Ambient ozone concentration and hospital admissions due to childhood respiratory diseases in New York State, 1991-2001

Background and objective: Respiratory diseases constitute one of the leading causes of ill health among children in New York State (NYS). The current project, a component of the NYS Environmental Public Health Tracking Program, investigated a potential association between ambient ozone (03) concentration and childhood respiratory hospital admissions over 11 years in NYS. Methods: We used a two-stage Bayesian hierarchical model to assess the exposure-disease associations within 11 geographic regions and statewide. The data included total daily hospital admissions due to respiratory diseases for children 0-17 years old from 1991 to 2001 in NYS (N 134,099) and daily ambient 03 level with different single-day lags. These analyses adjusted for particulate matter <= 10 mu m in size (PM10), meteorological conditions, day of the week, seasonality, long-term trends, and demographic characteristics. Results: In 5 of the 11 regions, including the Upper and Lower Adirondacks, Upper Hudson Valley, Staten Island, and New York City, positive associations were found between respiratory hospital admissions and ambient 03 level 2 days prior to the admission. Applying different statistical methods and sensitivity analysis of PM10 did not alter these findings. When region-specific results were combined, no statewide association was apparent. Conclusions: Geographic differences were found in the associations between 03 levels and respiratory hospital admissions among children. In addition, we found that the two-stage model may be an appropriate approach for tracking the health effects of air pollution over time in different geographic areas when heterogeneity of risk factors across regions is present. (C) 2008 Elsevier Inc. All rights reserved.