PREPARING FOR AN INFLUENZA PANDEMIC: Personal Protective Equipment for Healthcare Workers by Institute of Medicine of the National Academies

Author:Institute of Medicine of the National Academies
Language: eng
Format: epub
Tags: Health and Medicine : Medical Training and Workforce. Health and Medicine : Public Health and Prevention
Publisher: NATIONAL ACADEMY PRESS
Published: 2007-12-07T00:00:00+00:00

Current technologies necessitate a trade-off between enhanced filtration and physiologic burden to the wearer, particularly if the respirator has to be worn for extended periods of time. It has been suggested that 100 percent efficient respirator filter media be used in place of 95 percent efficient filter media to further reduce the risk of exposure to airborne pathogens as a result of filter penetration. However, the use of 100 percent efficient filters could create increased breathing resistance (pressure drop) across the filter causing increased flow rate through faceseal leaks, thus resulting in less overall protection. Studies using flow calculations based on theoretical leaks (Campbell, 1984) or measurements using fixed artificial leaks have demonstrated a positive correlation between pressure drop and faceseal leakage (Myers et al., 1991; Krishnan et al., 1994). Nelson and Colton (2000) observed an upward trend of actual faceseal leakage with increasing pressure drop as measured on several subjects. Janssen and Weber (2005) conducted a similar study with changes to address the limitations of the earlier study. They found that there was no increase in faceseal leakage with increasing pressure drop on respirators that fit well enough to pass the OSHA fit factor requirement of 100. These results would indicate that 100 percent efficient respirator filters would not result in increased faceseal leakage and decreased overall protection. Opportunities exist for improving both the comfort and efficiency of respirators.

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