Radon is a radioactive inert gas that is produced naturally from the decay of uranium to radium. As it is formed, it is released into air or water-containing pores between soil and rock particles. From soil and rock natural forces move it into the earth and it dissolves in groundwater. This is of great medical concern as environmental radon is one of the major causes of dangerous health problems such as lung cancer. Measurements of radon content in water was carried out in the northeastern part of India namely Aizawl district and Kolasib district of Mizoram using SMART RnDuo. About 30 sources of water were examined in each district during the winter of 2017. Water samples were collected from stream water, spring water, pump water, open well, pond and Government supplied water. Radon content in water from Aizawl district ranges between 0.309 Bq/L to 32.53 Bq/L, and those from Kolasib district the range is 1.11 Bq/L to 22.18 Bq/ L. The overall average content of radon in water was found to be 6.88 Bq/L. The radon content measured for most of the sources were found to be well within the range which is considered safe (EPA 1998) except for few samples analysed.

Indoor radon and thoron concentrations have been measured using solid state nuclear track detector (LR-115 type-ІІ) based twin cup dosimeter with single and double entry deployed side by side. The measurements have been carried out in 50 dwellings of 8 different villages/towns situated in Saiha and Lawngtlai districts, Mizoram. Dwellings were selected primarily from the gamma level measured using Micro-R survey meter and the construction type of the building. The average concentrations of radon and thoron were found to be 75.76 Bq/m3 and 96.50 Bq/m3 for single entry dosimeter and 63.47 Bq/m3 and 19.79 Bq/m3 for double entry dosimeter. The single entry dosimeter was found to give more reliable observations than that of double entry in terms of trends of seasonal data and also on the theory behind the manufacturing qualities.

Measurement of natural radioactivity in soil samples collected from Aizawl district, Mizoram, was carried out using gamma spectrometer 5"X 4" NaI (Tl) detector. Soil samples were collected from 15 different sites located in various parts of Aizawl district. The activity concentrations were measured for three specific radionuclides, viz. 238 U, 232 Th and 40 K. The activity concentration of 238 U nuclides was found to be in the range of 20.13 Bq/kg to 60.4 Bq/kg, with an average value of 34.03 Bq/kg. For 232 Th nuclides, the activity concentration ranges between 53.68 Bq/kg to 161.03 Bq/kg, with an average value of 90.71 Bq/kg. For 40 K nuclides, it ranges from 279.58 Bq/kg to 964.62 Bq/kg, with an average value of 765.35 Bq/kg. To assess the uniformity of natural radioactivity in soil with respect to exposure, the radium equivalent activity was calculated and was found to be in the range of 135.62 Bq/kg to 350 Bq/kg, with an average value of 217.32 Bq/kg. Except for 238 U nuclides, the overall average activity concentrations of 232 Th and 40 K nuclides in collected soil samples were found to be higher than world average, but lower than the critical value set by IAEA. The radium equivalent activity value in all the samples was found to be lower than the critical value of 370 Bq/kg. Hence, no radiological hazards were observed within the specified study area.