United States
Environmental Protection
Agency
Atmospheric Sciences
Research Laboratory
Research Triangle Park NC 2771
Research and Development
EPA/600/S3-85/041 July 1985
c/EPA Project Summary
An Emission Inventory for
Urban Particle Model
Validation in the Philadelphia
AQCR
D. A. Toohman, J. C. Thames, J. C. Yates, R. R. Segall, and J. N. Bolstad
The goal of this research project was
to prepare the necessary emission in-
puts for use in validation of an urban
particle model in the Philadelphia area.
The model, PEM-2, was developed by
the Atmospheric Sciences Research
Laboratory based on the Texas Episodic
Model. In compiling emissions data for
PEM-2, maximum use was made of the
inventory generated earlier for valida-
tion of the Urban Airshed photochemi-
cal oxidant model in Philadelphia.
Hourly emission estimates were
compiled for the mid-July to mid-
August 1982 ambient monitoring pe-
riod. Five pollutants were considered:
coarse particles, fine particles, coarse
sulfate, fine sulfate, and sulfur dioxide.
Emission source categories were di-
vided into major point, minor point, in-
dustrial process fugitive, highway vehi-
cle, and area sources. Limited source
testing and paved road silt load sam-
pling were conducted.
Validating the model with these in-
puts will not be straightforward since
the emissions do not represent real-
time conditions, relatively large (2.5 by
2.5-kilometer) grids were used, and
some of the monitoring sites are im-
pacted by nearby fugitive sources.
This Project Summary was devel-
oped by EPA's Atmospheric Sciences
Research Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
EPA is in the process of revising the
National Ambient Air Quality Standards
for total suspended particulates to ac-
count for the fact that smaller particles
are responsible for adverse health ef-
fects. The new standard has not been
finalized but is expected to be for PM10
paniculate matter with an aerodynamic
diameter <10 nm.
After the new standard is promul-
gated, the states will be required to re-
vise their State Implementation Plans
for attainment or maintenance of the
standard. The development and valida-
tion of an urban particle model for the
states to use is the responsibility of the
Atmospheric Sciences Research Labo-
ratory (ASRL). ASRL chose Philadelphia
for a validation study because it has a
good mix of industrial emissions and is
the site of an EPA validation program
for the Urban Airshed photochemical
oxidant model.
Model Input
To assist ASRL in the validation pro-
gram, emissions input for the urban
particle model PEM-2 were prepared.
Hourly emission estimates were devel-
oped during the monitoring period for
five pollutants: fine particles (<2.5), n,m
coarse particles (2.5 to 1 jtm), primary
sulfate (<2.5 jum), primary sulfate be-
tween 2.5 and 10 j*,m, and sulfur diox-
ide. The monitoring period extended
from 6 p.m. on July 14 to 6 p.m. on Au-
gust 13, 1982. All point sources other
than 300 major point sources were com-
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bined into the two hundred eighty nine
2.5 by 2.5-kilometer grid cells used for
area sources and highway vehicles.
Highway vehicle emissions data were
generated by the Delaware Valley Re-
gional Planning Commission under
subcontract. Limited source testing was
conducted and silt loading samples
were collected from selected paved
roads to provide Philadelphia-specific
data for model validation.
Conclusion
Model results should be interpreted
by keeping in mind that the emissions
data developed do not represent real-
time conditions. The use of relatively
large 2.5 by 2.5-kilometer grids in the
study complicates model validation
since impacts from paved roads very
near the monitors are likely to be the
most significant contributors. In addi-
tion, several of the monitoring sites
used to collect ambient data exhibit mi-
croscale source influences and one is
located on top of a building, which
makes comparisons with model predic-
tions more problematical.
D. A. Toothman, J. C. Thames. J. C. Yates. R. R. Sega/1, andJ. N. Bolstadare with
Engineering-Science, Fairfax, VA 22030.
Kenneth Knapp is the EPA Project Officer (see below).
The complete report, entitled "An Emission Inventory for Urban Particle Model
Validation in the Philadelphia AQCR," (Order No. PB 85-207 611/AS; Cost:
$43.00, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Atmospheric Sciences Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC27711
-V
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S3-85/041
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