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Concentration Response Curve for Ozone Realted Mortality at High Concentrations for presentation at International Society for Environmental Epidemiology
Citation:
Rappold, A., J. Crooks, AND L. Neas. Concentration Response Curve for Ozone Realted Mortality at High Concentrations for presentation at International Society for Environmental Epidemiology. Presented at International Society for Environmental Epidemiology (ISEE), Basel, SWITZERLAND, August 19 - 23, 2013.
Impact/Purpose:
This work examines concentration-response curve for ozone related mortality
Description:
Concentration Response Curve for Ozone related Mortality at High Concentrations Ana G. Rappold, James Crooks, Lucas M. Neas Background Rising temperatures and decreased global circulation in the upcoming decades are expected to have a detrimental impact on air quality, particularly with respect to ozone. The largest impacts are anticipated to occur in the form of the frequency and duration of summertime regional pollution episodes. These events are likely to induce nonlinear increases in ozone levels. Objective We examine concentration-response curve for ozone related mortality to evaluate the sensitivity of the health burden with respect to high end of ozone distribution. Methods A flexible two stage Bayesian hierarchical model is developed to allow for the nonlinear ozone risk curve with a shape parameter controlling the prior belief about the monotonicity of the risk. We use polynomial spline basis functions and their derivatives to evaluate relative at different quantiles of the ozone distribution. The model was applied to the data from the US National Morbidity, Mortality, and Air Pollution Study for 95 major US urban centers between 1987 and 2000. National estimates are obtained by pooling city specific estimates at the second stage. Results Under the assumption of linear effect, log relative risk associated with 10ppb increase in maximum hourly Ozone concentration is 0.12 (0.06, 0.19)%. Under a moderately strong assumption of monotonicity we estimate the expected log relative rate across the city specific interquartile range to double at 0.25 (0.14, 0.36)%. Above the 95% percentile of the city specific ozone distribution this estimate increase even further to 0.57 (0.39, 0.75)%. Conclusion Our preliminary results indicate that concentration-response relationship is not linear across all levels of ozone. Air pollution episodes are likely to impact high end of ozone distribution and thus contribute larger health burden per unit increase of ozone. Disclaimer: This abstract does not necessarily reflect U.S. EPA policy.