Exposure risk of an airborne pathogen in washroom

Pao Yue-kong Library Electronic Theses Database

Exposure risk of an airborne pathogen in washroom


Author: Li, Nan
Title: Exposure risk of an airborne pathogen in washroom
Degree: M.Eng.
Year: 2013
Subject: Airborne infection.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Building Services Engineering
Pages: ix, 83 leaves : ill. (some col.) ; 30 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2641105
URI: http://theses.lib.polyu.edu.hk/handle/200/7105
Abstract: Human is exposed to external environments whenever and wherever via the visible exterior (e.g. skin and openings into the body), and the washroom may have the highest exposure risk for its appropriate temperature and humidity for pathogens to survive. A number of studies discovered the airborne route of diseases transmission from human to human, however, limited discussions concern on feces or vomit relevant pathogens, though which have be proved that many viruses are shed in. When flushing the toilet, the pathogens escape to the indoor air, and can be inhaled by the user, human may be infected with the diseases. This study aims to identify the exposure risk of Escherichia coli (E. coli) in washroom, and discover the relationship between the ventilation rate and position of exhaust fan and the exposure risk. Both the measurements and computational fluid dynamics (CFD) modeling were adopted in the study, including the measurement of air change rate (ach) and DANTEC airflow velocity in the washroom, and the simulations of three ventilation rates and three positions of exhaust fan. The exposure risk is estimated by the Wells-Riley model. The comparisons indicates that both the increasing ventilation rate and the exhaust fan beside the toilet can reduce the exposure risk, while the fan beside the toilet has far more apparent effect than changing the velocity, whose risk is almost zero. The study suggests the design of exhaust fan in washroom is better approaching the pollution source to avoid the diffusion of the contaminants rather than increasing the air change rate. Once the pathogens spread again, the exposure risk would sharply increase.

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