While we don’t have a lot of research on the effectiveness of homemade masks in preventing the spread of infection, scientists who study airborne diseases can offer some guidance. A mask sewn from a pattern or an improvised face covering made with a T-shirt probably offers some protection. The thicker the fabric, the better: think heavy cotton T-shirt or a thick, felt-like fabric, said Dr. Marr, the Virginia Tech aerosol scientist.
While some people have suggested using a bandanna, the fabric is typically so thin and flimsy that it would likely offer little protection. Double or triple the bandanna fabric if that’s all you have.
“I’ve been saying some protection is better than none,” said Dr. Marr, who noted that local health departments had been asking aerosol scientists for guidance on potential mask materials to deal with supply shortages. She said her team would have results soon with more specific recommendations for materials to use in masks.
Dr. Soe-Lin said she believed an added benefit of a mask was that it serves as a constant reminder against touching your face, a major way that the virus is spread. But no face covering, whether it’s homemade or a medical mask, makes you invincible. Pulling a mask on and off or fidgeting with it will lessen its effectiveness. And in theory, fiddling with your mask could contaminate it. Always remove a mask by the ear loops or the tie — never the part that covers your face.
Dr. Soe-Lin said she had used cloth masks for three weeks and washed and dried them regularly. Someone with only one mask can hand wash at night and let it air dry. If a mask gets wet or damp while you are wearing it, it’s less effective, she said.
Other experts said worries that fabric masks won’t offer enough protection were misguided.
“I don’t think there is any evidence that this is going to make things worse, but there is evidence that it provides some additional good,” said Robert Hecht, professor at the Yale School of Public Health, who was the co-author of the face mask article with Dr. Soe-Lin. “Under this emergency situation we’re in, it seems, in our view, hard to argue against covering your face. We have large numbers of infections occurring which don’t need to happen if people were to use the masks.”
Article source: https://www.nytimes.com/article/coronavirus-N95-mask-DIY-face-mask-health.html