Citation:

Braggio, J., E. Hall, S. Weber, AND A. Huff. New Homogeneous Spatial Areas Identified Using Case-Crossover Spatial Lag Grid Differences between Aerosol Optical Depth-PM2.5 and Respiratory-Cardiovascular Emergency Department Visits and Hospitalizations. ATMOSPHERE. MDPI, Basel, Switzerland, 13(5):719, (2022). https://doi.org/10.3390/atmos13050719

Impact/Purpose:

The general approach for research designed to analyze health impacts of exposure to fine particulate matter (PM2.5) is to use the concentration data from the nearest ground-based air quality monitor(s). The schedule for filter collection of PM2.5 monitors causes temporal gaps in measurement, and the limited number of locations where those monitors are sited contributes to the large spatial gaps in PM2.5 measurements. Remotely measured Aerosol Optical Depth (AOD) data from satellites provides information on PM2.5 concentrations in overflown locations without monitors. The Community-Multiscale Air Quality (CMAQ) air quality model provides estimates of PM2.5 concentrations for various geographic regions using meteorological and emission inventory inputs, along with atmospheric chemistry reactions and deposition processes. An enhanced research paradigm is required to address the spatial and temporal gaps in PM2.5 measurement and generate realistic and representative concentration fields. The approach taken in this research project is to use a Hierarchical Bayesian Model (HBM) to combine measured PM2.5 monitor concentrations, PM2.5 estimates derived from satellite AOD data, and CMAQ model PM2.5 output to generate estimates of PM2.5 in areas with and without air quality monitors. This represents a significant step in developing PM2.5 concentration datasets to correlate with inpatient hospitalizations and emergency room visits data for myocardial infarction (MI), asthma, and heart failure (HF) using case-crossover analysis.

Description:

Optimal use of Hierarchical Bayesian Model (HBM)-assembled aerosol optical depth (AOD)-PM2.5 fused surfaces in epidemiologic studies requires homogeneous temporal and spatial fused surfaces. No analytical method is available to evaluate spatial heterogeneity. The temporal case-crossover design was modified to assess the spatial association between four experimental AOD-PM2.5 fused surfaces and four respiratory–cardiovascular hospital events in 12 km2 grids. The maximum number of adjacent lag grids with significant odds ratios (ORs) identified homogeneous spatial areas (HOSAs). The largest HOSA included five grids (lag grids 04; 720 km2) and the smallest HOSA contained two grids (lag grids 01; 288 km2). Emergency department asthma and inpatient asthma, myocardial infarction, and heart failure ORs were significantly higher in rural grids without air monitors than in urban grids with air monitors at lag grids 0, 1, and 01. Rural grids had higher AOD-PM2.5 concentration levels, population density, and poverty percentages than urban grids. Warm season ORs were significantly higher than cold season ORs for all health outcomes at lag grids 0, 1, 01, and 04. The possibility of elevated fine and ultrafine PM and other demographic and environmental risk factors synergistically contributing to elevated respiratory–cardiovascular chronic diseases in persons residing in rural areas was discussed.

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