Attention-deficit hyperactivity disorder in children chronically exposed to high level of vehicular pollution

Abstract

The purpose of this study is to explore whether sustained exposure to vehicular air pollution affects the behavior and activities of children. The prevalence of attention-deficit hyperactivity disorder (ADHD) was assessed in two childhood populations. In a cross-sectional study 969 school-going children (9-17 years) and 850 age- and sex-matched children from rural areas were assessed, following the criteria of Diagnostic and Statistical Manual of conduct disorders (DSM-IV) of American Pediatric Association. Data of ambient particulate matter with a diameter of less than 10 μm (PM₁₀) were obtained from Central Pollution Control Board and aerosol monitor. ADHD was found in 11.0% of urban children in contrast to 2.7% of the control group (p < 0.001). Major risk factors were male gender, lower socioeconomic status, 12-14 year age group, and PM₁₀ level in breathing air. ADHD was more prevalent among boys both in urban and rural areas. It was prevalent among 18.0% of the boys enrolled in Delhi against 4.0% of the girls, giving a male/female ratio of 4.5:1. Inattentive type of ADHD was predominant followed by hyperactive-impulsive type and combined type of ADHD. Controlling potential confounder, ambient PM₁₀ level was positively correlated with ADHD (OR = 2.07; 95% CI, 1.08-3.99). The results of this study point to a possible association between air pollution and behavioral problems in children. Though gender, socioeconomic status, and age play a very important factor in ADHD prevalence, the association is highest and strongest between particulate pollution and prevalence of ADHD.