PORTLAND, Ore. (AP) — Dangerously dirty air spewing from the West Coast wildfires is seeping into homes and businesses, sneaking into cars through air conditioning vents and preventing people already shut away by the coronavirus pandemic from enjoying a walk or trip to the park.

People in Oregon, Washington state and California have been struggling for a week or longer under some of the most unhealthy air on the planet. 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 wildfires getting larger and more destructive because of climate change and more people living closer to areas that burn, smoke will likely shroud the sky more often in the future.

“I don’t think that we should be outside, but at the same time, we’ve been cooped up in the house already for months, so it’s kind of hard to dictate what’s good and what’s bad. I mean, we shouldn’t be outside period,” Portland resident Issa Ubidia-Luckett said Monday.

The hazy air 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. Values above 500 — which multiple Oregon cities have reported during the past week — are beyond the index’s scale.

The air quality agency extended an alert to Thursday, and the air was so thick that Alaska Airlines stopped flights to Portland and Spokane, Washington, until Tuesday afternoon.

Zoe Flanagan, who has lived in Portland for 12 years, braved the smog to walk her two dogs Monday. In desperation, she and her husband turned on the heater a day earlier because it has a better filter than their air conditioner.

“I can feel it in my chest, and then I just feel hungover despite not drinking,” she said. “I felt really hungover all day Saturday. I just couldn’t get enough water. I had a headache.”

Health officials urged people to stay inside and keep windows and doors closed. Smoke can irritate the eyes and lungs and worsen some medical conditions.