Dog ownership enhances symptomatic responses to air pollution in children with asthma.
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 microm 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 microg/m3 for PM10-2.5 [95% confidence interval (CI), 0.91-1.87) to 1.91 per 1.2 microg/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.


CONCLUSIONS
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.
McConnell
Rob
R
Department of Preventive Medicine, University of Southern California, Los Angeles, California, USA. rmcconne@usc.edu
Berhane
Kiros
K
Molitor
Jassy
J
Gilliland
Frank
F
Künzli
Nino
N
Thorne
Peter S
PS
Thomas
Duncan
D
Gauderman
W James
WJ
Avol
Edward
E
Lurmann
Fred
F
Rappaport
Edward
E
Jerrett
Michael
M
Peters
John M
JM
D000293:Adolescent; D000397:Air Pollution / Q000009:adverse effects*; D000818:Animals; D001249:Asthma / Q000150:complications*; D002140:California; D002415:Cats; D002648:Child; D015331:Cohort Studies; D004285:Dogs; D005260:Female; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009585:Nitrogen Dioxide / Q000633:toxicity; D010067:Ownership; D010126:Ozone / Q000633:toxicity; D052638:Particulate Matter / Q000009:adverse effects; D012135:Respiratory Sounds / Q000209:etiology; D012140:Respiratory Tract Diseases / Q000209:etiology
D052638:Particulate Matter; D010126:Ozone; D009585:Nitrogen Dioxide