This post aims to provide a basic understanding of fabric mask filtration through a broad overview of particle physics, disease transmission, and biology of particles. Introduction: How well do fabric masks filter? The question of how well any specific mask fabric combination blocks SARS-CoV-2, the virus responsible for COVID-19, turns out to be rather complex. […]
In the spring of 2021 the CDC published advice on double-masking which was based on the results of a study published in February of this year. Although some people that have been fully vaccinated are wearing masks less frequently (per the CDC guidance published in May), there are many instances where mask use is still […]
A huge thank you to everyone that has contributed to our fabric mask material testing campaign! The results from the testing campaign are finally in. We tested two different 3-layer fabric combinations to establish baseline performance for fluid resistance, breathability, bacterial filtration efficiency (~3um particles), and submicron particle efficiency (~0.3um). These tests focused on two […]
Since February of 2020, we’ve been asking for standards for masks/face coverings used by our communities. Finally, the American Society for Testing and Materials (ASTM) has established a national standard for “Barrier Face Coverings” (ASTM F3502) that are neither medical masks according to ASTM F2100 standards nor respirators according to NIOSH standards. This new standard […]
On December 1, 2020, the World Health Organization (WHO) updated their guidance on fabric masks, “Mask Use in the Context of COVID-19 (December, 2020)”, including their “Updated Guidance on Non-Medical (Fabric) Masks” (p. 19-22). This post pulls out key quotes from the new WHO guidance, touching on their recommendations for layering, mask performance standards, and […]
This paper describes key differences between the WHO and the CDC fabric mask guidelines, including the rationale for the inclusion of hydrophobic polypropylene materials in the WHO guidance, and was initially shared on the SSRN Preprint Server on June 26, 2020. [Update: December 2020)] The WHO updated their guidance on Fabric Masks December 1, 2020. […]
This post is the first in a series of “Research Highlights” where we discuss select data and research from the literature in the context of community mask making efforts. In this post, we take a look at the filtration and breathability data for nonwoven polypropylene (NWPP) mask materials presented in: Long KD, Woodburn EV, Berg […]
How Do I Choose Fabrics for Masks for COVID-19? Since March, it seems like there has been a constant barrage of conflicting information about which fabrics are the best for masks for COVID-19. We’ve put together this crash course on mask fabrics to provide some of the fundamental concepts in fabrics and how they are relevant for our collective mask making efforts.