Planned burns are human-made events and as such need to follow all environmental compliance rules. That includes the Clean Air Act, which limits the emission of PM 2.5, or fine particulate matter, from human-caused events. In California, those rules are enforced by CARB, the state’s mighty air resources board, and its local affiliates. “I’ve talked to many prescribed fire managers, particularly in the Sierra Nevada over the years, who’ve told me, ‘Yeah, we’ve spent thousands and thousands of dollars to get all geared up to do a prescribed burn,’ and then they get shut down.” Maybe there’s too much smog that day from agricultural emissions in the Central Valley, or even too many locals complain that they don’t like smoke. Reforms after the epic 2017 and 2018 fire seasons led to some loosening of the CARB/prescribed fire rules, but we still have a long way to go.
“One thing to keep in mind is that air-quality impacts from prescribed burning are minuscule compared to what you’re experiencing right now,” said Matthew Hurteau, associate professor of biology at University of New Mexico and director of the Earth Systems Ecology Lab, which looks at how climate change will impact forest systems. With prescribed burns, people can plan ahead: get out of town, install a HEPA filter in their house, make a rational plan to live with smoke.