Abstract
RATIONALE: The effects of exposure to specific components of ambient fine particulate matter (PM(2.5)), including metals and elemental carbon (EC), have not been fully characterized in young children. OBJECTIVES: To compare temporal associations among PM(2.5); individual metal constituents of ambient PM(2.5), including nickel (Ni), vanadium (V), and zinc (Zn); and EC and longitudinal reports of respiratory symptoms through 24 months of age. METHODS: Study participants were selected from the Columbia Center for Children's Environmental Health birth cohort recruited in New York City between 1998 and 2006. Respiratory symptom data were collected by questionnaire every 3 months through 24 months of age. Ambient pollutant data were obtained from state-operated stationary monitoring sites located within the study area. For each subject, 3-month average inverse-distance weighted concentrations of Ni, V, Zn, EC, and PM(2.5) were calculated for each symptom-reporting period based on the questionnaire date and the preceding 3 months. Associations between pollutants and symptoms were characterized using generalized additive mixed effects models, adjusting for sex, ethnicity, environmental tobacco smoke exposure, and calendar time. MEASUREMENTS AND MAIN RESULTS: Increases in ambient Ni and V concentrations were associated significantly with increased probability of wheeze. Increases in EC were associated significantly with cough during the cold/flu season. Total PM(2.5) was not associated with wheeze or cough. CONCLUSIONS: These results suggest that exposure to ambient metals and EC from heating oil and/or traffic at levels characteristic of urban environments may be associated with respiratory symptoms among very young children.