Abstract
Contribution of radon and its decay products towards the total effective dose has been reported to be more than 50% and is a second leading cause of the lung cancer after cigarette smoking. It is an established fact that besides soil and rocks, naturally occurring radio nuclides are also associated with the petroleum extracted from the sedimentary deposits. Therefore, radon measurement around oil refineries is desirable. In this regard, an indoor radon measurement study was carried out in 40 dwellings which were situated in the vicinity of an oil refinery in the Rawalpindi district using CR-39-based radon detectors. For comparison, indoor radon levels were also measured in 40 dwellings situated at a greater distance (>2 km) from the refinery. The maximum measured indoor radon concentration was found to be 190 +/- 6 Bq.m(-3) whilst the minimum recorded concentration was 12 +/- 7 Bq.m(-3). The mean radon concentration in the dwellings surveyed was 57 +/- 29 Bq.m(-3). No significant difference was observed in the average indoor radon levels in the dwellings situated near the oil refinery premises when compared with those further away. From the measured radon concentrations, an annual effective dose was calculated to be 0.9 +/- 0.1 mSv which is below the ICRP recommended value.