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The paper analyses and evaluates the results of indoor radon concentration measured with solid state nuclear track detectors since 2000 in China.Comparison with the previous measurement results is drawn.The causes arising indoor radon level in China are discussed,and some suggestions to control indoor radon level in China are proposed.The result shows that the average concentration values by sample-weighted and population-weighted are 38.8 ±11.9Bqm.3 and 40.5±13.IBqm.3 respectively.It involves 39 cities and 4192 dwellings in total,and the population of the result accounts for 22.4% of China,and the number of the dwellings accounts for 0.1/104 0f China.The ratio between the results of recent and previous measurements ranges from l.00 t0 5.19,and the average value of the ratio by population-weighted is 2.35.Currently there are three main causes for the increase of the indoor radon level based on the analysis: (1) Industrial waste slag is widely used as building materials,which results in an increase of radiation level of building materials,and provide a higher concentration of the parent nuclides for indoor radon.(2) The widespread use of air-condition and better air tightness of dwellings which will reduce the ventilation rate of the room,and lead to cumulative increase of radon in the room.(3) The recent measurement results cover a higher radon concentration at night,while the previous measurement results were measured during the day,which is of relatively lower radon concentration.Conclusions and suggestions: (1) This paper collects and collates indoor radon concentration data of China comprehensively,which are measured since 2000 using solid state nuclear track detectors.It represents latest research results of indoor radon levels of China.However the analysis is still preliminary and needs to be further studying.Usually,the sampling rate of national radon survey should not be less than l/104,but the number of the dwellings collected in this paper is far less than that.Therefore,it needs to expand the scope of the investigation under a reliable quality assurance.(2) The standard of "Limitations on the Radioactivity of Industrial Waste Slag as Building Materials" Should be implemented as soon as possible,which will control the radionuclide concentrations of building materials from the origin,and control the radon exhalation rate of building material productions.(3) Study and draw up the national radon management strategy and the methods of prevention and remediation against indoor radon.