Inhalation of radon (222Rn) and its daughter products can cause lung cancer to human beings. Recent studies in different countries have shown that radon and its short lived progenies contribute the largest fraction of dose received by the general public from the environment. This makes the role of radon measurement in dwellings highly critical in monitoring human health and safety. An enhanced radon concentration had been observed in soil, air and water samples above many fault zones of the world. It is also revealed that radon concentration changes in conjunction with the earthquake. The...