A thick woolen yarn scarf filtered 21 percent of particles in two layers, and 48.8 percent in four layers. A 100 percent cotton bandanna did the worst, capturing only 18.2 percent when doubled, and just 19.5 percent in four layers.

What type of mask is recommended to prevent the spread of COVID-19?

CDC recommends community use of masks, specifically non-valved, multi-layer cloth masks, to prevent transmission of SARS-CoV-2.

How do cloth face coverings and face shields protect against COVID-19?

Cloth face coverings and face shields are types of source control that provide a barrier between droplets produced from a potentially infected person and other people, reducing the likelihood of transmitting the virus.