Making a homemade coronavirus mask? Doubled T-shirt fabric offers 98% droplet blocking protection

This shows a woman in a home made maskAs more states are requiring people to wear face masks in public to prevent the spread of COVID-19, researchers investigate the best materials people can use to create their masks at home. A single layer of T-shirt fabric is 40% effective at higher droplet blocking. When layers are doubled, the fabric is 98% effective, exceeding the effectiveness of a clinical medical mask.