Is it traffic type, volume, or distance? Wheezing in infants living near truck and bus traffic.

BACKGROUND

Previous studies of air pollution have not examined the association between exposure to varying types, distance, and amounts of traffic and wheezing in very young infants.

OBJECTIVE

We sought to determine the relationship between types of traffic, traffic volume, and distance and wheezing among infants less than 1 year of age.

METHODS

A geographic information system and a classification scheme were developed to categorize infants enrolled in the study as living near moving truck and bus traffic (highway >50 miles per hour, >1000 trucks daily, <400 m), stop-and-go truck and bus traffic (<50 miles per hour, <100 m), or unexposed and not residing near either. Symptom data were based on health questionnaires administered to parents when the infants were 6 months of age and monthly health diaries.

RESULTS

Infants living very near (<100 m) stop-and-go bus and truck traffic had a significantly increased prevalence of wheezing (adjusted odds ratio, 2.50; 95% CI, 1.15-5.42) when compared with unexposed infants. The prevalence of wheezing among nonwhite infants was at least twice that of white infants, regardless of exposure. Infants living less than 400 m from a high volume of moving traffic, however, did not have an increased prevalence of wheezing.

CONCLUSION

These results suggest that the distance from and type of traffic exposures are more significant risk factors than traffic volume for wheezing in early infancy.