Differential patterns of association between PM1 and PM2.5 with symptoms of attention deficit hyperactivity disorder

Few studies have evaluated the association between ambient particulate matter (PM) exposure and childhood attention deficit hyperactivity disorder (ADHD). We explored associations between long-term exposure to ambient PM1 and PM2.5 (particles with airborne diameters of <1 µm and <2.5 µm, respectively) with positive screening for ADHD among 164,081 school-aged children in China. Parents or guardians completed a checklist using DSM-IV, and PM1 and PM2.5 exposures linked via residential addresses were estimated using a spatial statistical model. Long-term exposure to higher ambient PM1 (odds ratio = 1.74; 95% confidence interval = 1.47–2.06 per 10.0 μg m–3) and PM2.5 (odds ratio = 1.65; 95% confidence interval = 1.45–1.88 per 10.0 μg m–3) was associated with greater odds of screening positive for ADHD. The associations were heterogenous across regions, with stronger associations for PM1 exposure than for PM2.5. Our findings highlight the potential importance of ambient PM mass concentrations, sizes, components and sources for protecting children’s neurological health in China, and in the design of interventions to decrease the health burden of children’s ADHD. This large study, conducted in school-aged children in China, evaluates the relationship between long-term exposure to ambient particulate matter and positive screening for attention deficit hyperactivity disorder (ADHD). The authors report stronger associations between ADHD and PM1 exposure than between ADHD and PM2.5.