How harmful are low levels of lead exposure to children's human capital development? We provide new causal evidence by exploiting a post-2007 surge in piston-engine aircraft activity, the largest remaining source of airborne lead emissions in the United States, driven by flight-training demand. Using a triple-differences design and longitudinal administrative data, we find that students attending schools within one mile of high-surge airports score 0.168 standard deviations lower on reading tests and are 6% and 25% less likely to graduate from high school and enroll in a public university, respectively. Estimated effects on behavioral outcomes are small and statistically insignificant.