California’s wildfire season has kicked off in earnest, with the Oak Fire chewing extraordinarily quickly through the parched landscape around Yosemite National Park. The fire has burned nearly 17,000 acres so far, forcing thousands from their homes and blanketing the surrounding area in smoke.
For millions of years, the creatures of Earth have dealt with wildfire smoke, a noxious blend of particulate matter and toxic gasses. They’ve had to, really: Lightning ignites wildfires, and occasional small blazes actually result in a net benefit by resetting the ecosystem for new growth.
No longer. A variety of factors—including climate change, a history of fire suppression, and growing human populations—have conspired to turn what were once mild blazes into monsters like the Oak Fire. And that means more smoke, and longer exposure to gasses like carbon monoxide and dioxide, benzene, formaldehyde, and ozone. It also increases exposure to the soot carried in the cloud, which can contain solids like lead, cadmium, and polyaromatic hydrocarbons. Scientists know how this smoke affects human health, exacerbating asthma and other respiratory problems, but they know almost nothing about other species. As wildfires grow bigger and more intense, researchers are racing to figure out how birds, nonhuman primates, and livestock might be suffering—and the early results are troubling.