As COVID-19 continues its spread and shelter-in-place orders keep people at home throughout the United States, the pandemic's effect on pollution has been one of the few silver linings in a bad situation. While initial reports of dolphins swimming in Venice's canals may not have been accurate, it's true that virus-related shutdowns are cleaning up air pollution around the globe, with satellite imagery showing drops in certain pollutants of up to 40% in some areas.
Now, there's evidence that the air may be getting cleaner not just in cities, but in nature as well.
Air quality data collected in four major national parks over the past week—Grand Canyon, Great Smoky Mountains, Sequoia and Kings Canyon, and Joshua Tree—shows lower ozone levels than any of the parks had seen over the same period for the last five years. In the Smokies, ozone dropped to 43% below the average; the Grand Canyon recorded a week straight of good air quality, a marked difference from previous years.
It's a much-needed piece of good news—and, says Stephanie Kodish, the senior director and counsel for clean air and climate at the National Parks Conservation Association, a glimpse into a possible future for America's wild places.
"I think there are some really important lessons here," she says. "Changes in our actions, even if they're inspired by horrible things like this, can have a real effect on resources that we need for survival."
It's instinctual for us to assume that national parks and other natural spaces are cleaner than the places we live. In reality, they suffer from the same air pollution issues that major metropolitan areas do. In a study, the NPCA found that 85% of parks occasionally had air that was unhealthy to breathe, while in 88% of parks, air pollution was "damaging sensitive species and habitats." In 2018, the report found, four parks—Sequoia, Kings Canyon, Joshua Tree, and Mojave National Preserve—had air that was unhealthy for most people to breathe for at least two months of the year.
Ozone is a common greenhouse gas that forms when two other classes of pollutants, nitrogen oxides and volatile organic compounds, react in sunlight. While some of that pollution in national parks comes from visitors' vehicles, the lion's share of emissions sources are outside of the park. The exact makeup of that pollution "cocktail" varies from place to place, Kodish says, but common culprits include oil and gas exploration, electricity generation, and the transportation sector.
Exactly which of those sources is responsible for the current drop in pollution is a tougher question. David Keiser, a professor of resource economics at the University of Massachusetts—Amherst, coauthored a study on air pollution's effect on visitation in national parks. With COVID-19 shocking the world economy and parks shutting their gates to visitors, he says, it's difficult to say exactly why air quality is improving.
"When 100 things change at once, and all 100 might have a plausible connection to what you are studying, it’s very hard to tease out any one signal," he says. "Is air pollution decreasing from a major economic shutdown? Almost surely. However, is it local vs. non-local impacts that are improving air quality in parks – that’s hard to know."
The bad news is any changes to parks' air quality are likely temporary; as furloughed workers return to factories, airlines spin up mothballed planes, and tourists with a severe case of cabin fever begin to line up at the national parks, ozone levels will almost certainly rise back up to normal.
But for Kodish, the data are a wake-up call—and a strong argument for restoring the myriad environmental protections, from vehicle emissions standards to regulations on fossil fuel exploration, that the Trump administration has stripped away over its time in office.
"We have a pause right now, right?" she says. "We have a moment to choose to learn about the potential that we have to make a difference, and actually institute some of the positive changes that we're seeing."