To protect yourself and others from the spread of the novel coronavirus (COVID-19), the Centers for Disease Control and Prevention recommends everyone who goes out in public to do essential things like purchase groceries should wear a cloth face cover over their noses and mouths. This extra step should be combined with social distancing to help prevent the spread of the disease. However, when it comes to walking outside during the pandemic, here’s what you need to know about whether or not to wear a face mask.

“We now know that there is significant asymptomatic transmission of COVID-19, which means that even someone who appears to be healthy may be infected,” says Dr. William Schaffner, medical director of the National Foundation for Infectious Diseases and professor of preventive medicine and infectious diseases at Vanderbilt University’s School of Medicine in Nashville. “The only way to interrupt transmission is to have everyone wear some sort of face covering.”

If you do wear a face covering while you’re walking for exercise, any cloth mask that has thicker fabric should be fine. “You do not need the type of mask that is normally worn by healthcare professionals,” says Schaffner. “A scarf or homemade mask will do, so long as it covers your nose and mouth.”

You may wonder if you should line a face covering that you’ll wear on walks with moisture-wicking fabric to keep the mask drier. This may not be necessary. The CDC’s recommendations for making face coverings include instructions for using cotton fabric or T-shirt material and don’t mention moisture-wicking materials. “If people want to try it, go for it,” says Schaffner. “The important thing is to wear some sort of facial protection.”

Whenever you wear a face covering for any length of time, some moisture will accumulate on the inside of the mask, caused by your exhalations, which is normal. Moisture may also accumulate from sweating, if you walk at a rapid clip, or from nasal secretions, if your nose is runny. This is to be expected, and “most people, even in the healthcare environment, let their mask hang and dry out after using them,” says Schaffner. “You might also want to have more than one mask on hand so you can alternate.”

The CDC recommendation doesn’t directly address whether people should wear face coverings while exercising outdoors; it only specifies what people should do when they come into contact with others in enclosed indoor spaces. For the time being, whether or not you choose to wear a face cover when you’re outside is at your own discretion.

Unlike going to the supermarket where it might be harder to keep six feet of distance in narrow aisles, “people generally do not need face coverings while walking in their neighborhoods and practicing social distancing,” says Judith Lightfoot, DO, chief of infectious disease at Rowan University School of Osteopathic Medicine in Stratford, New Jersey.

In rural and suburban neighborhoods where the foot traffic is light and people honor social-distancing guidelines, some people choose to walk without face coverings. You may feel comfortable doing this because you’re outside in fresh air, and you aren’t coming within six feet of anyone else in your travels. However, it can still be helpful as an extra precaution while practicing social distancing, especially in densely populated urban neighborhoods. If you’re more likely to encounter people on your walk, “I would recommend wearing a face covering since it can be difficult to adhere to social distancing in more populated areas,” says Lightfoot.

When you finish your walk and are ready to remove your face covering, don’t touch the front of the mask (which may have germs on it) or your eyes, nose, or mouth (these are common ways for germs to enter your system). “When you take the mask off, you should immediately wash your hands, either with soap and warm water for 20 seconds or use an alcohol-based hand sanitizer,” says Schaffner.

It’s also important to wash your face covering periodically. How often you wash it depends on when, where and how often you’ve worn it. For example, if you’ve worn your face covering to the supermarket for an hour, where you encountered others in an enclosed space, you may want to remove it carefully and throw it right in the washing machine before wearing it again. If you’ve only worn it while taking an early morning walk through your neighborhood, and you didn’t see anyone else along the way, it may be fine to wear it again before washing it. “I recommend washing your face covering whenever it gets soiled,” adds Schaffner.

If you’re unsure whether or not to use a face covering while exercising outdoors, it may be better to err on the cautious side and wear one, while also practicing social distancing. “Regardless of if you live in a city, the suburbs or a rural area, my advice is to take a face covering with you every time you leave your house,” says Schaffner. “This advice is the same whether you are alone on a path or passing others on the sidewalk, even while maintaining a social distance of at least 6 feet apart. At this point in the pandemic, my inclination would be to wear a face mask more often than not.” However, note that a face mask is not a substitute for social distancing.