Do I still have to wear a mask outside?

Infection and Spread Masks

A: It depends. Remember that outside is much safer, but it’s not magic!

☀️ We’re all anxious to get outdoors as the weather improves. Shedding our masks along with our long pants is SO tempting.

Because SARS-CoV-2 is most often spread through “swapping air” with others, ventilation is a key factor in transmission.

💨Outdoor air dilutes particles containing the virus very quickly compared to indoors, dramatically reducing the chances of transmission. ⚡Ultraviolet light may also inactivate the virus more quickly.

New variants like B.1.1.7 may be more transmissible, but this is likely due to changes that make it easier for the virus to enter our cells and make copies of itself.

The good news that the new variants can’t defy the laws of physics and suddenly travel farther through the air….or through masks.

While transmission outdoors is much less likely, it is still possible. A recent contract tracing study from Ireland found only 0.1% of identified cases were linked to outdoor transmission. These small number of cases were primarily linked to outdoor construction sites and sporting activities. If you are breathing or spitting directly in someone’s face, even outdoors, transmission can occur.

For outdoor activities, consider 3 key factors: (h/t Dr. Saskia Popescu in linked NatGeo article):

➡️ Distance (closer is riskier)
➡️ Duration (longer is riskier)
➡️ Intensity (heavy breathing, singing/shouting riskier)

😷 As the risk from these 3 factors increase, masks become more important.

Fleeting interactions like walking past someone are unlikely to be risky, but prolonged close conversation within 6 feet is riskier. Jogging beside or behind someone also carries more risk due to heavy breathing and duration. Crowded gatherings where you need to speak louder increase risk. Remember that risk is a continuum. Adding a mask as a layer of protection when other risks increase is a good idea.

Of course, vaccination is the new variable impacting individual’s and family’s risk assessments. If you are fully vaccinated, you have a dramatically lower risk of being infected or transmitting to others, whether indoors or outdoors.

Even if vaccinated, wearing a mask in crowded public spaces is still advised. This protects both you and others while vaccine coverage gradually increases in the whole population.
If you are fully vaccinated and only interacting with vaccinated family and friends, going without a mask outdoors is fine.

See our recent post on guidance for what fully vaccinated people can safely do, which includes seeing other vaccinated people unmasked outdoors OR indoors:

What about kids? Kids still count as unvaccinated people when assessing transmission risk, though they are low risk of severe disease themselves. See our recent tips for weighing risks with kids here:

Fully vaccinated adults with unvaccinated kids

Children, travel, and unmasked playdates


💥 Outdoors is MUCH safer than indoors for COVID-19 transmission risk.
💥 Wear a mask outside if you can’t avoid sustained close contact—especially if you are unvaccinated or around unvaccinated people.
💥 Every bit of prevention adds up as we push to get the world vaccinated. Let’s starve this virus of its hosts! #WeCanDoThis

Those Nerdy Girls

Further Reading:

“Does everyone need to wear a mask outside? Experts weigh in.”

“Should we be more careful outdoors as Covid-19 variants spread?”

“Covid: Can you catch the virus outside?”

Systematic Review of Outdoor Transmission

“Outdoor transmission accounts for 0.1% of State’s Covid-19 cases”

Link to original FB post