Published ahead of print on July 19, 2007, doi:10.1164/rccm.200611-1616OC Am. J. Respir. Crit. Care Med., Volume 176, Number 12, December 2007, 1236-1242 A more recent version of this article appeared on December 15, 2007
Submitted on November 9, 2006 Traffic-Related Exposures, Airway Function, Inflammation and Respiratory Symptoms in ChildrenFernando Holguin1*,1 Department of Pulmonary and Critical Care, Emory University, Atlanta, Georgia, USA, 2 Department of Environmental Health, National Institute of Public Health, Cuernavaca, Morelos, Mexico, 3 Zev Ross Spatial Analysis, Ithaca, New York, USA, 4 Department of Chemistry and Biochemistry, University of California San Diego, San Diego, California, USA, 5 Department of Atmospheric Sciences, Massachusetts Institute of Technology, Cambridge, Mass, USA, 6 United States Environmental Protection Agency, El Paso, Texas, USA, 7 Division of Environmental Health Sciences, University of California at Berkley, Berkley, California, USA, 8 Department of Preventive Medicine, University of Southern California, Los Angeles, California, USA * To whom correspondence should be addressed. E-mail: fch5{at}cdc.gov.
Introduction: Traffic-related emissions have been associated with respiratory symptoms in some studies. However, there is limited information on how traffic-related emissions relate to lung function and airway inflammation. Objective: Determine the differential association of traffic-related exposures with exhaled nitric oxide (NO) and lung volumes and symptoms in asthmatic and non-asthmatic children. Methods: Longitudinal study of 200 children from ages 6 to 12 years of which half had a physician-diagnosed asthma. Two-week NO2, and 48h average levels of elemental carbon (EC) and PM2.5 (particulate matter < 2.5 µm) were measured at participating schools. Road and traffic densities were determined at schools and each participant's house. Results: In children with asthma, an interquartile increase in road density within the 50, 100, and 200 meter home buffer areas was associated with increased exhaled NO (50m = 28%, [p=0.03 95% C.I. 3 - 60%]; 100m = 27%, [p=0.005, 95% CI, 8 - 49%]; 200m=17%, [p=0.09, 95% CI -2 - 40%]), and reduced FEV1 L (50m = -0.091, [p=0.038, 95% CI - 0.174 - -0.007]; 100m = -0.072, [p=-0.028, 95% CI -0.134 - -0.009]; 200m = -0.106, [p=0.002, 95% CI -0.171 - -0.041]). Exposure to NO2 at schools was marginally associated with reduced FEV1 (-0.020, p=0.060 [95% CI -0.042-0.001]). We did not observe significant associations with PM2.5 or elemental carbon on exhaled NO. Also, we did not observe significant reductions in lung volumes or changes in exhaled NO among healthy children. Conclusions: Vehicular traffic-exposures are associated with increased levels of exhaled NO, and reduced lung volumes in children with asthma. Key words: Air pollution, traffic, asthma, exhaled nitric oxide
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