Health Effects And Mitigation Of Radon Pollution In Underground Structures In China

Radon pollution has been paid attention by many countries for the health hazards. Due to economical developments, large numbers of underground structures have been used as public places in China. But there isn't any nationwide survey or research of radon pollution in underground structures in China. In this thesis, two techniques were used to measure radon concentration in underground structures. One technique was an accumulative detector, SSNTD (solid state nuclear track detectors) of CR-39 type; the other technique was an instantaneous device called Model 1027 Continuous Radon Monitor from The Sun Nuclear Corporation. More than 700 data were collected from 23 cities in one year, and all the relevant information was collected in questionnaires for each structure. From the point of view of environmental geochemistry, distributions of the radon concentration in different type structures and different cities were evaluated and discussed (Huhehaote, Baotou, Jining, Erdos in Inner Mongolia Autonomous Region as a case study). The values of annual effective doses from radon in the underground structures were estimated, and the reasons of high radon concentration were analyzed. In addition, feasible recommendations on how to mitigate and prevent radon pollution in the underground structures are proposed. Through detailed studies reported in this thesis, some main conclusions are listed as follows:1, The seasonal distribution of radon concentration in underground structures is: the overall summer average is higher than the overall winter average. This result is opposite to ground result, as earlier works by various groups who determine the radon concentration in caves. The seasonal variation of radon concentration in different types is: tunnels) underground shopping centers) basements of buildings.2, The values of radon concentrations in the three types: tunnels) basements of buildings) underground shopping centers. No matter the single-seasonal values or annual averages, the radon concentrations in tunnels are quite higher than that in basements of buildings and underground shopping centers. According to the analysis of basements of buildings and underground shopping centers, buildings above the underground structures is not the main factor of affecting the radon concentration.3, The annual overall arithmetic mean values of radon concentration in Huhehaote, Baotou, Jining, Erdos are: 190Bq/m3, 700Bq/m3, 190 Bq/m3, 270Bq/m3, respectively. The annual arithmetic mean values without single-season value in Baotou and Erdos are: 620Bq/m3, 250Bq/m3.The range of single-seasonal values of radon concentration in Huhehaote, Baotou, Jining, Erdos are: 31-830 Bq/m3, 57-3500Bq/m3, 26-650Bq/m3, 64-690Bq/m3, respectively; and the range of annual averages of radon concentration in Huhehaote, Baotou, Jining, Erdos are: 39-580Bq/m3, 94-2100Bq/m3, 35-460Bq/m3, 110-390Bq/m3, respectively. The percentage of value higher than 200 Bq/m3 in Huhehaote, Baotou, Jining, Erdos is 30.0%, 44.4%, 33.3%, 50.0%, respectively. The radon levels in the four cities is : Baotou> Erdos> Jining> Huhehaote.4, The annual effective doses of radon in the type â…¡and typeâ…¢ underground structures were estimated to be between 1.247mSv and 6.809mSv and between 1.195mSv and 8.531mSv, with the overall arithmetic mean values of 2.610mSv and 2.572mSv.All of the annual effective doses of radon in these structures are very high, and half of these values are more than twice as the ground public annual effective dose 0.924 mSv.5 , No matter concentration or annual effective dose, the radon level in underground structures is higher than that in ground buildings. So, the mitigation methods should be carried out in underground structures to reduce the radon level.6, Improving ventilation efficiency is the most simple and convenient way to mitigate the radon concentration in underground structures. Using radon sealant paint materials is the most economical way.