The 2008 wildfire season in California was a terrible one. Just like this year, air quality alerts were triggered across the northern part of the state, and even hundreds of miles from the actual fires, the air was filled with smoke. In the midst of this, 50 baby monkeys were born. They spent their first months of life outside, breathing that choking, sooty air. Now, they are one of the best sources we have for information about the long-term effects wildfires can have on public health. The results are … not comforting.
The current batch of California wildfires has reminded us of the acute short-term dangers of smoke inhalation. But the danger doesn’t stop there. A growing body of evidence suggests that wildfire smoke — whether from a single event or from multiple, recurrent exposures over several years — can have a big impact on children, increasing both individual risk of serious cardiovascular and respiratory illness later in life and the percentage of the adult population at higher risk of life-threatening breathing problems when new fires occur. As climate change increases the likelihood and size of wildfires in the western U.S., scientists say the next generation will likely find its biological future shaped by the choices of the past.
We are only beginning to understand how wildfire exposure causes chronic illness, scientists told me. Jeff Schlegelmilch, deputy director of the National Center for Disaster Preparedness at Columbia University, compared our understanding to a Monet painting — impressions that start to give you an idea that there’s a problem, even if the details are still fuzzy.
What happened to the monkeys is far clearer.
Nobody planned to expose newborn rhesus macaques to wildfire smoke, said Lisa Miller, who leads the respiratory diseases unit at the California National Primate Research Center. Instead, the monkeys happened to be born just before the 2008 fires began, in an outdoor enclosure at the center, which is part of the University of California at Davis, near Sacramento.
The monkeys were exposed to the smoke in the same way as the humans who lived and worked alongside them. But the monkeys were born as research subjects, so scientists like Miller have been able to follow them over the course of their lives — monitoring their health and regularly testing their lung function. The researchers have also compared the monkeys born in 2008 with 50 monkeys that were born in the same place but a year later, when there was no wildfire smoke hovering over the site. By age 3, the monkeys who had spent infancy in a wildfire haze had less lung capacity, stiffer lungs that couldn’t stretch as far when they breathed and reduced immune system function, compared with the second group of monkeys at the same age.
Exposure to wildfire smoke early in life seems to alter the way human lungs grow, Miller said. That’s especially the case in the alveoli — tiny sacs in the lungs that look like grape clusters and help absorb oxygen and release carbon dioxide. Humans are still adding alveoli throughout childhood, and breathing in air pollution seems to make them grow sparsely and in wonky ways. If those alveoli can’t work like they should, she said, children can grow up with a greater risk for lung diseases and infections — both of which also make their lungs less able to tolerate exposure to wildfire smoke later in life. Instead of healthy adults who can recover and adapt, they’re more likely to have trouble breathing, develop infections and even die. “It’s a vicious circle,” Miller said.
These findings are consistent with a series of studies that have shown that human children who grow up in areas with a lot of air pollution end up with lungs that don’t work as well as the lungs of kids who grow up breathing cleaner air. But those studies are looking at daily, years-long exposure.
The monkeys, on the other hand … “The adults now have evidence of early interstitial lung disease, and that’s just exposure to one fire season,” Miller said.
It’s not totally clear yet why a single summer can have such an outsized impact on a monkey’s whole life, how that might translate to humans or how best to protect human children. Although public health efforts have focused on passing out masks, those sources of protection can, themselves, inhibit children’s breathing in dangerous ways, Schlegelmilch said. The best course of action is probably to take kids someplace where the air is clean — something only a few, privileged families can realistically do.
But as evidence mounts and fires become more frequent, he said, the field of disaster preparedness is being forced to shift from thinking just about immediate triage to grappling with how to prevent a bad month from damaging a person’s entire life. The future of California is likely to involve more fires, more children exposed to wildfire smoke, and more families and communities that have to deal with the long-term consequences. Just stabilizing an immediate situation may no longer be sufficient to prevent disaster.