Environmental Engineering Reference
In-Depth Information
7.8 The Influence of Chemistry-Transport Model Scale
and Resolution on Population Exposure Due to
Aircraft Emissions from Three Airports in the United
States
Saravanan Arunachalam
1
, Bok Haeng Baek
1
, Hsiao-Hsien Hsu
2
, Binyu
Wang
1
, Neil Davis
1
, and Jonathan I. Levy
2
1
Institute for the Environment, University of North Carolina at Chapel Hill, 137 E. Franklin
St., #645, Chapel Hill, NC 27599-6116, USA
2
Harvard School of Public Health, Department of Environmental Health, Landmark Center
4th floor West, 401 Park Drive, Boston, MA 02215, USA
Abstract
Understanding the impact of aviation emissions on air quality is
becoming more important due to the projected growth in aviation transport and
decrease in emissions from other anthropogenic sources. Atmospheric chemistry-
transport models are often used to determine the marginal impact of emissions on
air quality and public health, but the uncertainties related to modeling assumptions
are rarely formally characterized from the perspective of public health impact
calculations. In this study, we estimate the incremental contribution of commercial
aviation emissions to air quality near three U.S. airports
-
Atlanta Hartsfield,
Chicago O'Hare, and Providence T.F. Green
-
using the Community Multiscale
Air Quality Model (CMAQ), a comprehensive chemistry-transport air quality
model. To evaluate the significance of model resolution and geographic scales of
influence, we ran a one-atmosphere version of CMAQ (with air toxics) at 36- and
12-km resolutions, and calculated the total population exposure per unit emissions
at various distances from each airport. Total population exposure per unit emissions
was systematically higher for air toxics with increased model grid resolution, and
the distance at which most of the population exposure was estimated varied by
compound and airport. A 108 × 108 km domain centered on the airport captured
most population exposure for reactive gases (e.g., formaldehyde) at airports with
high nearby population density, but more than half of the fine particulate matter
(PM
2.5
) exposure occurred outside of a 324 × 324 km domain centered on the
airport, given contributions from secondary formation. Our findings provide insight
about the model resolution and spatial scales necessary for population risk assess-
ment from airports and other combustion sources, and demonstrate the robustness
of risk-based prioritization across multiple grid resolutions.
