SEPA
United States
Environmental Protection
Agency
Environmental Sciences Research
Laboratory
Research Triangle Park NC 27711
EPA-600/4-79-009
February 1979
Research and Development
Association Between
Meteorological
Conditions and High
Ozone and Sulfate
Concentrations
A 1974 Episode in the
Eastern United States
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL MONITORING series.
This series describes research conducted to develop new or improved methods
and instrumentation for the identification and quantification of environmental
pollutants at the lowest conceivably significant concentrations. It also includes
studies to determine the ambient concentrations of pollutants in the environment
and/or the variance of pollutants as a function of time or meteorological factors.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
-------
EPA-600/4-79-009
February 1979
ASSOCIATION BETWEEN METEOROLOGICAL CONDITIONS
AND HIGH OZONE AND SULFATE CONCENTRATIONS
A 1974 Episode in the Eastern United States
by
Gerard A. DeMarrais
Meteorology and Assessment Division
Environmental Sciences Research Laboratory
Research Triangle Park, N.C. 27711
ENVIRONMENTAL SCIENCES RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, N.C. 27711
-------
DISCLAIMER
This report has been reviewed by the Office of Research and Development,
U.S. Environmental Protection Agency, and approved for publication. Mention
of trade names or commerical products does not constitute endorsement or
recommendation for use.
Mr. DeMarrais is a meteorologist in the Meteorology and Assessment
Division, Environmental Sciences Research Laboratory, Environmental Research
Center, Research Triangle Park, N.C. 27711. He is on assignment from the
National Oceanic and Atmospheric Administration, U.S. Department of Commerce.
ii
-------
ABSTRACT
2
A 1,000,000 km area of the Eastern United States had sulfate concentra-
tions exceeding 10 yg/m on July 10, 1974, and there were indications that
parts of the area had high concentrations on prior days. The meteorology
associated with the high concentrations and correlations of high ozone and
sulfate concentrations are discussed. It appeared that slow moving and
subsiding air contributed to the high concentrations of both pollutants. Long
range transport, as shown by trajectory analyses, was a factor in the problems
in most areas, but the worst situations with regards to sulfates were asso-
ciated with emissions from nearby, upwind sources. While high ozone concen-
trations were observed immediately prior to high sulfate concentrations in
many areas, there were high sulfate concentrations that were not associated
with high ozone concentrations. In the latter situation, the high sulfate
concentrations were associated with air which had earlier movement over areas
with high S02 emission.
m
-------
CONTENTS
Abstract iii
Figures vi
Tables y-j^-
Postscript and Acknowledgement ix
1. Introduction 1
2. Conclusions 2
3. Background and Methods 4
Sulfates, reactions producing sulfates, and measuring of
sulfates 4
The ozone episode 5
The SO,, to sul fate conversion and long-range transport.
Diurnal variations of sul fates 7
Meteorological conditions associated with high concentra-
tions of ozone and sulfates 7
Potential source areas of ozone and sulfate precursors. y
Meteorological resources 9
4. Results 11
Background 11
Sulfate data 11
The ozone data 14
Temperature data 15
Visibility 16
Synoptic weather situation 18
Other meteorological observations 20
Trajectories of the surface-to-1000-m layer 20
5. Summary 25
References 27-30
-------
FIGURES
Number Page
1. Annual hydrocarbon emissions by state in 1973 (1000 tons). . . . ;31
2. Annual S09 emissions from power plants by state in 1974
(1000 tons).
3. Locations of sulfate monitoring stations of state and local
agencies (see Table 1 for station names)
4. Sulfate concentrations (yg/m ) July 10, 1974
32
33
34
5. Station locations (see Table 4 for station names) TVA network. .
i
6. Maximum hourly ozone concentrations (ppb) July 6, 1974 j3^
7. Maximum hourly ozone concentration (ppb) July 7, 1974 |3?
i
8. Maximum hourly ozone concentration (ppb) July 8, 1974 ,38
j
9. Maximum hourly ozone concentration (ppb) July 9, 1974. i3^
i
! ._
10. Maximum hourly ozone concentrations (ppb) July 10, 1974. ....
11. Maximum hourly ozone concentration (ppb) July 11, 1974
41
42
12. Maximum temperatures (°F) July 6, 1974
13. Maximum temperatures (°F) July 7, 1974 i43
14. Maximum temperatures (°F) July 8, 1974 i44
15. Maximum temperatures (°F) July 9, 1974 i45
16. Maximum temperatures (°F) July 10, 1974. . . '46
17. Visibility (miles) July 6, 1974, 1 p.m., e.s.t 4?
18. Visibility (miles) July 7, 1974, 1 p.m., e.s.t 48
19. Visibility (miles) July 8, 1974, 1 p.m., e.s.t • 4$
20. Visibility (miles) July 9, 1974, 1 p.m., e.s.t. . 50
vi
-------
FIGURES (Contined)
Number Page
21. Visibility (miles) July 10, 1974, 1 p.m., e.s.t 51
22. Daily weather maps, July 6, 1974 52
23. Rainfall during sulfate sampling period of July 10, 1974 • • • • 53
24. 48-h trajectories (12-h segments) of layers of air between the
surface and 1000 m for selected cities, July 6, 19/4 (arrival
time 1 p.m., e.s.t.) 54
25. 47-h trajectories (12-h segments) of layers of air between the
surface and 1000 m for selected cities, July 7, 1974 (arrival
time 1 p.m., e.s.t.) 55
26. 48-h trajectories (12-h segments) of layers of air between the
surface and 1000 m for selected cities, July 8, 1974 (arrival
time 1 p.m., e.s.t.) 56
27. 48-h trajectories (12-h segments) of layers of air between the
surface and 1000 m for selected cities, July 9, 1974 (arrival
time 1 p.m., e.s.t.) 57
28. 48-h trajectories (12-h segments) of layers of air between the
surface and 1000 m for selected cities, July 10, 1974 (arrival
time 1 p.m. e.s.t.). 58
vii
-------
TABLES
Number Page
1. Names of Stations in Sulfate Monitoring Network (see Figure 3)
for station locations) 59
2. Sulfate Concentrations (yg/m3) at CHESS Stations in the New York
City Area, July 6-11, 1974 60
3. Sulfate Concentrations (yg/m ) at Electric Power Industry Sites |
in Northern United States, July 6-11, 1974 |61
4. Station Names, TVA Network (see Figure 5 for station locations). j62
5. Sulfate Concentrations (yg/m3) TVA Network, July 3-11, 1974. . .63-64
viii
-------
POSTSCRIPT
After the final draft of this report was completed, a technical
article examining the same sulfate episode was published. This article,
Spatial and Temporal Distributions of Airborne Sulfate in Parts of the
United States in Atmospheric Environment, V.12, 735-752, (1978), by
G. Hidy et al., briefly discusses with isoplethed maps the high sulfate
concentrations of July 8-11, 1974.
This EPA report differs from the technical article in that major
emphasis is given to the coexistence of high ozone and high sulfate
concentrations. In addition, more consideration is given to details.
These details show that isoplething masks out discrepancies and on
occasion does not show a significant feature; for example, the isoplethed
3
map for July 10 indicates a concentration of approximately 10 yg/m in
the vicinity of West Virginia whereas two stations in the area showed
concentrations four and five times as great.
ACKNOWLEDGEMENT
The patience of Mrs. Hazel Hevenor in retyping the many drafts of
this report was appreciated.
IX
-------
SECTION 1
INTRODUCTION
Sulfate concentrations are frequently above average when ozone
1 2
concentrations are relatively high . In a southern California investigation ,
it was shown that an 8-d sulfate episode coincided with an ozone episode.
To further test the cofrequency hypothesis, a period was sought during
which high ozone concentrations occurred in that 16-state area* that has
3
consistently shown higher sulfate concentrations than the rest of the nation .
Such an ozone event occurred over the area during July 6-10, 1974, and a
preliminary correlation of the ozone concentrations and meteorological
conditions was previously noted . In this report the available sulfate
data (they are not as abundant as ozone data), ozone concentrations, and
meteorological conditions for the period are discussed.
* This 16-state area is east of the Mississippi River, and is roughly bounded
by Illinois and Massachusetts to the north and Tennessee and North Carolina
to the south.
1
-------
SECTION 2
CONCLUSIONS
On the basis of the analysis of the daily ozone, sulfate, and meteorologi-
cal data, the following conclusions are drawn:
1. A large-scale ozone episode occurred over the Northeastern United
States from July 6 to 10, 1974, and midway through the episode sulfate
2
concentrations became high and eventually spread over a 1,000,000 km area
of the Eastern United States.
2. The ozone episode was initially associated with only the air behind
a cold front that pushed southeastward over the area on July 6. The
air mass eventually became the warmest of the year (most locations in
the ozone episode area had the highest temperatures of the year during
this 5-d period) and was characterized by slow movement at the surface
and aloft (stagnation) and subsidence. The high sulfate concentrations
each day were not restricted to the high temperature areas but were
associated with the slow moving and subsiding air.
3. The areas of high ozone concentrations on each day did not correspond
to the areas with restricted visibility or precipitation. The areas of
high sulfate concentrations on each day corresponded somewhat to the
areas with restricted visibility during several days when the sulfate data
were limited and on the one day (July 10) with abundant sulfate data. The
area with high sulfate concentrations on July 10 corresponded to the
area with rainfall. After the passage of a front toward the end of
the period, the ozone concentrations were reduced, and the restrictions
to visibility eliminated, but the sulfate concentrations remained high.
4. The trajectory analysis frequently showed that air with a high
ozone or sulfate concentration at a receptor had had a high concentration
-------
at an earlier time in an upwind location; long-range transport, although
limited by stagnation, did occur. However, at times air arrived from
areas that did not show a high ozone or sulfate concentration, but at
these times the air usually came from an area that was a large emitter
of precursors.
-------
SECTION 3
BACKGROUND AND METHODS
SULFATES, REACTIONS PRODUCING SULFATES, AND MEASURING OF SULFATES
Most sulfur in the atmosphere, land surface, and water exists as the
hexavalent oxidized sulfate ion (SO^pJ in such diverse forms as sulfuric
acid; amonium bisulfates; calcium sulfate (the major component of gypsum);
magnesium sulfate (epsom salts); sodium and potassium sulfates (in seawater);
and other metal salts, such as copper, nickel, iron, lead, and zinc sulfates .
On a global scale, natural sources contribute about two-thirds of the
sulfur compounds in the atmosphere by weight, and human activities the re-
mainder. In the continental United States, probably 90% of the atmospheric
sulfur is the result of anthropogenic emissions in the form of sulfur dioxide
(S02) . Most of the S02 is oxidized to the sulfate form within a few days,
and, while this oxidation is taking place, the pollutants in the air can be
transported long distances; the sulfate receptors may be hundreds of km from
the sources of primary emissions .
The important mechanisms by which S09 is converted to sulfuric acid and
36
sulfate salts ' are: 1) direct photopxidation; 2) indirect photooxidation;
3) air oxidation in liquid droplets; 4) catalyzed oxidation in liquid drop-
lets; and 5) catalyzed oxidation on dry surfaces.
A substantial fraction of the man-made sulfate problem is believed to
be associated with S02 emitted by large power olants . The 16-state area
with the higher sulfate concentrations correlates spatially with high S02
emission density, high rainfall acidity patterns, and a high density of
power plant locations .
The majority of sulfate data evaluated in this report were supplied by
the National Aerometric Data Bank (NADB) and the CHESS (Community Health and
Environmental Surveillance System) program of the U.S. Environmental Protection
-------
Agency (EPA). The sulfate data in the NADB came from State and local air
pollution control agencies and were generally collected every 12th day in
accord with a preset schedule (in July 1974 nearly all stations had data for
the 10th and 22nd); some stations sampled on additional days at random
times. The stations in the CHESS program were operated every day. Sulfate
data from stations in a network operated by the electric power industry and
49 stations in a Tennessee Valley Authority (TVA) network are also considered
in the analyses. Each sulfate measurement is made from a small strip of
filter on which suspended particulate had been collected in a high volume
air sampler. Each sampling period is 24-h, and the filters are changed at
midnight (local standard time). The filter strip is extracted with water,
and a portion of the aqueous extract is analyzed for sulfate by the methyl
thymol blue method.
At the present time no National Ambient Air Quality Standard (NAAQS)
exists for sulfates. In an EPA position paper on the regulation of atmos-
pheric sulfates the highest concentration tentatively associated with adverse
health effects was reported to be 10 yg/m (24-h average) and in this report
3
concentrations greater than 10 yg/m are labeled high.
THE OZONE EPISODE
The investigation of the ozone episode examined data from approximately
100 stations in the Eastern United States extending from Ohio and Massachusetts
4
in the north to Tennessee and North Carolina in the south. In the report
data for 50 representative stations in 11 states are presented (no ozone
data were available for West Virginia and South Carolina). Ozone monitoring
stations are usually operated by State and local agencies, with the State
agency being responsible for providing the Federal Government with a near-
complete and accurate record. More than two dozen agencies collected the
analyzed data. One station in Richmond, Virginia, used an ultraviolet
Dasibi instrument, but all others employed a chemiluminescence instrument.
The current NAAQS (hourly value) for ozone*, not to be exceeded more
than once a year, is 160 g/m3 or 80 ppb8; in this report, when the NAAQS is
violated, a concentration is called high. The ozone data presented came
from the NADB.
*It has been proposed that the NAAQS be revised upward to 200 yg/nT
5
-------
THE S02 TO SULFATE CONVERSION AND LONG-RANGE TRANSPORT
The conversion of S02 to sulfate in the air and the possibility of
long-range transport of the sulfate have been reported extensively ;
there are many observations and findings but the agreement is not universal.
Q
One group of investigators found no clear evidence of long-range transport,
another investigator reported obvious transport out to 1000 km, and others11
found transport readily occurred but was limited to several hundred km. An
incomplete knowledge of the meteorology, chemistry, and timing of processes
in the conversion of man-made S02 to sulfates and of the eventual return to
the surface by uptake and precipitation is the cause of the disagreement
about the long-range transport of sulfates. Various investigators have
12
hypothesized about features of the processes. Georgii , basing his hypothesis
on observations over Central Europe, noted three important features. First,
the vertical S02 concentration decreases rapidly with altitude, reaching
half the ground concentration at 800 to 1200 m above the surface. Second,
seasonal variations of the S02 concentration are limited to the 2000 m
immediately above the surface. Third, inversions prevent, and convection
accelerates the transport of S02 into higher layers; above the inversion and
haze layers, the S02 concentration decreased markedly, whereas the sulfate
concentration is not much influenced by the thermal structure of the atmos-
phere. The difference between the gas phase and liquid phase conversion of
S02 to sulfate was noted by Kellogg et al. . They reported the gas phase
conversion showed a half-life for S02 of 12 d while, when S02 was dissolved
in fog or cloud droplets, particularly where metal salts were present to
14
serve as catalysts, the S02 rapidly (within hours) oxidized. Weber
estimated that 50% of the S02 emitted by power plants and the space heating
chimneys in the Frankfurt area was oxidized in the first 20 min to 1 hr of
15
travel time during the winter (in relatively moist air). Atkins et al.
in discussing sulfate concentrations over Britain, stated that the concentra-
tions were indicative of the history of the air mass several days earlier and
showed air in which oxidation of S00 occurred at distances up to 1000 km up-
IE
wind over Central Europe. The authors further stated that the sulfate was
removed from the atmosphere almost solely by rainfall.
-------
Nisbet stated that after transport and oxidation, sulfur is returned
to earth by four principal routes:
1. absorption of gaseous SCL by the soil or vegetation;
2. deposition of SOp in rain or snow;
3. deposition of sulfates in rain or snow; and
4. dry deposition of particles containing sulfates.
DIURNAL VARIATIONS OF SULFATES
Since many meteorological phenomena (e.g., wind speeds, temperature,
relative humidity) usually show marked diurnal variations, a knowledge of the
diurnal variations of sulfates could indicate which meteorological phenomena
might account for sulfate variations. Unfortunately, investigators of the
diurnal variations of sulfate concentrations have produced inconsistent and
conflicting results15'17"20.
METEOROLOGICAL CONDITIONS ASSOCIATED WITH HIGH CONCENTRATIONS OF OZONE AND
SULFATES
Considerable documentation of the meteorology associated with high
24
oxidant concentrations has accumulated*. Middleton et al. , in 1950
reported that high ozone concentrations occurred with weak winds and stagnant
air. Other early, comprehensive investigations of the Los Angeles ozone
22-24
concentrations related variations in concentrations to variations in the
following: intensity and duration of solar radiation; surface temperature;
the depth of the polluted layer (the top coincided with the base of the
Of"
subsidence inversion); and wind speed and direction. Following the report
that winds aloft in the Los Angeles area are important in transporting that
which the author describes as "second-hand ozone" to unsuspecting downwind
areas, investigators examined the three dimensional air movements and
transport in the 200-km long Basin. Evidence26"28 confirms that high ozone
concentrations are frequently in the air aloft, even within the subsidence
layer, and that these ozone-laden layers move with the winds aloft.
Eventually, some of the ozone is brought to the surface in daytime mixing.
In recent years the long-range transport of ozone has been reported in many
oq TO
areas of the nation
-------
As previously noted, direct and indirect photochemical processes are
important in the production of sulfates, so intense solar radiation and
abundant sunshine are conducive to high concentrations. Whenever there is
good vertical motion in the daytime and ozone is carried aloft, SO^ in the
presence of this ozone aloft is oxidized at appreciable rates at night as
34
well as in the daytime . The heterogeneous rate of oxidation of S09 to
qc qc ^ qc
sulfate is dependent on relative humidity ' . In a laboratory study , no
oxidation was detected when the relative humidity was less than 70%, while
at higher humidities the oxidation rates were considerable (possibly because
catalyst particles changed from solid form into solution drop form). Low
37
speeds tend to keep sulfates near the sulfur sources; Bushtuveva found
that concentrations of sulfuric acid aerosol during "calm days" were 4.5
times greater than during days with winds averaging over 5 m/s. Sulfate
1o qo qg
concentrations will also vary with rainfall ' . Early investigators
found that the sulfate concentration of rainwater decreased with an increased
rate of rainfall; they suggested that there was a limited quantity of
sulfate in the lower atmosphere, which is removed in each period of pre-
Ifl
cipitation. In the other study it was reported that the sulfate concentra-
declined sharply as a result of rainfall and increased rapidly after the
rainfall ended. Sulfate concentrations in urban areas tend to peak in the
third quarter of the year (July, August, September) but occasionally peak
39
in the second quarter .
POTENTIAL SOURCE AREAS OF OZONE AND SULFATE PRECURSORS
Since ozone and sulfates are seldom emitted directly to the atmosphere,
their presence is dependent on the emission of precursors—pollutants that
after being emitted into the atmosphere react and become ozone and sulfates.
Hydrocarbon emissions are considered important forerunners of ozone, and S02
is the primary precursor of sulfates. Because differences in the observed
spatial patterns of concentrations of ozone and sulfates could be due
to differences in the emission patterns of the precursors, data on the emission
patterns were sought.
-------
Figure 1 shows the annual emissions of hydrocarbons in tons for 1973 (the
most recent year available) for each state in the study area. The large ton-
nages in Illinois, New York, Ohio, Michigan, and Pennsylvania show that those
states are major sources of ozone precursors. When emission density (emissions
per km ) is considered, a number of smaller states also have to be designated as
large emitters—Massachusetts, Connecticut, New Jersey, and Maryland. Thus,
the large emitters are primarily in the northern part of the Eastern United
States.
Figure 2 shows the annual SCL emissions from power plants for 1974. The
states with large emissions were_Michigan, Illinois, Indiana, Ohio, Pennsylvania,
New York, West Virginia, Kentucky, Tennessee and Alabama. The states of
Massachusetts, Connecticut, Rhode Island, New Jersey, Delaware, Maryland
2
and Virginia and the District of Columbia on an emissions per km basis
have to be considered small emitters.
METEOROLOGICAL RESOURCES
Daily weather data contained in the Local Climatological Data for 86
National Weather Service (NWS) stations in the Eastern United States were
evaluated. Major emphasis was given to maximum temperatures, visibilities,
and the occurrences of precipitation at these stations. Daily Weather
41
Maps were reviewed; this publication has maps for the United States showing
the conditions that prevailed at the surface and at 500 mb, about 5500 m
above the surface, at 7 a.m., Eastern Standard Time each day. These maps
were used to locate fronts, centers of high and low pressure, and areas of
precipitation and to relate the wind speeds and directions to high concentra-
tions.
Trajectory analyses were used to supplement the data from the Daily
Weather Maps by showing the likely paths of the layer of air prior to arrival
in the area. The trajectory analyses are based on the wind data from the
rawinsonde observations scheduled at 7 a.m. and 7 p.m. and the winds aloft
observations at 1 a.m. and 1 p.m. each day. In the basic calculation, a
point along the trajectory is determined every 3 h and data within a radius
of 300 nautical miles (556 km) are evaluated. The model includes a
-------
distance weighting factor (the closest observations receive the greatest
weight), an alignment weighting factor (observations upwind and downwind
receive the greatest weight), and a height weighting factor (the thicker
the subpart of the trajectory layer that the wind represents, the greater the
weight). Trajectory segments are linked together to produce a complete tra-
jectory for the desired period of time. Trajectories are usually started from
a source or receptor four times daily, 1 and 7 a.m. and 1 and 7 p.m. In this
report, trajectories are used to show the backward movement of the surface-
to 1000 m layer in 12-h segments for a number of designated cities. These
trajectories are approximations and thus become progressively less reliable
with each added segment. In this report the trajectories are limited to
48 h. A point on a trajectory indicates the general area and not a
specific location where a layer of air was located at an earlier time.
10
-------
SECTION 4
RESULTS
BACKGROUND
Whereas the air quality data collection program throughout the nation
provides continuous hourly data for ozone concentrations, sulfate date are
gathered only every 12th day and for a 24-h period. During early July 1974
the sulfate monitoring network, operated by the State and local agencies,
collected samples on the 10th. Since this was only 1 d during the ozone
episode, an ozone-sulfate correlation could be misleading unless the sulfate
concentrations were shown to be representative of the period. Accordingly,
the basic sulfate data were supplemented by: 1) Norfolk data in the NADB
for July 8 and 9; 2) data from a four-station network operated daily by the
CHESS program in the New York City area; 3) data from nine stations in a
network operated daily by the electric power industry in the Northeastern
United States; and 4) data from 49 monitoring stations at 18 locations in a
TVA network (this network collected samples on every sixth day).
The number of State and local sulfate monitoring stations in the Eastern
United States that operated on July 10 was 83. Although much more numerous in
the north, there were enough stations in the south to delineate the area
with high concentrations. The ozone stations were so numerous in the North-
east that all could not be conveniently plotted on a map, so a number are
not on the ozone figures that follow. In contrast to the Northeast, there
was no ozone data for West Virginia, South Carolina, Georgia, and Alabama
and a very limited amount of data for Michigan and Indiana.
SULFATE DATA
The locations of the State and local sulfate monitoring stations are
shown in Figure 3, and the names of the stations are shown in Table 1. The
sulfate data for the 83 stations on July 10 are shown in Figure 4. High
11
-------
concentrations prevailed in an area from Boston to Atlanta to Chicago to Boston,
2 3
an area of 1,000,000 km . The concentrations ranged from 63 yg/m in
southern Pennsylvania to 4 in northern Indiana with approximately three-fourths
3
of the stations showing concentrations exceeding 10 yg/m . Not to be over-
looked are the numerous areas reporting extremes in concentrations within short
distances, for example: 1) southern Michigan, 42 (Lansing) vs 9 (Flint); 2)
northern Indiana 25 (East Chicago)vs 4 (South Bend); 3) southeastern Pennsyl-
vania, 63 (York) vs 7 (Lancaster); and 4) northeastern New Jersey, 29 (Eliza-
beth) vs 7 (Newark). These contrasts indicate that individual observations
are representative of limited areas and that judgments about regional con-
ditions should be based on observations from several locations. With more
p
than 60 stations in the million km area showing concentrations in excess of.
3
10 ug/rn , it is concluded that an episode of at least a 1-d duration existed
in the region.
The data for Norfolk showed that the sulfate concentrations for July 8, 9,
o
and 10 were respectively 5.0, 12.7, and 14.7 yg/m . These limited data
indicate that Norfolk's relatively high concentrations extended back to the
9th, but not to the 8th.
The data for the four CHESS stations in the New York City area for July 6
to 11 are shown in Table 2. In the New York City area the sulfate concentra-
tions were markedly higher on the 10th than on the 5 other days. The con*
centrations were relatively low on the 8th, increased on the 9th, then
increased two or three fold on the 10th.
The data for the nine electric power company stations which gave
coverage from Illinois to New York, are shown in Table 3. The overall indi-
cation is that most of the area had concentrations in excess of 10 yg/m most
of the time. Three Indiana stations (and the fourth for 2 d) had high values
on all 6 d and the values were comparable to those at the NADB stations on
July 10 (see Figure 4). The only places and times at which low values were
recorded were Huntington on the 6th and 7th, Scranton on all days but the
22
9th, and Albany on the 6th, 7th, and llth. Tong et al evaluating the
concentrations at each of these stations, showed the following monthly average
concentrations (yg/m3) for July 1974; about 22 at the four Indiana stations
12
-------
and at Huntington, 27 at Wheeling, 16 at Collins, 13 at Scranton, and 9 at
Albany. Concentration levels twice the average values occurred at only one
of the four stations in Indiana and then on the llth, on the 8th and 9th at
Huntington, on the 7th, 8th, and 9th at Wheeling, and on the 9th at Scranton
and Albany.
The 18 locations from which the TVA obtained sulfate data are shown in
Figure 5, and Table 4 lists the names of the locations. The 6-d sampling
schedule provided large amounts of data for July 3 and 9 and a few data points
for July 6, 7, and 8. The observed concentrations on these days and the
average concentration observed during the July sampling days are shown in
Table 5. The data for the 3rd indicate that the area had many locations
3
exceeding 10 g/m , but the limited data for the 6th, 7th, and 8th indicate
3
that concentrations were relatively low; most were less than 10 g/m , and all
showed concentrations that were about half or less than the July average.
3
On July 9, a majority of locations had concentrations exceeding 10 g/m (again
most stations had concentrations below the July average). In a number of
areas there were sharp contrasts in concentrations within short distances;
for example, in northeast Alabama between Widows Creek (13) and Hytop (15),
in northwest Alabama between Colbert (3) and Muscle Shoals (9), and in
western Kentucky between Paradise (10) and Land Between the Lakes (16).
The indication of the TVA data is that the concentrations on July 9 over
the Southeastern United States were similar to those in the State and local
network on July 10 (Figure 4), but on the 2 prior days they were lower.
The composite picture drawn from the sulfate data from the four
2
sources is: 1) a 1,000,000 km area in the eastern United States had high
sulfate concentrations on July 10; 2) whereas some places had concentrations
exceeding 10 g/m on earlier days, the period of markedly high concentra-
tions over an extensive area appeared to be July 8 to 10; 3) there was
an apparent movement from west to east of a peak concentration with the
peak passing through West Virginia on the 8th and 9th, Pennsylvania and New
York on the 9th, and the New York City-Long Island area (and possibly Norfolk)
on the 10th; and 4) although no peak moved through the southern part of the
affected area, the area of high concentrations appeared to spread southward
•13
-------
from July 8 to 9.
THE OZONE DATA
The extent of the high concentrations of ozone on each day from
July 6 through 11 is shown in Figures 6 to 11. On July 5 only a half-dozen
locations had NAAQS violations while on July 6 (Figure 6) slightly more
than one-third of the stations had violations. The high concentrations, on
this date, were restricted to the northern areas and extended from Chicago to
eastern Connecticut in three separate areas. On July 7 (Figure 7), a Sunday,
almost two-thirds of the stations recorded violations of the standard, and the
higher concentrations were observed farther south than they had been on the
6th. There were only two separate areas of high concentrations (the area of
low concentration on July 6 in central New York and Pennsylvania was eliminated);
they were separated by an area of low concentrations oriented north-south
through western Ohio and eastern Kentucky and Tennessee. On July 8 (Figure 8)
about three-fourths of the locations had NAAQS violations, and again the
two separate areas with high concentrations were seen. This was the day
that the majority of stations recorded their highest concentrations. July 9
(Figure 9) was the day with the greatest number of locations showing
violations as more than three-fourths had concentrations exceeding 80 ppb.
There were still indications of eastern and western areas with high concentra-
tions, but the problem was moderating in the latter. On July 10 (Figure 10)
less than half of the stations had violations, since the high concentrations
-were concentrated in the Richmond-to-New York corridor and Pennsylvania
and Ohio. On July 11 (Figure 11) only five locations had violations,
while 57 did not show violations; the regional ozone episode had ended
by July 11.
The overall picture is that a large area in the Northeastern United States
had high ozone concentrations from July 6 to 10. The concentrations and
the number of stations with high concentrations were greatest on July 8 and 9.
There Was no gradual spreading of the area with high concentrations nor an
apparent movement of a peak concentration across the area, as there had been
with the sulfate concentrations.
14
-------
TEMPERATURE DATA
The initial high ozone concentrations occurred on July 6, so the analysis
of the temperature data start with that day. Figure 12, shows the maximum
temperatures reported at 86 NWS stations in the Eastern United States. In
order to locate the relatively warm areas, each station that observed a maximum
temperature 2.7°C (5°F) or more warmer than its July average is marked in
bolder print. Only three small warm areas are shown on July 6, indicating
that high temperatures were not associated with the initial occurrence of
high ozone concentrations. The overall comparison of July 6 maximum tempera-
tures and the July average indicated that this was a relatively cool day over
the whole area.
On July 7 (Figure 13) a large area across the northern section of the
Eastern United States and two separate stations had relatively-high tem-
peratures. Many stations with high ozone concentrations (Figure 7) were
within the area that observed high temperatures, but a large number were
south of the area. Although a few of the Electric Power Industry stations
showed high sul-fate concentrations in the high temperature area, most
stations in the area (Tables 2 and 3) had low concentrations.
On July 8 (Figure 14) the area with high temperatures included all of
the northernmost stations, and the southern boundary was farther south than it
was on July 7. It is interesting that temperatures in the north were on the
average about 2.7°C (5°F) warmer than those in the south. The areas with high
ozone concentrations (Figure 8) were for the most part in the same area as those
with high temperatures; the stations with high ozone concentrations extended
a little farther south. Comparison of the limited sulfate data with the
temperature pattern showed no consistent agreement; monitoring stations
(Tables 2 and 3) within the area of high temperatures showed a wide variation
in concentrations.
On July 9 (Figure 15) the area with relatively high temperatures covered
the greatest area that it was to cover during this period, and 17 stations had
the highest temperature of the month on this date. The area with high ozone
concentrations (Figure 9) was approximately the same as that with high
temperatures. Although many stations in the high temperature area had high
15
-------
sulfate concentrations, some stations outside the area had high sulfate con-
centrations (Tables 3 and 5).
On July 10 (Figure 16) two large separate areas and a station in West
Virginia had high temperatures. The high-temperature eastern area had many
locations with high ozone concentrations, but many locations with high
concentrations were not in the areas with high temperatures. The area with
high sulfate concentrations on this day (Figure 4) was practically the
entire area; the areas of high sulfate and relatively high temperature were
not similar.
Overall, the indication is that the initial high ozone concentrations
occurred before the high temperatures, but through the worst of the ozone
episode the area of high ozone concentrations was almost the same as the
area with high temperatures. However, in the case of the sulfates there "did"
not appear to be a good spatial agreement with regard to the areas of high
temperature and high sulfates. Even if one were to consider a lag between
the high temperatures and high sulfates, and compare the area of high
temperatures of July 9 with the area of high sulfates of July 10, there did
not appear to be agreement.
VISIBILITY
The NWS records always note the visibility restriction (fog, haze, smoke;,
precipitation, etc) whenever the visibility is less than 11.25 km (7 mi). The
visibility observations that are presented are for 1 p.m. Eastern Standard
Time, a time in the day when relative humidities are usually low and fog is
reported infrequently. " In the figures to follow the visibilities and obstruc-
tions to visibility are shown for the 86 NWS stations in the east, and areas
with obstructions to visibility, other than rain, are delineated. In the text
that follows, poor and restricted visibility are used interchangeably.
On July 6 (Figure 17) the first day with high ozone concentrations, the
restricted visibility area was a 350-km wide band, running from just below
New York City to near Richmond and extending 1300 km to southern Indiana in
the west. Outside the restricted visibility area, 16 km (10 mi) or greater
visibility was recorded at most stations. The majority of stations with high
ozone concentrations (Figure 6) were to the north of the restricted visibility
16
-------
area, and the majority of the ozone monitoring stations in the poor visibility
area did not have NAAQS violations. With regard to the limited sulfate
data (Tables 2,3, and 5), most of the stations with low concentrations were
outside the restricted visibility area, and most with high concentrations were
inside the area.
On July 7 (Figure 18) the restricted visibility area extended from
southern Michigan to northern Kentucky, then eastward to the Washington,
D. C., area. Most of the ozone stations (Figure 7) in the poor visibility
areas did not have violations of the NAAQS. To the northeast of the
restricted visibility area, the ozone concentrations were high, and visibilities
generally 16 km (10 mi) or more: to the west of the poor visibility area, all
but one NWS station had a visibility of 12.9 km (8 mi) or more, while all five
ozone monitoring stations showed violations. The EPRI sulfate monitoring sta-
tions (Table 3) with high concentrations were generally in the restricted
visibility area, while the relatively clean EPRI stations (Scranton, Albany),
CHESS stations (Table 2), and TVA stations (Table 5) were outside the area.
On July 8 (Figure 19) the area of poor visibility covered the Midwest
and extended into northern Virginia, Georgia, and southwestern Tennessee.
Although many of the ozone monitoring stations (Figure 9) in the poor
visibility area did have NAAQS violations, a much greater proportion
of stations had violations in the relatively good visibility area along the
east coast. The sulfate data for Norfolk, and from the EPRI (Table 3) and
CHESS (Table 2) networks, although limited, indicate that the stations with
high concentrations were generally in the area with restricted visibility and
those with low concentrations outside the area. The one TVA station reporting
on this day, Loves Mill in southwest Virginia (Table 5), had a low concentra-
tion and was in an area with good visibility.
On July 9 (Figure 20) most of the Northeastern United States had poor
visibility, and a large majority of the ozone monitoring stations (Figure 9)
in the area had NAAQS violations. The sulfate data from Norfolk, and from the
EPRI (Table 3) and CHESS stations (Table 2), indicate that stations with Con-
's
centrations in excess of 10 yg/m were generally in the restricted visibility
area, but the TVA data (Table 5) indicate that a large area with high concen-
trations did not have restricted visibility.
17
-------
On July 10 (Figure 21) the area of restricted visibility was smaller
than it was on July 9, but still covered a large portion of the Eastern
United States. Most stations with high ozone concentrations (Figure 10)
were in the restricted visibility area. The sulfate data for July 10 were
abundant (Figure 4) and show that the area of high sulfate concentrations
was larger than the area with obstructions to visibility.
Overall, the indication is that the area of restricted visibility was
not similar to the area with high ozone concentrations, except during the
height of the ozone alert, July 9 and possibly July 10. On the days with
limited sulfate data, the areas of restricted visibility and high sulfate
concentrations were similar, but on the day with the most abundant sulfate
data, the area with high concentrations was ;a little larger than the,
restricted vj'sfb 11 ity area.
SYNOPTIC WEATHER SITUATION
The broad scale weather conditions or synoptic weather data of July 6
to 10 are documented in the Daily Weather Maps . The conditions on the
first day, Jjuly 6, are shown in Figure 22; maps for the period July 7 to 10
were also examined, but were omitted because there were only small or gradual
changes after July 6.
the main features ofrthe swrface weather map^were: 1) a stationary
front extending from below New England, west southwestward to northwest
Tennessee; 2) a high pressure area centered over Lake Erie; and 3) the western
extensioh of the Bermuda high pressure area over the Southeastern United
States.. The location of the front practically coincided with the southern
boundary of the area of high ozone concentrations (Figure 6); the high
ozone concentrations were restricted to the air mass north of the front. The
area of reduced visibility (Figure 17) included locations on both sides of
the front and was practically centered on the front. The sulfate data from
the CHESS stations (Table 2) showed that the air immediately north of the
front was relatively clean, whereas the EPRI data (Table 3) showed that most
stations north of the front had high concentrations.
18
-------
"On July 7 there was just a remnant of the stationary front immediately
south of Pennsylvania and a weak high over the east was the only feature on
the surface maps on July 8 and 9. The July 10 map showed a cold front was
over southern Michigan, New York, and New England. Throughout the period
the areas with high ozone concentrations (Figures 7-10) and poor visibility
(Figures 18-21) expanded as the two high pressure areas of July 6 amalgamated.
High sulfate concentrations also gradually spread over the entire area as the
weak high pressure dominated the weather. Behind the cold front of July 10
the ozone concentrations were reduced and the visibility improved, but the
sulfate concentrations (Figure 4) appeared to be unaffected.
The 500-mb map for July 6 (Figure 22b) was typical of July 6 to 10.
High pressure with subsiding air over the Eastern United States was the
dominant feature of the maps for the period. The strong flow out of the
extreme Southeastern United States feeding the flow over the northern tier
of states in the east was a feature of the maps from July 6 to 8. Warm air
was being transported into the high over the east by this flow.
Overall, the synoptic situation was one that showed stagnation at the
surface and aloft and subsiding air over a large part of the Eastern United
States. This stagnation coupled with the subsidence appeared to have marked
effect on the observed ozone and sulfate concentrations and visibility. The
high ozone concentrations were restricted to one air mass in which the number
of stations with high concentrations increased with time as the air moved slowly
and became progressively wanner due to an influx of air from warmer areas and
the subsidence. In addition, the high ozone concentrations were not restricted
to the western side of the surface high pressure area, as reported by Lyons and
Cole , but were observed throughout the high pressure area. The sulfate
concentrations when the data were limited were highest near the center of
the surface high pressure area, but on the one day with abundant data, high
concentrations were widespread and extended beyond the area of poor visibility
at the surface. The visibilities were restricted in the vicinity of the
slow-moving front early in the period, and then the obstructions spread
throughout the slow-moving air mass. Next, the obstructions were
eliminated as the rapidly moving front passed through the area toward the
end of the period. The passage of the front was associated with an improvement
19
-------
in visibility and with a reduction in the ozone concentrations, but did not
simultaneously reduce the high sulfate concentrations.
OTHER. METEOROLOGICAL OBSERVTIUNS
Meteorological parameters other than those previously summarized were
also examined. These included minimum temperatures, visibility at 7 a.m.,
relative humidity at 6 a.m. and noon, percent of possible sunshine, and
precipitation for 24-h periods. The minimum temperatures, like the
maximum temperatures, were relatively high. None of the other parameters
showed a pattern that was considered noteworthy except precipitation.
During the period of July 6 to 9, the rainfall was usually in the form of
afternoon or evening showers and these occurred over widely separated areas.
The rainfall on these 4 d did not appear to be associated with the
ozone concentrations; some areas with high concentrations had rainfall
while most had no precipitation. The spatial distribution of sulfate
monitoring stations during these 4 d was inadequate for making comparisons
with rainfall patterns.
On July 10 (Figure 23) the rainfall was extensive. The rainfall again
occurred,-over both areas with high ozone and low ozone concentrations. With
regard to sulfate concentrations (Figure 4) the area with high sulfate
concentrations was about the same as the area that recorded rainfall. There
appeared to be no correlation between the 24-h rainfall and restricted visi-
bility (at 1 p.m.) patterns, although there was a rather consistent relation-
ship for 5 d (July 6-10); the southern part of the area with poor visibility
generally had rainfall, while the areas to the north and west did not.
TRAJECTORIES OF THE SURFACE-TO-1000-m LAYER
Backward trajectories indicate the general area from which air has come
to designated locations. The trajectories may be used in conjunction with
air quality data to show that air came from an area that already had a
pollution burden. The upper limit of the layer for which trajectories are
determined is the conservative height of 1000 m; the bulk of the pollution
in the atmosphere would be contained in the layer between the surface and
1000 m. Trajectories on occasion show that air from one area may be moved
in a period of 48 h to more than one downwind location. During periods
of weak winds, July 6-10, 1974, for example, trajectories readily crossed one
• 20
-------
another, and on some occasions air arrived in various areas by circuitous
routes.
Backward trajectories for 48-h periods for selected stations, mostly
state capitals, for July 6 to 10, 1974, are shown in Figures 24 to 28.
Although four trajectories were determined for each day, only that for the
ending time of 1 p.m. is shown. This ending time is close to the time when
maximum hourly ozone concentrations generally occur, and the trajectories for
this ending time were considered representative of the four daily trajectories.
The station coverage is dense in order to show the various areas from which
air moved into almost every state and the fact that air from over one area
reached widely separated receptors.
Figure 24 shows the trajectories for July 6. These trajectories indicate
that the high ozone concentrations (Figure 6) in the northeast were associated
with rapid flows from the west and northwest, while the high concentrations
in the northwest were associated with circuitous trajectories. The limited
sulfate data (Tables 2,3, and 5) showed that the lower concentrations
occurred in areas that had long and direct trajectories, while the high
concentrations occurred in the area where the air traveled a circuitous
path. The area of poor visibility (Figure 17) occurred in the boundary
area between the flows with the component from the north (in the northern
third of the area) and the flows with the component from the south. Comparison
of individual trajectories also showed interesting results. The trajectories
ending in central Connecticut (which had high ozone concentrations) and
eastern Massachusetts (which had low ozone concentrations) traversed locations
that were generally much closer than the terminal points (about 150 km
apart; although the air came to the two locations from the same general source
areas these downwind receptors observed different concentrations. The flows
ending in southeast New York and south-central Pennsylvania (both areas had
high ozone concentrations) traversed common areas in eastern Ohio and western
Pennsylvania. A point that was common to three plotted trajectories, those
ending in central and northeast Illinois and central Indiana, was 150 km
south of Chicago (not shown is a trajectory for central Ohio which also
crossed the area). The cities at the end of these trajectories had high
ozone concentrations.
On July 7 (Figure 25) the trajectories were markedly shorter than those
21
-------
for July 6 indicating that the air movement on July 7 was considerably
less than that on July 5. Most of the flow into the southern stations was
from the south, and the area did not have high ozone (Figure 7) or sulfate
(Table 5) concentrations. The flows into the northern stations were from
the west and northwest, and the stations in this area were those that had
high ozone and sulfate (Table 3) concentrations and restricted visibility
(Figure 18). The areas with high ozone concentrations in the north were
downwind of areas that had air with an ozone burden on July 6 (Figure 6).
The unpolluted areas in the south had flows from relatively clean areas.
If the ozone burden in the air was no more than 2 d old, the high contra-
trations at the individual stations must have been caused by emissions
within a state or from a state immediately adjacent to it; most of the
trajectories originated in one state and terminated in an adjacent state.
The sulfate data in Table 3 show that Wheeling had a markedly high concen-
tration, and the trajectory ending in West Virginia indicated that that area
had the least air movement; the high sulfate concentration was associated with
emissions from areas very close to Wheeling;
On July 8 (Figure 26) in all areas except the extreme northeast,
the trajectories were short. In the west and southeast the movement
was from the south, and in the northeast it was from the northwest. High
ozone concentrations were observed in practically all areas (Figure 8).
Most of the southerly flows brought air from areas that had relatively
low concentrations oh July 6 and 7 and normally emitted a small amount
of ozone precursors (Figure 1) yet the downwind stations observed high
ozone concentrations. The high ozone concentrations were not always associated
with flows from areas having high ozone concentrations on earlier days.
The limited sulfate data in Tables 2, 3, and 5 indicate that the area with the
highest sulfate concentrations, West Virginia, had the trajectory with the
shortest travel distance; the observed high concentrations at Huntington and
Wheeling were associated with emissions from nearby sources.
On July 9 (Figure 27) the trajectories were about as long or slightly
longer than those on July 8. In the northeast the flows were mostly from
the west, the ozone concentrations were high (Figure 9), and on prior days
the air was over areas with high ozone concentrations (Figures 8 and 9).
22
-------
In the northwest and south, where ozone concentrations were declining
(Figure 10 vs Figure 9), the flow during the most recent 12 h was
from the west or southwest, while earlier it was from the south; the upwind
areas had relatively low concentrations on July 8. It is interesting that
the area of high ozone concentrations is associated more with flows from the
areas of large emissions of ozone precursors (Figure 1) than the area with
the shortest trajectories (i.e., the weakest winds). The limited sulfate
data (Tables 2,3, and 5) showed high sulfate concentrations at Wheeling,
Huntington, and the one Lawrenceburg (near Cincinnati) station. The move-
ment of air over West Virginia was so slow that the polluted air could not
have come from a great distance; at the Lawrenceburg site for the most
recent 12-h flow, the flow was along the Ohio River Valley.
On July 10 (Figure 28) the lengths of the trajectories were generally
longer than they had been on July 9. The trajectories show that areas
with high ozone concentrations (Figure 10) were downwind of areas that also
had high concentrations on the prior days and are normally expected to have large
emissions of ozone precursors. The NADB sulfate data (Figure 4) show that
high concentrations occurred throughout the area. The most recent of the
12-h trajectory segments show that many of the high concentrations in the
north and east were associated with a flow out of the northwest. Earlier, how-
ever, all trajectories were generally of shorter length and showed movements
over all areas normally associated with large emissions of SOp (Figure 2);
the high concentrations were likely more affected by earlier slow movement
over source areas than by the most recent 12-h flow.
Overall, the trajectory analyses showed that the high concentrations
of ozone were associated with flows across the northern tier of states--
the area where the sources of ozone precursors are most numerous. The
indication was that air having an ozone violation on one day frequently
had shown a violation on an earlier day at an upwind location. Although
the trajectories indicated that interstate transport of ozone occurred,
48-h movements were frequently restricted to flows between adjacent
states; long-range transport was limited due to the stagnation conditions.
The highest sulfate concentrations were generally associated with the shortest
23
-------
trajectories; local emissions appeared to be the major cause of the worst
sulfate conditions. On the day when the sulfates were an area-wide problem,
practically all of the high concentrations could be traced back to slow move-
ment over source areas.
24
-------
SECTION 5
SUMMARY
2
1. On July 10 a 1,000,000 km area of the Eastern United States observed
high sulfate concentrations. The concentrations appeared to be high over
a large area from July 8 to 10, and the peak in concentration appeared
to move eastward during the period. On July 6 and 7 a few stations in
the north had high concentrations.
2. The ozone episode covered the Northeastern United States from July 6 to
10. Although the concentrations and number of stations with high concen-
trations was greatest on July 8 and 9, the ozone problem was fairly
widespread and severe on all 5 d. There was no apparent movement of
a peak concentration across the area.
3. The maximum temperature data analysis showed that: a) there were high con-
centrations of ozone over a large area before there were high surface
temperatures; b) during the worst of the ozone episode, the area with
high ozone concentrations was almost the same as the area with high
temperatures; and c) during the worst of the sulfate episode, the area
with high concentrations covered a much larger area than that with high
temperatures.
4. The visibility data analyses showed that: a) the area with high ozone
concentrations did not correspond day by day to the area with restricted
visibility; and b) there did appear to be considerable similarity in
areas with poor visibility and high sulfate concentrations on those days
when the data were limited, and to a lesser degree on the day when the
sulfate data were abundant. Areas with low sulfate concentrations were
generally outside the areas with restricted visibility.
5. The synoptic weather analysis showed that: a) large-scale stagnation oc-
curred at the surface and aloft; b) the high ozone concentrations were not
25
-------
restricted to the western side of the air mass but spread throughout it;
d) the sulfate concentrations were initially high near the center of the
surface high pressure area (based on a limited amount of sulfate data),
but eventually the whole area had high sulfate concentrations; e) the
restrictions to visibility were initially associated with a front
(obstructions were present on both sides) but after July 6 the high
sulfate concentrations generally occurred in the areas of restricted
visibility and low sulfate concentrations occurred outside the poor
visibility areas; and f) a frontal passage toward the end of the period
was associated with a lowering of the ozone concentrations and the
elimination of restrictions to visibility but did hot affect sulfate
cohcehtratidn.-
6. the rainfall analyses showed that: a) there was no.correlation between
rainfall arid ozone concentrations; and b) the area of rainfall oh July 10
had boundaries corresponding to the area with high sulfate concentrations.
7. the trajectory analysis showed that: a) high dzori£ concentrations were
usually associated with" flows over th£ area of highest emissions of ozone
bre'cursors and air that had ah ozone burden before" it arrived in the
area Where the high concentration was detected; b) long-range transport
was involved in moving the dzo'he-laderi layers; but the transport was
limited by the stagnation conditions prevailing; c) the highest sulfate
concentrations were associated with the shortest trajectories; and d) on
the day with the area-wide p'foblem with su'ifates, the high concentra-
tions Were traced back to slow-moving air over the area with high
precursor emissions.
26
-------
REFERENCES
1. Greeley, R. S., R. P. Ouellette, J. T. Stone, and S. Wilcox. Sulfates
and the Environment - A Review. The MITRE Corporation, McLean, Virginia,
1975. 131 pp.
2. DeMarrais, G. A. Meteorological Conditions During a Sulfate Episode in
Southern California. EPA-600/4-78-022, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, 1978, 1978. 32 pp.
3. Strategies and Air Standards Division. Position Paper on Regulation of
Atmospheric Sulfates. EPA-450/2-75-007, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, 1975. 87 pp.
4. DeMarrais, G. A. The 1974 Ozone Episode in the Baltimore-to-Richmond
Corridor. EPA-600/4-87-016, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, 1978. 33 pp.
5. Altshuller, A. P. Atmospheric Sulfur Dioxide and Sulfate. Environ.
Sci. Techno!., 7(8):709-712, 1973.
|6. Wilson, W. E.~, R. J. Charlsbn, R. B. Husar, K. T. Whitby, and D. Blumenthal
: Sulfates in the Atmosphere. EPA-600/7-77-021. U. S. Environmental Pro-
tection Agency, Research Triangle Park, North Carolina, 1977. 29 pp.
7. Environmental Research and Technology, Inc. Design of the Sulfate
Regional Experiment (SURE) EC-125. Volume III Appendices. Report prepared
for the Electric Power Institute, Palo Alto, California, 1976.
8. National Air Pollution Control Administration. Air Quality Criteria for
Photochemical Oxidants. AP-63. U.S. Department of Health, Education,
and Welfare, Washington, D.C., 1970. 178 pp.
9. Lipfert, F. W., H. Cowherd, and S. Kaufman. The Temporal and Spatial
Variations of Atmospheric Suspended Sulfates in the Northeastern United
States. Paper 77-39.2 presented at Air Pollution Control Association
Annual Meeting, Toronto, Ontario, June 20-24, 1977.
10. Rhode, H. A Study of the Sulfur Budget for the Atmosphere over Northern
Europe. Tell us XXIV:128-137, 1972.
11. Summers, P. W., and B. Hitchon. Source and Budget of Sulfate in Precipita-
tion for Central Alberta, Canada, J. Air Poll. Control Assoc. 23:194-199,
1973.
27
-------
12. Georgii, H. W. Contribution to the Atmospheric Sulfur Budget. J.
Geophys. Res. 75:2365-2371, 1970.
13. Kellogg, W. W., R. D. Cadle, E. R. Allen, A. L. Lazrus, and E. A. Martell.
The Sulfur Cycle. Science 175:587-596, 1972.
14. Weber, E. Contribution to the Residence Time of Sulfur Dioxide in a
Polluted Atmosphere. J. Geophys. Res. 75:2909-2914, 1970.
15. Atkins, D.H.F., R. A. Cox, and A.E.J. Eggleton. Photochemical Ozone
and Sulphuric Acid Aerosol Formation in the Atmosphere over Southern
England. Nature 235:372-376, 1972.
16. Nisbet, I. Sulfates and Acidity in Precipitation: Their Relationship to
Emissions and Regional Transport of Sulfur Oxides. Chapter 7 in Air
Quality and Stationary Source Emission Control. Committee on Public Works
United States Senate, Washington, D.C., 1975. pp. 276-312.
17. Meszaros, E. Seasonal and Diurnal Variations of the Size Distribution of
Atmospheric Sulfate Particles. Tell us XXII, 2:235-238, 1970.
18. Wagman, J., R. E. Lee, Jr., and C. J. Axt. Influence of Some Atmospheric
Variables on the Concentration and Particle Size Distribution of Sulfate in
Urban Air. Atmos. Environ. 1:479-489, 1967.
19. Tohg, E. Y., G. M. Hidy, T. F. Lavery, and F. Berlandi. Regional and Local
Aspects of Atmospheric Sulfates in the Northeast Quadrant of the United
States. In Preprint Volume: Third Symposium on Atmospheric Turbulence,
Diffusion, and Air Quality, Amer. Meteorol. Soc., Raleigh, North Carolina,
1976. pp. 307-310.
20. Corn, M., and L. Demaio. Particulate Sulfates in Pittsburgh Air. J. Air
Poll. Control Assoc. 15:26-30, 1965.
21. Middleton, J. T., J. B. Kendrick, and H. W. Schwalm. Injury to Herbaceous
Plants by Smog or Air Pollution. Plant Disease Reporter, 34(9):245-252,
1950.
22. Ne1burger, M. and J. Edinger. Meteorology of the Los Angeles Basin.
Report No. 1^ Southern California Air Pollution Foundation, Los Angeles,
California, 1954. 97 pp.
23. Renzettij N. A., Editor. An Aerometric Survey of the Los Angeles Basin,
August-November 1954. Report No. 9, Air Pollution Foundation, Los Angeles,
California, 1955. 334 pp.
24. Hitchcock, L. B., W. L. Faith, M. Nieburger, N. A. Renzetti, and L. H.
Rogers. Air Pollution Situation in Los Angeles-An Aerometric Survey.
In: Proceedings of the Third National Air Pollution Symposium, Pasadena,
California, 1955. pp 12-23.
28
-------
25. Lea, D. A. Vertical Ozone Distribution in the Lower Troposphere Near an
Urban Pollution Complex. J. Appl. Meteorol., 7:252-267, 1968.
26. Gloria, H. R., G. Bradburn, R. F. Reinisch, J. N. Pitts, Jr., J. V. Behar,
and L. Zafonte. Airborne Survey of Major Air Basins in California. J.
Air. Poll. Control Assoc., 24(7) :645-652, 1974.
27. Blumenthal, D. L., L. A. Farrow, and T. A. Weber. The Effects of Variations
in Bulk Meteorological Parameters on Ozone Concentrations. In Preprint
Volume: Symposium on Atmospheric Diffusion and Air Pollution, Amer.
Meteorol. Soc., Santa Barbara, California, 1974. pp. 115-120.
28. Kauper, E. K., and B. L. Niemann. Los Angeles to Ventura over Water Ozone
Transport Study. Report prepared for California Air Resources Board by
Metro Monitoring Services, Covina, California, 1975. 54 pp.
29. Tommerdahl, J. B., C. E. Decker, L. A. Ripperton, and J.J.B. Worth.
Airborne Ozone Monitoring Program. Part 3 of Investigation of Ozone
and Ozone Precursor Concentrations at Nonurban Locations in Eastern United
States. Report prepared for Environmental Protection Agency by Research
Triangle Institute, Research Triangle Park, North Carolina, Contract
GB-02-1343, 1974. 44 pp.
30. Lovelace, D. E., T. Kapsalis, R. C. Bourke, and P. P. Cook. Indianapolis
1974 Summer Ozone Study. Report of Indianapolis Center for Advanced
Research, Inc., Indianapolis, Indiana, 1975. 118 pp.
31. Department of Natural Resources. Ozone Monitoring-Wisconsin, Summer 1974.
State of Wisconsin, madison, Wisconsin, 1975. 23 pp.
32. Martinez, E. L. Temporal-Spatial Variations of Nonurban Ozone Concentra-
tions and Related Meteorological Factors. Presented at Conference on Air
Quality Measurements sponsored by Southwest Section of the Air Pollution
Control Association, Austin, Texas, 1975. 27 pp.
33. Karl, T. R., and G. A. DeMarrais. Meteorological Conditions Conducive to
High Levels of Ozone. In: Report of International Conference on Photo-
chemical Oxidant Pollution and Its Control (preprint), September 12-17,
1976, Research Triangle Park, North Carolina, 1977. pp 75-88.
34. Cox, R. A., and S. A. Penkett. Photo-Oxidantion of S02 in the Atmosphere.
J. Chem. Soc., Faraday Soc., 68:1735, 1972.
35. Penkett, S. A. Oxidation of S0? and Other Atmospheric Gases by Ozone in
Aqueous Solution. Nature (Physical Science), 240:105-106, 1972.
36. Cheng, R. T., J. 0. Frohliger^ and M. Corn. Aerosol Stabilization for
Laboratory Studies of Aerosol-Gas Interactions. J. Air Poll. Control
Assoc., 21:138-142, 1971.
29
-------
37. Bushtuveva, K. A. Ratio of Sulfur Dioxide and Sulfuric Acid Aerosol in
Atmospheric Air, in Relation to Meteorological Conditions. Gigiena i
Sanitariyce, 11:11-13, 1954.
38. Larson, T. E., and I. Hettick. Mineral Composition of Rainwater.
Tellus 8:191-197, 1956.
39. Frank, N. H., and N. C. Possiel, Jr. Seasonality and Regional Trends in
Atmospheric Sulfates. Paper presented to American Chemical Society, San
Francisco, California, August 30-September 3, 1976.
40. Environmental Data Service. Local Climatological Data. Monthly Summaries
for R. E. Byrd International Airport (Richmond), Washington National Air-
port, and Friendship International Airport (Baltimore). National Oceanic
and Atmospheric Administration, Asheville, North Carolina, July 1973.
41. Environmental Data Service (NOAA). Daily Weather Maps (for selected
weeks). U.S. Government Printing Office, Washington, D.C., 1974.
42. Heffter, J. L., A. D. Taylor, and G. J. Ferber. A Regional-Continental
Scale Transport, Diffusion and Deposition Model. National Oceanic and
Atmospheric Administration Tech. Memo ERL-ARL-50. Air Resources
Laboratories, Silver Spring, Maryland, 1975. 28 pp.
43. Lyons, W. A. and H. S. Cole. Photochemical Oxidant Transport: Mesoscale
Lake Breeze and Synoptic-Scale Aspects. J. Appl. Meteorol., 15:733-743,
1976.
30
-------
Figure 1. Annual hydrocarbon emissions by state in 1973 (1000 tons).
-------
Figure 2. Annual S02 emissions from power plants by state in 1974 (1000 tons).
32
-------
Figure 3. Locations of sulfate monitoring stations of state and local agencies (see Table
1 for station names).
33
-------
BOLD NUMBERS SHOW
CONCENTRATIONS > 10ug/m3
Figure 4. Sulfate concentrations (/Kj/m3) July 10, 1974.
34
-------
OJ
en
30e
(NUMBERS ENCIRCLED
INDICATE RURAL SITE)
\ X
Figure 5. Station locations (see Table 4 for station names) TVA network.
-------
BOLD NUMBERS SHOW
NAAQS VIOLATION
(M = MISSING)
\
40"
35°
Figure 6. Maximum hourly ozone concentrations (ppb) Jujy 6, 1974.
36
-------
BOLD NUMBERS SHOW NAAQS
VIOLATIONS (M = MISSING)
N \
40°
35°
Figure 7. Maximum hourly ozone concentration (ppb) July 7, 1974.
37
-------
BOLD NUMBERS SHOW
NAAQS VIOLATION
(M = MISSING)
,-A
Figure 8. Maximum hourly ozone concentration (ppb) July 8, 1974.
38
-------
BOLD NUMBERS SHOW
NAAQS VIOLATION
(M = MISSING)
Figure 9. Maximum hourly ozone concentration (ppb) July 9, 1974.
39
-------
Figure 10.. Maximum hourly ozone concentrations (ppb) July 10, 1974.
40
-------
BOLD NUMBERS SHOW
NAAQS VIOLATIONS
(M = MISSING)
Figure 11. Maximum hourly ozone concentration (ppb) July 11, 1974.
41
-------
BOLD NUMBERS SHOW TEMPERATURES
5° OR MORE ABOVE STATION AVERAGE
FOR JULY 1974
Figure 12. Maximum temperatures ( F) July 6, 1974.
42
-------
BOLD NUMBERS SHOW TEMPERATURES
5° OR MORE ABOVE STATION
AVERAGE FOR JULY 1974
:\
40°
35°
30"
Figure 13. Maximum temperatures (°F) July 1, 1974.
43
-------
BOLD NUMBERS SHOW TEMPERATURES
50 OR MORE ABOVE STATION
AVERAGE FOR JULY 1974
\ i \\
40°
35°
30°
Figure 14. Maximum temperatures (°F) July 8, 1974.
44
-------
BOLD NUMBERS SHOW TEMPERATURES
5° OR MORE ABOVE STATION
AVERAGE FOR JULY 1974
Figure 15. Maximum temperatures (°F) July 9, 1974.
45
-------
BOLD NUMBERS SHOW TEMPERATURES 5°
OR MORE ABOVE STATION AVERAGE
FOR JULY 1974
Figure 16. Maximum temperatures (°F) July 10, 1974.
46
-------
40°
35"
30"
OBSTRUCTIONS
F = FOG
H = HAZE
K = SMOKE
R = RAIN
Figure 17. Visibility (miles) July 6, 1974, 1300 EST.
4/
-------
= FOG
H = HAZE
K = SMOKE
R = RAIN
Fjgurp 18. Visibility (mjles) July 7, 1974, 1300 ESJ.
48
-------
F = FOG
= HAZE
K=SMOKE
R= RAIN
40°
35°
30"
Figure 19. Visibility (miles) July 8, 1974, 1300 EST.
49
-------
= FOG
H = HAZE
K=SMOKE
R= RAIN
Figure 20. Visibility (miles) July 9, 1974, 1300 EST.
50
-------
40°
35°
OBSTRUCTIONS
= FOG
H=HAZE
K=SMOKE
R=RAIN
30°
Figure 21. Visibility (miles) July 10, 1974, 1300 EST.
51
-------
(a) Surface weather map
C.00-MU L 'RAH HEIGHT CONTOURS _
U / 00 4 M E.S.T
(b) 500-mb map
i
Figure 22. Daily weather maps for July 6, 1974
52
-------
AMOUNTS IN HUNDRETHS OF INCHES
T = TRACE
25°
Figure 23. Rainfall during sulfate sampling period of July 10, 1974.
53
-------
Figure 24. 48-h trajectories (12-h segments) of layers of air between the
surface and 1000 m for selected cities, July 6, 1974 (arrival time 1 p.m.,
e.s.t.).
54
-------
30°
25°
Figure 25.48-h trajectories (12-h segments) of layers of air between the
surface and 1000 m for selected cities, July 7, 1974 (arrival time 1 p.m.,
e.s.t.).
55
-------
25°
Figure 26. 48,-h trajectories (12-h segments) of layers of air between the
surface and 1000 m for selected cities, July 8, 1974 (arrival time 1 p.m.,
e.s.t.).
56
-------
25°
Figure 27. 48-h trajectories (12-h segments) of layers of air between the
surface and 1000 m for selected cities, July 9, 1974 (arrival time T p.m.,
e.s.t.).
57
-------
25°
Figure 28. 48-h trajectories (12-h segments) of .layers of air between the
surface and 1000 m for selected cities, July 10, 1974 (arrival time 1 p.m.,
e.s.t.}.
58
-------
TABLE 1. NAMES OF STATIONS IN SULFATE MONITORING
NETWORK (see Figure 3 for station locations)
1. Ashland, KY
2. Bowling Green, KY
.3. Covington, KY
4. Charleston, WV
5. South Charleston, WV
6. Hampton, VA
7. Norfolk, VA
8. Portsmouth, VA
9. Lynchburg, VA
10. Richmond, VA
11. Roanoke, VA
12. Wythe Cnty, VA
13. Chattanooga, TN
14. Knoxville, TN
15. Memphis, TN
16. Nashville, TN
17. East St. Louis, 1L
18. Moline, IL
19. Peoria, IL
20. Rock Island, IL
21. Springfield, IL.
22. Atlanta, GA
23. Columbus, GA
24. Columbia, SC
25. Union Cnty., SC
26. Richland Cnty., SC
27. Charlotte, NC
28. Durham, NC
29. Greensboro, NC
30. East Chicago, IN
31. Evansville, IN
32. Gary, IN
33. Indianapolis, IN
34. Terre Haute, IN
35. Monroe Cnty., IN
36. Parke Cnty., IN
37. South Bend, IN
38. Solomons Island, MD
39. Akron, OH
40. Canton, OH
41. Cincinnati, OH
42. Allentown, PA
43. Bethlehem, PA
44. Clarion, PA
45. Erie, PA
46. Hazel ton, PA
47. Lancaster, PA
48. Pittsburgh, PA
49. Scranton, PA
50. Warminster, PA
51. Wilkes Barre, PA
52. York, PA
53. Albany, NY
54. New York City, NY
55. Niagara Falls. NY
56. Rochester, NY
57; Syracuse, NY
58. Utica, NY
59. Yonkers, NY
60. Hartford, CT
61. New Haven, CT
62. Waterbury, CT
63. Elizabeth, NJ
64. Glassboro, NJ
65. Newark, NJ
66. Perth Amboy, NJ
67. Trenton, NJ
68. Providence, RI
69. Washington Cnty., RI
70. Cambridge, MA
71. Fall River, MA
72. Springfield, MA
73. Worcester, MA
74. Burlington, VT
75. Orange Cnty., VT
76. Smyrna, DE
77. Newark, DE
78. Dearborn, MI
79. Detroit, MI
i80. Flint, MI
81. Lansing, MI
82. Saginaw, MI
83. Trenton, MI
59
-------
TABLE 2. SULFATE CONCENTRATIONS (yg/m3) AT CHESS STATIONS
IN THE NEW YORK CITY AREA, JULY 6-11, 1974
"^\Date
STATION ^^^X^
Rlverhead
Queens
Brooklyn
Bronx
July
6
4.9
6.8
M .
9.3
July
7
7.1
12.6
M
10.6
July
8
6.2
7.9
12.2
6.0
July
9
1 2 .5
15,6
16.2
M
July
10
27.2
38.5
54.1
M
July
11
11.0
11;2
M
M
M * Missing
60
-------
TABLE 3. SULFATE CONCENTRATIONS (yg/m3) AT ELECTRIC POWER
INDUSTRY SITES IN NORTHERN.UNITED STATES, JULY 6-11, 1974
^v. Date
Station ^s.
Collins, JL
Rockport, ID
Madison, ID
Lawrenburg I, ID
Lawrenburg II, ID
Huntington, M
Wheeling, W
Scranton, PA
Albany, NY
July
6
M
15.9
18.5
31.6
19.4
8.9
34.7
5.7
4.0
July
7
M
10.8
12.3
23.4
18.9
4.9
53.7
5.0
7.3
July
8
26.1
M
13.4
22.2
21.5
45.7
83.0
7.3
13.2
July
9
13.1
M
19.1
36.0
16.7
48.7
75.7
27.0
25.3
July
10
M
M
20.8
25.9
22.8
21.0
M
M
10.6
July
11
M
M
14.2
27.6
46.6
28.2
M
3.5
2.7
M = Missing
Source = Environmental Research and Technology7
61
-------
TABLE 4. STATION NAMES, TVA NETWORK
(See Figure 5 for station locations)
1. Allen
2. Bull Run
3. Colbert
4. Cumberland
5. Gallatin
6. John Sevier
7. Johnsonville
8. Kingston
9. DCAD (Muscle Shoals)
10. Paradise
11. Shawnee
12. Watts Bar
13. Widows Creek
(14.) Giles County
(15.) Hytop
(16.) Land Between Lakes
(17.) Loudon
(18.) Loves Mill
( ) B Rural sampling site
62
-------
TABLE 5. SULFATE CONCENTRATIONS (ug/m3) TVA NETWORK, JULY 3-11, 1974
Monitoring Site Data
Station
Allen
Allen
Allen
Bull Run
Bull Run
Bull Run
Col bert
Colbert
Col bert
Cumberland
Cumberland
Cumberland
Cumberland
Cumberland
Gal latin
Gal latin
Gallatin
John Sevier
John Sevier
Johnsonville
Johnsonville
Johnsonville
Johnsonville
Kingston
Kingston
Kingston
- Distances
.Distance1 Bearing Elevation
(Mi.) («) (Ft.)
4.2
2.9
3.2
2.6
4.9
4.3
1.8
2.3
2.4
4.3
6.2
1.1
4.6
19.2
1.8
4.2
4.8
1.9
1.0
2.6
2.8
2.6
2.1
3.6
2.9
1.3
and bearings
68
54
32
61
56
273
23
259
263
39
37
163
130
58
4
13
340
63
229
187
42
339
134
243
328
143
230
240
217
880
910
900
495
470
510
590
725
470
590
440
470
570
575
1220
1140
385
380
380
470
800
900
750
J
3 6
_
10.9
9.6
9.5
7.9
8.0
11.2
13.4
12.6
8.9
15.2
15.9
13.2
19.7
16.2
14.6
14.6
11.2
9.7
11.5
14.5
14.2
13.4
9.1
-
12.6
uly
789
8'.9
6.5
6.0
2.8
4.7
5.7
9.3
10.6
6.8
15.2
4.6
13.4
11.0
12.5
10.1
18.7
14.3
12.3
July 1974
Average
11.2
16.8
14.9
19.0
13.5
17.6
9.7
13.1
15.7
20.3
23.0
18.9
18.3
21.0
16.0
17.3
17.9
20.2
14.7
25.0
20.6
23.9
21.5
21.2
24.8
25.7
from power plant
(continued)
63
-------
TABLE 5. (Continued)
Monitoring Site Data
Station
DCAD
DCAD
DCAD
Paradise
Paradise
Paradise
Paradise
Paradise
Shawnee
Shawnee
Shawnee
Shawnee
Watts Bar
Widows Creek
Widows Creek
Widows Creek
Widows Creek
Widows Creek
Giles County
Hytop
Land Between
the Lakes
Loudon
Loves Mill
Distance1 Bearing
(Mi.) (°)
1.5
1.2
2.4
2.6
2.9
7.9
5.3
21.0
2.6
2.6
2.7
2.1
0.8
2.5
4.8
2.0
2.0
2.3
10.0
19.3
35.8
6.5
224-
168
26
41
31
284
126
301
158
256
35
84
3
135
27
102
167
30
(NE)
271
320
(SSE)
Elevation
(Ft.)
530
510
550
420
490
460
398
475
375
360
385
350
845
1450
680
1500
1570
640
800
1785
580
880
3 6
13.1
22.3
19.5
17.1
20.0
18.2
16.2
17,3
13.6
14.7
16.3
14.6
20.4
31.8
30.1
28.6
31.4
15.6
16.1
12.7
July
July 1974
789 Average
11.2
15.8
13.0
17.0
17.7
15.0
16.7
20.4
14.5
13.5
15.5
10.2
12.1
19.0
M
31.1
26.5
24.9
17.0
10.2
10.9
9.7
5.9
18.2
19.8
31.5
24.8
25.5
26.7
20.0
28.8
29.5
27.7
27.7
25.9
24.1
23.0
24.0
33.2
29.7
26.4
16.0
15.5
21.1
23.2
14.8
64
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/4-79-009
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
ASSOCIATION BETWEEN METEOROLOGICAL CONDITIONS AND
HIGH OZONE AND SULFATE CONCENTRATIONS
A 1974 Episode in the Eastern United States
5. REPORT DATE
February 1979
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Gerard A. DeMarrais
9. PERFORMING ORGANIZATION NAME AND ADDRESS
(Same as Box 12)
10. PROGRAM ELEMENT NO.
1AA603 (FY-78)
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Sciences Research Laboratory - RTP, NC
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
TnhniKiP ?/7«-in/7ft
14. SPONSORING AGENCY CODE
EPA/600/9
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A 1,000,000 km area of the Eastern United States had sulfate concentrations
exceeding 10 yg/m on July 10, 1974, and there were indications that parts of
the area had high concentrations on prior days. The meteorology associated
with the high concentrations and correlations of high ozone and sulfate concen-
trations are discussed. It appeared that slow moving and subsiding air contributed
to the high concentrations of both pollutants. Long range transport, as shown
by trajectory analyses, was a factor in the problems i.n most areas, but the worst
situations with regards to sulfates were associated with emissions from nearby,
upwind sources. While high ozone concentrations were observed immediately
prior to high sulfate concentrations in many areas, there were high sulfate con-
centrations that were not associated with high ozone concentrations. In the
latter situation, the high sulfate concentrations were associated with air which
had earlier movement over areas with high S02 emission.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
*Air pollution
*0zone
*Sulfates
*Meteorological data
Eastern United States
1974 episode
13B
07 B
04B
8. DISTRIBUTION STATEMENT
19. SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
75
RELEASE TO PUBLIC
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
65
------- |