[Study on formulation of standard limits for trichloroethylene and tetrachloroethylene in "Standards for indoor air quality（GB/T 18883-2022）" in China]

There are clear indoor air pollution sources of trichloroethylene and tetrachloroethylene. A large number of epidemiological evidence has confirmed their carcinogenic toxicity and non-carcinogenic toxicity. Several countries and international organizations have paid attention to indoor air trichloroethylene and tetrachloroethylene. It has been also assessed that there should be certain potential health risk of indoor air trichloroethylene and tetrachloroethylene in China. Based on the latest research results of health risk assessment of indoor air trichloroethylene and tetrachloroethylene, the "Standards for indoor air quality (GB/T 18883-2022)" added trichloroethylene and tetrachloroethylene as indicators. The index limit of trichloroethylene is 6 μg/m3 for an 8-hour average concentration. The index limit of tetrachloroethylene is 120 μg/m3 for an 8-hour average concentration. The technical contents related to the determination of the standard limits of trichloroethylene and tetrachloroethylene in indoor air were analyzed and discussed, including the sources, the exposure, the health effects, the determination of the limit values, and the recommendations for standard implementation. It also proposed recommendations for the implementation of"Standards for indoor air quality (GB/T 18883-2022)".

[Study on formulation and revision of standard limits for total bacteria count in "Standards for indoor air quality（GB/T 18883-2022）" in China]

The total bacteria count has been attracting attention as an important pollutant in indoor air, and its standard limit was tightened to 1500 CFU/m3 in "Standards for indoor air quality (GB/T 18883-2022)".The technical contents related to the determination of the indoor air standard limits for total bacteria count were analyzed and studied, including the environmental existence level, exposure status, the health effects and the derivation of the limit value. It also proposed prospects for the future development and revision of quality standards for total bacteria count in indoor air.