A woman inspects Brockwell Park in London, which has been closed to help stop the spread of coronavirus.Matt Dunham / AP

Across the world, from Zurich to St. Louis, authorities are closing down public parks and outdoor spaces—with many citing overcrowding, which they fear will fuel coronavirus infections. In one notable and much-discussed example, officials in London just announced in a scolding tweet that they were closing down Brockwell Park, after they claimed that about 3,000 people took to the park to enjoy the good weather.

In the short run, closing parks may seem prudent, when our hospitals are overrun and we are trying so hard to curb the spread of COVID-19. But in the medium to long run, it will turn out to be a mistake that backfires at every level. While it’s imperative that people comply with social-distancing and other guidelines to fight this pandemic, shutting down all parks and trails is unsustainable, counterproductive, and even harmful.

To start with, the park crackdown has an authoritarian vibe. In closing Brockwell Park, for example, pictures showed two police officers approaching a lone sunbather, who was nowhere near anyone else—well, except the police, who probably had something better to do. Such heavy-handedness might even make things worse, as it may well shift the voluntary compliance we see today into resistance.

Finding sustainable policies is crucial, especially since this pandemic likely isn’t going away in a few weeks. It’s plausible that we will be social distancing, on and off, for another year. That means we need to consider how to maintain compliance with strict measures over that long of a time.

Exercise, the outdoors, and sunshine are essential, not just as luxuries but as ways to sustain population health and resilience. That makes it important to set the right policies now. Once parks are closed, opening them back up will be harder. Authorities may dig in their heels and the issue may become more polarizing. Instead, we should start with sensible and viable policies as early as possible.

The outdoors, exercise, sunshine, and fresh air are all good for people’s immune systems and health, and not so great for viruses. There is a compelling link between exercise and a strong immune system. A lack of vitamin D, which our bodies synthesize when our skin is exposed to the sun, has long been associated with increased susceptibility to respiratory diseases. The outdoors and sunshine are such strong factors in fighting viral infections that a 2009 study of the extraordinary success of outdoor hospitals during the 1918 influenza epidemic suggested that during the next pandemic (I guess this one!) we should encourage “the public to spend as much time outdoors as possible,” as a public-health measure.

Mental health is also a crucial part of the resilience we need to fight this pandemic. Keeping people’s spirits up in the long haul will be important, and exercise and the outdoors are among the strongest antidepressants and mental-health boosters we know of, often equaling or surpassing drugs and/or therapy in clinical trials. Stress has long been known to be a significant suppressor of immunity, and not being able to get some fresh air and enjoy a small change of scenery will surely add to people’s stress. We may well be facing a spike in suicides and violence as individuals and families face significant stress and isolation: The Air Force Academy initially imposed drastic isolation on its cadets due to the coronavirus, but had to reverse course after two tragic suicides. Domestic violence is another real concern: Not having a place to go, even for an hour, may greatly worsen conditions in some households.

Unlike poorly ventilated apartment buildings that are often very conducive to spreading infections, sunlight and natural ventilation outdoors help decrease the threat of infection. This doesn’t mean that you can bake in the sun and consider yourself sterilized, or that you should ignore social-distancing rules outside. And plain sunlight shouldn’t be confused with medical sterilization methods such as UV-C light boxes. However, there’s a good reason sunshine was used as a form of treatment and disinfectant before we had more advanced methods. From many lab and other studies, we know that “ultraviolet radiation inactivates influenza virus and other viral pathogens and that sunlight kills bacteria.” While we should not allow any park to turn into a concert-like situation, with people standing shoulder to shoulder and no space between groups, there’s no reason to panic if a few thousand people are sunning themselves in a park the size of Brockwell, which is 125 acres and can easily accommodate many thousands with sufficient distance among them.

Besides, closing some parks may well cause what outdoor access remains to become even more crowded—people have already been reporting crowding elsewhere as a response to park closures. All this may avoid the pictures from parks that get people upset and encourage scolding, but it does not make us safer. Instead, our focus should be on restricting access to truly high-risk areas (such as playgrounds) while keeping open trails and lawns in a manner that is compatible with social-distancing requirements.

Young people are a particular challenge for any park and outdoor policies. It’s tempting to close a park because people are congregating there! In large groups! (As the tweet announcing the closure of Brockwell Park loudly proclaimed.) Preventing in-person social activity, though, especially among young people, is a matter of persuasion. Research into the effectiveness of abstinence-only education is instructive on this point: abstinence-only education is positively correlated with higher rates of teen pregnancy, even after controlling for factors such as socioeconomic status. Persuading teenagers to completely avoid sexual activity is quite difficult, and pretending we convinced them through instruction can just drive the behavior underground without safe-sex and birth-control practices.

A similar difficulty exists for youth socialization during a pandemic. Young people have repeatedly heard that the coronavirus disproportionately affects the elderly. And also, they’re young: Their own mortality rarely works as an argument to stop them from doing something. We would do better to appeal to their altruism, by explaining that they could spread the virus to vulnerable people, but doing so requires maintaining legitimacy. Keeping parks open could even be seen as a form of harm reduction for congregating youth. If a group of 10 young people goes to a park like Brockwell and is kept six feet away from every other group, the police shooing them away may end up being pandemic theater that might increase the risk of transmission among the group members if they instead spend that time socializing anyway in a cramped, poorly ventilated apartment. Parks could even put a limit on how many people can be together at once, which again would bring about harm reduction compared with an out-of-sight but larger gathering indoors. Meanwhile, we should keep trying to persuade the youth to socially-isolate but let’s also not kid ourselves that we have been completely successful if we merely manage to improve the optics by closing access to parks.

The history of disaster response is full of examples of extraordinary goodwill and compliance among ordinary people that disintegrate after authorities come down with heavy-handed measures that treat the public as an enemy. Rebecca Solnit’s book A Paradise Built in Hell details many such cases, such as the lives lost when the military was ordered into post-earthquake San Francisco in 1906 to control the dangerous and unruly “unlicked mob” that was primarily a figment of the authorities’ imagination. Unfortunately, the official response worsened the subsequent fire (which was more damaging than the earthquake itself) by keeping away volunteers “who might have supplied the power to fight the fire by hand.” Some ordinary citizens were even shot by soldiers on the lookout for these alleged mobs of looters and dangerous behavior from citizens. Similarly, in the aftermath of Hurricane Katrina, as a review of Solnit’s book summarized, “there were myriad accounts of paramedics being kept from delivering necessary medical care in various parts of the city because of false reports of violence.”

When the efforts to “flatten the curve” start working and the number of known infections starts going down, authorities will need to be taken seriously. Things will look better but be far, far from over. If completely kept indoors with no outlet for a long time, the public may be tempted to start fully ignoring the distancing rules at the first sign of lower infection rates, like an extreme dieter who binges at a lavish open buffet. Just like healthy diets, the best pandemic interventions are sustainable, logical, and scientifically justified. If pandemic theater gets mixed up with scientifically sound practices, we will not be able to persuade people to continue with the latter.

This doesn’t mean we shouldn’t limit park attendance at all, but there are better answers than poorly planned full closures. We could, for instance, reduce congestion by regulating inflows of people over time. In large cities with limited park space, households could be assigned days for visiting, with even and odd house numbers going on different days. This has to be mostly voluntary, of course, but this is a pandemic: Most everything has to be voluntary because there is no way to get through the next 12 months by arresting everyone who wishes to get some fresh air.

Governments could make a special appeal to people who have yards to leave parks for those who do not. (Wealthier people tend to have their own yards or lots, which is another reason not to shut down parks and deny outdoor access to poorer people.) We could install number counters in parks and on trails, similar to those in parking garages or some museums, and provide sensible limits. People could make or be given six-foot-long strips of cloth to be spread in all four directions around them in the park, providing visual barriers for distance. Some bikers around the country are already using pool noodles on their bikes as such physical aids to social distancing. Walking and running trails could assign directionality so that everyone runs and walks in one direction, avoiding close encounters. Runners and walkers could even be assigned different time periods, as mixing the two seems to create more social-distancing challenges, as well as maximum numbers allowed per time period.

We can also look at increasing available space for getting fresh air and exercise. Given that many people are working from home and not traveling or driving, some streets could be closed to cars and designated for responsibly distanced walking and running. Golf clubs, schoolyards, and other private outdoor spaces could be reappropriated for exercise and fresh air for the public. Just yesterday, I walked by a baseball field with a freshly manicured lawn. If the season isn’t happening, perhaps stadiums should be opened up to other people.

These are just a few suggestions, and there could be many others. Even if health authorities close some parks temporarily while they assess and develop evidence-based policies and best practices, they should do so with transparency and a timeline or conditions under which the parks will reopen. That’s the best of all possible worlds: The authorities will preserve much-needed legitimacy, and the public will retain access to the outdoors under sensible conditions that reduce risk while promoting health, well-being, and resilience—and we will certainly need all of that to get through the next many months.

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