Review of the Breathability and Filtration Efficiency of Common Household Materials for Face Masks

Abstract

The World Health Organization and the United States Centers for Disease Control have recommended universal face masking by the general public to slow the spread of COVID-19. A number of recent studies have evaluated the filtration efficiency and pressure differential (an indicator of breathability) of various, widely available materials that the general public can use to make face masks at home. In this review, we summarize those studies to provide guidance for both the public to select the best materials for face masks and for future researchers to rigorously evaluate and report on mask material testing. Of the tested fabric materials and material combinations with adequate breathability, most single and multilayer combinations had a filtration efficiency of <30%. Most studies evaluating commonly available mask materials did not follow standard methods that would facilitate comparison across studies, and materials were often described with too few details to allow consumers to purchase equivalent materials to make their own masks. To improve the usability of future study results, researchers should use standard methods and report material characteristics in detail.

Keywords: COVID-19; SARS-CoV-2; breathability; cloth mask; face mask; filtration efficiency; homemade mask; pressure differential.

Figure 1:

Light visibility through a more dense fabric (A; 200 threads per inch (tpi) cotton pillow case) and less-dense fabric (B; 60 tpi open-weave cotton)

Figure 2:

Pores in 2 layers of 75 tpi polyester chiffon that are (A) aligned and (B) misaligned. These two microscopy photos were backlit using crossed-polarized illumination; this results in the holes being black and the fibers being brightly lit and helps eliminate the ambiguity between a bright hole versus a bright fiber.

Figure 3.

Filtration efficiency versus pressure differential for (A) single and (B) multiple layers of various materials for studies with most material pressure differentials <150 Pa. Single data points from Aydin 2020 and Rengasamy 2010 omitted from (B) for clarity.

Figure 3.

Filtration efficiency versus pressure differential for (A) single and (B) multiple layers of various materials for studies with most material pressure differentials <150 Pa. Single data points from Aydin 2020 and Rengasamy 2010 omitted from (B) for clarity.

Figure 4.

Face velocity versus filtration efficiency for a single layer of various materials.

Figure 5.

Filtration efficiency for a (A) single and (B) multiple layer of various materials. Combinations of fabric with only one data point were omitted for clarity. The black dot indicates the mean filtration efficiency for each material type.

Figure 5.

Filtration efficiency for a (A) single and (B) multiple layer of various materials. Combinations of fabric with only one data point were omitted for clarity. The black dot indicates the mean filtration efficiency for each material type.