The impact of extreme reuse and extended wear conditions on protection provided by a surgical-style N95 filtering facepiece respirator

Abstract

Most respirators employed in health care settings, and often in first responder and industrial settings, are intended for single-use: the user dons the respirator, performs a work activity, and then doffs and discards the respirator. However, in the current COVID-19 pandemic, in the presence of persistent shortages of personal protective equipment, extended use and reuse of filtering facepiece respirators are routinely contemplated by many health care organizations. Further, there is considerable current effort to understand the effect of sterilization on the possibility of reuse, and some investigations of performance have been conducted. While the ability of such a respirator to continue to provide effective protection after repeated sanitization cycles is a critical component of implementing its reuse, of equal importance is an understanding of the impact that reusing the respirator multiple times in a day while performing work tasks, and even extending its wear over multiple days, has on the workplace protective performance. In this study, we subjected a stockpiled quantitatively fitted surgical style N95 filtering facepiece respirator device to extreme reuse and extended wear conditions (up to 19 uses over a duration of 5 days) and measured its protective performance at regular intervals, including simulated workplace protection factor measurements using total inward leakage. With this respirator, it was shown to be possible to maintain protection corresponding to an assigned protection factor greater than 10 under extreme usage conditions provided an individual is properly trained in the use of, and expertly fitted in, the respirator. Other factors such as hygiene and strap breakage are likely to place limits on reuse.

Keywords:

• Condensation particle counter
• pandemic
• quantitative respirator fit testing
• simulated workplace protection factor

Acknowledgments

We would like to thank the Royal Canadian Mounted Police for their kind support in donating N95 respirators and lending some of their equipment for the study, the test subjects from DRDC Suffield Research Centre for their time and support of the study, and Canadian Forces Base Suffield G4 Stores, for the tent structure used for the SWPF test chamber. This study was funded by Defence Research and Development Canada.