San Francisco, along with most U.S. cities, is now dotted with expanded patio seating, newly built parklets, and other creative options to dine outdoors. While it feels downright luxurious to be able to enjoy food and drinks at a restaurant again, is it really safe to eat and drink close to a table of maskless strangers, even outside?

Bottom line: While experts agree outdoor dining is a lot safer than indoors (given that the virus has a harder time overall spreading in open air), not all alfresco dining spaces are created equally safe.

To help you make safer dining decisions, we’ve distilled the official recommendations for diners from the state and city guidelines and talked with an infectious disease specialist about what specifically to look for when dining outside.

First, the science

Even though we’re a year into the pandemic, the science behind what’s considered safe restaurant dining is still largely unsettled. The only study from the CDC on this was in a July 2020 study, which showed people who visited restaurants were twice as likely to be infected with Covid-19 as those who didn’t — but the study didn’t take into account whether those diners were seated outside or inside, nor did it weigh their other life choices or circumstances that may have made them vulnerable.

So — in this vacuum of definitive findings — government, business, and individual interests have swirled into a variety of responses.

Every state, and every county, has different recommendations and thoughts on the matter. Here in California, state health officials released some of the most thorough guidelines last November for restaurants wanting to offer outdoor dining, and they’ve been continuously updated as new intel comes in about the virus. But by the time they were first published, many businesses had already built parklets and other dining additions without the guidance available. Even after they were published, some restaurant owners got creative in interpreting the guidelines given limited available space and other obstacles.

The reality is that the virus spreads through activities like eating and talking while maskless, where droplets are able to travel more freely, so eating at a restaurant does come with a risk, whether outside or inside. With guidelines constantly changing (like today in SF, where the city is soon entering the Red Tier). We recommend educating yourself and making your own judgment call on each individual dining setup. Here’s what to look for.

Unrestricted cross-ventilation

As the California guidance explains, for a structure to be considered “outdoors,” it should have “unrestricted cross-ventilation.” That means air should be able to flow freely from opposing sides.

To do this, dining environments should be, ideally, completely open air. At a minimum, they shouldn’t be more than half enclosed with impermeable walls. And these walls should not be adjacent (meaning, they shouldn’t form a corner) to allow for better flow.

Having a roof is fine if the walls are open, though again, the more airflow, the better.

Essentially, it’s best to look for a restaurant that has an actual outdoor dining space — not something that is outside but has been enclosed to feel indoors.

This illustration from California’s guidance document summarizes what’s considered indoors vs outdoors for California restaurants:

Enough space between tables

As most people know, the CDC recommends a social distance of at least six feet between people. Most experts agree you should look for outdoor dining with a minimum of six feet between tables, and more is better. Tables can be on a sidewalk, but there must be at least six feet of clearance for pedestrians to pass.

In San Francisco, previously, restaurants needed diners to be at least six feet apart even if there were wooden or plexiglass dividers between tables. That changes with the Red Tier — less space is allowed if dividers are used.

However, George Rutherford, MD, a UCSF infectious disease expert, says spacing is immensely important and he wouldn’t be comfortable with less than six feet, even with a divider.

“People need to be conscious of spacing,” he says. “Being outside is not magical; if you sit within six feet of someone who isn’t wearing a mask, you can still have droplet transmission. But if you have at least six feet of space between people, outdoor dining probably isn’t a higher risk than being in a crowded retail space.”

What about parklets and other structures?

Restaurants have gotten creative with their outdoor dining environments, offering everything from parklets to domes. Is there anything we should keep in mind with these?

One of the more common parklet designs seen in San Francisco has large wooden dividers or full-on walls around tables to give the nooks a private feel between the tables and block out particles from traveling between people. As long as only one household is in each of these nooks, this can be effective. But the virus can still spread around the wall — so distance is still important.

We’ve also seen a lot of plexiglass go up between tables. Similarly, experts agree any sort of barrier like this is meant to prevent large spray-born droplets released when someone talks or coughs at close range, but smaller particles can go around the barrier and be inhaled by someone.

Dome or tent structures aren’t advised if they contain more than one table, since the air becomes trapped in the area with no way to escape. However, if it’s just one household per tent, and it can be sanitized between uses and let to “breathe” for a period of time, it has less risk.

Number of people per table

Another major factor for safety is how many households are at your table, or at the table nearby. Currently, in San Francisco, tables may seat up to six diners from three households. Before the Red Tier, it was only two households.

Why would the state say that restaurants can seat two (now three) households at the same table?

“Because two (or three) households are better than four households,” said Rutherford. “But if you are going to sit at a table with people outside of your household, avoid eating with anyone who has a forward-facing job, like an unvaccinated doctor, nurse, retail worker.”

Would he personally eat with people outside of his household?

No, unless they’ve been vaccinated, Rutherford says.

What is the safest experience?

The safest outdoor dining experience then would be at a table under an umbrella or a canopy or in a structure with a single wall, or two nonadjacent walls. Any other table, or any pedestrian traffic, should be at least six feet away.

There are other features to consider, too.

Some suggest that having a heater in your dining area improves airflow since air rises when it’s heated and cooler air will take its place.

The more a restaurant limits interaction and implements safety practices, the better — including but not limited to: taking reservations and not walk-ups, asking customers if they’re experiencing any symptoms, taking people’s temperature, enabling a QR code for viewing the menu, and allowing ordering and paying using an app. In addition, requiring diners to wear a mask whenever restaurant staff approaches the table or when they are not eating or drinking helps limit exposure.

Web-based services such as OpenTable, Yelp, and especially Google Maps can help you identify restaurants that offer reservations, outdoor seating, and NFC mobile payment options.

As indoor dining expands, too, we may see restaurant owners use CO2 monitors to evaluate whether their space has sufficient ventilation. For example, if CO2 measures more than 1,000 parts per million, it’s a sign that increased ventilation is needed. Measures of CO2 closer to 400–500 parts per million are considered safe.

Getting through this pandemic without contracting the virus will include a bit of luck, but as an old Burmese proverb advises: The more you know, the more luck you will have.

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