Study On The Airborne Microbial Pollution And Influencing Factors In Residences And Public Buildings

Microorganisms are ubiquitous,diverse and have rich resources.Airborne microbial pollution could cause a variety of respiratory diseases,asthma,building syndrome and other diseases.In this study,characteristics of airborne bacteria and fungi were surveyed in 12residences,2 office buildings,1 hospital and 1 kindergarten in summer and winter in Nanjing.Concentrations and size distributions of airborne bacteria and fungi in homes and public buildings were measured,relationships between microbe and environmental parameters were investigated by using six-stage Anderson sampler.Community structure of microorganisms in residences were detected by bioaerosol sampler.The major research results are as follows:?1?Indoor microbial pollutions were found in residences,hospitals and kindergartens in Nanjing.The concentrations of airborne microbe in homes ranged from 841CFU/m³ to 2895CFU/m³ and average was 1509CFU/m³ in summer,ranged from 191CFU/m³ to 1956CFU/m³ and average was 887 CFU/m³ in winter.The concentrations in offices ranged from298CFU/m³ to 1122CFU/m³ and average was 620CFU/m³ in summer,ranged from298CFU/m³ to 1742CFU/m³ and average was 478 CFU/m³ in winter.The concentrations in hospital ranged from 922CFU/m³ to 3385CFU/m³ and average was 2295CFU/m³ in summer,ranged from 262CFU/m³ to 421CFU/m³ and average was 319 CFU/m³ in winter.The concentrations in kindergarten ranged from 832CFU/m³ to 2729 CFU/m³ and average was1399 CFU/m³ in winter.?2?There are totally 33 phyla and 631 genera of air-borne bacteria and 9 phyla and 231genera of airborne fungi identified in residences in summer.The dominant bacteria phyla identified were Proteobacteria?41.8%?46.8%?.The dominant fungal phyla identified were Ascomycota?46.0%?90.3%?.Indoor airborne fungi genera,outdoor airborne fungi genera and soil genera are similar.Indoor and outdoor airborne fungi genera are similar,but are different from soil genera.?3?The airborne microorganisms were collected on six stages,and the fifth stage accounted for the highest?18%?53%?of the total culturable microorganisms,following by the fourth stage?12%?28%?and the sixth stage?11%?25%?.It was found that most airborne microorganisms could enter human bronchi and lungs successfully,which is detrimental to human health.?4?In comparison of indoor and outdoor microbial concentrations,indoor bacterial and fungal concentrations were higher than outdoor in summer,indoor bacterial concentrations were higher than outdoor in winter,and fungal concentrations were lower than outdoor.In comparison of microbial concentrations in summer and winter,the concentrations of airborne bacteria in summer were higher than that in winter.The concentrations of airborne bacteria were higher than fungi and they were related closely.?5?The concentrations of airborne bacteria and fungi were compared in homes with different environment.Residences in urban areas had the higher indoor microbial concentration than that in suburban areas.Residences built before 2000 had the higher indoor microbial concentration than that built after 2000.Residences with residents at least 6 years had the higher indoor microbial concentration than that less than 6 years.Residences with visible mold had the higher indoor microbial concentration.The room with the higher frequency of dumping garbage had the higher indoor microbial concentration.?6?The relationships between airborne microbe and environmental parameters and were investigated.The positive correlations were found between airborne microbe and human numbers,temperature,humidity,CO₂ and PM_2.5 in summer.The correlations were unclear in winter.The correlations differed by natural ventilation and mechanical ventilation.