Level of environmental natural radiation in Yunnan province

The average absorbed dose rate of cosmic radiation in air is 4.8 x 10-8 Gy.h-1 in Yunnan Procince. The absorbed dose rates from terrestrial gamma radiation in air range from 1.5 to 29.4 x 10-8 Gy.h-1, with an average of 9.0 x 10-8 Gy.h-1. The effective dose equivalent to population per year from cosmic radiation is 406 μSv. The annual external effective dose equivalent to population ranges from 434 to 1,738 μSv, with an average of 1,118 μSv. Among them the contribution of cosmic radiation is 36.8%, and that of terrestrial radiation is 63.2%. The collective effective dose equivalent to population in this province is 3.5 x 104 man.Sv