Preliminary assessment of population dose in China

The natural background radiation sources contribute 93.4% of the total collective dose to the chinese population, of which 48% is due to exposure from radon and thoron daughters. Among the exposure from man-made activity, the maximum is medical exposure (4.21% of the total), the next is occupational exposure (1.25%), the public exposure is about 1.16%. Several practices and population groups need to pay special attention: (1)medical exposure, 60% of the total increase exposure from man-made activity; (2) the exposure of underground miners, 18%; (3) the exposure from coal energy electricity chain, 20.9%, the sum of 3 items equals to 98.9%. The collective dose from nuclear industry is approximately 4.9 x 10-4