| Acute Effects of Air Pollution on Pulmonary Function, Airway Inflammation, and Oxidative Stress in Asthmatic Children Ling Liu,1 Raymond Poon,1 Li Chen,1 Anna-Maria Frescura,1 Paolo Montuschi,2 Giovanni Ciabattoni,2 Amanda Wheeler,1 and Robert Dales1 1Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Ontario, Canada; 2Department of Pharmacology, Faculty of Medicine, Catholic University of the Sacred Heart, Rome, Italy Abstract
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 (PM2.5) were monitored from two stations. Once a week we measured spirometry and fractional exhaled nitric oxide (FeNO) , 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 SO2 (5.4 ppb) , NO2 (6.8 ppb) , and PM2.5 (5.4 µg/m3) 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. SO2, NO2, and PM2.5 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. O3 (5.3 ppb) was not associated with health end points. FeNO, 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. Key words: air pollution, asthma, children, exhaled breath condensate, inflammation, oxidative stress, pulmonary function. Environ Health Perspect 117:668–674 (2009) . doi:10.1289/ehp.11813 available via http://dx.doi.org/ [Online 28 November 2008]
Address correspondence to L. Liu, Health Canada. A.L. 4903B, 269 Laurier Ave., Ottawa, Ontario, Canada K1A 0K9. Telephone: (613) 954-4457. Fax: (613) 948-8482. E-mail: ling_liu@hc-sc.gc.ca Supplemental Material is available online at http://www.ehponline.org/members/2008/11813/suppl.pdf We gratefully acknowledge S. De Pauw of Health Canada for coordinating the study, B. Nadeau and K.L. Ku for running laboratory assays, M. Smith-Doiron for preparing the map, and D. Stieb and P. Villeneuve for reviewing the manuscript. This study was funded by the Canada-the United States Border Air Quality Strategy. The authors declare they have no competing financial interests. Received 17 June 2008 ; accepted 28 November 2008.
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