Long-term air pollution exposure and childhood ADHD prevalence

Fine particulate air pollution ( \(\hbox {PM}_{2.5}\) ) in the United States has fallen by roughly half since 2000, yet health outcomes may reflect pollution exposures accumulated over longer time scales. Using years of U.S. county-level data, we relate annual \(\hbox {PM}_{2.5}\) estimates to birth outcomes, diabetes prevalence, and small-area estimates of childhood attention-deficit/hyperactivity disorder (ADHD) across short and long time scales. Whereas associations with low birth weight and the apparent lag pattern for diabetes were substantially attenuated after accounting for county-specific temporal trends, the association between long-term \(\hbox {PM}_{2.5}\) exposure and childhood ADHD prevalence across 3,106 counties remained robust to socioeconomic and demographic adjustment, state-level heterogeneity, alternative exposure periods, and explicit spatial modeling. After accounting for residual spatial dependence, a 1 \(\mu\) g/ \(\hbox {m}^3\) increase in mean \(\hbox {PM}_{2.5}\) exposure over 2005–2015 was associated with a 0.312 percentage-point higher ADHD prevalence (SE = 0.058, \(p < 0.001\) ). These results identify a robust ecological association between long-term county-level \(\hbox {PM}_{2.5}\) exposure and childhood ADHD prevalence across the United States.