Scant data on smoky air’s health effects
Kaitlyn Daut was in her third trimester in October 2017, when the Wine Country fires spread to Solano County, not far from her Vacaville home.
Daut’s family and home survived the fire unscathed but she, like thousands of other Bay Area residents, spent days breathing smoky air caused by the wildfires. The same is happening now as the Camp Fire rages in Butte County, creating noxious air throughout much of Northern California. And climate experts say larger and more frequent blazes are likely to happen again.
“I was certainly worried,” said Daut, 28, who delivered her son Evan in December. “The smoke did affect me, and I thought, ‘Well, if I’m breathing in all these potential toxins, what is it
doing to my baby, since we are one system?’ ”
Evan, now 11 months old, is healthy and has not shown any signs of respiratory problems, Daut said. Still, she wonders if he may be more likely to develop asthma or experience other longer-term health effects from the fires. So last spring, when UC Davis researchers began recruiting Bay Area women who were pregnant at the time of the fires — or became pregnant shortly after — to try to answer that very question, Daut signed up. Researchers collected samples of her blood, breast milk and saliva, and saliva from Evan as well.
The study of pregnant women, and a second UC Davis study focusing on the general population, are among the first to try to uncover the long-term health effects of wildfire smoke exposure on people who lived in the fire zone and in surrounding counties, researchers said. Both are funded by the National Institute of Environmental Health Sciences, part of the National Institutes of Health, for two years.
There is little data on the long-term health impacts of wildfire smoke on the general population — those that would capture changes in one’s health 18 months or longer after exposure. This is in part because it’s difficult to conduct long-term studies on sporadic events, and because of a lag time in getting grants approved for event-specific research projects.
Most research has focused on how smoke exposure affects firefighters or how air pollution, not wildfire smoke specifically, affects people’s health. Many large studies have linked air pollution to heart and lung diseases; one 2012 study found that pregnant women who were exposed to smoke during the 2003 wildfires in Southern California delivered babies with slightly lower birth weight than normal.
“We knew these questions were on moms’ minds,” said Rebecca Schmidt, a UC Davis molecular epidemiologist who is leading the study of pregnant women. “It’s a particularly vulnerable time for the mom and the developing fetus, especially with recent fires hitting urban areas burning all kinds of plastics. Who knows what is going into the air?”
Schmidt’s team has collected specimen samples and survey responses from about 200 women from the 2017 North Bay fires, and it is seeking university approval to expand the study to include pregnant women from the Camp Fire.
The researchers are examining, among other things, what pregnant women did to limit their exposure, such as wearing masks. They are also looking at indirect health effects, such as prolonged stress from being displaced or losing family members or friends. They are just starting to analyze the data. Anecdotally, they have learned that some women delivered healthy babies while others did not — though that could be due to many factors other than the fires.
“We tell moms, ‘Right now we just don’t know,’ ” Schmidt said. “The flip side is the fetus is more protected than we think; maybe we’ll show there aren’t major effects. Either way, it’s good to know what they’ve done during the fires, any action they can take to limit their risk to exposure.”
Schmidt’s colleague Irva Hertz-Picciotto, a UC Davis environmental epidemiologist who is leading the study on the general population, has collected data from about 6,000 people from 2,000 households, mostly in Sonoma County. She is tracking whether they are experiencing respiratory problems, mental health issues like depression, trouble sleeping, and increased use of alcohol or cigarettes.
There are similarities between particles found in air pollution from fossil fuels and those found in wildfire smoke. Both contain toxic particles that are invisible to the naked eye that can penetrate into lung tissue and get into the bloodstream. These particles are 2.5 micrometers in size — about one-fortieth the width of a strand of hair. There are also differences, though, that scientists don’t fully understand.
When residential areas burn, they release chemicals into the atmosphere that aren’t emitted when wooded or grassy areas burn. Plastics, household cleaning products, metals from vaporized stoves and washing machines, and synthetic materials from carpets add to poor air conditions. Researchers don’t know what kind of long-term health conditions could be caused or exacerbated by exposure to these compounds.
“Our guess is that it’s much more toxic when that is involved, versus a pure forest fire,” said Dr. Mary Prunicki, an instructor at Stanford School of Medicine who has been studying the health effects of air pollution for five years and recently began shifting her focus to wildfires as they became more frequent. “But that’s not the easiest question to answer — what’s in wildfire smoke as opposed to air pollution caused by cars.”
One way to learn more about this could be to collect hair samples from people who were exposed to wildfire smoke, said Hertz-Picciotto, who is considering doing so for people who were close to the Camp Fire. Researchers know how quickly hair grows — about a fifth of an inch per month — and could work backward to see what chemicals someone was exposed to around the time of the fires. If small particles got into the bloodstream, they could eventually make their way to the hair follicles and into the hair shaft.
“My hope is we’ll be able to follow these people,” she said. “We also want to compare different neighborhoods — did the smoke affect people differently? Did recovery for people in wealthier neighborhoods who may have had better access to health care and resources to rebuild (differ)? We have a lot of questions we hope to answer.”