Study of ambient gamma dose levels at national atmospheric research laboratory, Gadanki, India

Simultaneous observations of ambient gamma dose levels, temperature, relative humidity, and atmospheric pressure were carried out at National Atmospheric Research Laboratory (NARL), Gadanki, India (13.459°N and 79.175°E), from November 2011 to May 2014. The results show that about 92% of ambient gamma dose values lie between 150 and 200 nSv/h and best possible fit resulted in Gaussian fit with adjusted R2 of 0.99. A weak Pearson's correlation coefficient was found between ambient gamma dose levels and selected meteorological parameters measured over the location. No seasonal trend was observed in ambient gamma dose levels, but pronounced seasonal variations in temperature, relative humidity, and air pressure were found. A sudden increase in ambient gamma levels was observed during precipitation event (Nilam cyclone) and may be attributed to an additional contribution of precipitation washed 222Rn progeny aerosols within the atmosphere. The mean ambient gamma dose over NARL was 186 ± 4.3 nSv/h and is within world average given by UNSCEAR