Do we still need to wear a mask outdoors?

“I’m vaccinated and I’m outside. Do I really still need to wear a mask?”

“If I’m on a run and not near a lot of people. Do I need a mask?”

“If I’m walking down the sidewalk and pass someone - should I put my mask on?”

As the warmer weather months arrive and the percentage of vaccinated Americans gradually ticks upwards, these are some of the questions a growing number of Americans are asking.

If you’re vaccinated, “I’d say for the most part, you don’t need to wear a mask outdoors,” Dr. Sanjay Gupta said Thursday on CNN’s New Day.

That’s because it’s known most viral transmission doesn’t happen outdoors.

A November review in the Journal of Infectious Diseases found that the odds of viral transmission are 18.7 times greater indoors than out, and less than 10% of Covid-19 infections studied occurred outside.

Nooshin Razani, one of the authors and an associate professor of epidemiology and biostatistics at the University of California, San Francisco, told Slate the true number of instances of outdoor transmission was “probably lower” than 10%.

Current guidance from the US Centers for Disease Control and Prevention makes it clear masks might not be needed outside. “Masks may not be necessary when you are outside by yourself away from others, or with people who live in your household,” it says. The CDC does not say anything specific for vaccinated people.

MIAMI, FLORIDA - FEBRUARY 01: A sign reading, 'masks required in this area,' is seen as travelers prepare to check-in for their Delta Airlines flight at the Miami International Airport on February 01, 2021 in Miami, Florida. An executive order signed by U.S. President Joe Biden last week mandates mask-wearing on federal property and on public transportation as part of his plan to combat the coronavirus (COVID-19) pandemic. (Photo by Joe Raedle/Getty Images)

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On Thursday, CDC Director Dr. Rochelle Walensky said the agency is considering revising its mask guidance.

“We’ll be looking at the outdoor masking question, but also in the context of the fact that we still have people who are dying of Covid-19,” Walensky said on NBC’s Today Show.

To Mask or Not to Mask?

As with most Covid-19 discussion, the evidence on whether it’s advisable to wear masks outdoors isn’t black and white, and should be based on a variety of factors such as vaccination status and community transmission rates.

Tourists without face masks walk past a sign in the tourist zone of El Condado in San Juan, Puerto Rico on March 14, 2021. (Photo by Ricardo ARDUENGO / AFP) (Photo by RICARDO ARDUENGO/AFP via Getty Images)

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“If you’re vaccinated and not in a vulnerable category, it’s probably fine not to wear a mask outdoors,” Linsey Marr, an expert on the airborne transmission of viruses at Virginia Tech, told CNN in an email.

For unvaccinated people, Marr recommends masks in situations when people are clustered closely together, like in a bar, a crowd or a line.

“If you’re unvaccinated and constantly passing by people close enough that you can reach out and touch them, then you should wear a mask,” Marr told CNN.

Vaccinated or not, an important factor in deciding to unmask outdoors is the levels of transmission and positivity in your area, Gupta said.

“The real question you need to try to answer is, what is the likelihood I’m going to breathe in someone else’s air? That’s basically it. The number of people, type of setting and what is the overall viral spread in their community,” Gupta said.

Group of young sporty people practicing yoga lesson with instructor, stretching in Child exercise, Balasana pose, working out, indoor close up, students training in club, studio

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A hodgepodge Response

Dr. Ashish Jha, dean of the Brown University School of Public Health, told CNN’s Abby Phillip on Inside Politics Sunday that he expects masking to become only an indoor thing soon.

“I expect, over the next few weeks, states to start lifting outdoor mask mandates,” Jha said, adding that most infections happen indoors, so people will need to wear masks inside for a while longer.

CDC releases illustration of the Coronavirus.

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Several states such as Texas and Alabama have already eliminated statewide mask mandates, and some others are planning to loosen outdoor mask requirements.

Rhode Island Governor Dan McKee announced Thursday that, starting May 7th, masks will only be required indoors or when it is not possible to maintain at least three feet of space outdoors.

Covid-19 restrictions are ending in Connecticut on May 19th, and Connecticut Governor Ned Lamont is advising people to still be cautious and wear masks indoors.

“There won’t be any requirements regarding masks outside. We still strongly recommend wearing the mask inside, unless you’ve been vaccinated, we’ll find some balance there,” Lamont said.