The study of size distribution of coughing droplet
Date Issued
2004
Date
2004
Author(s)
Chen, Cheng-Min
DOI
zh-TW
Abstract
Droplet exhaled from human may carry microorganisms capable of transmitting disease in short and long distances. The size of droplet will mainly influence the transmission mode of such infectious droplet. The aim of this study was to establish the size distribution of droplet and droplet nuclei exhaled by healthy individuals, and using sample bag and column to collect them. The droplets from human subjects performing coughing were measured by aerodynamic particle sizer (APS) and scanning mobility particle sizer (SMPS) system, and establish the droplet size distribution. Computing the evaporation time, falling distances, horizontal traveling distances with some assumptions. Furthermore, the data was treated with statistical analysis, comparing the difference of different ages and sexual classification.
The data of APS monitoring showed the respiratory droplets ranged from 0.5 to 20 mm and 90~95% of droplets were between 2 and 10 mm. The mode of droplet size distribution is between 5 and 7 mm. Most droplets were less than 10 mm. The diameter of droplet nuclei was found to range in diameter from 0.5 to 5 mm, and the most amount was between 0.6 to 2 mm. The droplets size were not significantly difference in age and sexual classification. The SMPS confirmed the existence of droplets ranged from 0.02 to 0.5 mm. In the environment of 20℃ and 50% relative humidity, it took only 0.04 seconds for 5 mm droplet to evaporate, and the falling distance was less than 0.002 cm, the horizontal traveling distance was about 0.008 cm. It showed the range of droplets produced by coughing was near the source, and evaporating to form droplet nuclei quickly. Droplet nuclei could suspend in the environment for a long time, and transport with air current. The microorganisms may transmit disease by air. Besides, if droplet or droplet nuclei fall on the surface of objects, one may be infected by toughing the infectious objects.
Subjects
傳染病控制
嚴重急性呼吸道症候群
飛沫粒徑
生物氣膠
bioaerosol
SARS
droplet diameter
infection control
SDGs
Type
thesis
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