Concentrations of radon and its daughter products in and around Bangalore city

Dosimetry of indoor alpha flux belonging to seasonal radon, thoron and their EECs

Radon (²²²Rn) and thoron (²²⁰Rn) are ubiquitous radioactive noble gases present in the earth's crust. The source term for these gases includes soil and building materials as well. The radiological impact of radon/thoron gases and their decay products on human life is a matter of concern and has been given due attention in research and policy. The present study aims to measure and quantify residential radon/thoron gas and the decay product's concentration and to discuss the associated interpretations for Ludhiana district of Punjab, India. Passive measurement techniques employing a single-entry pinhole dosimeter for gases and direct progeny sensors for the decay product's concentration have been used in this work. The obtained data from these measurements have been analysed using appropriate statistical techniques. The variations have been linked with the changes in the ventilation conditions, building material, room type and altitude. A higher concentration of radon and thoron gas was observed in the winter season for the study region. It was estimated that the contribution of radon and thoron decay products towards the annual average inhalation dose is 75% and 25%, respectively.

RADON IN GROUNDWATER OF MAGADI TALUK, RAMANAGARA DISTRICT IN KARNATAKA

Radon is a water-soluble radioactive noble gas produced from the alpha decay of 226Ra in uranium series. Its presence in drinking water and open air increases the risk of lung and intestinal cancers in human beings. In view of this, radon concentration in groundwater and its dose due to inhalation and ingestion to the population of Magadi taluk of Ramanagara district in Karnataka state, India was studied. The groundwater samples were analyzed for radon concentration using emanometry technique. The study showed that the radon concentration in this area varied from 27.4 ± 1.0 to 167.5 ± 3.9 Bq/L and the effective dose ranged from 104.2 ± 2.7 to 636.2 ± 11.0 μSv/a. The study also revealed that 95% of the 37 samples studied showed higher radon concentration compared to the UNSCEAR recommendation (40 Bq/L) and all the samples showed higher than the USEPA recommendation (11.1 Bq/L). Ten samples have concentration above the maximum permissible level prescribed by WHO (100 Bq/L). The groundwater samples are found to be slightly alkaline within the permissible limit of Indian Standards.

CONCENTRATION OF RADON IN DWELLINGS OF HEMAVATHI RIVER BASIN, KARNATAKA, INDIA

Indoor radon, thoron and their progeny levels were measured in various types of dwellings during 2016-17 in Hemavathi river basin, Karnataka by using solid state nuclear track detector based pin-hole dosemeters; dwellings of various types were chosen for the measurement. The dosemeters containing the detector (LR-115, Type II Film) was used for this purpose. The concentration of indoor radon in the study area varied from 30.72 to 196.08 Bq m-3 with a median of 83.13 Bq m-3 and thoron concentration varied from 15.56 to 227.78 Bq m-3. Higher concentrations of radon and its progeny were observed in granite flooring and cement roofing dwellings compared to other types of dwellings. The reason for higher concentration of indoor radon and its progeny is due to activity of radium present in granite and provision of less ventilation in dwellings. The equilibrium equivalent radon, thoron concentrations and annual effective dose are discussed.

STUDY ON RADON CONCENTRATION AT THE WORK PLACES OF MYSURU, BENGALURU AND KOLAR DISTRICTS OF KARNATAKA STATE, SOUTH INDIA

Concentrations of radon, thoron and their progeny inside the working place depend on the activity of radionuclides in the soil, building materials, atmospheric conditions, construction of the building, type of work and ventilation condition. Radon is a radioactive noble gas, and it is emanated from ²²⁶Ra present in earth crest and building material. Based on the type of work, construction of the building and ventilation condition, concentrations of radon, thoron and their progeny have been measured in 60 workplaces at 10 locations of Mysuru, Bengaluru and Kolar districts of Karnataka state using Solid-State Nuclear Track Detector technique. From the study, variations of radon, thoron and their progeny have been observed with the nature of work.

Indoor concentration of radon, thoron and their progeny around granite regions in the state of Karnataka, India

An extensive studies on the indoor activity concentrations of thoron, radon and their progeny in the granite region in the state of Karnataka, India, has been carried out since, 2007 in the scope of a lung cancer epidemiological study using solid-state nuclear track detector-based double-chamber dosemeters (LR-115, type II plastic track detector). Seventy-four dwellings of different types were selected for the measurement. The dosemeters containing SSNTD detectors were fixed 2 m above the floor. After an exposure time of 3 months (90 d), films were etched to reveal tracks. From the track density, the concentrations of radon and thoron were evaluated. The value of the indoor concentration of thoron and radon in the study area varies from 16 to 170 Bq m(-3) and 18 to 300 Bq m(-3) with medians of 66 and 82.3 Bq m(-3), respectively, and that of their progeny varies from 1.8 to 24 mWL with a median of 3.6 mWL and 1.6 to 19.6 mWL, respectively. The concentrations of indoor thoron, radon and their progeny and their equivalent effective doses are discussed.