It's primarily to protect other people from the person wearing the mask because we know that people can spread the coronavirus even if they aren't showing symptoms yet or never show symptoms. There's research showing even a loose-fitting surgical mask can block almost all the infectious droplets a person might emit when they're talking.

What about exercising with a mask? Is there a risk that you won't be able to catch your breath?

If you're doing something like running or biking outdoors and you're alone or just with the people you live with, it's OK to have your mask down if there's no one else around, says Abraar Karan, a physician at Harvard Medical School

As long as you haven't been touching stuff along the way, like benches or rails, you haven't had a close conversation with a stranger, it's OK to use your hands to pull it down. If you see someone coming, put up your mask until they pass. And if you're running and passing someone, give them at least 1.5 meters of space.

A lot of people find masks really uncomfortable to wear — they're hot, they make some people feel really anxious. Is it OK to take breaks from wearing a mask?

Experts say it's OK to take periodic breaks from wearing a mask. Make sure you do it when no one is around. Don't touch the front of the mask when you take it off, so you don't touch any infectious droplets it might have blocked. Instead, take it off by the ear loops.If you are in a crowded place, don't rush to take off the mask, go to an empty place first and then take off the mask.

The more people in high-risk areas, the more they must be vigilant at all times. No one can be 100% perfect, but all of us need to do our best.The important thing is that the more people are wearing a mask, the more everyone is protected. Your mask protects me, and mine protects you.