Study shows double-masking -- medical mask under cloth -- cuts COVID-19 spread

A procedure mask worn under a cotton bandana filtered out 77% of droplets released, while the procedure mask in combination with a cotton mask reduced droplet spread by 66%, the researchers said.

When used alone, the three non-medical-grade masks -- the polyester gaiter, the bandana and the cotton mask -- had fitted filtration efficiencies of just over 40%, meaning they provided the least protection, according to the researchers.

Disposable medical procedure masks worn alone reduced the flow of virus droplets by up to 60%, the data showed.

In addition, when the medical procedure masks were worn over cotton or polyester coverings, fitted filtration efficiencies ranged from 55% to 60%, they said.

This suggests that double masking with a cotton or polyester covering over a medical procedure masks offers the best protection against the release of respiratory droplets, the researchers said.

"The best form of double masking is when you and the person you are interacting with both have a mask," Sickbert-Bennett said.