Portland choked and wheezed under putrid skies Tuesday, its residents breathing in its fourth day of unhealthy air in two weeks. People stayed indoors when they could, outdoor activities were cancelled or moved inside, and the city generally operated as normal under skies tinged with brown.

But in Southern Oregon, where wildfire smoke has been a daily reality for more than a month in places like Ashland and Medford, the impacts have been far greater.

Portland may consider itself lucky in comparison to other cities in the state, but experts say that luck will not hold. Severe wildfires, and the smoky skies that accompany them, will be far more common in the decades to come, and climate change, which will make summers hotter and drier, will greatly exacerbate their impact.

Smoke exhausts Ashland

If you want to get into the Ashland YMCA, you have to run a bit of a gantlet. After going through the front door, you weave through a series of twists and turns before reaching a second door to actually enter the facility.

The idea, said associate director Laurie Schaaf, is to prevent both doors from being open at the same time, a low-tech airlock to keep smoke at bay.

"It's been really bad for a long time," she said Monday. "People are just so tired of not being able to see the sun, of not being able to see the hills. It's exhausting."

After a clinic by the local fire department on wildfire smoke earlier this year, Schaaf said the YMCA knew it had to be prepared. Officials installed high-efficiency particulate air filters for the air conditioning system and purchased air purifiers. They also ordered an air curtain, which creates an invisible barrier to smoke, which they plan to install soon.

That they knew it was coming did not make it any easier on their members, Schaaf said.

Many of the folks who frequent the facility are older and use the YMCA as their primary place to get out of the house. Despite all the measures they have in place, Schaaf said they've seen a drop in attendance, especially among seniors.

"Our numbers are low in the older classes," she said. "When they do come, they are tired and lack motivation. The Y is their social connection and, without that, they suffer."

At the Oregon Shakespeare Festival, the internationally renowned theater company known for outdoor summer plays, the box office has been hit hard, spokeswoman Julie Cortez said.

The festival has had to either move or cancel 19 outdoor performances this year. Of those, eight were canceled altogether. The other 11 were moved to a theater at the local high school, which seats about 400. The outdoor theater accommodates three times as many.

For context, in the previous four years, the festival had to cancel or move 20 performances total because of smoke.

Cortez estimated that the festival has lost at least $1 million because of wildfire smoke.

"We're a nonprofit without big surpluses," she said. "It's a huge hit. And it's not over."

There are other indicators of the financial impact. Both Schaaf and Cortez said downtown Ashland, usually bustling at the height of summer tourism season, has frequently looked like a ghost town during the last month. Restaurants have fewer patrons and outdoor patios sit empty. One realtor had a seller take their house off the market until air quality improves.

A new normal?

Nationwide, 84 percent of fires are started by people. Others are started by lightning. Approximately none are started by climate change.

But climate change, which is predicted to bring hotter and drier summers to the western United States, can make fires bigger and more severe, and that greatly affects the number and duration of smoky days.

The length of the fire season has grown over the last four decades, from 23 days in the 1970s to 116 days in the 2000s, according to a 2017 report from the Oregon Climate Change Research Institute, based at Oregon State University in Corvallis.

"Smoke in the (Willamette) valley is going to become a more-common occurrence," said Kathie Dello, associate director of the institute.

A 2016 study from researchers at Harvard and Yale used a fire prediction model to differentiate pollution from wildfire smoke from other types of toxins in the air. They coined the term "smoke waves," which refers to two or more consecutive days of unhealthy levels of air specifically from wildfire pollution.

The study's authors found that, across 561 counties in the western U.S., more than half are expected to see longer and more intense smoke waves during the next 30 years. Between 2004 and 2009, the authors said, some 57 million people experienced at least one smoke wave. That number will jump by 43 percent by midcentury, they estimated.

Of those affected, roughly 13 million will be children or seniors, according to the study, among the most-vulnerable groups to the health impacts of smoke.

Just how much more common smoke waves become depends on a lot of factors, both complex and simple. On the simple side, smoke goes where wind pushes it, so whether a specific location is inundated will be affected by which way the gusts blow.

On the complex side, just how quickly the climate warms is dependent on how much greenhouse gas we pump into the atmosphere. Fewer emissions will result in less warming which will lessen the prevalence of dry fuels that exacerbate wildfires.

John Abatzoglou, a climatologist at the University of Idaho, cautioned against attaching terms like "the new normal" to bad smoke years.

"We're don't expect every year to be the great smoke outs we've had this year and last," he said. "But we will have bad years and the deck is being stacked for more years with bad air quality across the west."

The solutions, Dello said, are like the causes: they are both simple and complex. On the simple side, people in areas prone to wildfires and the accompanying smoke can work to make their communities less susceptible to fires by clearing space around their homes.

But the only real solution to the larger issue of worsening wildfires is to stem the tide of warming temperatures.

"The only way to do that is to reduce the amount of greenhouse gases on a global scale," she said.

-- Kale Williams

kwilliams@oregonian.com

503-294-4048