After the Fire: UCSF Experts Talk Air Pollution Risks

Not only did the recent North Bay fires devastate communities, they created unprecedented levels of air pollution in the Bay Area. Now that the smoke has cleared, are we in the clear?

The answer to that question isn’t universal, says John Balmes, MD, a UC San Francisco pulmonologist and an expert on the respiratory and cardiovascular effects of air pollutants. Some populations are more likely to be affected: the elderly, people with pre-existing respiratory conditions, and children.

“Young children take more breaths per minute and they’re more active,” Balmes says. “So they get a greater dose of the smoke relative to their size.” In addition, the lungs of youngsters are still developing.

The campfire scent in the air indicated that most of the smoke came from burning wood, he says, which releases toxic hydrocarbon particles into the air.

Most worrisome are so-called PM2.5 particles, tiny particulate matter small enough to lodge deep in the lung. These hydrocarbon particles chemically injure the lung tissue, causing inflammation.

While these particles are dangerous over a long period of time, the week or so of heavy pollution we experienced was likely not long enough to do worrisome damage to otherwise healthy kids, says Tracey Woodruff, director of UCSF’s Program on Reproductive Health and the Environment and former public policy advisor at the Environmental Protection Agency.

It’s also not enough to be a major concern to pregnant women, she says—but there could be minor consequences. Prenatal exposure to severe air pollution has been proven to impact fetal growth and preterm birth.

“We could see a small effect across the population—not major risks, but we could see a small dip in birth weight or a small rise in preterm birth,” Woodruff says. “Studies on the impact of these kinds of fires on pregnancies have definitely found subtle relationships.”

Though the majority of the smoke was from wood and grass burning, the fires also burned through neighborhoods and other areas with buildings, adding particles from cars, furniture, and other goods.

Just what particles were released from the manmade materials remains unclear. Woodruff is most concerned for people who will be directly exposed when they return to the area to clean up or rebuild.

“If you look at 9/11, while that is an extreme case, it’s an example of people going in to clean up without adequate protection. Many people got very sick because they were breathing in dust that was full of everything from shards of glass to asbestos to chemicals from the burnt materials,” Woodruff says. “Whether home-owners or professionals, people should check with the local, county, and state government authorities. They’re coordinating cleanup efforts to make sure that people are not harmed during the process.”

Learn how toxic chemicals can threaten children’s health. On December 5, Tracey Woodruff will speak at our upcoming Conversations on Children’s Health event. For more information or to RSVP, contact Alicja Zelazny at 510-428-3362 or

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