Reaerosolization of MS2 Bacteriophage from an N95 Filtering Facepiece Respirator by Simulated Coughing

Abstract

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.

Comparison of Five Bacteriophages as Models for Viral Aerosol Studies

“…This phage demonstrated a good resistance to aerosolization and sampling, which is in line with the results obtained by others (14,23). Not surprisingly, phage MS2 has been used as a surrogate for pathogenic viruses in several sterilization, air filtration, and aerosolization studies (14,17,22,23,(36)(37)(38)(39)(40)(41)(42)(43)(44)(45). Its facility to be detected by culture is certainly one of the reasons for its widespread use.…”

The COVID‐19 pandemic, personal protective equipment and respirator: A narrative review

“…However, porous surfaces have a lower transfer rates due to entrapment of organisms within their matrix and the greater surface area in the recesses for attachment, hence, less accessible to human hands 83,84 . More than 99% pf pathogens remained trapped in the respirator after handling or following simulated cough or sneeze 85‐87 . Respirators may be contaminated with other pathogens that have prolonged environmental survival (eg, methicillin‐resistant Staphylococcus aureus) resulting in the risk of self‐inoculation 88 .…”

Considerations for Recommending Extended Use and Limited Reuse of Filtering Facepiece Respirators in Health Care Settings

“…examined virus reaerosolization from FFRs and concluded that the risk of virus transfer to the environment from the FFR was negligible, a finding key to extended use and reuse. ( 87 ) FFRs were challenged with virus-containing droplet nuclei with a size range of 0.65 to 7.0 μm (with the majority <1.1 μm) and challenged with reversed airflow to simulate a sneeze or cough. The highest reaerosolization of 0.21% occurred with a droplet nuclei challenge while a droplet challenge led to reaerosolization of less than 0.0001%.…”