An extensive indoor 222Rn/220Rn monitoring in Shillong, India

The behaviour of ubiquitous radon ( 2 2 2 Rn), thoron ( 2 2 0 Rn) and their progeny in the indoor atmosphere generally reflects a complex interplay between a number of processes, the most important of which are radioactive α-decay, ventilation, attachment to aerosols and deposition on surfaces. The present work involved a long-term (1997-2000) passive monitoring of 2 2 2 Rn and 2 2 0 Rn in the indoor environment of Shillong, Meghalaya. The north-east region of India being a zone of high seismicity, the indoor radon and thoron map of the region will provide a better insight and a valuable database for any study related to radon and thoron anomalies.