tetano
Editor, Senior Moderator
J R Soc Interface. 2011 Sep 21. [Epub ahead of print]
Effectiveness of facemasks to reduce exposure hazards for airborne infections among general populations.
Lai AC, Poon CK, Cheung AC.
Source
Department of Civil and Architectural Engineering (retitled from Building and Construction), City University of Hong Kong, , Tat Chee Avenue, Kowloon Tong, Hong Kong, People's Republic of China.
Abstract
Facemasks are widely used as a protective measure by general public to prevent inhalation of airborne pathogens including seasonal, swine and other forms of influenza and severe acute respiratory syndrome (SARS), etc. However, scientific data on effectiveness of facemasks in reducing infections in the community are extremely limited and even inconsistent. In this work, two manikins labelled as 'source' and 'susceptible' were used to measure the protection provided by facemasks under various emission scenarios. The source was modified to generate polydisperse ultrafine particles, whereas the susceptible was modified to mimic a realistic breathing pattern. The facemask was challenged by both pseudo-steady and highly transient emissions generated by an expiratory process where parameters, such as separation distance between manikins, emission velocity and expiratory duration, were controlled and measured systematically. Performances of four different types of facemask fits, varying from ideal to normal wearing practice, were also investigated. Under the pseudo-steady concentration environment, facemask protection was found to be 45 per cent, while under expiratory emissions, protection varied from 33 to 100 per cent. It was also observed that the separation between the source and the manikin was the most influential parameter affecting facemask protection.
PMID:
21937487
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/21937487
Effectiveness of facemasks to reduce exposure hazards for airborne infections among general populations.
Lai AC, Poon CK, Cheung AC.
Source
Department of Civil and Architectural Engineering (retitled from Building and Construction), City University of Hong Kong, , Tat Chee Avenue, Kowloon Tong, Hong Kong, People's Republic of China.
Abstract
Facemasks are widely used as a protective measure by general public to prevent inhalation of airborne pathogens including seasonal, swine and other forms of influenza and severe acute respiratory syndrome (SARS), etc. However, scientific data on effectiveness of facemasks in reducing infections in the community are extremely limited and even inconsistent. In this work, two manikins labelled as 'source' and 'susceptible' were used to measure the protection provided by facemasks under various emission scenarios. The source was modified to generate polydisperse ultrafine particles, whereas the susceptible was modified to mimic a realistic breathing pattern. The facemask was challenged by both pseudo-steady and highly transient emissions generated by an expiratory process where parameters, such as separation distance between manikins, emission velocity and expiratory duration, were controlled and measured systematically. Performances of four different types of facemask fits, varying from ideal to normal wearing practice, were also investigated. Under the pseudo-steady concentration environment, facemask protection was found to be 45 per cent, while under expiratory emissions, protection varied from 33 to 100 per cent. It was also observed that the separation between the source and the manikin was the most influential parameter affecting facemask protection.
PMID:
21937487
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/21937487