Environmental Engineering Reference
In-Depth Information
analyze and develop alternative emissions control strategies. One source-based
apportionment technique is to run the chemical transport model twice - once with
all emissions sources and once with emissions from a particular source category
“zeroed-out.” The resulting difference in estimated ambient concentrations provides
an estimated source contribution at the location of interest. Another source-based
apportionment approach is to calculate contributions from source regions using
spatially defined sensitivity coefficients calculated by techniques such as the
decoupled direct method in 3d (Napelenok et al., 2008) and model adjoints
(Hakami et al., 2006). These approaches also account for nonlinearities in the
chemical processes of air quality models to better represent source contributions.
4. Summary and Conclusions
Air pollution is a known contributor to adverse human health and ecological
outcomes. A complex mixture of local, urban, and regional sources contribute to
air pollution, presenting a challenge to separate sources dispersed across the range
of spatial scales. Understanding the relative contribution of these sources is important
because recent health studies suggest differences in exposure relationships and
health effects for different sources. In addition, air quality management decisions
require information on the sources contributing to air pollution to develop effective
air pollution control strategies. Receptor-based source apportionment approaches
and hybrid techniques, which incorporate components of receptor- and source-
based source apportionment models, are informative tools in the assessment of
local, urban and regional air pollution sources and source-specific health impacts.
Understanding the spatial gradients of pollutant concentrations in urban centers,
the personal exposures of sensitive populations to air pollutants, and the specific
contributions to air quality levels of specific sources are key information needs for
the development and implementation of effective air quality regulations. Integrated
source apportionment techniques show promise to address scientific information
gaps to inform air quality management decisions and protect public health.
Disclaimer
The views expressed in these Proceedings are those of the individual authors and do
not necessarily reflect the views and policies of the United States Environmental Protections
Agency (EPA). Scientists in the EPA have prepared the EPA sections and those sections have
been reviewed in accordance with EPA's peer and administrative review policies and approved
for presentation and publication.
References
Duvall RM, Norris GA, Willis RD, Turner JR, Kaleel R, Sweitzer T. 2008
. St. Louis Advanced
Monitoring Initiative (AMI) Project: Source Sampling and Ambient Monitoring Study
Design. 27th Annual Conference of the American Association for Aerosol Research, October
20-24, 2008, Orlando, Fl.
