Depth dependent study of radon, thoron and their progeny in tube-wells

Abstract Radon has been recognized to be one of themajor contributors to the natural radiation causing evenlung cancer if it is present at enhanced levels. Its moni-toring at highly confined locations such as undergroundcaves, mines and tube-wells is very essential for finding thehealth related hazards among the workers. This paperreports the investigations of the levels of radon, thoron andtheir progeny monitored in the tube-wells of the Halls ofresidence at A.M.U., Aligarh, which lies in the subtropicalregion of Indo-Gangetic plains situated in North India. Thetwin cup dosimeters were fixed for exposure at a depth of5–35 feet with a difference of 5 feet from the groundsurface. The values of radon and thoron concentrationswere found to vary from 6.58 to 1218.57 and7.41–3226.61 Bq m -3 , respectively. The preliminaryresults of this study for ‘bare mode’ detectors have beenseparately published and compared with the recent data.Keywords Radon/thoron gases and their progeny LR-115 type-II plastic track detectors Twin chamber dosimeter cupsIntroductionThere are various natural and manmade sources of radonpresent in the environment. Naturally occurring radon gashas a variable geographical distribution and is known toconcentrate in closed spaces. It has highest concentrationsin the underground buildings, mines and basements that arein contact with soil [1].The exposures of humans from radon, thoron and theirprogeny have received considerable attention because oftheir adverse health effects [2, 3] to people working inunderground spaces [4, 5]. Research on health riskscaused by the naturally occurring radioactive ubiquitousradon gas and its progeny has gained great attention,particularly in the aspects related to controlling highradon concentrations [6] and regulating the air quality inworkplaces [7, 8]. The radiation exposure from radon inthe workplace could be significant in cases where theradon concentration is relatively high [9]. The ICRPprovides guidance to regulatory authorities on the radonaction levels 200–600 Bq m