The wildfire smoke in Bend and across Central and Eastern Oregon is likely to linger at least into Friday.

Earlier this week, the Oregon Department of Environmental Quality placed air-quality advisories on counties across Central and Eastern Oregon that were scheduled to expire at noon Thursday. That morning, however, Oregon DEQ extended the advisory an extra 24 hours.

Marilyn Lohmann, hydrologist with the National Weather Service’s Pendleton office, said winds out of the west are expected to push smoke in Oregon east and eventually out of the state entirely. But that has happened more slowly than originally anticipated.

“We are starting to see some improvement,” Lohmann said Thursday morning.

Bend, like much of Oregon, has struggled all week with smoke from massive wildfires in northern Washington and British Columbia. Lohmann said a combination of more large wildfires than normal in Canada and winds out of the north have pushed the smoke hundreds of miles south into Oregon.

The Willamette Valley saw unhealthy amounts of smoke as well, with smoke being pushed up against the Cascade Mountains before eventually being carried east. While prevailing winds out of the west are still expected to push the smoke out of the state, Lohmann said the process takes time.

In Bend, smoke levels spiked once more into the unhealthy range at about 6 p.m. Wednesday, staying in that range for much of the night and early morning, according to Oregon DEQ’s weather data.

Oregon’s wildfires, while small compared with some of the fires burning in Canada, aren’t helping. The Terwilliger Fire, burning in the Willamette National Forest between Bend and Eugene, grew to more than 3,200 acres Thursday morning, with just 1 percent containment, according to the fire information site InciWeb.

The Stubblefield Fire, burning northeast of Bend, has grown to 57,703 acres and is 70 percent contained.

Katherine Benenati, DEQ spokeswoman, said smoke from the various fires is mixing in the atmosphere, contributing to the haze over much of the state.

“There’s plenty of smoke to go around,” Benenati said.

So far, four people have checked into St. Charles Bend with respiratory emergencies related to the latest round of smoke, including three on Thursday, according to Michelle Robinson, manager of the Bend Emergency Department at the hospital. Robinson said the patients had asthma or other pre-existing respiratory conditions that were aggravated by the smoke. While the hospital can treat smoke-related issues with steroids or nebulizers, Robinson said the best option is avoiding the smoke as much as possible.

While Lohmann said changing wind patterns could blow smoke from fires in other areas, including Southern Oregon, into Central Oregon, she said the current haze should dissipate somewhat Friday.

“Overall, conditions are likely to improve by the weekend,” she said.

— Reporter: 541-617-7818, shamway@bendbulletin.com