Faced with one of the worst COVID-19 outbreaks in the country, officials in New Jersey have steadily shut down much of the state, starting with nonessential businesses, then schools and places of worship. Earlier this month, Gov. Phil Murphy even closed state parks and urged local officials to shutter their outdoor recreational facilities, saying the state needed 100% compliance from residents.

But as we learn more about the coronavirus, it’s becoming clear that closing parks and recreation areas doesn’t accomplish much to stem the spread of the virus because people rarely contract it outside. More worryingly, encouraging people to stay home and out of parks may even be counterproductive. Several recent reports show why it’s time to reconsider the decision.

A recent study from China traced the transmission of the COVID-19 virus in 1,245 cases back to the environment in which they took place. These infections, the research found, overwhelmingly took place indoors, especially in homes and on mass transit. By contrast, the researchers were able to identify only a single case where transmission had occurred outdoors. Other work from infectious disease experts in Europe may help explain the above findings. Researchers there are finding that fresh air quickly disperses the virus and that UV rays from sunlight kill it.

The only exception to these findings is very large gatherings in outdoor venues, particularly professional sports events or outdoor concerts in stadiums where tens of thousands of people come together in close quarters. But these events are already banned under restrictions in the size of gatherings, and most of our parks and local recreational facilities aren’t really used for such events in the first place.

In ordinary times, health officials are happy to recommend fresh air and exercise. Their benefits to our physical and mental well-being are clear. We may need both even more now. As the shutdowns drag on, for instance, mental health professionals worry about “lockdown fatigue,” a product of stress, anxiety, and the monotony of everyday life under confinement. The open spaces of our parks offered a significant antidote to lockdown fatigue until the state closed them.

Even more to the point, sunlight has, in the past, demonstrated that it can be a powerful viral disinfectant, and it may be one against COVID-19, too. Studies from around the world have identified vitamin D deficiency as one factor that raises the risk that someone who is infected with the coronavirus will experience severe symptoms. That’s because vitamin D helps to bolster our immune system to fight the virus. Sunlight, of course, helps our body manufacture vitamin D, readying it for the battle.

In the last great pandemic, the 1918 Spanish flu outbreak, sunlight proved its efficacy as a viral killer. In one notable example, an outdoor emergency hospital erected in Massachusetts to house overflow patients exposed them to the sunlight. Those in the outdoor unit had a significantly lower mortality rate than those treated indoors. A key study of that epidemic found that places around America that receive more sunlight on average had lower fatality rates from the deadly flu.

When Gov. Murphy issued the order to close parks, he acknowledged that people “need to get fresh air,” but he also said they needed to “stay home.” For many residents, doing both is simply not possible.

New Jersey is part of a seven-state coalition, which includes Pennsylvania and New York, that has agreed to cooperate in a phased reopening of society. New York Gov. Andrew Cuomo said that their plans should be guided by “science.” The science suggests it may be time to reopen the parks.

Steven Malanga is the George M. Yeager fellow at the Manhattan Institute and senior editor of its City Journal.