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With the Fourth of July just around the corner and many states and communities relaxing coronavirus restrictions, the warm sunny weather beckons. But infectious-disease experts warn that the virus remains a threat as we return to travel, swimming, barbecues, ice cream shops and restaurants.

So what do we need to know about the new coronavirus and covid-19, the disease it causes, that is important as we embark on summer activities? To start with, while some people had hoped that summer might bring a drop in covid-19 cases, in much the same way that influenza fades during warmer months, "many researchers have their doubts that the covid-19 pandemic will enter a needed summertime lull," Francis Collins, director of the National Institutes of Health, recently wrote in a blog post. Instead, "humans' current lack of immunity to SARS-CoV-2 — not the weather — will likely be a primary factor driving the continued, rapid spread of the novel coronavirus this summer and into the fall."

Even if the covid-19 virus is as sensitive to climate as other seasonal viruses, Collins wrote, that wouldn’t be enough to slow its spread through the population right now — as evidenced by its rapid spread across such tropical nations like Brazil and Ecuador.

Still, summer does open up more opportunities for outdoor activities, which all agree are far safer than indoor ones. “We have very little evidence of outdoor transmission. It’s not zero — there are definitely cases reported — but it’s much, much lower than inside,” says Gretchen Snoeyenbos Newman, an infectious-disease physician at the University of Washington.

Of course, we can’t be outside all the time. When escaping the summer heat and mugginess indoors, try for as much ventilation as possible, and continue to observe safe behaviors: Wear a mask, keep interactions brief and make sure you’re not too close to other people, says Nahid Bhadelia, an infectious-diseases physician and the medical director of Special Pathogens Unit at Boston Medical Center.

A case study of indoor coronavirus transmission at an air-conditioned restaurant in China found that even people seated at a different table from the infected person were infected if they sat downstream from where the air conditioning was blowing. Tables in the restaurant were about one meter, or 3.3 feet, apart and the study’s authors hypothesize that strong airflow from the air conditioner may have spread respiratory droplets carrying the virus.

“To prevent the spread of the virus in restaurants, we recommend increasing the distance between tables and improving ventilation,” they wrote.

The basics of coronavirus spread haven’t changed now that it’s summer: Coming into close contact with infected people who have coughed, sneezed or breathed heavily or talked near you poses the greatest risk, according to the Centers for Disease Control and Prevention.

The risk of catching the virus from close contact is much higher than from touching shared surfaces, it says. What makes this tricky is that “there’s a lot of data to show that even if you don’t have symptoms, you can still pass the virus,” says Marilyn Roberts, a microbiologist in the School of Public Health at the University of Washington.

With this in mind, here is some guidance from health experts for common summer situations and activities.

Public restrooms

“Public restrooms are already gross,” Snoeyenbos Newman says. To make matters worse, they’re often poorly ventilated. Public toilets “have always been places where illness has been spread, so what I’m going to tell you — you should consider doing for the rest of time.”

First, wear a mask and clean your hands before you go in, she says. Once in the restroom, do your business, and before you flush, close the lid (if there is one). The coronavirus has been found in feces, and although it’s not clear yet whether it spreads this way, a new study suggests that “plumes” from the toilet when flushed may spread the virus.

When you’re done in the stall wash your hands with soap and water and dry them with whatever is available. Some studies have suggested that air dryers could potentially blow pathogens around the room, but it’s not clear that this is a source of covid-19 spread. “I would preferentially use a paper towel, but the air dryers aren’t enough of a worry to not use them,” Snoeyenbos Newman says. Don’t touch your phone or your face while you’re in the restroom, and as soon as you’re out, clean your hands again with a sanitizer, to make sure you didn’t pick up anything from the door. Do all of this, and you should be fine, Snoeyenbos Newman says.

As with other indoor space, don’t go into a crowded restroom, and if it’s a place that might be busy, look for some kind of monitoring to control crowding.

Restaurants

The risk at restaurants is from other people, not food, says Donald Schaffner, a food microbiologist at Rutgers University. To date, there’s no evidence that anyone has contracted the coronavirus via food, he says.

If you’re going to eat out, takeout poses the lowest risk. Dining at a restaurant is far riskier, because it puts you in proximity to other people. Your server and other employees should be wearing masks, and ideally so should patrons when they’re not eating, Schaffner says.

Eating outside is your best option, as it allows for natural ventilation and may give you more space for social distancing, says Saskia Popescu, an infection-prevention epidemiologist at George Mason University. Even outside, it’s important that there’s plenty of space between tables and room for servers to move between them without getting too close. Time spent in proximity to others is part of the risk equation, so you don’t want to linger too long after your meal.

Bike paths and other outdoor exercise spots

There’s been a lot of talk on social media and neighborhood message boards about the risk posed by people who exercise — breathing heavily — without a mask. But infectious-disease experts say that if you are outside and keeping a proper distance, the risk here is actually pretty low.

Although a European experiment that went viral earlier this year suggested that people who are walking, running or biking could spread droplets farther than six feet, the research wasn’t peer reviewed or published in a journal, and was widely criticized by public health experts for failing to understand transmissibility. Basically, outdoors in a non-crowded environment you’re unlikely to get a “minimum infectious dose,” Columbia University virologist Angela Rasmussen told Vox.

Even if they’re not wearing a mask, your exposure to people running or biking by you is very brief, and that reduces the risk, Popescu says.

Farmers markets

Best practices here comes down to some basic principles: Everyone should be wearing masks, and the arrangements of booths and lines should ensure adequate social distancing, Schaffner says. “I’d look for some kind of crowd control.” There should be an orderly flow where you come in here and walk in a one-way pattern and exit there, he says.

The risk of picking up the coronavirus from fresh produce is minimal, Schaffner says. “As far as we know, there are no documented cases of transmission from food.” Even so, it’s worth it for things to be arranged so that the vendor handles the produce wearing gloves and patrons don’t touch the food until it’s purchased. “Do you want someone picking up five apples to find the perfect one? Probably not,” Schaffner says. In any case, wash your stuff when you get it home, as you should do even when not in a pandemic.

Road trips with someone outside your household

A car is a confined space, and if you’re on a road trip, you’re probably sharing that space for multiple hours, which makes it a high-risk activity, Bhadelia says. You can reduce the risk by opening the windows, wearing masks and spacing yourself apart if you can (if you’ve got two people in the car have one of them ride in the back seat, on the passenger side), she says. But if you or someone you live with is in a high-risk category, you should probably drive separately when traveling with a non-household member.

Hotels and other lodging

Hotels, Airbnbs and other similar rental lodging should be considered a moderate risk, Bhadelia says. As long as the linens are clean and the surfaces have been disinfected, you’re very unlikely to catch the coronavirus in your room. It’s the interactions with other people that pose the risk. “You’re leaving home and have the potential to run into other people,” she says. It’s these interactions with other people, particularly if they have come from areas where coronavirus rates are high, that pose your greatest risk at hotels.

Experts advise you to call ahead and ask what measures are in place to ready the room or rental place and how long it’s been since the last guest. Ask for a room that nobody has stayed in recently — one study found that under laboratory conditions the virus could last a maximum of 72 hours on a surface, Snoeyenbos Newman said. “If the time is less than that, I would consider wiping down hard surfaces like remotes, light switches, faucets, etc., There aren’t major concerns about linens or bedding,” she said. The Environmental Protection Agency keeps a list of disinfecting products suitable to use against the coronavirus.

Find out how hotels are monitoring employees for the coronavirus — ideally there should be daily temperature checks, and any employee not feeling well should not come to work or should be sent home right away. And, of course, make sure that employees will be wearing masks.

As for your behavior in hotels, avoid common areas — don’t congregate in the lobby or other shared spaces — and wash your hands after touching things in the check-in area.

And again, when you get back to your room, wash your hands and wipe down high-touch surfaces. Snoeyenbos Newman says.

Barbecues

Barbecues can be a pretty high-risk activity, experts said, because they usually consist of people milling around the grill — and the chips and drink area — and socializing in close contact, Snoeyenbos Newman says. It’s hard to wear a mask in this situation, because people are eating and drinking. And people typically drink alcohol at a barbecue, which often further increases the risk.

“Most people, when they drink, tend to stand closer and talk louder, and both of those things increase the risk of transmission,” Snoeyenbos Newman says. Alcohol also decreases inhibition and so good intentions about social distancing can get pushed aside. If there’s going to be drinking, “you need to be really honest about how much you’re going to drink and how that will affect your group dynamic.”

If you’re going to host a Fourth of July barbecue, you should have some kind of stringent plan in place for ensuring that people don’t get too close (or too drunk). One way is to keep it small with widely spread out chairs and tables and assign people places to sit and hang out. Avoid shared utensils, and don’t have communal dip, but remember that your biggest risk is the person next to you, not the food, Schaffner says.

Camping

If you’re camping with people you live with, you’re basically just taking your house to a different place, and that’s fine, Snoeyenbos Newman says. Most campsites provide a good buffer between you and other camping groups, and that’s also good, she says. If you’re camping together with other people, you want to make sure to keep the six-foot distance rule. That means separate tents and some plans on how you’ll enforce social distancing, especially for circumstances like eating or sitting around the campfire where it’s easy to slip. As for using public bathrooms at camp grounds, see above.

Swimming (pools, lakes, ocean)

There’s no evidence to suggest that the coronavirus is transmitted through water, so the danger from swimming, whether it’s a pool, lake or beach, is from interacting with other people outside of the water, Popescu says.

Locker rooms and indoor showers are close, confined spaces that are best avoided.

Ideally, pools and public beaches should provide some kind of crowd control to help people stay six-feet apart, whether in the pool, on the beach or sitting along the edge of the water (except for household members, who can be together). This might mean having sign-ups for a pool to limit the number of people using the space at one time, or it could mean marking off poolside or beach spaces where people lay down their towel and lounge about when they’re not in the water.

Playgrounds

Playgrounds are a situation where there’s not much consensus on what to do, Snoeyenbos Newman says. One issue here, she says, is that a child with the coronavirus touches the monkey bars and then your child touches the monkey bars and then his face. “Kids are really just not reliable about not touching their faces,” she says, which is why in many areas where the pandemic has been severe, playgrounds have been closed.

Still, the biggest risk is probably interactions with other children or adults at the playground, which you’ll want to limit. The CDC and other public health groups have now said it’s unlikely — but not impossible — to get infected with the coronavirus from contaminated surfaces, Roberts says. Which means that the risk from your child touching the playground equipment is probably fairly low, though not zero. This is really an individual decision, Roberts says. If you allow your child to go to the playground, she advises you to monitor what they do and make sure you’ve got wipes and a means to wash their hands afterward.

Recreational games

Whether you’re playing tennis, pickle ball or bocce ball, the things to think about are keeping your social distance and avoiding a lot of touching shared objects, Bhadelia says. Keep some sanitizer nearby to keep hands clean, and use your own equipment, rather than sharing. As long as you can do that, it’s probably low risk. Stick to games where players can be spaced six-feet apart, and avoid such games as volleyball or basketball where players come into close contact and everyone is using the same ball (and potentially breathing all over it.)

Ice cream shops

There is evidence that the coronavirus survives better in low temperatures, so theoretically it’s possible that if someone with covid exhales into the freezer case you could be exposed via the ice cream, but to get infected you’d have to stick it up your nose very soon after, Schaffner says. Even if there was some exhaled virus on the ice cream, “it’s gross to think about, but there’s no evidence that it spreads that way,” he says. The single biggest risk — again — is going to be other people in the store. The clerk should be wearing a mask, and you need keep your distance from other patrons.

Correction: An earlier version of this article referred to a physician as Bhadelia Nahid. Her name is Nahid Bhadelia.