The coronavirus that causes COVID-19 is believed to pass from person to person primarily via respiratory droplets and contaminated surfaces, so properly used face masks can act as a barrier to help prevent its spread.

One major problem: Masks, along with other protective gear, are in short supply . That includes cloth and thin surgical masks as well as N95 respirators, which are used by construction workers and in hospital wards because they block at least 95% of airborne particles . Recognizing this, the U.S. Centers for Disease Control and Prevention recently issued guidance allowing health care workers to reuse N95 masks under certain conditions.

But what if youre not a health care worker and you have a limited supply of masks at home?

Before you worry about reusing a mask , consider which ones you should use. If you have an N95 mask and youre a healthy person not taking care of an infected individual, you could donate that unused mask to health care providers in dire need of them.

If you are outside running errands, use a cloth mask. When social distancing outside is not possible, the CDC recommends the use of cloth masks in public settings.

Reusing surgical masks is not ideal. The goal is not to reuse masks. Its really a stopgap measure for the mask shortage that were having, but its not the best practice, said Lucy Wilson, chair of the department of emergency health services at the University of Maryland Baltimore County. The best practice would be single-use.

The reality, though, is that supply is dwindling. You can reuse and rewash different mask materials under some conditions.