As Los Angeles heads into its second week under siege from wildfires, growing concerns over the health impacts of the resulting smoke are coming to the forefront.
Unlike wildfires, which typically ravage remote forests and rural areas, California's recent fires have brought urban devastation into sharp focus. And while the destruction of homes and infrastructure is immediately apparent, the invisible toll on air quality from urban fires could pose a more insidious threat to residents and first responders.
"All smoke is bad," Rory Hadden, a fire science professor at the U.K.'s University of Edinburgh, told Newsweek. "Any time you see smoke from a fire, that pretty much always means it's got some very nasty stuff in it."
Firefighters watch water drops on the Palisades fire in Los Angeles' Mandeville Canyon on January 11. Toxic smoke from burning properties can pose additional health risks.Firefighters watch water drops on the Palisades fire in Los Angeles' Mandeville Canyon on January 11. Toxic smoke from burning properties can pose additional health risks.Eric Thayer/AP Photo
Why Is the Smoke in L.A. So Dangerous?
While the smoke from burning vegetation is already hazardous, urban fires in Los Angeles introduce additional toxins as buildings, vehicles and other synthetic materials combust. Plastics, in particular, are a significant concern.
"The reason that the plastic burning smell is so distinctive is because most plastics, as we use them, are not just carbon and hydrogen in the molecules of the plastic—there's other stuff in there," Hadden said.
Some of the hazardous substances that may be present in the smoke are fire retardants, hydrogen chloride, bromine compounds and hydrogen cyanide—a fatally toxic chemical asphyxiant in high enough doses.
Legacy asbestos, still found in older buildings, could also contribute to the toxic mix, according to the Mesothelioma Center, a patient advocacy organization.
"The amount of asbestos contamination across the entire area is immeasurable," Asbestos Disease Awareness Organization president and co-founder Linda Reinstein told the center.
The Challenge of Measuring Toxicity in the Smoke
Despite the dangers, the full extent of the threat is difficult to measure. Tools like the Air Quality Index (AQI) may not account for all the toxic substances released during urban fires, which can vary depending on what materials are burning.
"It's never the poison; it's always the dose," Hadden said. "It's difficult to say that smoke from a house is worse than wildfire smoke because it will all depend on how long you're exposed to the cocktail of different products that there are there."
There is some positive news, however. In areas like Altadena, where neighborhoods were consumed in mere hours, most fires burned so intensely that little remained smoldering afterward.
This rapid, high-intensity burning tends to push the smoke higher into the atmosphere, reducing its concentration at ground level, Hadden said.
Additionally, the strong Santa Ana winds, while fueling the fires, have also carried much of the smoke offshore and out to sea.
Hadden added, "It's a really complex picture, and we're really, as scientists, just at the beginning of understanding some of that stuff."
Smoke from the Los Angeles fires blows out into the ocean on January 7. Powerful Santa Ana winds fueled the fires but also pushed much of the smoke out to sea. Smoke from the Los Angeles fires blows out into the ocean on January 7. Powerful Santa Ana winds fueled the fires but also pushed much of the smoke out to sea. Wanmei Liang/NASA Earth Observatory
How to Stay Safe Amid Hazardous Air Pollution
The fires have destroyed over 12,000 structures in the past week, according to California's Department of Forestry and Fire Protection.
While air quality in the region has improved slightly with diminishing winds and increased fire containment, forecasters warn that more strong winds are expected in the coming days, heightening the risk of additional fires and more toxic smoke.
Officials are urging residents, particularly those with underlying health conditions, to take precautions. People are advised to stay indoors, limit physical activity and wear properly fitted respirator masks when venturing outside.
Across Southern California, residents are taking the warnings seriously. As AQIs climbed to hazardous levels, demand for air purifiers surged. By the end of last week, many Home Depot locations in central Los Angeles had completely sold out of air purifiers.
Meanwhile, the full impact of this toxic urban smoke may take years to fully understand.
"Predicting where ash or soot from a fire will travel, or how winds will impact air quality, is difficult, so it's important for everyone to stay aware of the air quality in your area, make plans, and take action to protect your health and your family's health," Muntu Davis, Los Angeles County's health officer, said in a statement Saturday.
"Smoke and ash can harm everyone, even those who are healthy," he added.
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