Abstract

Thoron (²²⁰Rn), due to its-short half-life of 55.5 s is unable to travel far from its point of generation. A number of studies report indoor radon (²²²Rn) concentration in different locations of Azad Jammu and Kashmir, while no study reports indoor ²²⁰Rn concentration. The CR-39 based passive alpha track detectors were used for the measurement of ²²²Rn and ²²⁰Rn concentrations at different selected workplaces of Muzaffarabad. ²²²Rn and²²⁰Rn concentration were measured simultaneously. Alpha track detectors (ATD) were enclosed in a thin polyethylene film to exclude ²²⁰Rn (closed detector) while the other ATD has a coarse metal grid and cloth covering the large entry port allowing for rapid radon gas ingress. The results showed that the measured ²²²Rn concentration varied from 18.7 Bqm^-3 to 160.2 Bqm^-3 with an average value of 67.0 ± 3 Bq.m^-3. Whereas the ²²⁰Rn concentration varied from 14.7 Bqm^-3 to 100.4 Bqm^-3 with an average value of 50.0 ± 2 Bqm^-3. Preliminary results show that indoor ²²⁰Rn concentration is significantly higher and should be taken into consideration while calculating the dose due to radiation of natural origin.

Key words: Thoron, indoor radon, alpha track detectors, radiation dose, Azad Jammu and Kashmir.