| Indoor air quality is closely related to the human health, and adults spent about 80%～90% of time indoors, especially the old, infants living in the cities who might spend as high as 95% of time indoors. Indoor air biological pollution was one of the most important factors affecting indoor air quality, which could cause a variety of respiratory diseases, asthma, building syndrome and other diseases taking great harm to people’s health. In this study, we selected 60 households as sampling points from five main districts of Hangzhou, which carried on one-year system experiments, and studied the changes in airborne microbial community structure and dynamic characteristics of indoor air, meanwhile we also studied the effects of airborne microbial community structure and concentration at different height, then the main conclusions were as follows:(1) It found 836 strains indoor airborne bacteria in Hangzhou, which identified 45 genera 152 species, including 80.86% gram positive bacteria and 15.91% gram negative bacteria. The dominant bacterial genera were Micrococcus(15.79%),Kocuria(13.76%),Bacillus(11.72%), Staphylococci (10.05%), Pseudomonas (4.43%). The dominant bacterial species were Micrococcus luteus (12.56%), Kocuria roseus (11.96%), Bacillus megatherium (5.86%), Staphylococcus cohnii(4.31%). Indoor family airborne fungi were isolated 383 strains, and 27 genera 79 species were identified in Hangzhou. The dominant fungal genera in turn were Penicillium (26.37%), Aspergillums (14.88%), Cladosporium (12.53%), Alternaria (7.31%) and Trichoderma (3.66%). The dominant fungal species in turn were Cladosporium cladosporioides(6.53%), Penicillium chrysogenum(6.21%), Aspergillus syoowi(6.01%) and Alternaria alternata (5.74%).(2) In Hangzhou, the community structure of family indoor airborne bacteria and fungi varied significantly in time and space, whose superiority strains were almost unanimously in different seasons and districts, while a significant difference in the percentage and number of strains were found in different seasons and districts. It found more types of airborne bacteria in spring (43 genera 95 kinds), followed by the summer (30 genera and 77 kinds), autumn (38 genera 91 kinds) and less in winter (32 genera 94 kinds), while it found more airborne fungal species (27 genera) in summer, and the winter was the least (21 genera) in all of the seasons.(3) In Hangzhou, indoor airborne microbial concentration ranged from 314 to 2903 colony forming units (CFU)/m3, and the mean was 873 CFU/m3; Airborne bacteria:54～703 CFU/m3, mean:220 CFU/m3; Airborne fungi:240～2752 CFU/m3, mean:653 CFU/m3. Indoor airborne microorganisms were given priority to fungi, whose concentration has nothing important with the indoor per capita space, ventilation conditions and children’s gender in Hangzhou.(4) Indoor airborne microbial concentration varied from different districts in Hangzhou. The bacterial concentration from high to low in turn was the Gongshu District, Jianggan District, Shangcheng District and Xiacheng District, Xihu District. The fungal concentration from high to low in turn was Xihu District, Jianggan District, Gongshu District, Xiacheng District and Shangcheng District. It had the highest concentration of fungi (893 CFU/m3), but the lowest concentration of bacteria (109 CFU/m3) at Xihu District.(5) About indoor airborne bacteria and fungi, there were significant changes in different seasons. The higher concentration of indoor airborne bacteria were in the spring and autumn, next summer, and the lowest was winter, mean respectively:271 CFU/m3,251 CFU/m3,171 CFU/m3,81 CFU/m3. The Gongshu District was highest in different seasons (123-419 CFU/m3), and Xihu District was the lowest (46-147 CFU/m3). The highest concentration of airborne fungi was in summer, and the lowest was in winter, the mean from spring to winter respectively:941 CFU/m3, 689 CFU/m3,590 CFU/m3,317 CFU/m3. Xihu District has the highest concentration (429～1049 CFU/m3), and Shangcheng District has the lowest (219～597 CFU/m3) in different seasons.(6) Size distribution of indoor airborne bacteria and fungi present a different rule in Hangzhou. About 37% of the particle distribution of airborne bacteria were in the grade V of the sampler, and about 46% of the particle distribution of airborne fungi were in the grade IV of the sampler, which in the rest of other grades of the sampler had only a little change. It has no significative variation in space and time about size distribution of indoor airborne bacteria and fungi in Hangzhou. Ventilation conditions and children’s gender had no effects on the size distribution of indoor airborne bacteria and fungi.(7) In Hangzhou, outdoor airborne microbial concentration varied with the change of height, ranging from 303 to 738 CFU/m3. Airborne bacteria concentration ranged from 114 to 365 CFU/m3. Airborne fungi ranged from 191 to 508 CFU/m3. Generally, the microbial concentration (airborne bacteria and fungi) with the increase of height present the downward trend, and bacterial concentration increased when wind speed was larger. In a single day, significantly lower concentrations of bacteria were detected at 13:00 hours through all sampling sites, and at 18:00 reachesd the highest. The highest concentration of airborne fungi at 8:00, which lowest at 13:00. Therefore, different height had no effects on the size distribution of airborne bacteria and fungi. |
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