Long-term PM_2.5 exposure is associated with asthma prevalence and exhaled nitric oxide levels in children.

Abstract

Exhaled nitric oxide concentration (FENO) is a marker of airway inflammation. This study aimed to evaluate the association of air pollution exposure with FENO levels and asthma prevalence with respiratory symptoms in school children. We analyzed 4736 school children who reside in six townships near industrial areas in central Taiwan. We evaluated asthmatic symptoms, FENO, and conducted the environmental questionnaire. The personal exposure of PM_2.5, NO, and SO₂ was estimated using land-use regression models data on children's school and home addresses. Annual exposure to PM_2.5 was associated with increased odds of physician-diagnosed asthma (OR = 1.595), exercise-induced wheezing (OR = 1.726), itchy eyes (OR = 1.417), and current nasal problems (OR = 1.334) (P < 0.05). FENO levels in the absence of infection were positively correlated with age, previous wheezing, allergic rhinitis, atopic eczema, near the road, and for children with high exposure to PM_2.5 (P < 0.05). An increase of 1 μg/m³ PM_2.5 exposure was significantly associated with a 1.0% increase in FENO levels for children after adjusting for potential confounding variables, including exposures to NO and SO₂. Long-term exposures to PM_2.5 posed a significant risk of asthma prevalence and airway inflammation in a community-based population of children. Annual exposure to PM_2.5 was associated with increased odds of physician-diagnosed asthma and nasal problems and itchy eyes. Long-term exposures to PM2.5 were significantly associated with FENO levels after adjusting for potential confounding variables. This is first study to assess the association between FENO levels and long-term air pollution exposures in children near coal-based power plants. An increase of 1 μg/m³ annual PM_2.5 exposure was significantly associated with a 1.0% increase in FENO levels. Long-term exposures to PM2.5 posed a significant risk of asthma prevalence and airway inflammation in a community-based population of children.