FRESNO, Calif. -- The fires sweeping across millions of acres in California aren't just incinerating trees and houses. They're also filling the lungs of California's children with smoke, with potentially grave effects over the course of their lives.
The effect is not evenly felt. While California as a whole has seen a steady uptick in smoke days in recent years, counties in the state's Central Valley, which is already cursed with some of the most polluted air, were particularly hard-hit by wildfire smoke this year.
So for a child, it matters where you live. It matters how much foul air you breathe in on days when there are no fires at all. It matters whether your family can afford an air purifier at home or whether they can whisk you away when ash rains down from the sky.
Dr. Kari Nadeau, a professor of medicine at Stanford who specializes in pediatric allergies and asthma, said she worried that the damage to children might last a very long time. It is well-established that long-term exposure to fine particulate matter pollution, the kind that comes out of the tailpipes of cars and trucks, increases the risk of asthma in children and compromises their immune systems.
Her latest research suggests that exposure to wildfire smoke, which contains the same particulate pollution and more, is associated with genetic changes in children's immune cells. "It could," she said, "have irreversible consequences."
Already, an estimated 7.6 million children are exposed to wildfire smoke every year in the United States, and with climate change making the American West hotter and drier, many more children stand to be at risk.
"This is a problem that's not going to go away," Nadeau said. "We are going to see these very extreme weather conditions, and we should be prepared."
Patricio Gonzalez, 12 and a seventh grader, lives with his parents and two younger siblings in a neighborhood flanked by several busy roads, an airport and agricultural fields that fill the air with dust.
Patricio has asthma. Even when there are no fires, there have been times when the air in California's Central Valley is so thick with pollutants that he wheezes and struggles for air or suffers from a rash of respiratory infections. The fires are an additional assault.
"Everything about this area screams bad air quality," Patricio said. "If you had a child with asthma or any person in your household with asthma and you wanted to move into this area, it's not a good idea. I don't recommend it."
It's been a rough year. First, remote schooling because of the pandemic. Then a heat wave, with temperatures peaking above 100 degrees. Then, in mid-August, fires burning to the north and east, pouring smoke into the valley.
Ash settled over every tree. The air smelled like charcoal. Patricio looked outside and told his mother, Gilda Zarate-Gonzalez, that he felt an "impending sense of doom."
Even by mid-October, when the smoke had subsided enough for Zarate-Gonzalez to propose a family bike ride, it looked as if someone had taken a giant gray crayon and smeared it across the horizon.
Fresno and its neighboring counties in the Central Valley rank first in the country for particulate matter pollution, according to the American Lung Association. Its childhood asthma rates are far higher than the statewide average. Several busy highways pass through Fresno. Dust and chemicals swirl up from the fields. Smoke gets stuck for long stretches of time until the winds can blow it westward to the Pacific.
Fresno County has had more smoke days than any other county in the state this year, the culmination of a steady rise over the past 10 years, according to data collected from the National Oceanic and Atmospheric Administration and analyzed by Stanford researchers. Through mid-November, there were 152 days when at least some part of the county was blanketed in smoke. Bay Area counties had about half the number of smoke days.
Fresno is 55% Hispanic; 18% of its population lives below the poverty line. San Francisco, by contrast, is largely white and Asian, with 10% of its population living below the poverty line.
Zarate-Gonzalez, who has a master's in public health and is earning a doctorate, wants local officials to do more to cut the risks: Reduce traffic, for instance, when wildfire smoke worsens air pollution, and improve the ventilation system in public school buildings.
For now, it falls to her to adapt. She closes the windows of their two-bedroom house so outdoor air doesn't get in. She changes the air conditioner filter often. She has an air purifier that travels from room to room with Patricio. She would like to buy two more, but that will have to wait until they go on sale.
It upsets her that, through no fault of his own, Patricio can't play outdoors when his siblings can. "We just show him we adore him and love him and that's the reason he can't go outside," she said. "When the air is that bad and we are adding the fires to it, it's not a good idea."