A year into the pandemic, it’s even more clear that it’s safer to be outside

Even so, public health guidance about the outdoors remains cautious: Stay distanced, avoid crowds and wear a mask — even, in many jurisdictions, on beaches and trails. Experts say that is because it remains unclear precisely how much less risky outdoor activities are, in part because it is so difficult to trace contacts of strangers who were near each other at public events. More contagious variants are also “working against us,” Marr said. What’s more, some lower-risk outdoor activities, such as beach-going or partially filled stadiums, are often connected to far riskier ones, like public transportation or visiting bars. When Miami Beach imposed a curfew last month, officials cast blame on crowds of revelers, not sunbathers. Nooshin Razani, an associate professor of epidemiology and biostatistics at the University of California at San Francisco, studies the connection between nature and human health, and has long advised park agencies. As the pandemic progressed, Razani said, she realized these agencies needed “a bit more nuanced guidance than just, ‘It’s safer outside,’ ” she said. In a systematic review of published studies on transmission of the novel coronavirus and other respiratory viruses, Razani and colleagues found that less than 10 percent of cases described were spread outdoors. But they also found frustratingly few papers that detailed the settings or clearly compared indoor and outdoor situations.