Jul. 22—Frederick County residents out for a jog or coasting through their morning commute the past couple days may have noticed a striking haze hovering over parts of the area.
The origin of this smoky fog? The historic wildfires across parts of the West Coast.
The smoke has been traveling on a jet stream, explained National Oceanic and Atmospheric Association meteorologist Brendon Rubin-Oster. Jet streams are narrow air currents that typically flow from west to east, found roughly 30,000 to 40,000 feet in the air.
Oregon, California and Washington have endured — and continue to endure — sprawling blazes. The nation's largest wildfire, Oregon's Bootleg Fire, grew to 616 square miles (1,595 square kilometers) — just over half the size of Rhode Island. Fires have also burned on both sides of California's Sierra Nevada and in Washington state and other areas of the West.
"One of the things about this event that makes it so remarkable is that the smoke is affecting such a large swath of the U.S," said Jesse Berman, an assistant professor at the University of Minnesota School of Public Health and an expert on air quality. "You're not just seeing localized and perhaps upstate New York being affected, but rather you're seeing numerous states all along the East Coast that are being impacted."
The Oregon fire has ravaged the sparsely populated southern part of the state and has been expanding by up to 4 miles (6 kilometers) a day, pushed by gusting winds and critically dry weather that's turned trees and undergrowth into a tinderbox.
Rubin-Oster called the dried out material "fuel," defined as anything that retained moisture but then dried out. They make a perfect catalyst for a fire, he said, especially in an area that has dry storms, where there is little to no precipitation but still lightning strikes that can cause the fire.
The smoke from the fire rises up with the air, and some of the particles get to jet stream elevation. Then they go for a little ride. The smoke gets transported in a sort of wave formation: It dips out of the western coast and then rises up over central United States into central Canada. It then dips one more time into a "trough" on the East Coast.
"It's kind of following the wave train there, and it's transporting all the pollutants in the fires out with it," Rubin-Oster said.
Because of the haze, Frederick County has been around 104 on the Air Quality Index. Represented by the color orange, that figure means the air is unhealthy for sensitive groups, including those with heart or lung disease, asthma, older adults and children. People in these groups should limit their time outside and wear N95 masks to protect themselves from the fine smoke particles.
The haze shouldn't last for much longer, however, with a cold front coming from Pennsylvania and creating thunderstorms in the area. Rubin-Oster said it's possible local residents could see the smoky fog again based on the fires' lifespans and the position of the jet streams, but the haze should eventually dissipate.
"So that should usher out a majority of the air pollutants and so we do expect an improvement of air quality tomorrow," he said Wednesday.
The Associated Press contributed to this report.
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