Indoor Radon Survey in 31 Provincial Capital Cities and Estimation of Lung Cancer Risk in Urban Areas of China

Objective We aimed to analyze the current indoor radon level and estimate the population risk of radon-induced lung cancer in urban areas of China.Methods Using the passive monitoring method,a new survey on indoor radon concentrations was conducted in 2,875 dwellings across 31 provincial capital cities in Chinese mainland from 2018 to 2023.The attributable risk of lung cancer induced by indoor radon exposure was estimated based on the risk assessment model.Results The arithmetic mean(AM)and geometric mean(GM)of indoor radon concentrations were 65 Bq/m^(3)and 55 Bq/m^(3),respectively,with 13.6%of measured dwellings exceeding 100 Bq/m^(3)and 0.6%exceeding 300 Bq/m^(3).The estimated number of lung cancer deaths induced by indoor radon exposure was 150,795,accounting for 20.30%(95%CI:20.21%-20.49%)of the lung cancer death toll.Conclusion This study provided the most recent data on national indoor radon levels in urban areas and the attributable risk of lung cancer.These results served as an important foundation for further research on the disease burden of indoor radon exposure and radon mitigation efforts.

Study on the effect of Fresh Air Ventilation system for reducing indoor ^(222)Rn

Objective:To explore the reduction effect for the indoor ^(222)Rn(Rn)by Fresh Air Ventilation(FAV)system,a novel commercial ventilation device in China.Methods:The indoor concentrations of Rn and its decay products(RnD)in three residential rooms,two in Beijing and one in Hefei city,Anhui province,before and after FAVS functioned were measured using an active continuous method.The air exchange rate was monitored by measuring CO_(2) concentration using the tracer gas method.Results:In the three rooms,the FAVS reduced the Rn concentrations from(162±80)Bq/m^(3) to(63±22)Bq/m^(3) and decreased the RnD concentrations from(64±35)Bq/m^(3) to(13±6)Bq/m^(3) on average,a decrease of(59±25)% in the Rn concentrations and a drop of(77±18)%in the RnD concentrations.Considering dose conversion factors of Rn and RnD,FAVS decreased the exposure dose by(76±20)%.Besides,FAVS increased the air exchange rates from 0.17 h^(-1) to 0.56 h^(-1) on average.Conclusions:FAVS can effectively reduce indoor Rn and RnD concentrations by improving the air exchange,serving as a valuable supplement to existing radon mitigation methods,especially in extreme climates.