Stahl Connor, Frederick Kevin, Chaudhary Sachin, Morton Christopher J, Loy Douglas, Muralidharan Krishna, Sorooshian Armin, Parthasarathy Sairam
Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, United States.
Department of Materials Science and Engineering, University of Arizona, Tucson, AZ, United States.
Front Med (Lausanne). 2021 Jul 2;8:654317. doi: 10.3389/fmed.2021.654317. eCollection 2021.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic can spread through virus-containing aerosols ( ≤ 5 μm) and larger airborne droplets. Quantifying filtration efficiency of different kinds of masks and linings for aerosols that fall within the most penetrating particle size (80-400 nm) is critical to limiting viral transmission. The objective of our experiment was to compare the "real-world" filtering efficiency of different face masks for fine aerosols (350 nm) in laboratory simulations. We performed a simulated bench test that measured the filtering efficiency of N95 vs. N99 masks with elastomeric lining in relation to baseline ("background") aerosol generation. A mannequin head was placed within a chamber and was attached to an artificial lung simulator. Particles of known size (350 ± 6 nm aerodynamic diameter) were aerosolized into the chamber while simulating breathing at physiological settings of tidal volume, respiratory rate, and airflow. Particle counts were measured between the mannequin head and the lung simulator at the tracheal airway location. Baseline particle counts without a filter (background) were 2,935 ± 555 (SD) cm, while the N95 (1348 ± 92 cm) and N99 mask with elastomeric lining (279 ± 164 cm; <0.0001) exhibit lower counts due to filtration. The filtration efficiency of the N95 (54.1%) and N99 (90.5%) masks were lower than the filtration efficiency rating. N99 masks with elastomeric lining exhibit greater filtration efficiency than N95 masks without elastomeric lining and may be preferred to contain the spread of SARS-CoV-2 infection.
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）大流行可通过含病毒的气溶胶（≤5μm）和较大的飞沫传播。量化不同种类口罩和衬里对最具穿透性粒径（80 - 400nm）气溶胶的过滤效率对于限制病毒传播至关重要。我们实验的目的是在实验室模拟中比较不同口罩对细气溶胶（350nm）的“实际”过滤效率。我们进行了一项模拟台架试验，测量了带弹性衬里的N95与N99口罩相对于基线（“背景”）气溶胶产生的过滤效率。将一个人体模型头部放置在一个室内，并连接到一个人工肺模拟器上。在模拟潮气量、呼吸频率和气流的生理设置下呼吸时，将已知尺寸（空气动力学直径为350±6nm）的颗粒雾化到室内。在人体模型头部和肺模拟器之间的气管气道位置测量颗粒计数。无过滤器时的基线颗粒计数（背景）为2935±555（标准差）个/cm，而带弹性衬里的N95（1348±92个/cm）和N99口罩（279±164个/cm；P<0.0001）由于过滤作用颗粒计数较低。N95（54.1%）和N99（90.5%）口罩的过滤效率低于过滤效率评级。带弹性衬里的N99口罩比不带弹性衬里的N95口罩表现出更高的过滤效率，可能更有利于遏制SARS-CoV-2感染的传播。
