Should You Wear a Mask When Exercising Outdoors?

Kinnier Lastimosa, a claims examiner in Chicago and his wife, Jennifer Cheng, who works as a project manager in the corporate real estate department of a major U.S. airline, are both marathoners and have felt social pressure to wear masks when they go outdoors to run. The couple tried wearing medical masks but they were tough to breathe in and fogged up their sunglasses. Over the years, they have collected dozens of gaiters from races and have found folding them in thirds creates a barrier that feels safe but breathable. In addition to their homespun masks, they have been vigilant about social distancing on city streets, keeping up to 15 feet from others and detouring from routes that look crowded. Many exercisers are experimenting with different types of masks and fabrics and are taking extra precautions to protect themselves and others when they head outdoors. We asked experts to weigh in on best practices.

Should I wear a mask during outdoor exercise?

The Centers for Disease Control and Prevention recommends that everyone now wear a mask of some kind when they leave home, and some cities and towns require a facial covering if you are outside. However, there is no compelling medical reason for people who are exercising outside and maintaining social distancing to wear a mask, says Henry Chambers, a professor in the Division of Infectious Diseases at the University of California, San Francisco.

You’re wearing a mask to protect others so that if you are infected and discharging a virus through your mouth and nose—which is believed to be the most common mode of transmission—then the mask serves as a barrier between others and the infected droplets, he says. If you didn’t have the mask on, and are breathing really hard, could someone else breathe in those droplets? “That’s where the distancing comes in,” Dr. Chambers says.

Paul Auerbach, an emergency medicine doctor at Stanford University School of Medicine, suggests having a mask hang around your neck while walking, running or cycling so that you can pull it over your mouth and nose when you see other people. “It’s an act of solidarity and courtesy, letting everyone know you are trying to be respectful, smart and safe,” he says. If you are in the water surfing, kayaking or paddling, he says you probably don’t need a mask, because it will most likely get wet and be difficult to use.

How likely are you to transmit or be infected by the virus outdoors?

“There is a lot of air space and air flow outside,” Dr. Chambers says. “Data suggests that people who are infectious and generating infectious droplets are of greatest contagion within 6 feet of you.” If you are outdoors and closely packed together at the start of a foot race, for example, there is a risk, he says. “If you are outdoors and appropriately distanced from other people, then it is highly unlikely you will be exposed,” he says. Research simulating the aerodynamics of contagious droplets that walkers and runners leave in their slipstream has been criticized for not taking into account how air can dilute the droplets, he says. Whether running or walking, you are breathing in a large volume of air that is distributed over a broad area. Every breath is over 10 feet of air space. “It’s highly unlikely you’ll come in contact with someone’s airflow unless you’re directly behind them,” he says.

This article was originally featured in the Wall Street Journal, read more here.