When can you ditch your mask outdoors? Experts weigh in on the risks

Three million Americans are getting vaccinated against COVID-19 every day and half the country has received at least one shot. Cases of the deadly virus are well below peak levels.

Doctors and scientists agree that, at least for the foreseeable future, indoor masking is here to stay. Vaccines may not offer complete protection and contagious variants continue to pose a risk. Masks remain an important tool in preventing spread, both indoors and outdoors. But experts suggest that when you are alone outdoors and far from others you may not need to wear your mask. But definitely keep it handy.

Even when outside, “the risk is not zero,” said Dr. Jay Bhatt, an internist in Chicago. “With people that you're not sure if they're vaccinated or not, then you have to consider masking.”

It’s important to think like a doctor would -- consider the amount of time you’ll be in a specific place, what’s the air flow like, how many people are around you and the amount of COVID cases in your area.

The spread of more contagious variants also remains a concern.

“The enhanced contagiousness of these variants means, obviously, that we should take greater care. We should be more careful than carefree,” said Dr. William Schaffner, an infectious disease and preventative medicine specialist at Vanderbilt University.

But experts suggest that the data guiding masking policies outdoors is limited.

Dr. John Brownstein, an epidemiologist at Boston Children’s Hospital, said wearing masks outdoors gained momentum when “we were in the height of surges, when there was not a huge amount of insight into how transmission was occurring.”

As we’ve gathered more data, Brownstein said “the bulk of all transmission events are taking place indoors and outdoor transmission is very low.”

So when can you consider going mask-less outside?

When you are alone outside or with your household, you may not need to mask up, although you’ll want to keep your mask handy, experts suggest. Even if you don’t expect to run into other people, you can’t plan for everything -- and it’s better to be safe.

“If you're out walking your dog, do I think you need to wear a mask? No. Should you have your mask with you? Yes,” said Dr. Mary Beth Graham, medical director of infection prevention and control at Froedtert Hospital in Wisconsin.

And it’s important to keep local laws in mind regarding mask use, even if you are alone outside.

“We do have to comply with local rules and laws so it's most important to make sure you know what the rules are, wherever you happen to be,” said Dr. Nirav R. Shah, a senior scholar at Stanford University.

For outdoor locations with lots of people, wearing a mask is still recommended.

“We know that these infections can be transmitted outdoors with large gatherings of people in proximity such as rallies, parties and concerts,” said Bhatt. "Even a socially distanced concert or socially distant event. I would mask.”

Also, in areas where the overall rates of COVID-19 infection remain high, taking your mask off may not be the best option.

“There's contexts in which we may want to keep masking outdoors, especially if there's a major surge, like a place like Michigan,” said Brownstein.

Despite ongoing vaccination efforts, we still have a ways to go before we reach the herd immunity that may be needed so we can stop wearing masks altogether, said Schaffner.

Getting to “that level of community protection, where we can all go back to what looks like an old normal, that's going to be very, very difficult unless we get very, very much increased participation,” Schaffner added. “Supply of vaccine now exceeds demand. We have vaccine in the refrigerator, waiting for arms to show up to go into. And vaccine in the refrigerator never prevented any disease.”

ABC News' Dr. Jay Bhatt and John Brownstein contributed to this report.

Sara Yumeen, M.D., is a preliminary-year internal medicine resident at Hartford Healthcare St. Vincent's Medical Center in Connecticut and is a contributor to the ABC News Medical Unit.

Olivia Davies, a fourth-year student at the Medical College of Wisconsin and who will be starting her residency at Massachusetts General Hospital this summer, is a contributor to the ABC News Medical Unit.