| As one of the main criteria for evaluating indoor air quality,the concentration of microbial aerosol has an extremely important impact on human health.Previous research of our research group has sampled and analyzed indoor bacterial and fungal aerosols in hospitals,campuses,subway stations,electronic cities,supermarkets and other places,and explored the distribution characteristics of indoor bacterial and fungal aerosols in different places.However,less attention has been paid to densely populated places,and there is a lack of test data for such places.Therefore,it is of great significance for the study of indoor microorganisms in densely populated places.In the paper,shopping malls,bird and flower markets,agricultural product markets,gymnasium and railway stations were selected as the test objects in summer,and partition research according to different functions and characteristics in different places.The places with serious bacterial and fungal aerosol pollution in the summer test were selected as the autumn test objects for further study.The characteristics of microbial aerosols in different areas in different seasons were studied by analyzing the concentration and particle size distribution characteristics of bacterial and fungal aerosols in different areas in summer and autumn.The test results of similar places in summer and autumn were compared to study the differences of microbial aerosols in densely populated places in different seasons.The effects of air microbial exposure in densely populated places on human health were evaluated in the paper.The environmental parameters in different areas were detected to analyze the correlation between environmental parameters and microbial aerosol concentration,and the improvement measures were put forward to control microbial aerosol pollution.The main conclusions of the study are as follows:（1）The bacterial aerosol concentrations in different types of places are significantly different in summer tests.The concentration of bacterial aerosol in the shopping mall is 96～420cfu/m3,in the flower and bird market is 232～5393 cfu/m3,in the agricultural product market is946～2733 cfu/m3,in the gymnasium is 147～226 cfu/m3,in the railway station is 644～1418cfu/m3.And the bacterial aerosol concentration in the pet area of the flower and bird market and the fresh area of the agricultural product market reached a high level of pollution.（2）In the summer test,the fungal aerosol concentration in the shopping mall is 76～315cfu/m3,in the flower and bird market is 428～4036 cfu/m3,in the agricultural product market is749～3298 cfu/m3,in the gymnasium is 377～569 cfu/m3,and in the railway station is1020～1823 cfu/m3.Fungal aerosol concentrations in the plant and pet area of the flower and bird market,the fresh area of the agricultural product market,the ticket areas and check area of the railway station reached high levels of pollution.（3）In the autumn test,the bacterial aerosol concentration in the flower and bird market is1943～7617 cfu/m3,and the fungal aerosol concentration is 563～4114 cfu/m3.The bacterial aerosol concentration in the agricultural product market is 379～3303 cfu/m3,and the fungal aerosol concentration is 846～2235 cfu/m3.The bacterial aerosol concentration in the railway station is 240～907 cfu/m3,and the fungal aerosol concentration is 411～2274 cfu/m3.（4）Comparing the concentrations of microbial aerosols of three palaces in summer and autumn test,the variation trends of bacterial and fungal aerosol concentrations are the same.The average concentration of bacterial and fungal aerosols in the flower and bird market is autumn>summer,in the agricultural product market is autumn<summer,in the railway station is autumn<summer.（5）The particle size distribution of bacteria and fungi aerosols in different areas of the five types of places in summer is different.The peak values of bacteria and fungi aerosols are mainly distribute in grade IV（2.1～3.3μm）and grade V（1.1～2.1μm）.The median diameters of bacteria and fungi are 1.70～2.91μm and 1.60～2.49μm.The particle size distributions of bacterial and fungal aerosols in different areas of the three places are different in autumn.The peak value of bacterial aerosol is mainly distribute in grade IV（2.1～3.3μm）,grade V（1.1～2.1μm）and grade VI（0.65～1.1μm）.The peak value of fungal aerosol is mainly distribute in grade IV（2.1～3.3μm）and grade V（1.1～2.1μm）.The median diameters of bacteria and fungi are 1.49～2.62μm and1.92～2.72μm.（6）In summer and autumn,the average daily exposure and health impact coefficient of each place are different.The influence of microbial aerosol on male health was greater than female health.The average daily exposure and health impact coefficient of microbial aerosol in summer are higher than autumn in the same place.In the summer and autumn test,the health impact coefficients of the pet area of the flower and bird market for men and women and the plant area for men are greater than 1.（7）The correlation between relative humidity and the total concentration of fungal aerosol was significantly positive in summer and autumn tests.The correlation between PM2.5concentration and total bacterial aerosol concentration in summer and autumn tests was significantly positive.In autumn test,CO2 concentration was positively correlated with the total concentration of bacterial aerosol,but not with fungal aerosol. |
