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Volume 12, No. 6, December 2012, Pages 1336-1344 PDF(281 KB)  
doi: 10.4209/aaqr.2012.03.0066   

Concentrations and Size Distributions of Airborne Microorganisms in Guangzhou during Summer

Xinyu Chen1,2, Pixin Ran1, Kinfai Ho3,4, Wenju Lu1,5,6, Bing Li1, Zhongpeng Gu7, Chaojie Song8, Jian Wang1,5

1 State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Disease, The First Affiliated Hospital, Guangzhou Medical University, Guangzhou 510182, China
2 Department of Pathogenic Biology, Guangzhou Medical University, Guangzhou 510182, China
3 Key Lab of Aerosol, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710043, China
4 School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong
5 Division of Pulmonary and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
6 Department of Laboratory Medicine, The First Affiliated Hospital, Guangzhou Medical University, Guangzhou 510182, China
7 Bureau of Education of Guangzhou Municipality, Guangzhou 510030, China
8 Preventive Medicine Grade2005, Guangzhou Medical University, Guangzhou 510182, China




The concentrations and size distributions of airborne microorganisms were determined for outdoor air samples collected with cascade impactors on hazy summer days in Guangzhou. The percentage of airborne bacteria was markedly higher than that of fungi, and the concentrations of bacteria were much higher in a densely populated area (Guangzhou Medical College) than in a clean area (Guangzhou Liuhua Lake Park) or one with heavy traffic (Dongfengxilu Road). Moreover, the concentrations of bacteria at 8:00 and 23:00 were higher than those at 12:00 and 17:00. Sixteen species of bacteria belonging to eight genera were identified, and all were opportunistic pathogens. Of these, 11 species from four genera were Gram-positive, and five species from four genera were Gram-negative. Staphylococcus, Bacillus, Enterobacter, and Serratia were the dominant bacterial genera, and the most abundant species were Staphylococcus hominis (8–58%) and Staphylococcus lugdunensis (14 to 35%). Size distribution studies showed that 36 to 76% of the microorganisms deposited on stages 3 to 6 of the sampler (0.65–4.7 µm aerodynamic equivalent diameter), and particles of this size could penetrate the lower respiratory tract of humans.



Keywords: Microbial aerosol; Bacterial community composition; Size distribution; Clean area; Densely populated area; Traffic dense area.



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