Assessment of radioactivity of different types of houses in Imphal city, Manipur, India

An assessment of radioactivity concentration of different types of houses was conducted at 437 houses of Imphal City, Manipur, India. The average annual effective doses of gamma radiation level in indoor and outdoor were determined as 1.22 ± 0.09 (range: 0.79-1.41) mSvy^-1 and 0.79 ± 0.08 (range: 0.57-1.07) mSvy^-1 for reinforced cement concrete houses, followed by 1.06 ± 0.08 (range: 0.84-1.27) mSvy^-1 and 0.78 ± 0.08 (range: 0.59-0.94) mSvy^-1 for Assam-typed (AT) brick houses, 0.85 ± 0.08 (range: 0.63-1.28) mSvy^-1 and 0.76 ± 0.08 (range: 0.52-1.01) mSvy^-1 for AT mud houses, 0.77 ± 0.08 (range: 0.58-0.96) mSvy^-1 and 0.73 ± 0.07 (range: 0.65-0.85) mSvy^-1 for AT katcha houses, and 1.04 ± 0.07 (range: 0.88-1.22) mSvy^-1 and 0.73 ± 0.07 (range: 0.65-0.84) mSvy^-1 for adobe laid earthen houses, respectively. Moreover, the annual effective dose conceived from building materials was recorded as 1.8 mSvy^-1 from sand, 1.5 mSvy^-1 from brick, and 1.0 mSvy^-1 from Portland cement. The worldwide average indoor dose limit of radon conceiving and its decay product by inhalation is 1.15 mSvy^-1 prescribed by the UNSCEAR (2000). (author)