United States
Environmental Protection
Agency
Atmospheric Research and
Exposure Assessment Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-92/157 October 1992
i@r EPA Project Summary
Atlanta Ozone Precursor
Monitoring Study Data Report
Larry J. Purdue, James A. Reagan, William A. Lonneman, Thomas C.
Lawless, Ronald J. Drago, George M. Zalaquet, Michael W. Holdren,
Deborah L. Smith, Alan D. Pate, Bruce E. Buxton, and Chester W. Spicer
Monitoring was conducted during the
summer of 1990 to address the mea-
surement of ozone (O3) and ozone pre-
cursors in Atlanta, Georgia. Data were
collected using automated gas chro-
matography. Resolved individual spe-
cies were detected via a flame ioniza-
tion detector (FID) and an electron cap-
ture detector (ECD). The study area in-
cluded six continuous and six enhance-
ment sites located in and around the
greater metropolitan Atlanta area.
The collected data provide an infor-
mation base to support the develop-
ment and implementation of improved
strategies to reduce O3 in metropolitan
areas. This data base contains more
than 300,000 hourly measurements of
the various parameters and species
identified for the study.
This Project Summary was developed
by EPA's Atmospheric Research and
Exposure Assessment Laboratory, Re-
search Triangle Park, NC, to announce
key findings of the research project
that is fully documented in a separate
report of the same title (see Project
Report ordering information at back).
Introduction
During the summer of 1990, the U.S.
Environmental Protection Agency (EPA)
conducted a major monitoring study in
Atlanta, Georgia, to address the measure-
ment of ozone (O3) and O3 precursors.
This project was undertaken to obtain an
information base to support the develop-
ment and implementation of improved
strategies for reducing O, in cities that are
not in compliance with EPA's National Am-
bient Air Quality Standards (NAAQS).
The study was sponsored jointly by
EPA's Atmospheric Research and Expo-
sure Assessment Laboratory (AREAL) and
Office of Air Quality Planning and Stan-
dards (OAQPS), located in Research Tri-
angle Park (RTP), North Carolina. It was
conducted with contractual assistance from
the Atmospheric Science and Applied
Technology Department of Battelle Me-
morial Institute in Columbus, Ohio, and
with operational assistance from EPA Re-
gion IV and the Georgia Department of
Natural Resources (DNR) in Atlanta, Geor-
gia.
Six primary field sites and six enhance-
ment sites were identified and made ready
for use. Approximately 1000 hourly mea-
surements were taken for the parameters
and species listed in Tables 1 and 2. The
resulting data set contains more than
300,000 hourly measurements of the 60
parameters addressed. In addition, ap-
proximately 20,000 measurements resulted
from analyzing 375 canister samples for
hydrocarbon species, and approximately
750 measurements resulted from analyz-
ing the 250 cartridge samples for formal-
dehyde.
The hourly measurements from the six
primary sites and the periodic carbonyl
measurements are available for assess-
ment and interpretation on a 3.5-in disk.
The measurements resulting from the
analysis of the 375 canister samples also
are available on a separate disk. These
disks, along with the full data report, may
be obtained from EPA. The back of this
Project Summary provides the necessary
ordering information.
Background and Rationale
The high number of O3 nonattainment
areas across the country indicates a need
to develop new, improved strategies for
O3 control. Extensive reviews of past and
current O3 control strategies, generated
over the last several years in conjunction
Printed on Recycled Paper
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over the last several years in conjunction
with agencywide planning, have identified
promising directions for action. For ex-
ample, more complete nonmethane or-
ganic compound (NMOC) emissions in-
ventories would allow EPA and other agen-
cies to predict and address appropriate
reductions for bringing nonattainment ar-
eas into compliance with the O. standard.
The control strategies for photochemi-
cal O3 that have been implemented in
recent years involve reducing NMOC com-
pounds and/or NO. The Empirical Kinetic
Modeling Approach (EKMA), as well as
airshed models, often have been used to
determine necessary nonmethane organic
compounds (NMOC) or oxides of nitrogen
(NO,) controls. These models relate NMOC
and NO, to maximum O3 concentrations
typically observed during afternoons at
sites located downwind of an urban area.
They predict the NMOC and NOX control
requirements needed to attain NAAQS for
°3-
Although measurement requirements
are somewhat different for the EKMA and
airshed models, both require source-emis-
sions data and ambient-air data for NMOC
and NO,. With this information, states and
local control agencies can develop control
approaches aimed at bringing their
nonattainment areas into compliance with
the O3 NAAQS. Measurements of O3 pre-
cursor concentrations will be useful in car-
rying out the necessary modeling exer-
cises. Interpretations of NMOC species
data collected at various times of day will
help determine not only whether certain
control measures have been implemented
but also whether they are effective.
Within the next two to three years, EPA
and other agencies will pursue O3 control
strategies that require more monitoring
data. Unfortunately, historical data bases
of concurrent NMOC species and NOX are
limited, and they do not provide sufficient
Information for design and tracking func-
tions. They provide little information, for
example, that can be used to design the
ambient monitoring networks and special
monitoring projects needed to support fu-
ture, intensified O3 control strategies. Nor
do they allow for tracking the effective-
ness of ongoing control programs. As a
result of recent developments and improve-
ments in NMOC and NMOC-speciation
methodology, however, it is possible to
obtain sufficiently accurate and precise
monitoring data for these O3 precursors.
The above discussion describes part of
the context for the present study, which
was conducted to accomplish three goals:
1. To evaluate new measurement tech-
nology.
2. To demonstrate its feasibility and ap-
plicability to emerging needs.
3. To provide the information on the
spatial/temporal variability of NMOC, its
component species, and NOX to develop
the needed monitoring guidance.
Objectives
The primary objective of this project was
to develop a comprehensive, quality-as-
sured data base for NMOC species, NOX,
O3, carbonyls, and meteorological variables
with high-time resolution, at sites distrib-
uted across the Atlanta urban area. This
data base may be used to address a
number of questions relating to:
• spatial and temporal variations in the
concentrations of O3 precursors
• specific pollutants (for example, toxic
air pollutants) and pollutant ratios
• the adequacy of precursor data require-
ments for air-quality models
• the accuracy of emissions data used in
air-quality models.
Examples of specific question:; that may
be addressed with the aid of the Atlanta
data base are:
1. Spatial variability—
a. How do pollutant concentrations
and precursor ratios vary from
site to site across an urban area?
b. To what extent and under what
conditions can pollutant concen-
trations and precursor ratios mea-
sured at one site be extrapolated
to other parts of the urban area?
c. How do meteorological conditions
influence spatial pollutant variabil-
ity?
2. Temporal variability—
a. How do pollutant concentrations
and precursor ratios vary during
the day?
b. How representative of short-term
concentrations are time integrated
samples?
c. Does temporal variability vary
from site to site?
d. How do meteorological conditions
influence temporal variability?
3. Nature and distribution of emissions
sources—
a. What sources contribute to urban
air-pollutant concentrations?
b. Do ambient measurements of
NMOC species substantiate ex-
isting emissions inventories?
c. What is the relative importance
of anthropogenic and biogenic
emissions?
4. Photochemical models
a How well do photochemical mod-
els predict O3 levels downwind of
the urban area?
b. How do spatial and temporal
variations in precursor ratios and
levels influence model predic-
tions?
c. Are the default reactivity assign-
ments used in models adequate?
Methodology
Air monitoring was conducted during the
summer of 1990 for O3 and its precursors
at 12 sites spatially distributed across the
Atlanta metropolitan area. Hourly mea-
surements of O3, carbon monoxide (CO),
NOX, meteorological parameters, total
NMOC, and NMOC species were collected
on a continuous basis using automated
sampling and analysis techniques. Supple-
mentary integrated measurements for to-
tal NMOC and NMOC species (canisters)
and carbonyls (cartridges) were made pe-
riodically on predetermined schedules
throughout the study. A schematic dia-
gram of the field station is shown in Fig-
ure 1.
In addition, several ancillary experiments
were conducted, including:
• operation of a long-path analyzer at
Site 2
• operation of continuous PM10 moni-
tors at Sites 2 and 3
• limited operation of a continuous form-
aldehyde analyzer at Site 6
• collection of integrated samples for
volatile organic C14 determinations for
estimating the contribution of biogenic
sources ;
• collection of several samples for
source signature determinations
Monitoring was conducted primarily at
six fixed-sampling locations distributed
across the Atlanta urban area. These sites
were selected to satisfy the following cri-
teria:
1. Must provide broad spatial coverage
of the Atlanta area not dominated by local
sources.
2. Three sites must be located along
the northwest direction of prevailing winds
for Atlanta in the O3 season.
3. Three sites must be located along
the southwest direction perpendicular to
prevailing winds.
4. One site must be upwind to supply
background measurements.
5. One site must be located downwind
in an expected high-O3 area.
The locations of the six primary sites
are shown in Figure 2. These sites are
identified by the numbers 1 -6 and appear
as circles. To increase the spatial resolu-
tion of the NMOC species portion of the
data set, additional samples were collected
for NMOC analysis during certain periods.
These additional samples were collected
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/f^
Sample /(
Inlet / \
WD
Solenoid Valve
Control Relays
Vent
Figure 1. Station layout.
• Continuous Site • Enhancement Site
1.
2.
3.
4.
5.
6.
Mars Hill
Georgia Tech
MLK
Ft. McPherson
Tucker
So. DeKalb
7. Fire Station #8
8. Health Dept.
9. Baptist Church
10. Flat Shoals Rd.
11. Momingside Park
12. Georgia Dept. of
Natural Resources
I-85
Figure 2. Location of sites in the Atlanta, Georgia, Metropolitan Area.
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The names and general characteristics
of the six main sites are listed below:
1. Mars Hill is located approximately 35
km NW of the Atlanta beltway (I-285). The
site is in a rural, residential neighborhood
with no industry and is in the predomi-
nantly upwind direction from the Atlanta
metropolitan area during the O3 season.
Mars Hill serves as a background site to
measure concentrations of pollutants trans-
ported into the Atlanta area.
2. The Georgia Institute of Technology
is located in downtown Atlanta. There are
several industries located from 4-5 km
NE, NW, and W of the site. The site is
representative of the downtown area and
is located approximately 4 km NW of the
Martin Luther King (MLK) site, identified
below.
3. MLK is located on the fringe of down-
town Atlanta. The site is located in an
area with several localized sources, in-
cluding a reclamation operation, scrap-
metal operation, two small incinerators,
and a Metro Atlanta Rapid Transit
(MARTA) substation. The site also is af-
fected by the I-75/85 downtown connec-
tor. MLK is approximately 4 km SE of the
Georgia Tech site and 11 km NW of the
Dekalb Junior College site, identified be-
low. MLK has been used in the past to
collect NMOC and NO/NOX samples to
evaluate the EKMA model.
4. Fort McPherson is located on a mili-
tary base and is approximately 8 km SW
of MLK. This site is approximately 1 km
north of Highway 166 and 2 km west of
the I-75/85 and 166 interchange. The site
lies in the SW direction and is perpendicu-
lar to prevailing winds from downtown At-
lanta during the O3 season.
5. Tucker is located on the grounds of
an inactive hospital, approximately 22 km
NE of the MLK site and 23 km NNE of the
Dekalb Junior College site. The site is
located in a residential area affected by I-
285, approximately 2 km west, and by the
I-285/I-85 interchange, approximately 5 km
NW. In addition, a tank farm is located 7
km NNW, and a manufacturing plant is 7
km NW of the site.
6. The Dekalb Junior College site is
located on the campus approximately 1
km SE of I-285. The site is in a predomi-
nantly residential and commercial urban
fringe area, and it is located 12 km SE of
downtown Atlanta in the prevailing wind
direction during the O3 season. The site
traditionally measures the highest O3 lev-
els and, of all the sites in the existing
Atlanta O, monitoring network, most often
exceeds NAAQS. The site was used to
collect NMOC samples for the Atlanta
EKMA study.
Target Chemicals
The target pollutants and meteorologi-
cal parameters for continuous monitoring
at the six field sites are listed in Table 1.
The hydrocarbons, halocarbons, and car-
bonyls initially selected for measurement
at the six sites are shown in Table 2. To
aid comparisons between target chemi-
cals and those actually reported, Table 3
lists the resolved organic species.
Continuous Monitoring
Instruments
Automated analyzers approved by EPA
under the Ambient Air Monitoring Refer-
ence and Equivalent Methods Regulations
(40 CFR Part 53) were used for continu-
ous measurements of O,, CO, and NOX.
The instruments were calibrated in accor-
dance with approved calibration proce-
dures using dynamically generated gas
mixtures.
Automated Gas
Chromatography
An automated gas chromatographic sys-
tem was used to obtain the hourly NMOC
species measurements. This system was
developed and manufactured in Bilthoven,
The Netherlands, and is marketed in the
United States by Chrompack, Inc., of
Raritan, New Jersey. It is equipped with a
three-phase adsorbent trap to
preconcentrate the individual species. The
trap materials were Carbotrap C,
Carbotrap, and Carbosieve S-llll. The trap
was held at -35°C during the collection of
a 30-min sample at a flow rate of approxi-
mately 20 cc/min.
The collected species were thermally
desorbed from the preconcentration trap
at 250 °C. A second trap was used to
refocus the desorbed compounds. This
trap consisted of deactivated fused silica,
30-cm by 0.53-mm ID, filled with 3-in glass-
wool plugs. The trap was held at -186 °C
during sample transfer from the primary
trap and then was heated rapidly to 200
°C to direct components onto the analyti-
cal column. A CP-Sil-5 50-m by 0.32-mm
ID fused silica column with 5-u. film thick-
ness was used to resolve the species,
which ranged in carbon number from C2
through C10. The critical GC parameter
settings were as follows:
1. Oven initial temp. = -20 °C
2. Oven final temp. = 210 °C
3. Oven ramp temp. = 8 °C/min
4. Oven initial time = 3 min
5. Oven final time = 10 min
6. Detector temperature = 300 °C
7. Injector temperature = 200 °C
The resolved individual species were
detected using an FID and an ECD con-
nected in parallel to the analytical column.
From the resulting chromatograms, 54 hy-
drocarbon species and total NMOC, plus
five halocarbon species, were identified
and named on the basis of their retention-
time characteristics. Based on an NIST-
certified, benzene-standard response, a
per-carbon response factor was deter-
mined for the FID detector for the hydro-
carbon species. The targeted hydrocar-
bon species were quantified using the per-
carbon response factor and were reported
in units of ppb C. The unidentified hydro-
carbon species were quantified using the
same per-carbon factor. An estimate of
the total NMOC was determined by sum-
ming the Identified and unknown hydro-
carbon species. Individual compound re-
sponse factors for each of the halocarbon
species were determined for the ECD
based on responses from a known mix-
ture of the species. The targeted halocar-
bon species were reported as ppb com-
pound. ;
Canister Samples
Approximately 375 whole-air canister
samples were collected throughout the
study and analyzed for total NMOC and
NMOC species. These samples were col-
lected for the following purposes:
1. To compare measurements of the
automated-GC system with measurements
obtained with established GC procedures.
2. To confirm the qualitative identifica-
tion of selected species and to identify
persistent unknown compounds.
3. To enhance the spatial representa-
tiveness of the six primary sites by collect-
ing canister samples at six additional sites.
4. To establish source signatures at
known significant emission sources.
Approximately 185 routine samples were
collected in Summa polished canisters for
comparison with established GC proce-
dures to confirm compound identifications
and to evaluate the adequacy of the auto-
mated-GC system. An automated canister
collection system (Anderson*, Model 87-
100) was used to collect the samples.
The collection system filled the evacuated
canister (initial pressure less than 0.1 torr)
with sample air at a flow rate of 400 cm3/
min'1, resulting in a final pressure of ap-
proximately 15 psig. Samples were col-
lected every other day at every primary
site for 30-min periods concurrent with the
sampling interval of the automated GC
system. Sample collection , was rotated
through the following periods: 8:00 a.m.,
10:00 a.m., 12:00 noon, 3:00 p.m., 6:00
p.m., and 12:00 midnight.
'Mention of trade names or commercial products does
not constitute endorsement or recommendation for
use.
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Table 1. Continuous Measurements Performed During the Atlanta Field Study
Target Pollutants Meteorological Measurements
NO
NOX
CO
Wind speed
Wind direction
Sigma theta
Temperature
Relative humidity
Solar radiation
Table 2. Target Species Selected for Measurement by the Automated Gas Chromatograph During the Atlanta Study
Hydrocarbons
1. ethylene
2. acetylene
3. ethane
4. propene
5. propane
6. isobutane
7. 1 -butene
8. n-butane
9. lrans-2-butene
10. c\s-2-butene
11. 3-methyl-1-butene
12. isopentane
13. 1-pentene
14. n-pentane
15. a-pinene
16. b-pinene
17. isoprene
18. tcans-2-pentene
Halocarbons
1. chloroform
2. 1,1,1-trichloromethane
3. carbon tetrachloride
4. trichloroethytene
5. perchloroethylene
Carbonyls
1. formaldehyde
2. acetaldehyde
3. acetone
19. c\s-2-pentene
20. 2-methyl-2-butene
21. 2,2-dimethylbutane
22. cyclopentene
23. 4-methyl-1-pentene
24. cyclopentane
25. 2,3-dimethylbutane
26. 2-methylpentane
27. 3-methylpentane
28. 2-methyl-1-pentene
29. n-hexane
30. \rans-2-hexene
31. c\s-2-hexene
32. methylcyclopentane
33. 2,4-dimethylpentane
34. benzene
35. cyclohexane
36. 2-methylhexane
37. 2,3-dimethylpentane
38. 3-methylhexane
39. 2,2,4-trimethylpentane
40. n-heptane
41. methylcyclohexane
42. 2,3,4-trimethylpentane
43. toluene
44. 2-methylheptane
45. 3-methylheptane
46. n-octane
47. ethylbenzene
48. m/p-xylene
49. styrene
50. o-xylene
51. n-nonane
52. isopropylbenzene
53. n-propylbenzene
54. 1,3,5-trimethylbenzene
55. 1,2,4-trimethlybenzene
56. Total NMOC
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Table 3. Resolved Organic Species"
Hydrocarbons
1. ethylene
2. acetylene
3. ethane
4. propene
5. propane
6. isobutane
7. 1-butene
8. n-butane
9. trans-2-butene
10 . cis-2-butene
1 1. 3-methyl- 1 -butane
12. Isopentane
13. 1-pentene
14. n-pentane
15. isoprene
16. trans-2-pentene
17. cls-2-pentene
18. 2-methyl-2-butene
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
2,2-dimethytbutane
cyclopentene &
4-methyl-1-pentene
cyclopentane &
2,3-dimethylbutane
2-methylpentane
3-methylpentane
2-methyl- 1-pentene
n-hexane
trans-2-hexene
c\s-2-hexene
methylcyclopentane &
2,4-dimethylpentane
benzene
cyclohexane &
2-methylhexane
2,3-dimethylpentane
3-methylhexane
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
2,2,4-trimethylpentane
n-heptane
methylcyclohexane
2,3,4-trimethylpentane
toluene &
2-methylheptane
3-methylheptane
n-octane
ethylbenzene
m/p-xylene
styrene
o-xylene &
n-nonane
isopropylbenzene
n-propylbenzene
1,3,5-trimethylbenzene
1,2,4-trimethlybenzene
Total NMOC
Halocarbons
1. chloroform
2. 1,1,1-trichloromethane
3. carbon tetrachloride
4. trichloroethylene
5. perchloroethylene
'Individual co-eluted species are indented following each ampersand.
A set of 72 additional canister samples
was collected to enhance the spatial cov-
erage of the six primary sites. Two three-
day experiments were conducted at the
six sites identified in Figure 2 as enhance-
ment sites. These sites were selected to
fill in the grid of primary sites and to pro-
vide spatial information at scales of less
than 10 km to more than 50 km. In each
three-day experiment two samples were
collected per day, one at 9:00 a.m. and
one at 3:00 p.m., for 30-min periods con-
current with the 30-min sampling time of
the automated-GC systems operated at
the six primary sites. Portable collection
systems consisting of a mass-flow con-
troller and canister were used at the six
enhancement sites. The collection system
filled the evacuated canisters (initial pres-
sure* less than 0.1 torr) at a flow rate of
120 cm'/mlrr1, resulting in a final pressure
of 500-550 torr.
Another set of approximately 120 canis-
ter samples was collected at sites repre-
senting mobile sources, which are the pre-
dominant component of Atlanta's
nonmethane hydrocarbon emission inven-
tory. The sites included a roadway, a park-
ing lot, and the Hatsfield International Air-
port. These samples were collected with a
portable 12-volt, battery-operated pump
(Metal Bellows, Model 158, Sharonville,
Massachusetts) and a throttle va,lve to con-
trol flow rate at approximately 1.2 L/min'1.
Carbonyl Sampling
During the study, approximately 250
samples were collected during the study
using silica gel cartridges coated with 2,4
dinitrophenylhydrozine (DNPH). They were
analyzed for formaldehyde, acetaldehyde,
and acetone using Method TO-11. All of
the cartridges were shipped directly to RTP
for analysis, by AREAL personnel using
high-pressure liquid chromatography
(HPLC). Samples were collected at every
site every other weekday at alternating
periods of 6:00 a.m. to 12:00 noon (six
hr); 12:00 noon to 6:00 p.m. (8 hr); and
6:00 p.m. to 6:00 a.m. (12 hr) each week-
end at every site on alternating Saturdays
and Sundays.
An automated analyzer that, was ca-
pable of making continuous, real-time mea-
surements of formaldehyde was operated
for a two-week period (August 8 to Au-
gust 15) at the Dekalb site.
Ancillary Experiments
In addition to the spatial and temporal
variability experiment, several ancillary
experiments were conducted. One in-
volved operating a differential optical ab-
sorption spectrometer (DOAS) at the Geor-
gia Tech site. The DOAS is a long-path
analyzer manufactured by OPSIS, Inc., of
Lund, Sweden. Its operation is based on
the remote spectroscopic analysis of vis-
ible and ultraviolet light. ;
Transmitters located on the Southern
Bell Building, the Coca-Cola Headquar-
ters Building, and a near-by campus dor-
mitory beamed light to three receivers
located at the Georgia Tech site, where
the light was spectroscopically analyzed
for O3 and several other species, includ-
ing benzene and toluene.', The primary
purpose for operating the DOAS during
the study was to compare long-path mea-
surements with fixed-site point measure-
ments and to determine the feasibility of
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long-path measurements for addressing
future regulatory and research monitoring
needs.
Additional ancillary experiments included
limited vertical-profile measurements of
winds, temperature, moisture, and O3; lim-
ited acid aerosol measurements at se-
lected sites; collecting samples for volatile
organic C14 determinations to estimate the
contribution of biogenic sources; limited
operation of a continuous formaldehyde
analyzer at one site; and operation of con-
tinuous PM10 monitors at two sites.
Data Acquisition and
Processing
The basic components of the data-ac-
quisition system (DAS) included hardware
and software at the field monitoring sta-
tions, the Operations Center, and the re-
mote data-monitoring centers. DAS hard-
ware and software were located in the
shelters installed at each of the six field
sites.
The Odessa Data Logger was the data-
acquisition and initial data processing de-
vice for all the nonchromatographic sys-
tems. Data were stored as hourly aver-
ages and transmitted by an external mo-
dem that was attached to the data logger.
Via modem, the central computer polled
the data logger at each site on a daily
basis. To track instrument operation, each
site also was polled from a computer at
RTF. The data were stored on removable
cartridges installed in the data logger.
These cartridges were used to fill in areas
where .data were missing as a result of
communication problems.
The on-site personal computer (PC) was
responsible for data acquisition, initial data
processing, data display, and data trans-
mission for the automated gas chromato-
graphs. The data from the chromatographs
(raw signal files and result files) were ac-
quired by the PC and stored on the hard
drive. The data files were copied to floppy
disks each day, with backups. One copy
was carried to the Operations Center for
archival, and one copy was stored at the
field site.
Data Quality Objectives
Data quality objectives (DQOs) are re-
quired by the U.S. EPA Quality Assur-
ance Management Staff for all data col-
lection activities. DQOs are statements of
the quality of data needed to support spe-
cific program objectives. DQOs are de-
fined in terms of the study objectives,
rather than equipment or analysis method
characteristics. Quality assurance objec-
tives for the measurement data are also
required, however, and are stated in the
Quality Assurance Plan for this study.
The primary goal of this monitoring pro-
gram was to develop a comprehensive
data base with which to address a num-
ber of questions concerning spatial and
temporal variations in the ambient con-
centrations of a variety of pollutants, in-
cluding O3 and O3 precursors. Specifi-
cally, the objective was to study these
spatial and temporal variations during one
or more episodes of high ambient O3 lev-
els.
Assessing temporal variations statisti-
cally requires measurements with high time
resolution for the complete period of a
high-O3 episode (i.e., one or more days).
For most of the pollutants in this study,
the time resolution was one hour.
Assessing spatial variations statistically
requires measurements at a variety of lo-
cations that adequately characterize the
entire urban area. In addition, to account
for temporal variations when performing
the spatial analysis, the measurements
must be made simultaneously at all sam-
pling locations. For most of the pollutants
in this study, simultaneous measurements
were made at six fixed locations across
the Atlanta area. This basic spatial cover-
age for hydrocarbon species was en-
hanced during certain periods by sam-
pling at six additional sites.
To meet the study objectives described
above, the program DQO specified that
ambient-air samples must be collected and
analyzed with appropriate techniques to
ensure continuous detection at six sam-
pling locations of a target list of pollutants,
including O3 and O3 precursors, for every
sampling period covering at least one high-
O3 episode.
'U.S. Government Printing Office: 1992— 648-080/60146
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7?7e EPA authors, Larry J. Purdue (also the EPA Project Officer), James A
Reagan, William A. Lonneman, Thomas C. Lawless, and Ronald J. Drago are
with the Atmospheric Research and Exposure Assessment Laboratory, Re-
search Triangle Park, NC 27711. George M. Zalaquet is with Mantech Environ-
mental Technology, Research Triangle Park, NC 27711, and Michael W. Holdren,
Deborah L Smith, Alan D. Pate, Bruce E. Buxton, and Chester W. Spicerare with
Battelle Memorial Institute, Columbus, OH 43201.
The complete report, entitled "Atlanta Ozone Precursor Monitoring Stud!/ Data
Report," (Order No. PB92-220 656/AS; Cost: $26.00; subject to change) will be
available from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
For a copy of the report and the disks containing the collected data, contact Larry
J. Purdue at:
Atmospheric Research and Exposure Assessment Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use $300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-92/157
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