MEASUREMENT OF RADON, THORON AND THEIR PROGENY IN DIFFERENT TYPES OF DWELLING IN ALMORA DISTRICT OF KUMAUN HIMALAYAN REGION.

The indoor concentrations of radon (222Rn), thoron (220Rn) and their daughter products were measured in the dwellings of Almora district in Kumaun Himalaya, India using pin-hole dosemeters and deposition progeny sensors. The measurements were made in the residential houses built of mud, stone with cement plaster and cemented house during winter season. Average [geometric mean (GM) values] radon and thoron concentrations for all dwellings were found to be 99.82 and 79.70 Bq m-3, respectively, while average equilibrium equivalent radon concentration and equilibrium equivalent thoron concentration (measured for the first time for this region) were measured at 35.22 and 2.52 Bq m-3, respectively. Radon concentration (GM values) was found to be 110.73, 97.00 and 93.85 Bq m-3 for mud houses, stone with cemented plaster houses and cemented houses, respectively. On the other hand, thoron concentration values were 87.10, 75.79 and 75.68 Bq m-3 for cemented houses, mud houses and stone with cemented plaster houses, respectively. Interpretations have been made on the basis of measured radon/thoron and progeny concentration values with respect to the difference of construction material of the dwellings.