Current Research Paper Studies on indoor radon and its progeny levels around Bangalore rural district and Bangalore city KEYWORDS Radon; Radon progeny; Indoor; SSNTDs; Granite quarries. ABSTRACT Indoor radon and its progeny levels were measured during 2005-2006 around Bangalore rural district and in Bangalore city using Solid State Nuclear Track Detector based dosimeters. More than 50 dwellings of dif- ferent construction and types were chosen for the study in and around the city. The geometrical mean value of radon concentration level in indoor atmosphere of granite quarries varies from 55 Bq.m -3 to 300 Bq.m -3 with a median of 152.5 Bq.m -3 and its progeny varies from 0.24 to 19.6 mWL with a median of 8 mWL respectively. In Bangalore city the concentration level of radon varies from 18.4 Bq.m -3 to 104 Bq.m -3 with a median of 45 Bq.m -3 and its progeny varies from 1.62 to 11.24mWL with a median of 4.78 mWL respectively. Higher concentration of radon and its progeny were observed in granite quarries compared to Bangalore city due to the mining activity and types of the bedrock in granite quarries.  2008 Trade Science Inc. - INDIA INTRODUCTION All organisms including human beings are always continuously exposed to radiation by natural sources. Among all the natural sources of radiation dose to man, inhalation of radon, thoron and their progenies contrib- ute 50% of global effective dose [1-4] . The exposure to  - radiation emitted from radon and its daughter prod- ucts gave health hazard not only to people working in uranium mines, but also to people living in normal houses, working places like thermal power plant, coal fields, granite areas and other related industries [5] . Exposure of persons to high concentrations of radon and its short lived progenies for a long period leads to pathological effects like the respiratory functional changes and oc- currence of lung cancer [6-7] . Many authors have investi- gated radon and its progeny owing to the effect of natural radiation exposure on health, particularly in relationship with various type of cancer [8-17] . In 1988, the Interna- tional Agency for Research on Cancer (IARC) identi- fied radon is a lung concerning gas [18] . Nature has gifted several geological materials to mankind for building construction purposes. Granite is the one of the most important rock is used in building materials. The granite C.Ningappa 1 , J.Sannappa 2 *, M.S.Chandrashekara 3 , L.Paramesh 3 1 Vidya Vikas Institute of Engineering and Technology, Mysore - 570 010, (INDIA) 2 Department of Physics, Yuvaraja s College, Mysore-570 005, (INDIA) 3 Department of studies in Physics, University of Mysore, Manasagangotri, Mysore -570 006, (INDIA) E-mail: sannappaj@yahoo.com Received: 9 th September, 2007 ; Accepted: 14 th September 2007 Environmental Science An Indian Journal Trade Science Inc. Volume 3 Issue 1 ESAIJ, 3(1), 2008 [106-110] January 2008 Environmental Science