The Department of Mechanical Engineering, Faculty of Engineering, University of Alberta, Edmonton, Canada.
The Department of Mechanical Engineering, Faculty of Engineering, University of Alberta, Edmonton, Canada; Lovelace Biomedical, Albuquerque, NM, USA.
Am J Infect Control. 2023 Aug;51(8):912-918. doi: 10.1016/j.ajic.2023.01.010. Epub 2023 Feb 1.
Differences in physiology and breathing patterns between children and adults lead to disparate responses to aerosols of varying sizes. No standardized method exists for measuring the filtration efficiency (FE) of children's masks to reflect such differences.
Using an adult N95 mask as a control and two different face velocities (v) (9.3 cm/s representing adults and 4.0 cm/s representing school-aged children), we tested the pressure drop (ΔP) through children's nonwoven masks (surgical and KN95) and children's woven masks (100% cotton and partially-cotton-based masks), as well as their size-specific FE between aerodynamic particle diameters of 0.02 and 2.01 μm.
All three types of mask showed a 1 to 9% absolute increase in minimum FE at the lower v and a significant decrease in ΔP. For children's surgical masks the increase in FE was significant for most of the examined particle sizes, but for children's woven masks the increase was limited to particles smaller than 0.04 μm.
Lower v for children is likely to lead to a higher FE, lower ΔP, and consequently higher filter qualities in children's masks. For woven masks, the FE for particles larger than 0.04 μm was low (typically <50%) for both v's studied.
儿童和成人在生理和呼吸模式上存在差异，导致对不同大小气溶胶的反应不同。目前还没有标准化的方法来测量儿童口罩的过滤效率（FE），以反映这种差异。
我们使用成人 N95 口罩作为对照，使用两种不同的面部速度（v）（代表成人的 9.3cm/s 和代表学龄儿童的 4.0cm/s），测试了儿童非织造口罩（手术口罩和 KN95）和儿童机织口罩（100%棉和部分基于棉的口罩）的压降（ΔP），以及它们在 0.02 和 2.01μm 的空气动力学粒径之间的特定于尺寸的 FE。
所有三种类型的口罩在较低的 v 下，最小 FE 绝对增加了 1%至 9%，而 ΔP 显著下降。对于儿童手术口罩，FE 在大多数检查的粒径上都有显著增加，但对于儿童机织口罩，增加仅限于小于 0.04μm 的颗粒。
对于儿童来说，较低的 v 可能会导致更高的 FE、更低的 ΔP，从而提高儿童口罩的过滤质量。对于机织口罩，对于两种研究的 v，大于 0.04μm 的颗粒的 FE 都较低（通常 <50%）。
