Decreases in ambient nitrogen dioxide and fine particulate matter (PM2.5) are associated with lower asthma incidence in children, according to a study published in the May 21 issue of the Journal of the American Medical Association.
Erika Garcia, Ph.D., from the University of Southern California in Los Angeles, and colleagues examined whether reducing regional air pollutants was associated with a lower incidence of childhood asthma in a multilevel longitudinal cohort drawn from three waves of the Southern California Children's Health Study. Each cohort was followed for eight years. Data were included for 4,140 children with no history of asthma.
The researchers identified 525 incident asthma cases. For nitrogen dioxide, the incidence rate ratio (IRR) for asthma was 0.80 for a median reduction of 4.3 parts per billion. The absolute incidence rate decrease was 0.83 cases per 100 person-years. For a median reduction of 8.1 µg/m² in PM2.5, the IRR for asthma was 0.81, with an absolute incident rate decrease of 1.53 cases per 100 person-years. No statistically significant associations were seen for ozone or PM10.
"This study also adds to the urgency of controlling ambient air pollution to benefit the next generation, and makes recent efforts to discredit and ignore evidence on health effects of ambient pollution even more concerning," write the authors of an accompanying editorial.
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