If California children growing up breathing in wildfire smoke end up showing the same patterns as kids raised inhaling bad air pollution, experts say they could wind up with reduced lung function and other health conditions several decades from now.

Scientists are also looking into whether children’s immune systems are negatively affected by the chemicals in wildfire smoke, and whether fetuses that develop during wildfires are at higher risk for neurodevelopmental disorders.

With smoke from California’s many late-summer fires causing unhealthy air days throughout the state, scientists and pediatricians are urging parents to keep their children indoors as much as possible.

Dr. Mary Prunicki, who studies air pollution and health at Stanford University, says young children are more susceptible to smoke than teens or adults, because their airways are smaller, and they’re more likely to be running around when they’re outside.

“Especially ages zero to four, we’ll see an increase in ER and hospital admissions for respiratory disorders in that young age group when there’s wildfire smoke exposure,” she said. “They are the more vulnerable population.” 

While some scientists say a few weeks of bad air every fall likely won’t create the same chronic health effects as year-round exposure, many feel that wildfire seasons growing longer  and more intense with every year is a huge concern for kids.

Lung Health

There are numerous studies showing children who are exposed to heavy pollution from vehicles and city smog develop more respiratory problems later in life than those who grew up in cleaner air.

Ed Avol, a professor of clinical medicine at the University of Southern California, helped conduct a landmark study of 12,000 California children, who researchers followed from 1990 until 2015. 

“Children growing up in more polluted areas have slower growing lungs and don’t attain the kind of lung health that other children grow to,” Avol said. “And we have no proof that those children catch up. If they don’t get that start early in life, they may always be at a disadvantage.”

Now, scientists are wondering if children exposed to prolonged wildfire smoke year after year will experience the same problems. LIke the smog that pollutes many major cities, wildfire smoke contains small particulate matter that can penetrate deep in the lungs and cause lasting damage.

Avol says it takes about 18 years for children’s lungs to fully develop, and even longer for chronic diseases such as lung cancer to emerge, so it could be decades until we know whether today’s kids are going to see long-term health issues.

There are also many unknowns about the effects of toxins from burnt-up homes and buildings carried in California’s wildfire smoke.

“Paints and solvents and the insulation … Look in your garage and what’s under your kitchen sink,” Avol said. “When all that burns there are many, many chemicals that are released into the air.”

Immune Health

Wild fire smoke has been shown to cause damage to children’s immune systems, at least in the short term.

Stanford University researchers recently studied 7-to-8-year-olds from Fresno who had been exposed to smoke in 2015. Of the participating children, some had been exposed to smoke from a controlled burn, some had been exposed to smoke from a wildfire, and some had been exposed to no smoke at all. 

Pollution levels were higher in the areas where wildfires burned, and blood tests performed on participants 90 days after exposure showed the children who breathed the wildfire smoke had lower levels of type-1 T helper cells, which boost immune response, then children in the other groups. The wildfire group also showed reduced activity in a gene that regulates allergies.

“So the changes can occur very quickly in the body,” said Dr. Prunicki of Stanford, who led the study. “We hope that [the helper cells] come back. Long term exposure to wildfires, the health impacts are not as well known.”

UC Davis researchers found that rhesus monkeys that were exposed to wildfire smoke as infants during the summer of 2008 had weaker immune responses by age three than infant monkeys who did not inhale smoke. Adult monkeys exposed to the same wildfire smoke did not suffer reduced immune responses, the study shows.

Neurodevelopment 

There may also be long-term impacts to women who are exposed to wildfire smoke during pregnancy and their children, researchers say. 

Scientists at UC Davis have been collecting blood, urine and other biological samples from women who had exposure to wildfire smoke while pregnant.

Epidemiologist Irva Hertz-Picciotto says one of the issues they want to track is whether the children of these women experience any neurodevelopmental disorders. She says the toxins in wildfire smoke could be inhaled by mothers and then pass through the fetal blood-brain barrier. 

“As the brain is forming, it could be a target for these chemicals,” she said. “One of the really important parts is that cells have to migrate to the right locations. If they don’t migrate at the right time, certain structures may not develop fully.”

There’s some research linking exposure to toxins in air pollution to autism, but the same connection hasn’t been made for wildfires. 

A recent study out of Colorado found that exposure to wildfire smoke during the second trimester of pregnancy was associated with preterm birth.

Hertz-Picciotto says pregnant women should be careful about breathing in wildfire smoke, particularly if the fire burned down homes or other structures.

“We know there are large numbers of chemicals that are not found in the ash samples from parks where vegetation burned,” she said. “That really does suggest we’re producing a kind of smoke that our evolution has not prepared us for.”

People who must go outside on bad air days can benefit from wearing a properly fitted N95 mask, though these are in short supply and are also needed for hospital workers treating COVID-19.

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