Presence of other allergic disease modifies the effect of early childhood traffic-related air pollution exposure on asthma prevalence.
Nitrogen dioxide (NO2), a surrogate measure of traffic-related air pollution (TRAP), has been associated with incident childhood asthma. Timing of exposure and atopic status may be important effect modifiers. We collected cross-sectional data on asthma outcomes from Toronto school children aged 5-9years in 2006. Lifetime home, school and daycare addresses were obtained to derive birth and cumulative NO2 exposures for a nested case-control subset of 1497 children. Presence of other allergic disease (a proxy for atopy) was defined as self-report of one or more of doctor-diagnosed rhinitis, eczema, or food allergy. Generalized estimating equations were used to adjust for potential confounders, and examine hypothesized effect modifiers while accounting for clustering by school. In children with other allergic disease, birth, cumulative and 2006 NO2 were associated with lifetime asthma (OR 1.46, 95% CI 1.08-1.98; 1.37, 95% CI 1.00-1.86; and 1.60, 95% CI 1.09-2.36 respectively per interquartile range increase) and wheeze (OR 1.44, 95% CI 1.10-1.89; 1.31, 95% CI 1.02-1.67; and 1.60, 95% CI 1.16-2.21). No or weaker effects were seen in those without allergic disease, and effect modification was amplified when a more restrictive algorithm was used to define other allergic disease (at least 2 of doctor diagnosed allergic rhinitis, eczema or food allergy). The effects of modest NO2 levels on childhood asthma were modified by the presence of other allergic disease, suggesting a probable role for allergic sensitization in the pathogenesis of TRAP initiated asthma.
The Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada; Department of Pediatrics, University of Toronto, Canada. Electronic address: sharon.dell@sickkids.ca.
Sharon D
SD
Dell
University of California, Berkeley, 50 University Hall MC7360, Mail Drop Suite 710, Geographic Information Health and Exposure Science Laboratory (GIS HEAL), School of Public Health, Berkeley, CA 94720-7360, USA. Electronic address: jerrett@berkeley.edu.
Michael
M
Jerrett
University of California, Berkeley, 50 University Hall MC7360, Mail Drop Suite 710, Geographic Information Health and Exposure Science Laboratory (GIS HEAL), School of Public Health, Berkeley, CA 94720-7360, USA. Electronic address: beckerman@berkeley.edu.
Bernard
B
Beckerman
Environment Canada, Air Quality Research Division, 4905 Dufferin St., Toronto, ON M3H 5T4, Canada; Dalla Lana School of Public Health, University of Toronto, Canada. Electronic address: jeff.brook@ec.gc.ca.
Jeffrey R
JR
Brook
The Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada. Electronic address: richard.foty@sickkids.gc.ca.
Richard G
RG
Foty
Public Health Agency of Canada, Maternal and Infant Health Section, 200 Églantine Dr., 1910C, Ottawa, ON K1A 0K9, Canada. Electronic address: nicolas.gilbert@phac-aspc.gc.ca.
Nicolas L
NL
Gilbert
The Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada. Electronic address: laura.marshall@sickids.ca.
Laura
L
Marshall
Carleton University, Department of Chemistry, College of Natural Sciences, 228 Steacie Building, Ottawa, ON K1S 5B6, Canada. Electronic address: david_miller@carleton.ca.
J David
JD
Miller
The Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada; Dalla Lana School of Public Health, University of Toronto, Canada. Electronic address: teresa.to@sickkids.ca.
Teresa
T
To
Department of Clinical Epidemiology and Biostatistics, McMaster University, CRL, Room 233, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada. Electronic address: walter@mcmaster.ca.
Stephen D
SD
Walter
Health Canada, Population Studies Division, 445-757 West Hastings Street, Federal Tower, Vancouver, BC V6C 1A1, Canada. Electronic address: dave.stieb@hc-sc.gc.ca.
David M
DM
Stieb
D000397:Air Pollution / Q000009:adverse effects*; D001249:Asthma / Q000453:epidemiology* / Q000209:etiology*; D002170:Canada / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000150:complications*; D008297:Male; D009585:Nitrogen Dioxide / Q000032:analysis; D015995:Prevalence
D009585:Nitrogen Dioxide
Air pollution; Asthma; Atopy; Epidemiology; Traffic