Alaska Air temporarily suspended flights into Portland, Oregon, and Spokane, Washington, over concerns aboutblanketing the Northwest.
"Across the West, fires are creating thick smoke and haze, causing very poor air quality conditions in the Portland and Spokane areas. We made the difficult decision to stop our operation so that our employees and guests can remain safe," the airline said in a blog post on Monday.
Flights were set to resume at 3 p.m. Pacific Time, the airline said.
The cancellations are just the latest example of the disruption caused by historic wildfires across California. Many West Coast residents have been struggling for a week or longer under some of the most unhealthy air on the planet, which turned skies. Dozens have so far.
The smoke closed businesses like Whole Foods and the iconic Powell's Books in Portland and suspended garbage pickup in some communities. Pollution and fire evacuations canceled online school and closed some college campuses in Oregon.
"It is so bad that you can likely smell (smoke) inside your house," said Sarah Present, the health officer for Clackamas, Multnomah and Washington counties. "In some areas, the air quality is so hazardous it is off the charts of the EPA's rating scale."
The Oregon Department of Environmental Quality's Air Quality Index is considered hazardous between 301 and 500. Over the past week, multiple Oregon cities have reported valued over 500, which are beyond the index's scale.
The acrid yellow-green smog may linger for days or weeks, scientists and forecasters said. It is also a sign of things to come. With human-caused climate change making wildfires more destructive, and more people living closer to areas that burn, smoke will likely shroud the sky more often in the future.