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The results of radon concentration measurements carried out in dwellings with natural ventilation for 1 y in Bangalore are reported. Measurements, covering three sessions of the day (morning, afternoon, night) were performed two times in a month for 1 y at a fixed place of each dwelling at a height of 1 m above the ground surface in selected dwellings. The low-level radon detection system (LLRDS), an active method, was used for the estimation of radon concentration. The measurements were aimed to understand the diurnal variation and the effect of ventilation rate and flooring type on indoor radon concentration. The geometric mean (± geometric standard deviation) of indoor radon concentration from about 500 measurements carried out in 20 dwellings is found to be 25.4 ± 1.54 Bq m−3. The morning, afternoon and night averages were found to be 42.6 ± 2.05, 15.3 ± 2.18 and 28.5 ± 2.2 Bq m−3, respectively. The approximate natural ventilation rates of the dwellings were calculated using the PHPAIDA—the on-line natural ventilation, mixed mode and air infiltration rate calculation algorithm and their effects on indoor radon concentrations were studied. The inhalation dose and the lung cancer risk due to indoor radon exposure were found to be 0.66 mSv y−1 and 11.9 per 106 persons, respectively. The gamma exposure rate was also measured in all the dwellings and its correlation with the inhalation dose rate was studied. [ABSTRACT FROM PUBLISHER]

The concentration of radon daughters in outdoor air was measured continuously from January 2006 to December 2006 near the Department of Physics, Bangalore University campus, Bangalore. The concentration was measured by collecting air samples at a height of 1 m above the ground level on a glass micro fibre filter paper with a known air flow rate. The results show that the radon progeny concentration exhibits distinct seasonal and diurnal variations that are predominantly caused by changes in the temperature gradient at the soil-atmosphere interface. The concentration was found to be high from 20.00 to 8.00 hrs, when the turbulence mixing was minimum and low during the rest of the time. In terms of the monthly concentration, January was found to be the highest with September/August being the lowest. The diurnal variations in the concentrations of radon progeny were found to exhibit positive correlation with the relative humidity and anti-correlation with the atmospheric temperature. From the measured concentration, an attempt was made to establish the annual effective dose to the general public of the region and was found to be 0.085 mSv/a. In addition, an attempt was also made for the first time to study the variation of inhalation dose with respect to the physical activity levels. Results show that in the light of both the effect of chemical pollutants and radiation dose due to inhalation of radon daughters, evening jogging is advisable. [ABSTRACT FROM AUTHOR]

This paper discusses the concentrations of natural radionuclides in soil in Bangalore, India. The authors measured the concentrations of Radium, Thorium and Potassium isotopes by gamma ray spectrometry. They also measure the absorbed dose rates in air and estimated radium equivalent activity, annual effective dose rate, external and internal hazard indices. They compared these levels with published worldwide values and found that the overall mean values were similar. They concluded that the annual effective dose to the general population and hazard indices were comparable to other normal background regions of India and the world.

Potable waters from various locations of the Bangalore environment were investigated for their 222Rn concentrations by the emanometry method. About 94 groundwater (borewell) samples were analysed for 222Rn concentrations and found to vary in the range 5.3–283.4 Bq L-1 with a mean value of 87 Bq L-1. Frequency distribution showed the 222Rn concentration in a large number of samples in the range of 0–50 Bq L-1. From the measured concentrations, the effective doses (lung and stomach) for the population of the region were estimated. The effective dose was found to vary from 42.6 to 2280.2 µSv y-1 with a mean value 702.5 µSv y-1. The effect of boiling of water showed a drastic reduction in the 222Rn concentration. The results of the present investigation are systematically analysed, compared with the literature values and discussed. [ABSTRACT FROM AUTHOR]