“We know they’re more transmissible, so the risk is greater inside or outside,” said Dr. John Swartzberg, an infectious disease expert with UC Berkeley.

Health experts agree that outdoor activities are still much safer than indoors, since viral aerosols don’t have a chance to accumulate in the air. But with the most transmissible variants yet, chances are you have less protection in certain situations.

“Being at parks and outdoor sporting events is still what we should turn to,” said Dr. Anne Liu, an infectious disease doctor at Stanford. “But if you are in a dense crowd or in an outdoor space that has been modified to look like an indoor space, then the risk becomes higher.”

In other words, walking on an isolated hiking trail or a breezy beach is a lot safer than standing shoulder-to-shoulder with celebrants under a tent at a wedding or singing and dancing with fans crammed into an outdoor concert.

The omicron sub-lineages are so new that infectious disease experts are still measuring their potential impact, even in outdoor settings.

“The risk outside is going to be substantially less than inside but we don’t know if it’s changed because we haven’t had a lot of experience with BA.4 and BA.5,” said Swartzberg. “We’re basing our assumptions on BA.1 and BA.2.”

Given the high rate of infection across the Bay Area, there is more virus circulating in the air, so it’s better to be cautious in any environment. That means masking, social distancing, and being aware of your surroundings.

“The chances of being around someone outside or inside who is shedding virus is very high,” said Swartzberg.

Even for those who were recently infected, the new variants don’t offer much protection against catching the virus again, according to Dr. Peter Chin-Hong, an infectious disease expert with UCSF.

“The newest kids on the block, BA.4 and BA.5, cause a lot more reinfections,” he said.

There are certain outdoor situations when you should even consider wearing a mask.

“If I was crowded together with other people where I couldn’t keep my distance, or if somebody near me was talking loudly or singing, I would just carry a mask with me and put it on if I feel uncomfortable,” said Swartzberg.

Wedding receptions and concerts are some examples of high-risk environments where you would likely slip on a high-quality mask, such as an KN95 or KF94, especially if you need to go inside to use the restroom or pick up drinks from the bar.

“These are really transmissible variants. It doesn’t take much time to pick up the virus,” Liu said.

So far, the CDC guidance for outdoor masking is unchanged: People generally don’t need masks outdoors, regardless of vaccination status. However, face masks are recommended in areas of high transmission for individuals not fully vaccinated in a crowded outdoor setting, or in situations with sustained close contact with others who are not fully vaccinated.

Testing is also an effective tool in helping catch potential infections when large groups of people gather, especially if attendees are traveling from different locations.

Keep in mind that BA.4 and BA.5 are taking longer to detect than previous strains of the virus, so anyone showing symptoms should stay at home and isolate. Swartzberg said it is not unusual to see tests with negative results up to three days after people become infected.

“If I was having a party outside, I would ask everybody to do a rapid test recognizing that it’s not going to be foolproof but might pick up a few positive cases,” he said. “If you wanted to add a layer of protection, you would ask people to do a PCR test the day before. We’re now getting results back for those within 24 hours.”

People should also test if they plan on spending any time inside.

“Outdoor activities are often associated with indoor activities,” said Liu. “Any time people are staying in close quarters, like an Airbnb, it is advisable to do testing. The antigen testing has proven to help detect the presence of infection even if doesn’t completely rule it out.”