Associations between Speciated Particulate Pollution and Cardiorespiratory Emergency Department Visits in St. Louis, MO

STEFANIE EBELT SARNAT (1), Andrea Winquist (1), Mitch Klein (1), Jeremy Sarnat (1), Jay Turner (2), Paige Tolbert (1)

(1) Emory University, Atlanta, (2) Washington University, St. Louis

     Abstract Number: 384
     Last modified: November 9, 2009

Abstract
INTRODUCTION: Substantial evidence supports an association of particulate matter (PM) with cardiorespiratory illnesses, but less is known regarding characteristics of PM that contribute to this association. Here, we present results from a time-series investigation of emergency department (ED) visits in St. Louis, MO. METHODS: Individual-level data were obtained from the Missouri Hospital Association for all ED visits to acute-care hospitals in the St. Louis Metropolitan area during 1/1/2001-6/30/2007. The data set included data for 37 hospitals and >5,600,000 ED visits. Daily ambient air monitoring data for 8-hr maximum ozone, 1-hr maximum carbon monoxide (CO), 1-hr maximum nitrogen dioxide (NO2), 1-hr maximum sulfur dioxide (SO2), and 24-hr average fine particulate matter (PM) were obtained from the USEPA Air Quality System for representative sites within the St. Louis study area. Daily speciated data were also obtained from the St. Louis Supersite for a 2-year period. We used Poisson generalized linear models, controlling for long-term temporal trends and meteorological variables, to examine associations between three-day moving average (of lags 0, 1, and 2) air quality measures and daily counts of respiratory and cardiovascular ED visits. The respiratory outcome group included visits for upper respiratory infections, bronchiolitis, pneumonia, chronic obstructive pulmonary disease, and asthma [principal International Classification of Diseases, 9th revision (ICD-9) codes: 460-465, 466.0, 466.1, 466.11, 466.19, 477, 480-486, 491, 492, 493, 496, 786.07)]. The cardiovascular outcome group included visits for ischemic heart disease, dysrhythmia, congestive heart failure, ischemic stroke, and peripheral vascular disease (principal ICD-9 codes: 410-414, 427, 428, 433-437, 440, 443-445, 451-453). RESULTS: Over the study period, we observed mean ED visit counts of 282/day for respiratory outcomes and 100/day for cardiovascular outcomes. In preliminary epidemiologic analyses, positive associations were observed between respiratory ED visits and ambient levels of ozone, CO, NO2, and fine PM; and between cardiovascular ED visits and ambient levels of CO, NO2, SO2, and fine PM. Planned analyses will consider associations between these outcomes and fine PM components, including sulfate, elemental carbon, organic carbon, and metals. DISCUSSION. Preliminary results indicate impacts of both primary (e.g., CO, NO2, SO2) and secondary (e.g., ozone) pollutants on acute cardiorespiratory morbidity in St. Louis, and are comparable with results of previous similar studies in other cities. Inclusion of speciated PM data in these analyses will provide a more detailed examination of the impacts of the pollutant mix.