PT  - JOURNAL ARTICLE
AU  - Chris Carlsten
AU  - Anne Dybuncio
AU  - Allan Becker
AU  - Moira Chan-Yeung
AU  - Michael Brauer
TI  - Traffic-related air pollution and incident asthma in a high-risk birth cohort
AID  - 10.1136/oem.2010.055152
DP  - 2011 Apr 01
TA  - Occupational and Environmental Medicine
PG  - 291--295
VI  - 68
IP  - 4
4099  - http://oem.bmj.com/content/68/4/291.short
4100  - http://oem.bmj.com/content/68/4/291.full
SO  - Occup Environ Med2011 Apr 01; 68
AB  - Objectives The risk of incident asthma and bronchial hyper-reactivity associated with early life exposure to traffic-related air pollution has not been fully elucidated. We aimed to evaluate the hypothesis that the risk of new onset asthma is positively associated with early exposure to traffic-related air pollution in a well-characterised high-risk birth cohort.Methods Infants at high-risk for asthma were recruited for an intervention study. Birth year exposures to NO, NO2, black carbon and PM2.5 were estimated by land use regression. At 7 years of age, asthma was assessed by a paediatric allergist and bronchial hyper-reactivity was measured by methacholine challenge. Associations between exposures and outcomes were analysed by stepwise multiple logistic regression, adjusted for potential confounding variables.Results Exposure estimates were available for 184 children; 23 were diagnosed with asthma and 68 with bronchial hyper-reactivity. The IQR (4.1 μg/m3) of birth year PM2.5 was associated with a significantly increased risk of asthma (OR 3.1, 95% CI 1.3 to 7.4) and with a trend to increased risk of bronchial hyper-reactivity. Similar findings were noted in association with NO and NO2, while black carbon did not appear to confer increased risk.Conclusion Modest elevations in exposure to some traffic-related air pollutants during the year of birth are associated with new onset asthma assessed at age 7. That significant associations were revealed in spite of a limited sample size emphasises the strengths of a high-risk birth cohort model, along with individual air pollution exposure estimates and well-characterised data on covariates and outcomes.