Radon is a naturally occurring, radioactive element, usually produced as the result of uranium or thorium decay. However, unlike other radioactive elements, radon is a gas – the heaviest naturally occurring noble gas. Due to its radioactivity, radon is considered a health hazard. It is estimated that inhaling radon is the leading cause of lung cancer, after smoking. Since radon is a heavy gas continuously emitted from the ground and is short-lived, its concentration varies temporally and spatially, depending on several factors. Many countries have produced radon concentration maps while some countries have imposed a law that a report showing radon levels should be produced when a property is sold. However in Sri Lanka, no attempt had been made to measure the radon levels or to produce a radon map. We took the initiative to produce a preliminary radon map of Sri Lanka. In addition to pinpointing the potentially hazardous locations, elevated radon levels will indicate the mineral deposits rich in U and Th. In-situ and ex-situ radiation measurements of air, soil and water were taken at selected locations for comparison. Preliminary results identified certain areas with high background radiation in Sri Lanka.
Radon mapping programme was started with 50 passive radon detectors donated by Japan. They were used for outdoor monitoring. This was followed by another 2 batches of 50 detectors from Japan and 50 indoor detectors from International Atomic Energy Agency (IAEA) in Austria. In addition, active measurements of radon is also conducted around the country.
Prof. Deepal Subasinghe