Pollutants distribution on platforms and station halls at different times during the operation cycle of subways： A case study of Xi'an, China

With the acceleration of urbanization, studying the distribution of pollutants during subway operation is more significance for safeguarding the physical and mental health of personnel. This paper takes a subway line in Xi'an as an example, conducts testing and research on the distribution characteristics of pollutants in the platform and station hall at different times. The results show that the temperature at platforms and station halls is greatly influenced by passenger flow, and the CO2 concentration is higher during morning and evening rush hours than during non-peak hours. The concentration of particulate matter inside the station is higher during morning and evening rush hours than during non-peak hours, and the concentration of particulate matter during the morning rush hour is higher than that during the evening rush hour. Particle size of less than 0.5 ?m dominates in subway platforms, station halls, and outdoors. The correlation coefficients between the concentrations of PM10 and PM2.5 in platforms and station halls are 0.597 and 0.808. The correlation coefficients between the concentrations of PM2.5 and PM1.0 in platforms and station halls are 0.907 and 0.953. It provides reference value for creating a comfortable and healthy subway environment.