Wearing an N95 respirator concurrently with a powered air-purifying respirator: effect on protection factor

Respir Care. 2008 Dec;53(12):1685-90.

Abstract

Objective: To determine if using an N95 filtering face-piece respirator concurrently with a loose-fitting powered air-purifying respirator (PAPR) offers additional protection to the wearer.

Methods: We used a breathing mannequin programmed to deliver minute volumes of 25 L/min and 40 L/min. We measured the baseline protection factor of the PAPR with its motor operational and then deactivated (to simulate mechanical or battery failure). We tested 3 replicates of 3 different N95 models. We glued each N95 to the breathing mannequin and obtained a minimum protection factor of 100 at 25 L/min. We then placed the PAPR on the mannequin and took protection factor measurements with the N95-plus-PAPR combination, at 25 L/min and 40 L/min, with the PAPR operational and then deactivated.

Results: The N95 significantly increased the PAPR's protection factor, even with the PAPR deactivated. The effect was multiplicative, not merely additive.

Conclusions: An N95 decreases the concentration of airborne particles inspired by the wearer of a PAPR.

MeSH terms

  • Adult
  • Air Microbiology*
  • Disease Transmission, Infectious / prevention & control*
  • Equipment Design
  • Equipment Failure Analysis
  • Humans
  • Inhalation Exposure / prevention & control*
  • Manikins
  • Models, Biological
  • Respiratory Protective Devices*