Pacific Northwest wildfires send smoke across much of the United States

Smoke from a series of large wildfires in the Pacific Northwest continued to blanket a broad swath of the United States on Tuesday, prompting air quality advisories in several states. Authorities reported 46 major uncontained fires in Oregon and Washington that, together with smaller blazes, have burned more than 1.6 million acres. Across the border, more than 17 fires remain uncontrolled in British Columbia.

The highest pollution levels were recorded near Boise, Idaho, where particulate concentrations reached “very unhealthy” thresholds. Eastern Oregon and southern Idaho also experienced generally unhealthy conditions, leading state officials to advise residents to limit outdoor activities.

Forecasters expect hazardous air quality to develop near the fire zones on Wednesday and predict the smoke plume will travel eastward through Montana, the Dakotas and parts of Minnesota before moving southward, with only minor impacts anticipated in Florida.

Experts linked the severity of this season’s fires to a combination of unusually warm winter conditions, reduced snowpack and prolonged heat waves that have dried vegetation across the region. Climate scientist Daniel Swain noted that “the conspicuous overlap between record-breaking warmth, dryness, and low snowpack and these fires is simply not a coincidence.”

Health officials warned that fine particulate matter from wildfire smoke can penetrate deep into the lungs and enter the bloodstream, posing risks especially to people with heart or lung disease, older adults, children and outdoor workers. They recommended limiting exposure, using N95 respirators rather than surgical masks, keeping windows closed and employing indoor air filtration where possible.