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Crosscurrents is our award-winning radio news magazine, broadcasting Mondays through Thursdays at 5 p.m. on 91.7 FM. We make joyful, informative stories that engage people across the economic, social, and cultural divides in our community. Listen to full episodes at kalw.org/crosscurrents

Study shows more smoky days could also mean more preterm births.

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irlenginerd / Flickr Creative Commons
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California wildfire smoke encroaches on a residential neighborhood

Kai Frolich is playing with her six-month-old baby, Poppy. Poppy’s big blue eyes search around the room, and widen at new shapes and colors. She smiles when Kai sings to her.

Kai lives Truckee, California and had Poppy in April. She was 5 weeks early.

“I was thirty five weeks pregnant and my water broke in the middle of the night. And at that point, there's just no turning back,” she says.

After she was born, little Poppy was breathing too rapidly. She had to ride in an ambulance to a Reno Hospital, and she stayed there, in the NICU, for a few weeks before she could come home.

“It was just really hard. For us, living in a small town in the mountains, it means that you leave the hospital and your baby goes in an ambulance without you. With this team of medical staff that work in a hospital that you've never been to drives your hours-old infant down to the NICU. It was so scary.”

Kai’s doctor said they don’t know why she gave birth so early. But there’s one thing that has been on her mind, and it has to do with when she first found out she was pregnant, in August 2020.

“There was a pretty intense wildfire season, and it didn't really let up for about six weeks. And I think that I got pregnant right around then, like right in the middle of August that year,” Kai says.

And then they were in wildfire smoke pretty consistently for weeks after.

The 2020 wildfire season was a record setting one –– over 4 million acres burned across the state. Kai’s family took precautions, like checking the air quality indexes, and wearing N95 masks.

“Really not going outside, not having the windows open, making sure that we had air purifiers.”

But now, she wonders if that was enough, and if all that smoke made Poppy come early. A new study backs up Kai’s theory. Stanford researchers found that breathing in wildfire smoke can increase the risk of giving birth early. That matters because preterm birth can cause a whole range of complications –– from short term breathing problems, heart issues, a high risk of infection to things like learning disabilities, and cerebral palsy. In this study, the cause essentially all boils down to pollution.

“And if you care about pollution in California and in the United States, and that means that you have to care about wildfires,” says Stanford researcher and study author Sam Heft-Neal. He says growing up in Northern California, he always felt lucky to live in a place with clean air. And It’s true. Over the last few decades, the U.S. and California have managed to reduce their air pollution by stricter laws and regulations. Cars are cleaner, there are limits on coal power plants.

“But in the last few years, what we've seen is that these 30-year declines in pollution are all of a sudden starting to be reversed in the western U.S. because you get these huge emissions from these large scale wildfires,” Heft-Neal says.

And so, in the last five years, Californians have been seeing daily pollution levels that are among the highest in the world, all because of wildfires. And even though wildfire smoke may seem more natural than say the dirty cloud of smoke you can picture pumping out of a factory, it’s still pollution. And when scientists are studying pollution, it’s important to pay attention to something called PM 2.5s.

“They’re really small particles that are just a fraction of the size of a single human hair,” Heft-Neal says.

If you use an air quality tracker like Purple Air during wildfire season, part of what you're looking at is PM 2.5. And the scientific community knows that they’re not healthy, regardless of the source.

“Because they're so small, they're really good at getting inside our body and getting to places where they shouldn't be causing inflammation,” he says.

They can cause premature death, worsening dementia, respiratory issues, and cardiovascular problems. And while there’s not enough research to say for sure that breathing in wildfire smoke is as bad as breathing coal power plant emissions, Heft-Neal says think about what else burns in a wildfire besides wood.

“It's also household chemicals,plastics and everything that is being burned up when a house burns.”

PM 2.5s are especially unhealthy for young kids, the elderly, and pregnant people. Going into the study Heft-Neal knew that exposure from other sources, like power plants can cause preterm birth.

“And so it's only natural that exposure to wildfire smoke could also have similar effects,” he says.

So they did their study in California to see if they could predict preterm birth, and they did.

Here’s how the study worked. They looked at millions of California birth records from 2006 to 2012, all across the state. The study didn’t include twins, because they have a higher risk of preterm birth anyway. Then, they looked back at PM2.5 data and satellite images of smoke plumes. That’s to see smoke was overhead and how intense it was on any given day in a pregnancy. And what they found was every day of wildfire smoke increased the chances for an early birth. Exposure during the second trimester was the worst.

“We estimated 7000 preterm births were attributable to wildfire smoke during the six year study,” Heft-Neal says.

And here’s something that’s unusual for pollution studies: researchers found there was no difference across socio economic backgrounds. It didn’t matter where you lived, wildfire smoke affected all pregnant people. Since the end of this study in 2012 wildfires have gotten more common, and more intense.  

“2020 was about 2.5 times worse than the worst year in our study period.”

So he thinks the estimates in the study could be really low.

With more funding, Heft-Neal and other researchers plan to look at the more recent wildfire years, like the year Kai Frolich had Poppy.

And while her first month was rough, Poppy is growing quickly, without any health problems. But Kai’s already thinking about the next fire season. She says, breathing in wildfire smoke can’t be great on a six-month-olds lungs, either.

“You know, we've actually just made the decision to move back to the East Coast because we don't really think it's sustainable to live in really hazardous air every summer,” she says.

And Unfortunately, it just seems to be getting worse.