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Personal Protective Equipment: Efficacy in Containing and Shielding Particulate Matter with a Diameter between 1 and 5 µm
ALBERTO BALDELLI, Kevin Heieis, Steven Rogak, Andrew Poznikoff, Robert Purdy, The University of British Columbia
Abstract Number: 231
Working Group: Infectious Aerosols in the Age of COVID-19
Abstract
Airborne viruses, such as SARS-CoV-2, can spread by droplets and aerosols. Besides social distancing, using personal protective equipment (PPE) is assumed to reduce the probability of both transmitting and contracting airborne viruses.
To test the shielding efficiency of different types of PPE, a 0.9% saline solution was nebulized into the upper respiratory tract of a manikin. Five face masks and three shields were tested. An optical particle sizer was used to measure particulate matter (PM) with a diameter between 1 and 5 µm at the mouth of the receiving manikin with simulated breathing. The eight types of PPE were: medical mask, medical mask with eye shield, N95, KN95, cloth mask, cloth mask with valve, disposable face shield, 3D printed pivot face shield, and a shop shield. Samples were collected over 5 minutes at three separate distances (2, 4, 6 ft) and were repeated at three angles (0, 45, 90 degrees). A room baseline and baseline with aerosols being freely generated was measured.
We validated that the distance between the aerosol source and receiving manikin was important. When compared to the aerosol baseline, a cloth mask was found to reduce average PM by 20% over the three distances. The worst shielding efficacy is seen with the disposable face shield, which increased the PM concentration by 33% and 7%, at 2 and 4 feet respectively. In contrast, the best performing PPE with our model was a medical mask, which reduced average PM by 63%. When a disposable medical mask was placed on both the receiving and aerosol manikins, the concentration of PM was reduced to the room baseline at all distances, with the lowest value of 7 µg/m3 at 6 feet. The effectiveness of any given PPE was highly influenced by their fit on the face of our model in these results.