Household Materials for Homemade Masks: How Effective Are They?

Introduction: With the fear of uncertain behaviours and mechanisms of the coronavirus in the rapidly evolving COVID-19 pandemic, people are required to cover their mouth and nose to prevent the spread of the virus. This has become a challenge as most countries struggle with the dwindling stocks of face masks. However, the Centers for Disease Control and Prevention suggested the use of cloth masks as a substitute. In an effort to find suitable materials that serve this purpose and ensure sufficient protection afforded, the masks need to be tested. Methods: In this study, the penetration and breathing resistance of 13 easily obtained household materials potentially used by the public as face masks, were randomly selected and tested by using TSI Model 8130 Automated Filter Tester, while the thickness was measured by S-Cal EVO Proximity caliper. Results: The level of thickness ranged between 0.25 mm (satin) and 4.83 mm (diaper). Double-layer denim material showed the lowest percentage of penetration (Median, IQR: 27.50%, 27.05-28.80) while the greatest was single-layer lycra (Median, IQR: 90.60%, 80.80-92.10). Single-layer chiffon fabric showed the best breathing resistance (Median, IQR in mmH2O: 1.30, 0.90, 1.45) while the worst was diaper (Median, IQR in mmH2O: 87.20, 86.95, 87.25). Conclusion: Double-layer dried wet tissue, single-layer tissue paper and double-layer non-woven fabric can be considered to be used as face masks due to their efficiency based on penetration and breathing resistance factors. © 2021 UPM Press. All rights reserved.

A fluid mechanics explanation of the effectiveness of common materials for respiratory masks.

OBJECTIVES: Face masks are an important component of personal protection equipment employed in preventing the spread of diseases such as COVID-19. As the supply of mass-produced masks has decreased, the use of homemade masks has become more prevalent. It is important to quantify the effectiveness of different types of materials to provide useful information, which should be considered for homemade masks. METHODS: Filtration effects of different types of common materials were studied by measuring the aerosol droplet concentrations in the upstream and downstream regions. Flow-field characteristics of surrounding regions of tested materials were investigated using a laser-diagnostics technique, i.e., particle image velocimetry. The pressure difference across the tested materials was measured. RESULTS: Measured aerosol concentrations indicated a breakup of large-size particles into smaller particles. Tested materials had higher filtration efficiency for large particles. Single-layer materials were less efficient, but they had a low pressure-drop. Multilayer materials could produce greater filtering efficiency with an increased pressure drop, which is an indicator of comfort level and breathability. The obtained flow-fields indicated a flow disruption downstream of the tested materials as the velocity magnitude noticeably decreased. CONCLUSIONS: The obtained results provide an insight into flow-field characteristics and filtration efficiency of different types of household materials commonly used for homemade masks. This study allows comparison with mass-produced masks under consistent test conditions while employing several well-established techniques.