Washington Post: Wildfire smoke is eroding decades of air quality improvements, study finds

by Joshua Partlow, Washington Post

In more than a half century since the Clean Air Act was enacted, there have been dramatic improvements in air quality in the United States, as regulations demanding less-polluting cars and factories helped lift cities from clouds of dirty smog.

But a big chunk of recent air quality progress has been rolled back for one reason — wildfire smoke — and it’s happening far beyond the smoldering forests of Western states.

Over the past two decades, air quality improvements have slowed or been reversed in most of the country, eroding about a quarter of the recent gains, according to a new study in the journal Nature. Some states — Colorado, Montana, New Mexico, Washington and Wyoming — have rolled back 50 percent or more of their progress since 2000. In Oregon and Nevada, wildfire smoke has completely erased their gains.

“We had had so much success, and wildfires, just in five to six years, are really unraveling a lot of this progress,” said Marshall Burke, the paper’s lead author and a professor of Earth system science at Stanford University. “And that’s unfortunate.”

The study builds on previous work by Burke and his colleagues, who had created a detailed map of how much wildfire smoke there has been in the country over the past two decades. That effort relied on melding data from air quality sensors, satellite images of smoke plumes, and computer models that could estimate smoke levels in remote areas without sensors.

The new paper seeks to answer the question: What has all this wildfire smoke done to overall air pollution levels?

What they found was sobering.

Data from air quality sensors around the country had been showing steady improvement since 2000 in most states. But around 2016 — and earlier in some Western states — the trend broke. Since then, air quality progress has significantly slowed in 30 states. In 11 others, it began to reverse.

One of the main reasons is wildfire smoke.

The statistical analysis by Burke and his colleagues through 2022 found that wildfire smoke significantly influenced air quality trends in 35 of the contiguous states. States that are still improving would have done so faster without smoke, they found. In some Western states, air quality that otherwise would have kept improving is now getting worse because of that smoke. …

Childs said if their study had been redone with 2023 data, “the results we’d find would only be stronger.” …

“This problem, if we don’t do something about it,” Childs said, “is only going to get worse.”


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