Making sure a mask fits snugly on the face and use of two masks is likely to significantly reduce a person's exposure to the coronavirus, laboratory experiments described by US health officials showed.
The US Centers of Disease Control and Prevention (CDC) in January conducted experiments to see how well wearing a cloth mask over a three-ply medical procedure mask, and knotting the ear loops of a surgical mask and then tucking the excess material close to the face, protects against Covid-19.
They found that both these methods helped reduce the exposure to potentially infected aerosols by more than 90% in laboratory simulations.