Modeling and prediction of loading characteristics of electret filter media for PM2.5

Filtration efficiency of N95 filtering facepiece respirators during multi-cycles of ‘8-hour simulated donning + disinfection’

“…As can be observed, under all three simulated breathing flow rates, the aerosol penetration of all three tested N95 respirators increases linearly with the passage of testing time. This finding, which is consistent with several previous studies [ [56] , [57] , [58] , [59] , [60] ], can be explained by the following reasons: First, during the simulated donning process, aerosols in the inhaled airflow will continuously deposit on the electret fibre. Second, the 37°C and 100% RH exhaled airflow will also cause continuous condensation of water vapor on the electret fibre.…”

“…This phenomenon can be explained as follows: during the respirator donning process, the deposition of inhaled aerosols on the filter and the wetting of filter by exhaled hot and humid air occur simultaneously. The former will weaken the electrostatic attraction of the filter on the one hand and promote the mechanical filtration efficiency (including diffusion, interception, and inertial collision) on the other hand [ 56 , 57 ], while the latter will continuously neutralize the charge on the electret filters [ [58] , [59] , [60] ]. It is well known that electrostatic attraction and diffusion dominate the filtration of nanoscale aerosols by electret filters [ 63 ].…”