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Reaerosolization of MS2 bacteriophage from an N95 filtering facepiece respirator by simulated coughing.
Fisher EM; Richardson AW; Harpest SD; Hofacre KC; Shaffer RE
Ann Occup Hyg 2012 Apr; 56(3):315-325
The supply of N95 filtering facepiece respirators (FFRs) may not be adequate to match demand during a pandemic outbreak. One possible strategy to maintain supplies in healthcare settings is to extend FFR use for multiple patient encounters; however, contaminated FFRs may serve as a source for the airborne transmission of virus particles. In this study, reaerosolization of virus particles from contaminated FFRs was examined using bacteriophage MS2 as a surrogate for airborne pathogenic viruses. MS2 was applied to FFRs as droplets or droplet nuclei. A simulated cough (370 l min(-1) peak flow) provided reverse airflow through the contaminated FFR. The number and size of the reaerosolized particles were measured using gelatin filters and an Andersen Cascade Impactor (ACI). Two droplet nuclei challenges produced higher percentages of reaerosolized particles (0.21 and 0.08%) than a droplet challenge (<0.0001%). Overall, the ACI-determined size distribution of the reaerosolized particles was larger than the characterized loading virus aerosol. This study demonstrates that only a small percentage of viable MS2 viruses was reaerosolized from FFRs by reverse airflow under the conditions evaluated, suggesting that the risks of exposure due to reaerosolization associated with extended use can be considered negligible for most respiratory viruses. However, risk assessments should be updated as new viruses emerge and better workplace exposure data becomes available.
Respirators; Infection control; Infectious diseases; Respiratory equipment; Respiratory protection; Respiratory protective equipment; Pulmonary system; Viral diseases; Viral infections; Particulates; Aerosol particles; Airborne particles; Author Keywords: infection control; influenza transmission; respiratory protection
Edward M. Fisher, National Institute for Occupational Safety and Health, National Personal Protective Technology Laboratory, Pittsburgh, PA 15236
Issue of Publication
Healthcare and Social Assistance
Annals of Occupational Hygiene
Page last reviewed: December 17, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division