Over the last few decades, air in the U.S. has undergone a remarkable transformation: pollution levels of health-damaging tiny particles have dropped by roughly 40 percent since 2000, primarily thanks to the country's decades-long effort to improve air quality through the Clean Air Act, a landmark environmental law.
Smoke from wildfires fueled by human-driven climate change, however, has erased roughly 25 percent of those air quality gains, according to a new study published Wednesday in Nature.
"We've seen really remarkable improvements in air quality," said Marissa Childs, one of the authors of the study and a researcher at Harvard's Center for the Environment. "But wildfire smoke is undoing that progress in many states."
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