Volume No. 12 Issue No.: 3 Page No.: 285-291 January-March 2018




Sathish L. A.

Department of Physics, Government Science College (Autonomous), Bangalore, Karnataka (INDIA)


Received on : September 29, 2017




Natural radiation is the largest contributor to the collective radiation dose to the world population. Relatively constant exposure to the population at a location is the distinctive characteristics of this radiation. The major contribution of dose from natural radiation in normal background regions arises due to inhalation of 222Rn,220Rn and its progeny. In view of this, an attempt has been made to measure inhabitant dose rate exposure due to different granite floorings at Bangalore Metropolis, Karnataka, India. The region of present study is Bangalore Metropolis covering an area of about 220 km2. The common rocks are pink, grey and porphyritic gneisses with large feldspars and black dolerite. These rocks form geological band of a width 1525 km. Mass Exhalation rates, Surface exhalation rates, gamma active radio nuclides, absorbed dose rates in air, the 222Rn & 220Rn concentration were analyzed by using the standard protocol provided by Bhabha Atomic Research Center, Mumbai, India. Fifteen different granite samples which were used as a flooring material while constructing buildings in Bangalore Metropolitan were analyzed for a period of 3 years and an attempt has also been made to arrive at an exposure of dose rate due to the granite floorings to the inhabitants. Minimum about 25 measurements have been carried out for all the 15 type of granite samples. The obtained results showed that, the Arithmetic Mean values of dose rate in Bangalore Metropolitan were found to vary between 2.01 0.10 and 1.34 0.06 mSvy-1. Higher dose rates were observed in Granite and lower in Dolerite coarse grained. This is may be due to the higher activity concentration of radio nuclides present in granite samples around Bangalore Metropolis, which intern results higher dose rates.


Keywords : Radon, Radium, Granite, Dose rate, Background gamma