When it comes to wildfires, the people of Wenatchee remember 2012.

The air was so choked with smoke that summer camps were canceled and kids kept inside. Clinics and drug stores ran out of masks.

Anastazia Burnett was pregnant with her first child that summer. More than once, asthma attacks drove her to the walk-in clinic for emergency treatment.

It was scary, she said, “because when your blood oxygen is low, your baby’s blood oxygen is low, too.”

Climate change is advancing. Snowpack is decreasing, and summers are hotter and drier. A century’s worth of fire suppression has left forests overloaded with fuel. All of that is creating the conditions for wildfires to spread quickly and widely and burn huge trees along with the underbrush. Fire seasons are now 105 days longer in the western U.S. than they were in the 1970s. And longer wildfire seasons means more smoke pouring into cities and towns.

Although air quality has generally improved across the U.S. since the passage of the Clean Air Act, air quality is getting worse in large swathes of the West during fire season. That is a major threat to public health, because air pollution aggravates conditions like asthma and emphysema, and it can harm healthy people.

Dan Jaffe, a professor at the University of Washington Bothell, published a paper this summer that showed the most polluted days of the year are even more polluted in the Intermountain West.

A separate look at air quality data by the non-advocacy news and science organization Climate Central researchers found a similar trend: In Washington, Oregon and California’s Central Valley, a higher percentage of poor air quality days are occurring during wildfire season.

“These effects are very clearly linked to climate change,” Jaffe says — which means as climate change advances air quality is likely to get worse.

Poor air quality is unavoidable for everyone.

“When the air quality is bad, we don’t get breaks until ... the fires get contained or the wind shifts,” says Dr. Craig Kunz, a pulmonologist in Wenatchee. “It’s more of a constant exposure that you can’t really avoid.”

Public health officials advise people to stay inside during smoke waves, but people still have to go outside for groceries, medications, and doctor visits. That was true for Burnett, whose asthma flared up during the wildfires.

“Your chest starts to feel tight, and then it will get tighter and tighter, and you feel really short of breath like you’ve been running a lot,” Burnett said. “It just doesn’t go away.”

People with lung conditions are more likely to refill their prescriptions, go to the doctor, and be hospitalized during wildfires. Researchers with the EPA estimate that, between hospital admissions, emergency room visits, and premature deaths, wildfire smoke exposure costs the U.S. between $11 billion and $20 billion per year.

People with pre-existing conditions aren’t the only ones who are affected. Children are also vulnerable because their lungs are developing. Low-income people are at risk as well, in part because they’re less likely to have well-sealed homes and air conditioning.

When pregnant mothers are exposed to wildfire smoke, there’s a “small but significant decline in birth weight,” says Colleen Reid, a geography professor at the University of Colorado in Boulder who researches the public health effects of wildfire smoke.

Reid says scientists haven’t finished teasing out all the other potential health effects of wildfire smoke. They’re most worried about PM2.5, a component of wildfire smoke and other sources of air pollution that is so small it can make its way into human lungs and bloodstream.

Other, more extensively studied sources of air pollution are known to harm cardiovascular health and can increase the risk of obesity and diabetes.

“What we’ve wondered is can these really high air pollution but short time period events such as wildfires impact the cardiovascular system in the same way that chronic long-term exposure to lower levels of air pollution can,” Reid says. Some of the studies that have looked at that question have found an impact — and some have not.

Changing fire strategies

Some researchers suggest one way to help the communities hit hardest by smoke would be to change how forests are managed.

By setting prescribed fires during the shoulder seasons, forest managers could reduce the risk of summer megafires, while burning the forest at times when the wind will carry smoke away from major population centers.

Prescribed fires produce less pollution per acre than wildfires, adds Janice Peterson, an expert on wildfire smoke and air quality with the Forest Service. That’s because they’re set when the forest is wetter, so they don’t burn the forest crown or smolder in the forest floor.

Even if prescribed fires would be beneficial in the long-term, though, there are obstacles to setting them.

“If wildfire smoke pollutes the community for days on end,” Peterson said, “nobody is responsible. Nobody gets in trouble.” But, if the Forest Service sets a fire and there’s smoke for a few hours or a couple of days, “we do get in trouble for that.”

Peterson says Washington’s Methow Valley and Bend, Oregon, are particularly resistant to having to deal with any smoke from prescribed fires. Both locations depend on year-round outdoor tourism to fuel their economies, and, in recent years, they’ve attracted upper-income residents and vacation-home owners.

Both Washington and Oregon have strict smoke management plans that side with communities like the Methow Valley and Bend.

“We don’t burn the amount of acres we would like to,” Peterson said. “There’s too much concern about affecting public air quality.”

After the severe wildfires of 2014 and 2015, the Washington State Legislature asked the Department of Natural Resources to update the smoke management plan to make it easier to set prescribed fires.

From a public health standpoint, Kunz, the pulmonologist, says short-lived smoke exposure is better than out-of-control wildfires.

With prolonged exposure, he said, patients with lung diseases get much worse, and patients who have never had lung problems see him for the first time.

“I don’t see patients when they’ve had short-term smoke exposure,” he said.

In the Wenatchee Valley, the smoke came later than usual this year, but it’s here. The early-August air is thick and stings after a walk outside.

Anastazia Burnett can normally see the Cascades out her back window, but today smoke obscures the view. “When I opened up the hatchback of my car, you could see ash falling,” she said.

When the smoke gets bad, Burnett keeps her kids, ages 5 and 2, indoors. She has an air filter in the living room. She says, sure, they get cabin fever, but summer smoke east of the Cascades is like rain in western Washington: a fact of life.

“If every year were as bad as 2012,” she said, “I would definitely consider moving.” This story was produced through a partnership with Climate Central, a non-advocacy group that researches and reports on the changing climate. Climate Central reporter Maya Miller contributed to this report.