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N95 filtering facepiece respirator deadspace temperature and humidity.

Authors
Roberge-RJ; Kim-J-H; Benson-S
Source
J Occup Environ Hyg 2012 Mar; 9(3):166-171
NIOSHTIC No.
20040491
Abstract
The objective of this study was to determine the levels of heat and humidity that develop within the deadspace of N95 filtering facepiece respirators (N95 FFR). Seventeen subjects wore two models each of N95 FFR and N95 FFR with an exhalation valve (N95 FFR/EV) while exercising on a treadmill at a low-moderate work rate for 1 and 2 hr in a temperate ambient environment. FFR deadspace temperature and relative humidity were monitored by a wireless sensor housed within the FFR. Each FFR was weighed pre- and post-testing to determine moisture retention. After 1 hr, FFR deadspace temperature and humidity were markedly elevated above ambient levels, and the FFR deadspace mean apparent heat index was 54 degree C. N95 FFR/EV use resulted in significantly lower deadspace temperatures than N95 FFR (p = 0.01), but FFR deadspace humidity levels were not significantly different (p = 0.32). Compared with the first hour of use, no significant increase in FFR deadspace heat and humidity occurred over the second hour. FFR mean moisture retention was < 0.3 grams over 2 hr. N95 FFR/EV offer a significant advantage in deadspace heat dissipation over N95 FFR at a low-moderate work rate over 1 hr of continuous use but offered no additional benefit in humidity amelioration. Moisture retention in N95 FFR and N95 FFR/EV is minimal after 2 hr of use. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a file containing N95 filtering facepiece respirator deadspace mean RH and temperature recordings for 17 subjects treadmill exercising at 5.6 Km/H over 1 hour.]
Keywords
Respirators; Respiratory-equipment; Respiratory-protective-equipment; Face-masks; Filters; Filtration; Personal-protective-equipment; Temperature-effects; Heat; Humidity; Testing-equipment; Equipment-design; Equipment-reliability; Relative-humidity; Author Keywords: deadspace; exhalation valve; humidity; N95 filtering facepiece respirators; temperature
Contact
Raymond J. Roberge, NIOSH-NPPTL, 626 Cochrans Mill Road, Pittsburgh, PA 15236
CODEN
JOEHA2
Publication Date
20120301
Document Type
Journal Article
Email Address
dtn0@cdc.gov
Fiscal Year
2012
NTIS Accession No.
NTIS Price
Identifying No.
B03282012
Issue of Publication
3
ISSN
1545-9624
NIOSH Division
NPPTL
Priority Area
Healthcare and Social Assistance
Source Name
Journal of Occupational and Environmental Hygiene
State
PA
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