Acute Effects of Air Pollution on Pulmonary Function, Airway Inflammation, and Oxidative Stress in Asthmatic Children

bacKgrOund: Air pollution is associated with respiratory symptoms, lung function decrements, and hospitalizations.However, there is little information about the influence of air pollution on lung injury.Objective: In this study we investigated acute effects of air pollution on pulmonary function and airway oxidative stress and inflammation in asthmatic children.MethOds: We studied 182 children with asthma, 9-14 years of age, for 4 weeks.Daily ambient concentrations of sulfur dioxide, nitrogen dioxide, ozone, and particulate matter ≤ 2.5 µm in aerodynamic diameter (PM 2.5 ) were monitored from two stations.Once a week we measured spirometry and fractional exhaled nitric oxide (Fe NO ), and determined thiobarbituric acid reactive substances (TBARS) and 8-isoprostane-two oxidative stress markers-and interleukin-6 (IL-6) in breath condensate.We tested associations using mixed-effects regression models, adjusting for confounding variables.results: Interquartile-range increases in 3-day average SO 2 (5.4 ppb), NO 2 (6.8 ppb), and PM 2.5 (5.4 µg/m 3 ) were associated with decreases in forced expiratory flow between 25% and 75% of forced vital capacity, with changes being -3.1% 95% confidence interval (CI), -5.8 to -0.3, -2.8% (95% CI, -4.8 to -0.8), and -3.0%(95% CI, -4.7 to -1.2), respectively.SO 2 , NO 2 , and PM 2.5 were associated with increases in TBARS, with changes being 36.2%(95% CI, 15.7 to 57.2), 21.8% (95% CI, 8.2 to 36.0), and 24.8% (95% CI, 10.8 to 39.4), respectively.Risk estimates appear to be larger in children not taking corticosteroids than in children taking corticosteroids.O 3 (5.3ppb) was not associated with health end points.Fe NO , 8-isoprostane, and IL-6 were not associated with air pollutants.cOnclusiOn: Air pollution may increase airway oxidative stress and decrease small airway function of asthmatic children.Inhaled corticosteroids may reduce oxidative stress and improve airway function.