Early on in the pandemic, there was some controversy over the use of homemade and reusable face masks, with the public expressing concerns over whether these common materials could suitably slow the spread of airborne droplets. A number of studies have validated the use of these masks, though they’ve focused on smaller droplets, not the larger ones expelled forcibly when sneezing.
Aerosolized particles are tiny droplets that measure less than 5 micrometers, but there are also larger droplets that can be expelled, particularly when someone coughs or sneezes. Measuring up to around 1mm in diameter, these larger droplets can essentially ‘squeeze’ through the tiny gaps in fabrics if they have enough force behind them — sneezes and severe coughing, in this case.
These larger droplets then break up when they escape the mask barrier, becoming smaller particles that can travel through the air, potentially infecting those who are nearby. The entire purpose of the mask is to block many of these particles and to reduce the distance the ones that make it through can travel. Paper medical masks are the best solution for this, but reusable fabric masks are also surprisingly capable.
This latest study from the University of Illinois at Urbana-Champaign studied fabric face masks made out of a variety of common materials, including used clothing, new clothes, bedsheets, dishcloth, and quilted materials.
These fabrics offer more comfort and better breathability compared to medical masks — and, it turns out, they’re ‘considerably effective’ at blocking high-velocity droplets measuring up to 100 nanometers. A single layer is effective, but the researchers note that two or more layers will bring the droplet-blocking capabilities up to near the level of medical masks.