Alaska Airlines has suspended all flights in and out of Portland until Tuesday afternoon, as wildfire smoke inundates the region. It’s also shutting down operations in Spokane, Eugene, Medford, Redmond, Pasco and Walla Walla.

“Across the West, fires are creating thick smoke and haze, causing very poor air quality conditions in the Portland and Spokane areas,” Alaska said in a statement Monday. “We made the difficult decision to stop our operation so that our employees and guests can remain safe.”

Alaska is the busiest airline serving PDX. It wasn’t immediately clear if other airlines will take similar steps. The airline said the decision affects “dozens of flights.”

“Improving weather conditions in the coming days could begin to dissipate smoke in Portland and Spokane,” Alaska said. “However, other airports in the West could be impacted by drifting smoke.”