Shared from the 4/2/2020 Houston Chronicle eEdition

Cleaner air a silver lining of pandemic

POLLUTION: Isolation offers look at life with fewer emissions

WASHINGTON — Around the globe people are noticing something missing in the air.

Whether it’s blue skies over Beijing, satellite imagery showing emissions dropping in Milan or air monitors in Houston recording less ozone than normal, mankind’s sudden hunkering down in response to the coronavirus pandemic has resulted in visibly cleaner air with remarkable speed.

The primary reason, experts say, is fewer vehicles on the road, which means fewer emissions from the petroleum-based fuels on which so much of the Texas economy relies.

“I’ve been looking at the satellite imagery, and it’s been dramatic,” said Daniel Cohan, an environmental engineering professor at Rice University. “We have satellites observing nitrogen dioxide (a major contributor of smog) every day, and those showed an incredibly steep fall off over the Hubei province and the Wuhan region [where the coronavirus outbreak began]. You can see it in northern Italy, and even over New York and Los Angeles.”

The reduction in pollutants such as nitrogen dioxide and microscopic particulate matter, not to mention the carbon dioxide that is warming the planet, offers a temporary window on what a world burning less fossil fuel might look like as governments worldwide move to cut greenhouse gas emissions to net-zero by mid-century.

On Twitter, people marveled at the change in conditions, with one user writing, “clear water in Venice, blue sky in Beijing... I wish we could take care of Earth a bit better and pollute less after this coronavirus quarantine is over!”

Michael Webber, an energy resources professor at the University of Texas, said he was surprised at how much “clearer” and “crisper” the Austin skyline had become while driving around the city with his wife earlier last week.

Since the passage of the Clean Air Act in the 1970s, U.S. air quality has steadily improved with technological advances in filtering emissions out of car tail pipes and power plant stacks, making U.S. the pollution in cities like Houston a far cry from that in China. But air pollution still persists here, pumping huge volumes of carbon dioxide into the atmosphere and killing more than 100,000 Americans each year, according to the National Academy of Sciences.

“There’s been a lot of improvement, but you could argue it’s at a glacial pace,” Webber said. “A question we should be asking is, how do we maintain the better air quality without the economic consequences of shutter in place orders?”

During the 2008 global financial crisis, U.S. carbon dioxide emissions fell 10 percent and never came back, in large part due to investments in the years following the crisis in wind turbines and solar panels, as well as energy efficiency and replacing coal-fired power plants with natural gas.

Whether this latest taste of cleaner air will inspire a similar effect — through faster adoption of electric cars or tougher regulations on fossil fuels — is anyone’s guess.

Even as air quality improves, the Trump administration and the Texas Commission on Environmental Quality are relaxing enforcement of air pollution rules, to help industrial facilities struggling under the weight of a global economic crisis. On Tuesday, the Trump administration finalized a rule to roll back Obama-era fuel-efficiency standards and efforts to cut tailpipe emissions.

And while air pollution from cars might be down, there is so far little indication of a reduction in emissions from the petrochemical plants lining the Houston Ship Channel.

“It will be interesting to see how it plays out,” said Catherine Fraser, clean air advocate at the Austin-based activist group Environment Texas. “With air pollution you don’t always see it or know it’s there. Maybe this will be a way to recognize the problem we have.”

In Houston, where the huge volumes of commuters and sprawl of industrial facilities often result in a lingering smog, emissions of nitrogen oxides, which combine with other pollutants in the atmosphere to form ozone, are already down 15 percent this month compared to last year.

This time of year, the combination of pollution with rising heat and humidity usually results in Houston regularly violating the federal limit on ozone levels. But so far this spring the city’s ozone levels have not reached that mark, said Cohan, the Rice professor.

“How much is emissions and how much is weather? It’s hard to say,” he said. “But it’s moving in the right direction. It’s certainly been a cleaner month for ozone.”

While social distancing measures might improve air quality close to the ground, the impact on climate emissions are less dramatic.

Many pollutants such as nitrogen dioxide will dissipate in a matter of days once emissions are reduced, but carbon dioxide continues to build up in the upper reaches of the atmosphere, and will continue to do so as long as emissions of the greenhouse gas exceed the planet’s ability to absorb it.

“Even cutting emissions in half, which I don’t think we’ve done, emissions would be much larger than how quickly oceans and trees can take it out of the atmosphere,” Cohan said. “CO2 levels won’t start coming down until we get to net zero.” james.osborne@chron.com twitter.com/osborneja

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