Study of radon exhalation rate from different types of building construction materials using SSNTDds and estimation of lung cancer risk

Uranium is a radiotoxic element found in trace quantities in almost all naturally occurring materials like soil, rock and sand etc. Building materials are derived from these materials. Radon, an inert radioactive gas whose predecessor is uranium is emitted from soil beneath the house and from building materials. Building materials are the main source of radon inside the dwellings. Because of low level of radon emanation from these materials, long term measurements are needed. Can technique using LR-115 type II solid state nuclear track detector has been employed for the measurement of radon activity and radon exhalation rate from a number of building materials commonly used for construction in Kerala. Radon activity is found to vary from 75.0 to 2212.7 Bqm-3 with an average value of 477.7 Bqm-3, radon exhalation rate from 44.0 to 1337.7 mBqm-2h-1 with an average value of 286.3 mBqm-2h-1 and effective dose equivalent from 5.2 to 157.7 μSv y-1 with an average value 33.7 μSv y-1 for different building construction materials. Radon emanation from granite is found to be maximum while cement brick (hollow) and Kadappa stone give minimum radon emanation. In the case of plastered bricks covered with sealants, radon exhalation is found to increase slightly with acrylic exterior and acrylic emulsion while it decreases with others. (author)