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Childhood Incident Asthma and Traffic-Related Air Pollution in a Longitudinal Cohort Study

McConnell, R

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doi: 10.1097/01.ede.0000276913.45372.95
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To evaluate the relationship of local pollution exposure estimated from traffic near homes and new onset asthma.

Materials and Methods:

We evaluated 2505 participants in the southern California Children's Health Study with no lifetime history of asthma or wheeze reported at study entry (at age 5–7 years). During 3 years of follow up there were 120 cases of new doctor-diagnosed asthma reported. Residential exposure to traffic-related pollutants at study entry was assessed based on modeled estimates, traffic density within 150 m of the home and on distance to major roadways. Ambient NO2, PM2.5, PM10, and ozone were measured at central site monitors in each community. Associations were assessed in a Cox model with allowance for community-level random effects.


Increased risk of asthma was associated with the contribution to estimated exposure to NOx modeled from local roadways near homes [hazard ratio (HR) 1.51 over the interquartile range; 95% confidence interval 1.25, 1.82]. There was also an increased risk of asthma associated with NO2 measured at the community central site monitor (HR 2.18 over the range of 24 ppb observed across communities; 1.18, 4.01), but this effect was not significant after adjusting for exposure modeled from traffic.


New onset asthma in primary school children is associated with local traffic-related pollution near homes.

© 2007 Lippincott Williams & Wilkins, Inc.