Wildfires in Western North America are becoming more severe, harming people, the environment, and undoing years of air quality progress. Prescribed burns—small, controlled fires—can help reduce future wildfire risk, but they also produce smoke, raising concerns about short-term air quality impacts. This study uses 20 years of satellite data from California to measure the long-term effects of low-severity fire, a stand-in for prescribed burning. The findings show that areas treated with low-severity fire had a 92% immediate drop in the chance of very severe wildfire, with reduced risk lasting up to 10 years and extending to areas up to 5 kilometers away.Importantly, the smoke avoided from fewer severe wildfires far outweighs the smoke produced by the initial treatments. The benefits exceed the costs by more than six to one over a decade, even with conservative assumptions. If California had treated 500,000 acres annually for 10 years, wildfire smoke pollution would have been cut by about 23%. In short, expanding prescribed fire could be a highly effective way to improve long-term air quality while reducing the risk of severe wildfires.