Study On Air Quality And Pollutants Distribution Characteristics In Typical Chengdu Metro Stations

The subway is a common mode of transportation for urban residents to travel on a daily basis,greatly relieving ground traffic congestion,and in recent years,with the advancement of urban construction in China,subway construction has also developed rapidly.However,air quality problems such as excessive pollutants in certain stations,discomfort of staff and complaints from residents around the wind pavilions occur in subway operations.Therefore,it is especially important to investigate and analyze the air quality in metro stations systematically and explore the distribution pattern of metro air pollutants.In this research,a combination of subjective and objective air pollutant testing and research is conducted on the air pollutants in the station space and at the air kiosks of typical stations of Chengdu subway,using subjective questionnaires,objective field tests and numerical simulation analysis to analyze the current situation of air quality in subway stations under different conditions.The main research results and conclusions are as follows.（1）According to the existing air quality research methods,referring to the evaluation methods and specific indicators of such problems,and according to the characteristics of subway stations,the main influencing factors of subway air quality are analyzed,and the test objects of air pollutants in subway stations are determined as particulate matter,VOCs and formaldehyde.（2）The results show that the concentration of particulate matter in transfer station and wind Pavilion is higher than that in intermediate station,the concentration in autumn and winter is higher than that in spring and summer,and the concentration in peak period is higher than that in low peak period;Formaldehyde and volatile organic compounds were higher in summer than in other seasons.（3）Under different passenger flow conditions,the specific distribution law of PM_2.5 is analyzed by numerical simulation.It is found that PM_2.5 is mainly concentrated in the first part of the platform and around the escalator.By setting different air outlet speeds,the optimal air supply speeds are 3.2m/s and 2.3m/s under different passenger flow conditions.（4）A questionnaire survey was conducted among the staff and passengers of Chengdu metro station.The results showed that the respondents were satisfied with the air quality of Chengdu metro station,but the odor of the air did not meet the standard requirements.It was necessary to analyze and deal with the odor sources of the subway station.