Experts say it’s important for people to understand that a simple face covering offers enough protection for someone who is practicing social distancing and has only limited exposure to others during brief time outside for exercise or groceries.

The highest-quality, most expensive medical masks — called N95 respirator masks — should be reserved for hospital workers and emergency responders who are regularly exposed to high viral loads from infected patients, both from frequent contact as well as medical procedures that can spew tiny viral particles into air.

“The potential for exposure is so much lower in a grocery store compared to working in a hospital close to patients,” said Linsey Marr, a Virginia Tech scientist and an expert in the transmission of viruses in the air.

If you’re not a health care worker and you have a stash of N95 masks or standard surgical masks, consider donating it to a hospital.

If you’re staying home and nobody in your family is infected, you don’t need a mask most of the time. Studies of mask use to prevent the spread of respiratory illnesses, including SARS, another form of coronavirus, show a simple mask can lower risk of infection. The effect is greatest when masks are used along with hand hygiene and social distancing.

“I think the vast amount of data would suggest that the coronavirus is an airborne infection carried by respiratory droplets, and it also can be passed on by direct contact,” said Dr. Mukherjee, who recently wrote an article about how the coronavirus behaves inside patients. “The mask works two ways — not only to protect you from me, but me from you.”

If you decide to start wearing a mask, you should know that it takes some getting used to. A mask can be hot and uncomfortable and fog your glasses if you wear them. But pulling it up and down defeats the purpose of wearing it.