Residential outdoor air pollution and allergen sensitization in schoolchildren in Oslo, Norway.
BACKGROUND
Epidemiological studies that have investigated the association between air pollution and atopy have found inconsistent results. Furthermore, often exposure to outdoor air pollution has had limited quality, and more individual exposure is needed.


OBJECTIVE
To investigate the relations between early and lifetime exposure to residential outdoor air pollution and allergen sensitization in 9-10-year-old children in Oslo, Norway.


METHODS
Sensitization to common allergens was measured by skin prick tests (SPTs), which were performed in 2244 children who had lived in Oslo since birth. Several definitions of positive SPT were used. Information on potential confounding variables was collected by a parental questionnaire. Exposure to outdoor air pollution was assessed by the EPISODE dispersion model, which calculates hourly concentrations of nitrogen dioxide (NO2), particulate matter (PM) with aerodynamic diameter <10 microm (PM10) and <2.5 microm (PM2.5), respectively.


RESULTS
We found no associations between long-term air pollution exposure and sensitization to any allergen, any indoor or any pollen allergen. However, lifetime air pollution exposure was associated with sensitization to the house dust mite Dermatophagoides farinae. One interquartile increase of lifetime exposure to NO2, PM10 and PM2.5 was associated with 1.88 (adjusted odds ratio) (1.02, 3.47) [95% confidence interval (CI)], 1.61 (0.96, 2.72) and 1.46 (0.96, 2.22), respectively, for D. farinae. Lifetime exposure was also associated with sensitization to cat in a subpopulation. Both associations diminished after adjusting for a contextual socio-economic factor.


CONCLUSIONS
Long-term exposure to traffic-related pollutants was generally not associated with allergen sensitization in 9-10-year-old Oslo children. However, lifetime exposure was associated with sensitization to D. farinae, and with sensitization to cat in a subpopulation, which may be explained by socio-economic confounding or multiple comparisons. The air pollution levels in Oslo may be too low to reveal associations with sensitization.
Oftedal
B
B
Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway. bente.oftedal@fhi.no
Brunekreef
B
B
Nystad
W
W
Nafstad
P
P
D000397:Air Pollution / Q000009:adverse effects* / Q000032:analysis; D000485:Allergens / Q000276:immunology; D000818:Animals; D002415:Cats; D002648:Child; D040001:Dermatophagoides farinae / Q000276:immunology; D004781:Environmental Exposure / Q000009:adverse effects* / Q000032:analysis; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D007428:Intradermal Tests / Q000379:methods; D008297:Male; D009585:Nitrogen Dioxide / Q000032:analysis; D009664:Norway / Q000453:epidemiology; D052638:Particulate Matter / Q000032:analysis; D012737:Sex Factors; D011795:Surveys and Questionnaires; D014505:Urban Population
D000485:Allergens; D052638:Particulate Matter; D009585:Nitrogen Dioxide