Radon daughter levels in some public and private buildings in India.

Radon daughter concentrations have been measured in some public and private buildings of Aligarh city. Approximately 320 CR-39 detectors were mounted in 30 sample sites. It was found that the Rn daughter concentrations vary from 3.5 mWL to 8.1 mWL with a geometric mean of 5.6 +/- 1.3 mWL. The average annual effective dose equivalent due to Rn daughters is found to be 1.46 mSv using an equilibrium factor of 0.45 and an occupancy factor of 0.8. About 33% of buildings were estimated to have a Rn concentration below 40 Bq m-3 and 79% below 60 Bq m-3. The measured levels do not require any intervention as recommended by the U.S. Environmental Protection Agency.