As Portland woke up to another sepia-toned sky this morning, several local restaurants have closed today due to air quality that has transitioned from "really, really bad" to borderline dangerous—including almost the entire Burgerville franchise.

The Vancouver, Wash.-based fast food chain is closing nearly all of its 39 locations in Oregon and Washington, the lone exception being its outpost at Portland International Airport.

In a press release, the company says it is "assessing all restaurant ventilation systems to ensure safe, comfortable working environments for employees" and will reopen dependent upon smoke conditions.

Burgerville is also donating $10,000 to the Wildfire Relief Funds of the United Way Columbia Willamette and Mid-Willamette Valley chapters.

Several other Portland-area restaurants have announced temporary closures, including Pine State Biscuits, Magna, Eem and Ava Gene's. Eater is keeping a running list of businesses that are closing either today or through the weekend.

At the time of publication, Portland has the worst air quality of any major city in the world, well surpassing the closest competitors, San Francisco and Seattle, which are also dealing with smoke from nearby wildfires. It is currently classified as "very unhealthy," and older adults, children and people with lung or heart disease are advised to stay indoors.