Trends in childhood and adolescent asthma burden attributable to nitrogen dioxide pollution: a global burden of disease analysis, 1990–2021

Asthma is a major cause of morbidity among children and adolescents, with nitrogen dioxide (NO₂) identified as a key traffic-related pollutant. We aimed to assess the trend and burden of asthma attributable to NO₂ exposure among children and adolescents aged 0–19 years, the global and regional burden between 1990 and 2021 by age, gender, SDI, and income. We analyzed Global Burden of Disease (GBD) 2021 data for children aged 0–19 years. Outcomes included disability-adjusted life years (DALYs) and age-standardized DALY rates per 100,000 with 95% uncertainty intervals (UIs). Estimates were stratified by age, sex, World Health Organization (WHO) regions, Socio-demographic Index (SDI), and income groups. Temporal changes were assessed using a 31-year cumulative percent change (CPC). Globally, NO₂-attributable asthma DALYs declined from 292,258 in 1990 to 176,734 in 2021, representing a 39.5% reduction in age-standardized rates. The steepest decline occurred among children aged 0–4 years (–47.2%), while the smallest decline was seen in the 5–9 years group (–37.2%). High-SDI and high-income regions showed sharp reductions, whereas Africa (+ 26.6%) and South-East Asia (+ 42.1%) recorded increases. Males consistently carried higher burdens, with reversals in adolescence in the high-SDI and Latin America & Caribbean regions. A rebound in 2021, especially in high-SDI countries, might be due to COVID-19-related disruptions. While cleaner air policies have reduced NO₂-attributable asthma in children, rising burdens in low-SDI regions highlight urgent needs for stronger emission control and equitable health interventions.