An apparatus for nondestructive and rapid comparison of mask approaches in defense against infected respiratory aerosols

TL;DR

This paper introduces a nondestructive, rapid testing apparatus for evaluating mask breathability, filtration efficiency, and fit sensitivity, aiding quick assessment of various mask designs especially during supply shortages.

Contribution

It presents a simple, reproducible testing method using off-the-shelf sensors to compare mask properties, facilitating local quality control and evaluation of improvised or uncertified masks.

Findings

Effective measurement of pressure drop and particle transmission

Rapid comparison of mask filtration and fit characteristics

Apparatus suitable for use in diverse settings

Abstract

At the front lines of the world's response to the COVID-19 pandemic are hero-clinicians facing a lack of critical supplies including protective medical grade breathing masks and filtering materials. At the same time, the general public is now being advised to wear masks to help stop the spread. As a result, in the absence of centrally coordinated production and distribution efforts, supply chains for masks, respirators, and materials for advanced filtration technology are immensely burdened. Here we describe experimental efforts to nondestructively quantify three vital characteristics of mask approaches: breathability, material filtration effectiveness, and sensitivity to fit. We focus on protection against water aerosols $>$0.3$\mu$m using off-the-shelf particulate, flow, and pressure sensors, permitting rapid comparative evaluation of these three properties. We present and discuss both the pressure drop and the particle transmission as a function of flow to permit comparison of relative protection for a set of proposed filter and mask designs. The design considerations of the testing apparatus can be reproduced by university laboratories and medical facilities and used for rapid local quality control of respirator masks which are of uncertified origin, monitoring the long-term effects of various disinfection schemes, and evaluating improvised products not designed or marketed for filtration.