Indoor radon measurements in the dwellings of Kangra District of Himachal Pradesh, India, using LR-115 nuclear track detectors

Study of indoor radon was carried out in the domestic environment of 15 villages of Kangra district of Himachal Pradesh, India. Time integrated track etch technique has been used for the measurement of indoor radon levels. Bare cellulose nitrate LR-115 type II films have been used as detectors in the survey of indoor radon for four seasons of three months each covering a period of one year from March 2012 to March 2013. The houses were chosen randomly in such a way that the dwellings constructed with different types of building materials such as soil, bricks, cement, marble, concrete, wood in different localities of the village are covered. It has been found that indoor radon concentration depends upon the type of house, ventilation condition etc. The calibration constant of 1 track cm-2 day-1 which is equal to 50 Bqm-3 has been used to express radon concentration in Bqm-3. The conversion factors have been used to calculate the exposure (an exposure of an individual to radon progeny of 1 WLM is equivalent to 3.54 mJ h m-3), the annual effective dose (1 WLM=3.88 mSv) and the lifetime fatality risk (3 x 10-4 WLM). Indoor radon concentrations were found to vary from 132.25 Bqm-3 to 449.75 Bqm-3 with an average value of 261.40 Bqm-3. Annual effective dose in these dwellings were found to vary form 2.78 mSv to 7.68 mSv with an average value of 4.5 mSv. The average radon concentration in dwellings in most of the villages falls in the action level (200-600 Bqm-3) recommended by International Commission on Radiological Protection. Document available in abstract form only. (authors)