Concentrations and Size Distributions of Airborne Microorganisms in Guangzhou during Summer

Xinyu Chen,Pixin Ran,Zhongpeng Gu,Wenju Lu,Bing Li,Kinfai Ho,Jian Wang,Chaojie Song

doi:10.4209/aaqr.2012.03.0066

Abstract

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.

Highlights

IntroductionAirborne microorganisms (bioaerosols) are particles of biological origin (e.g., bacteria, fungi, pollen, viruses), and they are important constituents of the atmosphere because they have the potential to cause a variety of diseases in humans and animals and to damage vegetation (Lee et al, 2003; Ho et al, 2005)
Airborne microorganisms are particles of biological origin, and they are important constituents of the atmosphere because they have the potential to cause a variety of diseases in humans and animals and to damage vegetation (Lee et al, 2003; Ho et al, 2005)
Airborne bacterial concentrations can be affected by ground disturbances, including those caused by the movements of pedestrians and motor vehicles

Summary

Introduction

Airborne microorganisms (bioaerosols) are particles of biological origin (e.g., bacteria, fungi, pollen, viruses), and they are important constituents of the atmosphere because they have the potential to cause a variety of diseases in humans and animals and to damage vegetation (Lee et al, 2003; Ho et al, 2005). Bioaerosols are droplets or particles suspended in the air; they typically range in size from 0.3 to 30 m in diameter (Koch, 1996), and their composition varies depending on their sources, the aerosolization mechanisms that produce them, and the environmental conditions along the pathways from the source to the sampling site. In order to correlate human disease with exposure to bioaerosols, it is critically important to measure the size distributions of bacteria and fungi in places where people are likely to be exposed. Most bio-particles that deposit in the alveoli and terminal bronchi range in size from 1 to 2

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