Effect of exhaled moisture on breathing resistance of N95 filtering facepiece respirators.
This study evaluated the effect of exhaled moisture on the breathing resistance of three classes of filtering facepiece respirators (FFR) following 4 h of continuous wear at a breathing volume of 40 l min(-1), utilizing an automated breathing and metabolic simulator as a human surrogate. After 4 h, inhalation and exhalation resistance increased by 0.43 and 0.23 mm of H(2)O pressure, respectively, and average moisture retention in the respirators was 0.26 ml. Under ambient conditions similar to those of the current study, and at similar breathing volumes, it is unlikely that exhaled moisture will add significantly to the breathing resistance of filtering facepiece respirators (FFR) over 4 h of use.
National Institute for Occupational Safety and Health, National Personal Protective Technology Laboratory, Pittsburgh, PA 15236, USA. rroberge@cdc.gov
Raymond J
RJ
Roberge
Emily
E
Bayer
Jeffrey B
JB
Powell
Aitor
A
Coca
Marc R
MR
Roberge
Stacey M
SM
Benson
D000403:Airway Resistance; D045853:Exhalation; D005374:Filtration / Q000295:instrumentation; D006801:Humans; D006813:Humidity; D001239:Inhalation; D019570:Inhalation Exposure / Q000517:prevention & control; D008348:Manikins; D008422:Materials Testing / Q000379:methods; D009314:National Institute for Occupational Safety and Health, U.S.; D016273:Occupational Exposure / Q000517:prevention & control; D010316:Particle Size; D012134:Respiratory Protective Devices / Q000592:standards* / Q000706:statistics & numerical data; D013227:Steam / Q000009:adverse effects / Q000032:analysis*; D013499:Surface Properties; D013696:Temperature; D013990:Tidal Volume; D013997:Time Factors; D014481:United States
D013227:Steam