Seasonal variation of radon, thoron and their progeny levels in dwellings of Haryana and Western Uttar Pradesh

Radon and thoron are invisible, odorless, heavy and radioactive gases which are ubiquitously present in dwellings and in the environment. In the present work, seasonal variation of indoor radon, thoron and their progeny concentrations has been studied in the dwellings of industrially polluted cities in District Faridabad, Haryana and District Mathura in Uttar Pradesh. LR-115, Type-II [Kodak Pathe, France], peelable, plastic track detectors commonly known as solid state nuclear track detectors [SSNTDs] were used to measure the radon thoron concentration over long integrated times. The measurements were carried out in the mixed field of radon and thoron and the detectors were exposed for about 90 days. The average value of radon and thoron concentration in the dwellings varied from 23.5 Bq/m[3] to 65.2 Bq/m[3] and 9.8 Bq/m[3] to 18.7 Bq/m3 respectively in different seasons. The average annual exposure and annual effective dose in living rooms due to radon and thoron progeny was estimated to be 0.195 WLM [working level month] and 0.74 mSv respectively. The average life time fatality risk of lung cancer from the chronic radon and thoron progeny exposure was estimated to be 5.8 ' 10[-3] [0.58%]. The seasonal variations of measured radon levels in the environment of LPG bottling plant, radon-thoron levels and inhalation dose due to radon and thoron and their progeny in dwellings indicate that the levels were higher in winter [October to January] than in summer [April to July]

Radiological risk assessment of use of phosphate fertilizers in soil

The radiological impact of the use of phosphate fertilizers in soil is due to the internal irradiation of the lung by the alpha particles, short lived radon-thoron progeny and the external irradiation of the body by gamma rays emitted from radionuclides in situ. This paper describes the results of gamma spectrometric measurements of the concentration of the natural radionuclides namely [226]Ra, [232]Th and [40]K in the soil samples collected from the fields where a variety of phosphate fertilizers are being used by the farmers to enhance the crop yield. The experimental work utilizes actual measurements of [226]Ra, [232]Th and [40]K using gamma spectrometry and radon concentration and exhalation rates measurements using solid state nuclear track [LR-115, Type- II plastic] detectors to asses a first order exposure risk for the persons working in the fields where lot of fertilizers are being used to enhance crop yield in terms of occupational exposure. The concentration of Radium, Thorium and Potassium in the mixed soil sample from crop fields is 16.2 +/- 0.22, 68.1 +/- 1.44 and 875.0 +/- 9.68 Bq/kg, where as in barren soil sample is 9.1 +/- 0.13, 59.4 +/- 1.45 and 668.4 +/- 8.01 Bq/kg respectively. The radium equivalent activity [Ra[eq]] in the mixed soil sample from crop fields is 225.9 Bq/kg, where as in barren soil sample is 193.1 Bq/kg. The values of absorbed dose and annual effective dose [indoors and outdoors] are found to vary from 90.87 nGyh[-1] to 119.71nGyh[-1], 0.45mSv/y to 0.59mSv/y and 0.11mSv/y to 0.15mSv/y respectively in soil sample from crop fields, whereas the value of absorbed dose and annual effective dose [indoors and outdoors] is 92.29 nGyh[-1], 0.45mSv/y, 0.11 respectively in soil sample collected from barren land. The radon concentration and exhalation rates have also been reported. The activity concentration, exhalation rate and absorbed dose were found to increase substantially with the use of phosphate fertilizers and it varies from sample to sample. The radium equivalent activities in all the soil samples were found to be lower than the limit [370 Bq/kg] set in the Organization for Economic Cooperation and Development [OECD] report and the dose equivalent is within the safe limit of 1mSv/y