Pollution status and distribution characteristics of indoor air bacteria in subway stations and compartments in a city of Central South China
Shuyan CHENG,
Zhuojia GUI,
Liqin SU,
Guozhong TIAN,
Tanxi GE,
Jiao LUO,
Ranqi SHAO,
Feng LI,
Weihao XI,
Chunliang ZHOU,
Wei PENG,
Minlan PENG,
Min YANG,
Bike ZHANG,
Xianliang WANG,
Xiaoyuan YAO
Affiliations
Shuyan CHENG
National Institute of Environmental Health/ China CDC Key Laboratory of Environment and Population Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China
Zhuojia GUI
Xiangtan Center for Disease Control and Prevention, Xiangtan, Hunan 411100, China
Liqin SU
National Institute of Environmental Health/ China CDC Key Laboratory of Environment and Population Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China
Guozhong TIAN
National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
Tanxi GE
National Institute of Environmental Health/ China CDC Key Laboratory of Environment and Population Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China
Jiao LUO
National Institute of Environmental Health/ China CDC Key Laboratory of Environment and Population Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China
Ranqi SHAO
National Institute of Environmental Health/ China CDC Key Laboratory of Environment and Population Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China
Feng LI
National Institute of Environmental Health/ China CDC Key Laboratory of Environment and Population Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China
Weihao XI
National Institute of Environmental Health/ China CDC Key Laboratory of Environment and Population Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China
Chunliang ZHOU
Environmental Health Division, Hunan Provincial Center for Disease Control and Prevention, Changsha, Hunan 410005, China
Wei PENG
Xiangtan Center for Disease Control and Prevention, Xiangtan, Hunan 411100, China
Minlan PENG
Xiangtan Center for Disease Control and Prevention, Xiangtan, Hunan 411100, China
Min YANG
Xiangtan Center for Disease Control and Prevention, Xiangtan, Hunan 411100, China
Bike ZHANG
National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
Xianliang WANG
National Institute of Environmental Health/ China CDC Key Laboratory of Environment and Population Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China
Xiaoyuan YAO
National Institute of Environmental Health/ China CDC Key Laboratory of Environment and Population Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China
BackgroundBacteria are the most diverse and widely sourced microorganisms in the indoor air of subway stations, where pathogenic bacteria can spread through the air, leading to increased health risks. ObjectiveTo understand the status and distribution characteristics of indoor air bacterial pollution in subway stations and compartments in a city of Central South China, and to provide a scientific basis for formulating intervention measures to address indoor air bacteria pollution in subways. MethodsThree subway stations and the compartments of trains parking there in a city in Central South China were selected according to passenger flow for synchronous air sampling and monitoring. Temperature, humidity, wind speed, carbon dioxide (CO2), fine particulate matter (PM2.5), and inhalable particulate matter (PM10) were measured by direct reading method. In accordance with the requirements of Examination methods for public places-Part 3: Airborne microorganisms (GB/T 18204.3-2013), air samples were collected at a flow rate of 28.3 L·min−1, and total bacterial count was estimated. Bacterial microbial species were identified with a mass spectrometer and pathogenic bacteria were distinguished from non-pathogenic bacteria according to the Catalogue of pathogenic microorganisms transmitted to human beings issued by National Health Commission. Kruskal-Wallis H test was used to compare the subway hygiene indicators in different regions and time periods, and Bonferroni test was used for pairwise comparison. Spearman correlation test was used to evaluate the correlation between CO2 concentration and total bacterial count. ResultsThe pass rates were 100.0% for airborne total bacteria count, PM2.5, and PM10 in the subway stations and train compartments, 94.4% for temperature and wind speed, 98.6% for CO2, but 0% for humidity. The overall median (P25, P75) total bacteria count was 177 (138,262) CFU·m−3. Specifically, the total bacteria count was higher in station halls than in platforms, and higher during morning peak hours than during evening peak hours (P<0.05). A total of 874 strains and 82 species were identified by automatic microbial mass spectrometry. The results of identification were all over 9 points, and the predominant bacteria in the air were Micrococcus luteus (52.2%) and Staphylococcus hominis (9.8%). Three pathogens, Acinetobacter baumannii (0.3%), Corynebacterium striatum (0.1%), and Staphylococcus epidermidis bacilli (2.2%) were detected in 23 samples (2.6%), and the associated locations were mainly distributed in train compartments during evening rush hours. ConclusionThe total bacteria count in indoor air varies by monitoring sites of subway stations and time periods, and there is a risk of opportunistic bacterial infection. Attention should be paid to cleaning and disinfection during peak passenger flow hours in all areas.
