon levels during winter was found to be about 35% higher than t he annual average value. The annual average radon levels were found to vary from 45.4 to 65.0 Bq m(-3) with an arithmetic mean value of 56.3 Bq m(-3) The annual effective dose equivalent to the population of th e region due to inhalation of radon was found to be in the range 0.78- 1.12 mSv y(-1) with a mean value of 0.97 mSv y(-1) A moderate positive correlation was observed between indoor radon levels and radium conte nt in the underlying soil, while a weak negative correlation was found to exist between indoor radon levels and indoor gamma dose rates in a ir. These results are discussed and possible inferences are drawn. (C) 1998 Elsevier Science Ltd. All rights reserved.