Protecting yourself from germs starts with making sure you don’t accidentally get any on the inside of your mask. “Face masks are worn in close vicinity to the face, so any contaminants on a face mask are likely to be inhaled by the wearer,” says Sangwei Lu, professor of infectious diseases and vaccinology at the University of California, Berkeley. “It is important to keep face masks clean so people who wear them do not accidentally infect themselves with the germs on the face masks.”
Contaminants can even diminish the germ-blocking ability of certain mask materials, undermining the reason you’re wearing a mask in the first place. Masks that use electrostatic charges to filter particles, like N95s and polypropylene surgical masks, become less effective when too many particles accumulate and interfere with the charges, Lu says. Simply having somewhere safe and clean to store your mask when you’re not wearing it will prolong its effectiveness.