Traffic-related air pollution and incident asthma in a high-risk birth cohort

Occup Environ Med. 2011 Apr;68(4):291-5. doi: 10.1136/oem.2010.055152. Epub 2010 Oct 15.


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, NO(2), black carbon and PM(2.5) 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/m(3)) of birth year PM(2.5) 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 NO(2), 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.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Air Pollutants / analysis
  • Air Pollutants / toxicity
  • Air Pollution / adverse effects*
  • Air Pollution / analysis
  • Asthma / etiology*
  • Asthma / genetics
  • Asthma / prevention & control
  • Bronchial Hyperreactivity / etiology
  • Bronchial Hyperreactivity / prevention & control
  • Environmental Exposure / adverse effects
  • Environmental Exposure / analysis
  • Environmental Monitoring / methods
  • Epidemiologic Methods
  • Epidemiological Monitoring
  • Female
  • Geographic Information Systems
  • Humans
  • Infant, Newborn
  • Male
  • Particulate Matter / analysis
  • Particulate Matter / toxicity
  • Vehicle Emissions / analysis
  • Vehicle Emissions / toxicity*


  • Air Pollutants
  • Particulate Matter
  • Vehicle Emissions