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Journal of Environmental and Public Health
Volume 2011, Article ID 473143, 8 pages
Research Article

Inward Leakage in Tight-Fitting PAPRs

1Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
2National Personal Protection Technology Laboratory, National Institute for Occupational Safety and Health, Pittsburgh, PA 15236, USA

Received 16 September 2010; Revised 16 February 2011; Accepted 16 March 2011

Academic Editor: Issam Al-Khatib

Copyright © 2011 Frank C. Koh et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A combination of local flow measurement techniques and fog flow visualization was used to determine the inward leakage for two tight-fitting powered air-purifying respirators (PAPRs), the 3M Breathe-Easy PAPR and the SE 400 breathing demand PAPR. The PAPRs were mounted on a breathing machine head form, and flows were measured from the blower and into the breathing machine. Both respirators leaked a little at the beginning of inhalation, probably through their exhalation valves. In both cases, the leakage was not enough for fog to appear at the mouth of the head form.