Dog Ownership Enhances Symptomatic Responses to Air Pollution in Children with Asthma Rob McConnell,1 Kiros Berhane,1 Jassy Molitor,1 Frank Gilliland,1 Nino Künzli,1 Peter S. Thorne,2 Duncan Thomas,1 W. James Gauderman,1 Edward Avol,1 Fred Lurmann,3 Edward Rappaport,1 Michael Jerrett,1 and John M. Peters1 1Department of Preventive Medicine, University of Southern California, Los Angeles, California, USA; 2Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa, USA; 3Sonoma Technology, Inc., Petaluma, California, USA Abstract Background: Experimental data suggest that asthma exacerbation by ambient air pollutants is enhanced by exposure to endotoxin and allergens ; however, there is little supporting epidemiologic evidence. Methods: We evaluated whether the association of exposure to air pollution with annual prevalence of chronic cough, phlegm production, or bronchitis was modified by dog and cat ownership (indicators of allergen and endotoxin exposure) . The study population consisted of 475 Southern California children with asthma from a longitudinal cohort of participants in the Children's Health Study. We estimated average annual ambient exposure to nitrogen dioxide, ozone, particulate matter < 10, 2.5, and 10–2.5 µm in aerodynamic diameter (PM10, PM2.5, and PM10–2.5, respectively) , elemental and organic carbon, and acid vapor from monitoring stations in each of the 12 study communities. Multivariate models were used to examine the effect of yearly variation of each pollutant. Effects were scaled to the variability that is common for each pollutant in representative communities in Southern California. Results: Among children owning a dog, there were strong associations between bronchitic symptoms and all pollutants examined. Odds ratios ranged from 1.30 per 4.2 µg/m3 for PM10–2.5 [95% confidence interval (CI) , 0.91–1.87) to 1.91 per 1.2 µg/m3 for organic carbon (95% CI, 1.34–2.71) . Effects were somewhat larger among children who owned both a cat and dog. There were no effects or small effects with wide CIs among children without a dog and among children who owned only a cat. Conclusion: Our results suggest that dog ownership, a source of residential exposure to endotoxin, may worsen the relationship between air pollution and respiratory symptoms in asthmatic children. Key words: air pollution, asthma, cats, child, dogs, endotoxin, epidemiology, indoor allergens, particulate matter. Environ Health Perspect 114:1910–1915 (2006) . doi:10.1289/ehp.8548 available via http://dx.doi.org/ [Online 29 August 2006] Address correspondence to R. McConnell, Department of Preventive Medicine, USC School of Medicine, 1540 Alcazar St., CHP 236, Los Angeles, CA 90033 USA. Telephone: (323) 442-1096. Fax: (323) 442-3272. E-mail: rmcconne@usc.edu S. Hering developed the 2-week sampler for elemental and organic carbon, and the analysis of these PM constituents in archived filters was done by L. Salmon, K. Mertz, P. Mayo, and G. Cass. S. Alcorn of Sonoma Technology performed extensive quality assurance of the air pollution data used for this study. J. Samet provided helpful comments on the manuscript. Programming support was provided by I. Manila. This study was supported by the National Institute of Environmental Health Sciences (grants 5 P30 ES07048, 5 P30 ES05605, 5 P01 ES09581, and 1 P01 ES11627) , the Southern California Particle Center, the U.S. Environmental Protection Agency (grant R 82670801) , the National Heart Lung and Blood Institute (grant 5R01HL061768) , the California Air Resources Board, and the Hastings Foundation. The authors declare they have no competing financial interests. Received 29 July 2005 ; accepted 24 August 2006. The full version of this article is available for free in HTML or PDF formats. |