I like to run. And bike. And go for walks.

Especially during the pandemic. It's a time I can almost forget about the novel coronavirus.

But some people are trying to make me feel guilty about outdoor exercise.

My own nephew said, "Uncle Marc, if you're infected and don't know it, you could be huffing and puffing out virus."

Does he have a point? I talked to half-a-dozen experts to see about the risks of outdoor exercise for the exerciser and for others — and whether masks are helpful.

And let me clarify: I mean solo exercise. Going out shoulder-to-shoulder with a bunch of pals is not a good idea during a pandemic.

First of all, my sources told me, studies all show that the biggest risk of catching coronavirus is indoors, with face-to-face contact with others for a few minutes or more. Being outdoors for a solo activity is much lower risk. It appears that viral particles may not survive as long in the outdoor air as they do inside, although it's not certain whether wind, sun or other environmental factors are responsible.

Here are some tips to keep your risk – and the risk to others — as minimal as possible.

First, there's the matter of the mask.

The experts I spoke to all said wearing a mask is a good thing. Now you probably don't think you have coronavirus if you feel good enough to exercise. But some people are asymptomatic – they never show symptoms – or presymptomatic – sick but not yet feeling it. A mask will protect others by blocking respiratory droplets you breathe out that can carry viral particles. A mask with a tight weave (i.e. you can't see the sunlight through the fabric) and multiple layers may give you a measure of protection as well by preventing you from inhaling viral particles expelled by someone who's infectious.

The exception for mask-wearing might be if you're 100% certain you won't come within 12 feet of any human, my sources did note.

As for mask material, I'm told there's no definitive study on cotton vs. synthetic materials.

I've tried ... a bandana (too much tying and retying and in retrospect the fabric was too thin), a folded up cloth towel with scrunchies (they pinched my ears as did the ear loops on store bought cloth masks) and an undershirt I converted into a mask (it slipped off my nose a lot and looked kind raggedy.)

My current mask of choice is a neck gaiter made of synthetic fiber with an inside flap that sits over the mouth and nose and can be used to hold a filter, offering additional layers of protection. It's also called a buff and is basically a long tube of fabric that slips over the head. And it's got a nice elastic rim that clings to my face just above my nostrils and hardly ever slips.

Second, there's timing and location.

Pick a time and place where you won't likely be in close contact with people. So aim to get out when there aren't a lot of folks around. And look for routes that aren't hyper-crowded.

If you do come near someone and want to pass, make sure you allow for six feet of distance as you run, bike or walk by them. Think of it the way you'd pass a car – start moving away early on, execute the pass, then gradually return to the path.

And you don't want to be directly behind one person for an extended period of time. If that individual is infected, they could be exhaling or coughing or spitting out infectious droplets.

Third, keep your hands to yourself. Don't touch "high-touch" areas where a lot of people might have put a hand down, like a bench or a stair railing, says Jill Weatherhead, assistant professor of adult and pediatric infectious diseases at Baylor College of Medicine. It's possible that someone who's infected might have touched it and left behind droplets that can survive a little while on surfaces.

Now let's talk about what happens with your mask when you're exercising.

I can tell you from firsthand experience: It's hard to exercise with a mask on.

One of my sources said trying to breathe while exercising with a mask is a bit like trying to work out at high altitude. "You do have a barrier to getting in air," says Dr. Michael Fredericson of Stanford University's Department of Orthodopaedic Surgery, whose specialties include sports medicine. "As you start to perspire and mask gets wet, it's makes it even more difficult — almost like you're exercising in a sauna."

So ... stop.

And look around.

If there's no one near you and no one you can see up ahead, pull the mask down. Continue on until you see someone. And then pull it back up.

Now I want to stress that it's important not to touch your mask in, say, a grocery store, where your fingers might have come into contact with virus in droplets left on objects by other shoppers.

But if you've not been touching anything or having a close chat with anyone during your outdoor exercise, it's okay to pull the mask down, says Dr. Abraar Karan, who's an internal medicine physician at Harvard Medical School. (He told me he had his mask pulled down when he was walking home and being interviewed on the phone by me 'cause no one was around).

But they experts suggest pulling the mask down without touching the front of it, just so you don't get in the habit of fiddling with the front of your mask over your nose and mouth (which is how you'd get infected). And of course, whatever you do, don't stick your finger up your nose or into your eye or mouth – that's how viral particles enter the body.

When you finish your activity, if it's hot and humid, the mask is going to be wet. With sweat. And with nasal excretions.

So when you get home, wash it out thoroughly with soap and water. And wash your hands, too. Because ... it can't hurt!

And if you're not into running, biking or hiking, there are other outdoor activities you can consider. Not shooting hoops with some pals. Too much prolonged close contact. But Dr. Paul Sax, clinical director of the Infectious Disease Clinic at Brigham and Women's Hospital, told me he's very much looking forward to a socially distant game of tennis — but no high-fiving!

Thanks to my additional sources for this story: Bryanne Bellovary, a Ph.D. candidate at the University of New Mexico who ran a study on exercising with and without masks; Linsey Marr, professor of civil and environmental engineering at the Global Change Center at Virginia Tech; Lauren Sauer, assistant professor of emergency medicine at Johns Hopkins Medical;

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