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Mathematical models for assessing the role of airflow on the risk of airborne infection in hospital wards

Noakes, CJ and Sleigh, PA (2009) Mathematical models for assessing the role of airflow on the risk of airborne infection in hospital wards. Journal of the Royal Society Interface, 6 (Supp.6). S791 - S800 . ISSN 1742-5662

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Abstract

Understanding the risk of airborne transmission can provide important information for designing safe healthcare environments with an appropriate level of environmental control for mitigating risks. The most common approach for assessing risk is to use the Wells-Riley equation to relate infectious cases to human and environmental parameters. While it is a simple model that can yield valuable information, the model used as in its original presentation has a number of limitations. This paper reviews recent developments addressing some of the limitations including coupling with epidemic models to evaluate the wider impact of control measures on disease progression, linking with zonal ventilation or computational fluid dynamics simulations to deal with imperfect mixing in real environments and recent work on dose-response modelling to simulate the interaction between pathogens and the host. A stochastic version of the Wells-Riley model is presented that allows consideration of the effects of small populations relevant in healthcare settings and it is demonstrated how this can be linked to a simple zonal ventilation model to simulate the influence of proximity to an infector. The results show how neglecting the stochastic effects present in a real situation could underestimate the risk by 15 per cent or more and that the number and rate of new infections between connected spaces is strongly dependent on the airflow. Results also indicate the potential danger of using fully mixed models for future risk assessments, with quanta values derived from such cases less than half the actual source value.

Item Type: Article
Keywords: Air Microbiology, Air Pollution, Indoor, Community-Acquired Infections, Cross Infection, Disease Outbreaks, Hospital Design and Construction, Hospitals, Humans, Infection, Models, Theoretical, Normal Distribution, Risk Assessment, Stochastic Processes, Ventilation
Institution: The University of Leeds
Academic Units: The University of Leeds > Faculty of Engineering (Leeds) > School of Civil Engineering (Leeds)
Depositing User: Symplectic Publications
Date Deposited: 17 Nov 2011 15:25
Last Modified: 08 Feb 2013 17:35
Published Version: http://dx.doi.org/10.1098/rsif.2009.0305.focus
Status: Published
Publisher: The Royal Society
Identification Number: 10.1098/rsif.2009.0305.focus
URI: http://eprints.whiterose.ac.uk/id/eprint/43434

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