x'/EPA
United States
Environmental Protection
Agency
O\1
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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.
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EPA-600/4-79-074
December 1979
ANALYSIS OF HIGH SULFATE CONCENTRATIONS IN
GREATER NEW YORK CITY AIR
by
Gerard A. DeMarrais and Dale H. Coventry
Meteorology and Assessment Division
Environmental Sciences Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
ENVIRONMENTAL SCIENCES RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
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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 commercial products does not constitute endorsement
or recommendation for use.
AFFILIATION
Messrs. DeMarrais and Coventry are meteorologists in the Meteorology
and Assessment Division, Environmental Sciences Research Laboratory,
Environmental Research Center, Research Triangle Park, N.C. 27711. They
are on assignment from the National Oceanic and Atmospheric Administration,
U.S. Department of Commerce.
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ABSTRACT
The meteorological phenomena occurring during April 15 to 21, 1976,
when high sulfate concentrations were measured in the New York City area,
are summarized. Findings of earlier investigations of relationships
between meteorological phenomena and high sulfate concentrations are
compared to the findings of this investigation. Since ozone readily occurs
with the same meteorological conditions that are associated with sulfate
episodes, the ozone concentrations are also discussed. Finally, the
results of two other detailed investigations into correlations between
meteorological phenomena and air pollution concentrations (sulfate and
ozone) during mid-April 1976 over the northeastern United States are
compared to the results of this investigation.
Results showed that the current procedure for sampling sulfate every
sixth day does not provide sufficient data for adequately determining
how sulfate concentrations relate to meteorological phenomena. In
particular, the sampling schedule is not sufficient for determining when
prolonged periods of high sulfate concentrations begin and end. The
sampling schedule only allows for indicating what the meteorological
conditions were when the concentrations were a certain value and not how
the concentrations changed with changing meteorological conditions.
This report covers a period from December, 1978 to August, 1979
and work was completed as of August, 1979.
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CONTENTS
Abstract iii
Figures vi
Tables vii
1. Introduction 1
2. Conclusions 2
3. Background and Methods 4
4. Data Summaries, Analyses, and Comparisons 10
5. Summary 30
References 32
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FIGURES
Number Page
1 CHAMP stations in the New York City area 6
2 Daily weather maps for 4/14/76 14
3 Daily weather maps for 4/18/76 16
4 Daily weather maps for 4/20/76 17
5 Daily weather maps for 4/22/76 18
6 Trajectories associated with sulfate concentrations in the New
York City area, 4/14-22/76 20
7 Sulfate concentrations (yg/m ) in the area surrounding New
York City, 4/18/76 24
8 Sulfate sampling sites of Ontario Ministry of the Environment
and Ontario Hydro 25
VI
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TABLES
Number Page
•3
1 Sulfate Concentrations (yg/m ) at CHAMP Stations in the New
York City Area, 4/14-22/76
2 Sulfate Concentrations (yg/m ) at NASN Stations in the New York
City Area, 4/76 . . . "." • . ................. 11
3 Pertinent Surface Weather Data at La Guardia Airport, 4/76. . . 13
q
4 24-Hour Sulfate Concentrations (yg/m ) in Maryland, New York
and Ohio, 4/12 and 4/18/76 .................. 23
o
5 24-Hour Sulfate Concentrations (yg/m ) for the Province of
Ontario, 4/12-22/76 ..................... 26
6 24-Hour Sulfate Concentrations (yg/m ) in West Virginia and
the Tennessee Valley Authority (TVA) Network, 4/12-20/76. . . 27
7 Maximum Hourly Ozone Concentrations (pphm) in the New York
City Area, 4/76 ....................... 28
vn
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SECTION 1
INTRODUCTION
Twenty-four-hour air samples, taken every twelfth day in the National
Air Surveillance Network (NASN), are analyzed for sulfate (SOi*) by the II. S.
Environmental Protection Agency (EPA). These samples are routinely supple-
mented by SOit samples collected by numerous State and local air pollution
control agencies on every twelfth day, offset 6 days from the NASN schedule.
Ideally, the combined operations of the EPA and the control agencies produce
a record of S04 concentrations for every sixth day. For the investigator
trying to understand the variations in SOi* concentrations, the question
arises, "How representative are these SOi* data in regards to time and space?"
In a separate report discussing spatial representativeness, analysis of 2 years
of daily SQ^ data from a four-station network in the New York City area
indicated that S0i> concentrations varied regionally over the area with
station separations as great as 125 km.
In this report, the temporal representativeness of the current national
sampling program is evaluated. Daily S0i» data collected at a four-station
network in the New York City area are examined for a selected episodic period
(April 15 to 21, 1976). The meteorological conditions that prevailed through-
out the episode are summarized. Those results are then compared to earlier
2-13
investigations - relating SO, episodes to meteorological phenomena in
order to determine what meteorological prerequisites characterized the
duration and intensity of the SOit episode. Trajectory calculations are used
to designate suspected upwind source areas of high S0i> concentrations in the
New York City area. In addition, supplementary S0i+ data are reviewed for
locations upwind of the New York City area. The results of two independent
7 14
investigations ' of air pollution during April 15 to 21, 1976, also are
compared to the results of this study.
1
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SECTION 2
CONCLUSIONS
Analyses of SOi, data from CHAMP stations in the New York City area and
supplementary networks, plus a comparison of our results with earlier inves-
tigations ~ yielded the following conclusions:
The SOi, episode, which persisted in the New York City area from April 15
to 21, 1976, was primarily associated with a meteorological phenomenon
common to high SO^ concentrations: a relatively warm, slow-moving, near-cloud-
less air mass (stagnating high pressure area). However, the SOi* concentrations
were high prior to the influx of very warm air and continued although the
initial air mass was replaced by another. Either the replacement of the second
SOit-polluted air mass by a third air mass, or the precipitation associated
with an active front caused the S0i+ episode to terminate.
Forty-eight-hour trajectories of air in the surface-to-1000-m layer,
in conjunction with the limited SOi* data, indicated that the high S0i» concen-
trations could have resulted from long range transport. Further verification
of this finding should be pursued through continuous sampling at potential
upwind sites as well as at receptor sites.
The potential for photochemical reactions was great during a period of
high ozone Os (>8 pphm) and SOn concentrations in the New York City vicinity.
A 6-day SO^ sampling cycle provides insufficient data for adequately
understanding the relationship between meteorological phenomena and sulfate
p
concentrations. While an independent analysis from the NASN for April 18,
1976, noted the severity of the episode in addition to the meteorological
conditions associated with the worst conditions, data on the corresponding
-------
meteorology during initiation or termination of the episode were lacking.
In addition, the duration of the episode and the time-representativeness
of the SOi* observations could not be inferred.
An ozone investigation coinciding with the suTfate episode in the
New York City area concluded that the areas of high ozone concentrations
corresponded to areas of low visibility. The results of our study cast doubt
on the inference that gaseous ozone was the prime cause of reduced visibility.
Use of the limited S04 data available for the easte* United States showed
that areas of high S04 concentrations also corresponded to areas of restricted
visibility. Until SO^ concentrations are measured continuously, it will be
difficult to evaluate the effects of this and other oollutants on visibility.
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SECTION 3
BACKGROUND AND METHODS
SULFATE DATA
Sulfate was recognized as an air pollution hazard more than 25 years
15 1 fi '
ago ' . However, it was only with the publication of the Community
Health and Environmental Surveillance System (CHESS) report17 in 1971 that
widespread interest in health hazards associated with high SOi, concentrations
was rekindled. Subsequent to that report, EPA published two documents '19
releasing data about SQu and presenting a strategy for investigating the
18
SO!* problem. Although the S0i» data base was found inadequate , the papers
did not recommend increasing the sampling frequency nor comment on the disad-
vantages of using discontinuous SOi* observations. However, preliminary findings
20
in one investigation did indicate that more useful data would be collected
if sampling was continuous, particularly for correlating high concentrations
with specific meteorological phenomena.
The combined operations of the NASN, State, and local agencies are
scheduled to determine SOit concentrations every sixth day. The standard
procedure at individual monitoring sites is to collect a sample for each
24-hour period starting at midnight. The SOn measurement is made from a
small strip of filter which collects suspended particulate via a high volume
(Hi-Vol) air sampler. The strip of filter is extracted with water and a por-
tion of the aqueous extract is analyzed for SO^ by the methyl thymol blue
method modified for use in the auto-analyzer. There is no standard for S0i»,
o
but concentrations as low as 10 yg/m (24-hour average) have been associated
with adverse health effects in preliminary epidemiological health studies .
Since there is no additional documentation on possible hazardous SQk concen-
3
trations, 10 ug/m or more is labeled high.
-------
Daily SOn data came from the Community Health Air Monitoring Program
(CHAMP) of the EPA. From January 1974 through June 1976, daily S04 data were
collected from a network of four stations in the New York City vicinity.
Three of the stations, those in Queens, Brooklyn, and the Bronx, were in
New York City, and the fourth, at Riverhead, was 125 km east of the city.
The locations of the stations are shown in Figure 1. These stations were
operated in the same manner as a NASN station, the only difference was in the
timing of filter changes. The filters in the CHAMP were changed 11 a.m.
each day while the NASN operated its stations from midnight-to-midnight.
There were many missing samples in the first 6 months of operation, so the
data for that period were not evaluated.
Examination of the S04 data for July 1974 to June 1976, showed six
periods of five or more consecutive days yielding high concentrations through-
out the four-station network. The longest period was April 15 to 21, 1976.
The SCLt data for that period were selected for subsequent detailed examination
and comparison with the SOi* data from the NASN, State, and local agencies as
2
well as the meteorological data. An earlier investigation had summarized
the meteorological phenomena associated with high S(K concentrations recorded
by the NASN over the northeastern United States on April 18, 1976. These
conclusions could be compared to those based on the daily 24-hour data
of CHAMP. In addition, a second study summarized the meteorological
conditions for the period April 12 through April 23, 1976 that were associated
with photochemically-produced ozone. The data from that investigation for
03 are compared to the results found in this investigation for SCK.
METEOROLOGICAL PHENOMENA PREVIOUSLY ASSOCIATED WITH HIGH S04 CONCENTRATIONS
Numerous meteorological phenomena have been associated with high SOi*
2-13
concentrations . In an analyses of relatively large amounts of SOi* and
o
meteorological data, one group found high temperatures (about 18°C, or
65°F, and greater) and high dew point temperatures (about 16°C, or 60°F, and
245
greater) accompanied high SO.* concentrations. A number of investigators ' '
discovered that a high potential for photochemical reactions (inferred by
-------
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abundant sunshine) was an important contributing factor to high SCK concen-
trations. Slow moving or stagnant air masses have previously been associated
p 4 c
with high concentrations '. Furthermore, the oxidation of S02 to SOi,
occurs more readily at higher relative humidities ' , particularly at
g
humidities of 70 percent or more . Visibility reductions due to smoke and
910
haze have been positively correlated with high S04 concentrations '
Visible plumes from large point sources have been observed at distances as
11 12
great as 80 km . Other plumes have been detected at distances of 160 km
and 400 km from the source; the likely source-receptor relationships
910
produced from visible plumes have been demonstrated by trajectory analyses '
Precipitation has been reported as the most effective means of removing
SOu from the ambient air .
METEOROLOGICAL RESOURCES
Surface weather observations from four stations were examined: La Guardia
Airport, Kennedy Airport, the Urban Station (Manhattan) in New York City, and
Islip (MacArthur Airport 40 km west of Riverhead and 85 km east of New York
City). The locations of these sites are shown in Figure 1. Observations
which were evaluated included temperatures, sunshine*, wind direction and
speed, relative humidity, weather (fog, haze, occurrence of precipitation),
and amount of rainfall. Examination of the data from the four sites for the
episode period indicated that there were only minor differences between
stations, so the summarized data, with the exception of sunshine data, were
solely from La Guardia Airport. The sunshine data were derived from the
only station which records that variable, the Urban Station (the Urban
Station does not record as many parameters as the other stations). A single
episode of precipitation occurred on April 22 (0.16 in, or ^0.4 cm of rain-
fall) at La Guardia Airport.
*Sunshine is recorded in percent and shows the observed duration of sunshine
in minutes divided by the daily maximum possible number in minutes for a
specific date.
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21
Daily Weather Maps of the United States, showing daily conditions at
the surface and at 500 mb (about 5000 m above sea level) at 7 a.m. Eastern
Standard Time (EST) were reviewed. These maps depict fronts, sea-level
isobaric configurations, air flow aloft, and areas of precipitation.
22
Trajectory calculations supplemented the data from the Daily
Weather Maps by showing the likely paths of air parcels prior to their
arrival in the New York City area. The trajectories are based on wind data
from the rawinsonde observations scheduled at 7 a.m. and 7 p.m. EST each
day. In the trajectory calculations, wind observations within a radius of
300 nautical miles (556 km) of the air parcel center are evaluated. A point
along the trajectory is determined every 3 hours. Trajectories are started
from a source or receptor four times daily, 1 and 7 a.m. and 1 and 7 p.m.
In this report, backward trajectories were computed to reveal air movements
in the surface- to 1000-m layer terminating over New York City. Trajectories
were limited to 48 hours. Individual points along a trajectory indicate
the general area, and not a precise location where air was located earlier.
SULFATE DATA IN UPWIND AREAS
In order to provide additional meaning, trajectory analyses data are
discussed in conjunction with SOi* concentrations in upwind areas. While
there are shortcomings in the data, in regard to spatial coverage and the
number of observations available on specific days, crude indications of
source-receptor relationships can be implied. These supplementary SOi* data
include: 1) the NnSN data for the northeastern United States for April 18,
1976; 2) the State and local data for April 12 and 18, 1976, for Maryland,
New York and Ohio (some States have SOi, data for April 18 that are excluded
in the NASN data); 3) data from West Virginia and the Tennessee Valley
Authority (TVA) network (stations in Alabama, Kentucky, Illinois, Tennessee,
and Virginia) for various days from April 12 to 20, 1976; and 4) data for
the Province of Ontario, Canada for April 12 to 22, 1976. The extensive
network of sulfate monitoring stations in the Ohio River Valley, which
operated on a daily basis for tre Electric Power Research Institute in
1974 and 1975, was inoperative at this time.
8
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COEXISTENCE OF HIGH SULFATE CONCENTRATIONS AND HIGH OZONE CONCENTRATIONS
High ozone concentrations are frequently synchronous with high
concentrations, particularly during meteorological conditions favoring
3 5
photochemical reactions * .
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SECTION 4
DATA SUMMARIES, ANALYSES, AND COMPARISONS
SULFATE CONCENTRATIONS
CHAMP Network
The 24-hour concentrations of Sd, at the four CHAMP stations for April
14 to 22, 1976, are listed in Table 1. To denote the relative severity of the
episode (high concentrations from April 15 to 21) average concentrations for
non-episodic days in 1976 and in April 1975 are listed. The filters, removed
at 11 a.m. on April 14, showed that the Queens and Brooklyn sites had high
concentrations while the Riverhead and Bronx sites did not. Concentrations
were high at all stations on April 15, and gradually increased until they
peaked on April 18 and 19. Thereafter, the concentrations gradually de-
creased and by April 22 the episode had terminated. Even though the River-
head monitoring site was 125 km from the other three sites, it also recorded
similar high concentrations.
NASN and State and Local Agency Stations
The 24-hour SOi, concentrations for the every sixth day sampling cycle
for April 1976 for sites in and close to New York City are listed in Table 2.
There was little input (sampling on April 12 and 24) from local agencies.
It is obvious that the NASN stations were operated near the time of peak
concentrations (see Table 1) and that concentrations on April 18 averaged
about three times higher than for other NASN sampling days in April.
10
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TABLE 1. SULFATE CONCENTRATIONS (ug/nr) AT CHAMP STATIONS
IN THE NEU YORK CITY AREA, 4/14-22/76*
Date
4/14
4/15
4/16
4/17
4/18
4/19
4/20
4/21
4/22
Non-episode
Average 4/75
Riverhead
7
10
Mt
22
25
30
22
16
6
4/76 7
6
Stations
Queens
11
15
21
23
30
31
25
17
8
8
6
Brooklyn
10
12
19
22
27
32
26
19
8
8
7
Bronx
7
14
21
31
26
37
27
24
10
7
6
* Note: Sample collected for 24-hour period ending at 11 a.m. for date listed
t M - Missing
TABLE 2. SULFATE CONCENTRATIONS (yg/m3) AT NASN
STATIONS IN THE NEW YORK CITY AREA, 4/76*
Date
Stations
New Haven, Waterbury, Elizabeth, Paterson, N.Y.C. N.Y.C. N.Y.C.
CT CT NJ NJ (Harlem) (Welfare (CCNY)
Island)
4/6
4/12t
4/18
4/24t
4/30
8
32
11
9
32
9
7
29
8
7
33
9
8
15
10
11
6
33
14
7
8
* Sample collected for 24-hour period on listed day.
t Stations operated by local agencies.
11
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Surface Weather Data In The New York City Area
The surface weather associated with the high S0i» concentrations starting
with the day before the observed high concentrations at all four CHAMP
stations (Table 1), is summarized in Table 3. Since the filter is changed
toward mid-day, the SOU data reported for a particular day must be compared
to the prior as well as the listed day. The episode beginning on April 15
(Table 1), started with a period of marked warming, on a day showing wind
speeds lower than the day before. Temperatures continued to increase until
they were comparable to summertime temperatures, 14° to 15°C (25° to 27°F)
above April normals. Thereafter, the concentrations decreased as the tempera-
tures declined, but remained high through April 21. The average dew point
temperature was only 2°C (36°F) on the first day with high S0i» concentrations.
When the concentrations peaked the dew point temperatures were lower than
3
those associated with high SO., concentrations in a prior study . The
sunshine exceeded 95 percent throughout the episode. Winds were out of
the southwest quadrant from the beginning of the episode until the concen-
trations peaked. Thereafter, the winds had an easterly component (from the
Riverhead area toward New York City). Wind speeds ranged from 3 mph (vl.4mps)
to 14 mph ('vS.S mps) and at the time of the peak averaged near 11 mph (5 mps).
The relatively high resultant winds (compared to the average speeds) indicate
that the winds were fairly persistent on those days. All relative humidities
(eight observations daily) were below 70 percent for all days but one prior
to the period of declining concentrations. Haze was present throughout the
SC\ episode. Rainfall occurred on April 22.
BROAD SCALE WEATHER FEATURES
The surface map for April 14 (Figure 2a) shows the meteorological
pattern at the onset of high concentrations. The outstanding feature is the
weak pressure gradient and high pressure area centered over the eastern
United States. The center of this high was over Lake Michigan on April 12
and northwestern Ontario on April 11; the air mass originally came from
Canada behind a rapidly moving vigcrous cold front. Winds at the 500-mb level
over the eastern United States on April 14 (Figure 2b) were out of the
12
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500 MILLIBAR HEIGHT CONTOURS _
AT700AMEST .
Figure 2. Daily weather maps for 4/14/76. (a) Surface weather map. (b) 500 mb map.
14
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northwest and generally 30 knots or stronger. The change in surface and
500-mb maps from April 14 to the time of peak concentrations on April 19
was gradual. The surface weather map for April 18 (Figure 3a) shows a
dominant high pressure feature over the eastern United States. At the
500-mb height on April 18 (Figure 3b), a high pressure area was centered
over Virginia and caused light winds (generally 10 knots) over the eastern
United States. Although surface maps revealed little change in the New York
City vicinity from April 14 to 19> the map for April 20 (Figure 4a) indicated
that a weak dissipating cold front would pass through New York City, bringing
in prevailing westerly winds averaging about 13 mps (28.6 mph) over the north-
eastern United States. In spite of the frontal passage (accompanied by a
10° F drop in minimum temperature and a wind shift, but no rain and practically
no clouds) and rapid air movement aloft on April 20, the S04 concentrations
on April 21 were still high. The surface map for April 22 (Figure 5a)
illustrates that meteorological conditions were changing as two fronts were
approaching (both passed through the New York City area during the day).
The 500-mb map for April 22 (Figure 5b) shows southwest winds of 15 to 20
mps (30 to 40 knots) over the New York area. Due to the advancing fronts,
after midnight on April 22, there was drizzle, fog, and extremely low clouds
with bases at 100 feet, and moist air (see Table 3).
Thus, the high S04 concentrations were initially associated with a
rapidly moving air mass traveling from northwestern Ontario to the eastern
Unites States. The air mass remained practically stationary from April 14
to 19, and SOi* concentrations increased and peaked during that interim.
After April 19, concentrations decreased as the high moved eastward but
3
remained above 10 yg/m for 2 days. The first change in air mass after
April 18 brought in air from the west. Possibly because of its movement
23
over a large SOa source area to the west and northwest , this air had a
relatively high SOi* concentration. After two additional changes in air mass
and the passage of an active front, S04 concentrations finally decreased to
relatively low values.
15
-------
"iijn- MILLIBAR HEIGHT CONTOURS
AT 700AM.FST
\
Figure 3. Daily weather maps for 4/18/76. (a) Surface weather map. (b) 500 mb map.
16
-------
500-MILLIBAR HEIGHT CONTOURS
AT700AM.EST ~.
Figure 4. Daily weather maps for 4/20/76. (a) Surface weather map. (b) 500 mb map.
17
-------
(b) "
Figure 5. Daily weather maps for 4/22/76. (a) Surface weather map. (b) 500 mb map.
18
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TRAJECTORY CALCULATIONS
Trajectory calculations based on rawinsonde data gathered every 12 hours,
are indicators of transport winds. Although trajectories are determined
objectively, they are only approximations of the true air flow. If the input
data is non-representative (for example, based on radiosonde data taken
during a frontal passage), or lacking at a key station, the calculated
trajectory could be misleading. The trajectories discussed for a specific
day, following the S0i» sampling schedule, are for 7 p.m. (evening) on the
previous day and 7 a.m. (morning) on the listed day.
The analyses for April 14 (Figure 6a) indicate that the New York City
area received air from the west during the evening of April 13 and the morning
of April 14. Trajectories were respectively 700 and 1000+ km long.
The analyses for April 15 (Figure 6b) show air arriving from a more
southerly direction than that for April 14. Both the evening and morning
trajectory was 700 km long or longer. The shift in direction from the
previous day not only denotes the different source areas, but also reveals
that the air mass centered over Canada on April 12 was modified by an influx
of warm air from the south..
On April 16 (Figure 6c) the 48-hour trajectory for the evening period
was over 1200 km long and traveled up the east coast. However, an examination
of the input data disclosed that data for the lowest 1000 m for the New York
City radiosonde station were missing. Thus, the calculation was based
primarily on low level data for surrounding sites and the resulting tra-
jectory appeared to be misleading. The morning trajectory was over 2000 km
long and originated over the Gulf of Mexico.
On April 17 (Figure 6d) flows for the evening and morning were from
the west; each was 800 km long or longer.
Trajectories for April 18 (Figure 6e) were among the shortest of this
episodic period, but still 600 km long or longer. The evening flow was from
19
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(a)
(b)
(c)
,'\
(d)
(e)
(f)
\
(g) (h)
ARRIVAL TIMES = o 1900 hr PRIOR DAY, • 0700 hr LISTED DAY, •-
(i)
-• 12 HOURS DURATION
Figure 6. Trajectories associated with sulfate concentrations in New York City area, 4/14-22/76.
(a) 4/14/76 (b) 4/15/76 (c) 4/16/76 (d) 4/17/76 (e) 4/18/76 (f) 4/19/76 (g) 4/20/76
(h) 4/21/76 (i) 4/22/76
20
-------
the ocean and along the coast to the south. The morning trajectory brought
in air from the west.
The evening trajectory for April 19 (Figure 6f) illustrates a directional
flow and length similar to April 18. The morning trajectory (April 19)
shows a flow from western areas with a length exceeding 1500 km.
The trajectories for April 20 (Figure 6g) show the effects of a frontal
passage through New York City in the morning (Figure 4). The evening
trajectory showed a pre-frontal flow from the south and morning trajectory
a post-frontal flow from the northwest. The evening air traveled more than
1000 km and moved over the Richmond to New York corridor. The morning
trajectory showed movement over northwestern New York and a major source
area in sou
trajectory.
23
area in southern Ontario , and was slightly shorter than the evening
Trajectories on April 21 (Figure 6h) reveal air from widely separated
areas. Each trajectory is at least 900 km long. Flow in the evening was
along the east coast and from the south; a reverse flow occurred in the
morning.
On April 22, the evening trajectory (Figure 6i) was only 24 hours long
since the 36-hour and 48-hour locations were off the plotting diagram.
Evening flow was from the ocean and covered 600 km in 24 hours. Morning flow
originated over land and traversed over 1500 km in 48 hours. The widely
separated upwind areas for each trajectory were due to fronts approaching
New York City at 7 a.m. (Figure 4) which passed through on April 22.
Although a slow moving high pressure area was associated with this S04
episode, all the trajectories were long. The shortest 48-hour trajectories
were over 600 km; long range transport occurred continuously throughout the
episode. No single general source area was upwind of the City area through-
out the episode or for any major part of it.
. 21
-------
SULFATE CONCENTRATIONS IN UPWIND AREAS
The S04 data from upwind source areas came from numerous air quality
sampling groups. The data in Table 4 came from the State air pollution
control agencies in Maryland, New York, and Ohio and list the 24-hour
concentrations recorded on April 12 and 18. Figure 7 shows the locations of
stations in the NASN and their corresponding concentrations for April 18,
plus the concentrations observed at five stations in the Province of Ontario.
Figure 8 depicts the names and locations of air quality stations in Ontario
Province; their concentrations for April 12 to 22 are listed in Table 5.
Table 6 lists the S04 concentrations recorded from April 12 to 20 at
individuals locations in West Virginia and at groups of stations in the
TVA network (Alabama, Kentucky, Illinois, Tennessee, and Virginia).
The trajectories ending in New York City on April 14 (Figure 6a) reveal
that the predominant upwind areas on April 12 and 13 were Ohio and New York
State. Sulfate concentrations at upwind locations on April 12 (Table 4)
were low; thus, the potential for long range transport of high sulfate
concentrations was negligible and the New York City area generally had
low concentrations. The area to the southwest, extending to West Virginia
and Virginia, was upwind of New York City during the 48 hours prior to
April 15 (Figure 6b). Limited data for this period from Wellsburg, West
Virginia indicated increasing concentrations in the upwind area (Table 6).
The evening trajectory for April 16 (Figure 6c) according to available
calculations, was along the east coast; there were no S04 data for upwind
locations. However, the morning trajectory showed the TVA area as upwind
on April 15 with high SOi* concentrations (Table 6). Upwind areas for April 17
were: 1) West Virginia and Pennsylvania producing evening air for New York
City; and 2) the Toledo-Detroit area, southern Ontario, and New York State
with air arriving in the morning. The Parkersburg, West Virginia data
(Table 6) indicate the evening trajectory could have brought in high SOi*
concentrations. In addition, Ontario data (Table 5) indicate morning tra-
jectories possibly containing SOn burdened air. Both trajectories for April 18
(Figure 6e) were relatively short and lacked SOi, data for upwind locations
22
-------
TABLE 4. 24-HOUR SULFATE CONCENTRATIONS (yg/m3) IN
MARYLAND, NEW YORK, AND OHIO, 4/12 AND 4/18/76
Station
Maryland
Baltimore
Cambridge
Hagerstown
Salisbury
New York
Al bany
Binghamton
Buffalo
Jamestown
Massena
Ohio
Akron
Ashtabula
Barberton
Cambel 1
Canton
Cleveland
Columbus
Dayton
Norwood
Sandusky
Struthers
Toledo
Date
4/12
5
5
6
6
8
6
5
2
6
2
6
3
6
7
8
2
7
6
6
4/18
26
26
20
26
26
16
14
16
14
16
17
16
37
16
13
11
13
12
11
37
29
23
-------
85'
80'
75l
70°
33
401
351
Figure 7. Sulfate concentrations (/ug/m3) in the area surrounding New York City, 4/18/76.
24
-------
QUEBEC PROV.
ONTARIO PROV.
LAKE SUPERIOR '
SAULTSTE MARIE
KINGSTON
^(•PETERBOROUGH
LAKE HURON
LAKE Em E
PICKERING
TORONTO*^ /
LAKE
MICHIGAN
_ ONTARIO
WINDSOR X
Figure 8. Sulfate sampling sites of Ontario Ministry of the Environment and Ontario Hydro.
25
-------
on April 16 and 17. However, there were abundant data for April 18
(Tables 4 and 5, Figure 7) revealing an extensive area of high concentrations
in the northeastern United States and Ontario. There was a possible influx
of high SO i, concentrations into the New York City area from upwind sources
on April 18. However, transport was an insufficient explanation for the
simultaneous influx of such high S04 concentrations at all these sites. Con-
q
centrations exceeding 20 yg/m were recorded in Ontario, Ohio, New York,
Massachusetts, New Jersey, Pennsylvania, Delaware, Maryland, Virginia, and
West Virginia. Due to the extensive area of high concentrations surrounding
New York City on April 18, trajectories for April 19 and 20 (Figures 6f and 6g)
had to show sources of high S04 concentrations were upwind of New York City.
Trajectories for April 21 (Figure 6h) indicate upwind locations all along the
Atlantic Coast; however, there were no S04 data for these locations. On
April 22 (Figure 6i) the evening trajectory originated from ocean sources;
data were unavailable for that area. However, the morning trajectory of
TABLE 5. 24-HOUR SULFATE CONCENTRATIONS (yg/m3)
FOR THE PROVINCE OF ONTARIO 4/12-22/76*
Station
Sault Ste. Marie
Sarnia
Sudbury
Windsor
Peterborough
Toronto
Pickering
Frankford
Kingston
Ottawa
Date
4/12 4/13 4/14 4/15 4/16 4/17
14 11
6 9
3
6
28
4 6 11 12 16
359 15
11
7
9
4/18
4
12
11
11
15
15
24
17
4/19 4/20 4/21
6
7
4
5
10 7
2
4/22
8
8
8
* Courtesy of Ontario Hydro.
26
-------
April 22 showed movement over the TVA area on April 20, and that upwind area
(Table 6) had high SOi* concentrations. Thus, long range transport may have
been moving S04 toward New York City on April 22, but rainfall may have
limited its concentration.
TABLE 6. 24-HOUR SULFATE CONCENTRATIONS (ug/m3) IN WEST VIRGINIA AND
THE TENNESSEE VALLEY AUTHORITY (TVA) NETWORK, 4/12-20/76
Date
Location 4/12 4/13 4/14 4/15 4/16 4/17 4/18 4/19 4/20
West Virginia
Beckley 44 13
Huntington 6
Parkersburg 13
Wellsburg 9 10 27
TVA Network*
11 stations 11
2 stations . 10
1 station 11
41 stations 7
2 stations • 10
11 stations 12
* Averages for all stations on a day.
OZONE DATA
The maximum hourly ozone concentrations observed at sites in and near
the New York City area from April 14 to 22, 1976, are listed in Table 7.
Prior to the promulgation by EPA of the new ozone standard (12 pphm) on
January 26, 1979, the standard was 8 pphm. Using 8 pphm as a reference,
only one station in the New York City area had a high concentration on
April 14. On both April 15 and 16 three of the eight sites had high concen-
trations while on April 17 and 18 all stations had high concentrations. On
27
-------
April 19 only half of the sites (none in New York State) had high concen-
trations; while on April 20, the number of sites with high concentrations
was seven. The ozone episode ended on April 21, when all the stations
showed concentrations of 8 pphm or less.
TABLE 7. MAXIMUM HOURLY OZONE CONCENTRATIONS (pphm)
IN THE NEW YORK CITY AREA, 4/76
Station
Bridgeport, CT
Danbury, CT
Groton, CT
Hartford, CT
Babylon, NY
Hempstead, NY
Mamaroneck, NY
New York, NY
4/14
5
7
9
6
6
5
6
7
4/15
7
10
12
10
7
5
3
5
4/16
7
10
10
7
10
4
6
4
Date
4/17
11
21
11
13
18
15
12
19
4/18
20
19
13
20
21
18
12
19
4/19
12
23
13
21
8
6
5
4
4/20
12
10
10
10
12
9
6
15
4/21
5
7
6
8
6
8
3
2
4/22
5
4
5
5
3
3
3
3
High SOit and high 03 concentrations, including peak concentrations of
both pollutants, occurred almost simultaneously. Abundant sunshine was a
possible contributor (Table 3) to the photochemical production of both
pollutants; however, 03 levels were normal when the SO^ episode developed.
The 03 episode appeared to terminate a day earlier than the S04 episode.
COMPARISON OF PREVIOUS AIR POLLUTION STUDIES TO OUR RESULTS
o
The investigators of the high SOi* concentrations of the NASN data for
April 18, 1976, and the accompanying meteorological phenomena concluded that a
major contributing factor was the warm high pressure area that was moving
slowly across the eastern United States. Using this warm air mass as a
criterion for determining the beginning and end of the SOi, episode, the
duration of the episode could not be determined. (The investigators had
28
-------
insufficient data for determining the period representing the SCU sample).
The Daily Weather Maps show that it was April 16, 1976, before the air mass
coming from Canada was modified. This air mass was moved out of the
New York City area by a front on the morning of April 20. From the over-
all weather pattern showing only relatively small changes from April 17
to 19, one could assume that the April 18 SOi* concentration was represent-
ative of all 3 days; thus, the intensity and duration of the worst condition
can be inferred.
14
A highlight of the ozone investigation over the April 12 to 23
period noted that areas of low visibility generally coincided with areas
of elevated ozone under specific conditions. Earlier investigators *
showed good agreement between movements of high sulfate concentrations and
14
areas of restricted visibility and the ozone investigators attempted a
14
similar technique. The report did not consider the possibility that
4 5
areas of high S(K concentrations corresponded to areas of high 03 ' .
Table 3 shows that the New York City area had restricted visibility from
April 15 to 22 which practically coincided with periods of high ozone and
high sulfate. In addition, the area of high SCK concentrations over the
northeastern United States on April 18 (Figure 7) corresponded to high 03
14
concentrations on April 18 and restricted visibility on April 19 .
(There was no restricted visibility map for April 18). Although these
comparisons are limited, they do indicate that correspondence between areas
of high ozone concentrations and areas of restricted visibility possibly
resulted from the presence of high SOi* concentrations over designated areas.
Since visibility restrictions are usually caused by aerosols the size of
oc 9C
sulfate particles ' and not by gases such as ozone, it seems more
li.kely that sulfates rather than ozone were responsible.
Due to the discontinuous S(K sampling procedure the strongest state-
ment derived is the supposition that SCK rather than 03 was the major cause
of the visibility restrictions over the northeastern United States from
April 14 to 22, 1976. Until S04 is sampled on a continuous basis it will
be very difficult to accurately evaluate the effect of S(K on air quality
and the effect of related pollutants.
. 29
-------
SECTION 5
SUMMARY
The S(K concentrations at all four CHAMP stations in the New York City
area exceeded 10 yg/m from April 15 to 21, 1976. During much of the episode
concentrations were several times greater than those typical for April.
3
These concentrations first exceeded 10 yg/m on April 15, increased for
several days, peaked on April 18 or 19, decreased for a few days, and fell
3
below 10 yg/m on April 22. The NASN stations in the New York City area,
operating every twelfth day, monitored S04 near the peak of the episode on
April 18, and had comparable concentrations to those observed in the CHAMP
network.
The meteorological phenomena typical of the period were: high tempera-
tures (mid-80s to 90°F), abundant sunshine (96% or more daily), relatively
low average dew point temperatures (mid-50s°F) and relative humidities
(few >70%), and a slow moving high pressure area.
The episode did not terminate with a frontal passage on April 20, but
terminated with an active front which passed through the area bringing in a
fresh polar air mass on April 22; rain and very low clouds accompanied the
second front.
Air parcels between the surface and 1000 m could have moved into the
New York City area from as far away as 2000 km in 48 hours (based on
trajectory analyses) and not less than 600 km away; long range transport
occurred continuously during the episode. Sulfate data available for upwind
locations shown by the trajectories indicated high concentrations in those
locations which could have been transported to the New York City area. Un-
fortunately these S04 data were limited and need further verification with
30
-------
continuous sampling at locations upwind of areas with high SOt, concentrations.
Analyses of 03 data from the New York City area reveal 03 concentrations
exceeding 8 pphm occurring concurrently with high SC\ concentrations. The
initial high concentration of each pollutant was April 15. Their concen-
trations each peaked simultaneously; however, there was a difference in that
markedly lower Os concentrations accompanied the air mass change on April 20
while the SCU concentrations remained high.
2
An earlier investigation of NASN data for April 18 reported that
the warm slow moving air mass over the eastern United States was a
factor in the SOU episode. Since this air persisted from April 16 to 20
while high S0i» concentrations persisted from April 15 to 21, other meteoro-
logical phenomena must have contributed to some of the high concentrations.
Overall: 1) there was insufficient information concerning which period the one
day NASN sample represented, and 2) the one-day-in-six observational program
is inadequate for relating meteorological phenomena with the initiation and
termination of a prolonged episode.
The ozone investigation evaluating meteorological data for April 12-23
concluded that areas of low visibility generally coincided with areas of
elevated ozone concentrations. However, when the available but limited S04
data from the CHAMP stations for the entire period, the NASN stations on
April 18, the TVA plus several State networks in the eastern United States,
and the Province of Ontario were compared, it appeared that all areas with
high S04 concentrations closely corresponded to areas of restricted visibi-
lity. It is impossible to say which pollutant contributed to the reduced
visibility. Until SO.+ is monitored on a continuous basis, evaluating the
effects of SOit and other similarly produced pollutants on visibility will
remain difficult.
31
-------
REFERENCES
1. DeMarrais, G.A. and D.H. Coventry. Relationships Between Total
Suspended Participate, Sulfate, and Respirable Suspended Particulate
Concentrations. U.S. Environmental Protection Agency, 1979 (in press).
2. long, E.Y. and R.B. Batchelder. Aerometric Data Compilation and
Analysis for Regional Sulfate Modeling. Report to U. S. Environmental
Protection Agency. Teknekron, Inc., Berkley, California, 1978. 135 pp.
3. Hidy, G.M., E.Y. long, P.K. Mueller, S. Rao, I. Thompson, R. Berlandi,
D. Muldoon, D. Naughton, and A. Majahad. Design of the Sulfate
Regional Experiment (SURE). Volume I. Environmental Research and
Technology, Westlake Village, California, 1976. 100 pp.
4. Greeley, R.S., R.P. Quellette, J.T. Stone, and S. Wilcox. Sulfates
and the Environment—A Review. The MITRE Corporation, McLean, Virginia,
1975. 131 pp.
5. 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. 32 pp.
6. Gartrell, F.E., F.W. Thomas, and S.B. Carpenter. Atmospheric Oxidation
of S0? in Coal-Burning Power Plant Plumes. Industrial Hygiene
Journal, 24:113-120, 1963.
7. Penkett, S.A. Oxidation of S02 and Other Atmospheric Gases by Ozone
in Aqueous Solution. Nature (Pnysical Science), 240;105-106, 1972.
8. Cheng, R.T., J.O. Frohliger, and M. Corn. Aerosol Stabilization for
Laboratory Studies of Aerosol-Gas Interactions. 0. Air Poll. Control
Assoc., 21:138-142, 1971.
9. Hall, F.P., Jr., C.E. Duchon, L.E. Lee, and R.R. Hagan. Long-Range
Transport of Air Pollution: A Case Study. Monthly Weather Review,
101:404, 1970.
10. Husar, R.B., N.V. Gillani, J.D. Husar, C.C. Paley, and P.N. Turner.
Long-Range Transport of Pollutants Observed Through Visibility Contour
Maps, Weather Maps and Trajectory Analysis. Preprint, Third Symp. Atmos.
Turb., Diff., and Air Quality, American Meteorological Society, Raleigh,
North .Carolina, 1976. 344-347 pp.
32
-------
11. Millan, M.M. and Y.S. Chung. Detection of a Plume 400 km from the
Source. Atmospheric Environment, 11:939-944, 1977.
12. Peterson, K.R. Continuous Point Source Plume Behavior Out to 160
Miles. J. Appl. Meteor., 7:217-223, 1968.
13. Junge, C.E. Air Chemistry And Radioactivity. Academic Press, New
York, New York, 1973
14. Wolff, G.T., P.S. Lioy, G.D. Wright, R.E. Meyers, and R.T. Cederwall.
An Investigation of Long-Range Transport of Ozone Across the Midwestern
and Eastern United States. Atmospheric Environment, 11: 797-822, 1977.
15. Dehalu, Schoofs, Mage, Batta, Bovy, et Firket (no initials included).
Sur les causes des accidents dans la vallee de la Meuse, lors des
brouillards de decembre 1930. Bull. Acad. Roy. Med. Belg. 2:683-734, 1931,
16. Hemeon, W.C.L. The Estimation of Health Hazards from Air Pollution.
Arch. Ind. Health, 11:397-402, 1955.
17. Human Studies Laboratory Health Consequences of Sulfur Oxides; A Report
from Community Health and Environmental Surveillance System, 1970-1971.
EPA-650/1-74-004. U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina, 1974. 368 pp.
18. 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.
19. Office of Research and Development. Statement of Sulfates Research
Approach. EPA-600/8-77-004. U.S. Environmental Protection Agency,
Washington, D.C., 1977. 43 pp.
20. Liggett, W.S., Jr. and W.J. Parkhurst. Suspended Particulates and
Sulfates at Rural Locations in the Tennessee Valley Report.
I-AQ-77-14. Tennessee Valley Authority, Chattanooga, Tennessee, 1977.
21. Environmental Data Service (NOAA) Daily Weather Maps (April 1976).
U.S. Government Printing Office, Washington, D.C., 1976.
22. 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.
23. Clark, T.L. Gridded Pollutant Emissions in the U.S. and Southern
Canada East of the Rockies. Paper presented at 71st Annual Meeting of
the Air Pollution Control Association, Houston, Texas, June 25-30, 1978.
33
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24. long, E.Y., G.M. Hidy, T.F. Lavery, and F. Berlander. Regional and
Local Aspects of Atmospheric Sulfate in the Northeast Quadrant of the
U.S. In: Preprints, Third Symp. on Atmos. Turb., Diff., and Air
Quality, American Meteorological Society, Raleigh, North Carolina, 1976.
25. White, W.H. and P.T. Roberts. On the Nature and Origins of Visibi-
lity-Reducing Aerosols in The Los Angeles Air Basin. Atmospheric
Environment, 11:803-812, 1977.
26. Gartrell, G. Jr. and S.K. Friedlander. Relating Particulate Pollution
to Sources: The 1972 California Aerosol Characterization Study. At-
mospheric Environment, 9:279-299, 1975.
34
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/4-79-074
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
ANALYSIS OF HIGH SULFATE CONCENTRATIONS IN GREATER
NEW YORK CITY AIR
5. REPORT DATE
December 1979
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Gerard A. DeMarrais and Dale H. Coventry
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
(Same as Block 12.)
10. PROGRAM ELEMENT NO.
1AA603 AE-013 (FY-79)
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
Environmental Sciences Research Laboratory - RTP, NC
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
Inhouse 12/78-8/79
14. SPONSORING AGENCY CODE
EPA/600/09
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The meteorological phenomena occurring during April 15 to 21, 1976, when high
sulfate concentrations were measured in the New York City area, are summarized.
Findings of earlier investigations of relationships between meteorological phenomena
and high sulfate concentrations are compared to the findings of this investigation.
Since ozone readily occurs with the same meteorological conditions than are asso-
ciated with sulfate episodes, the ozone concentrations are also discussed.
Results showed that the current procedure for sampling sulfate every sixth
day does not provide sufficient data for adequately determining how sulfate
concentrations relate to meteorological phenomena. In particular, the sampling
schedule is not sufficient for determining when prolonged periods of high sulfate
concentrations begin and end. The sampling schedule only allows for indicating
what the meteorological conditions were when the concentrations were a certain
value and not how the concentrations changed with changing meteorological condi-
tions.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
* Air pollution
* Sulfates
Ozone
* Meteorological data
* Analysis
Sampling
New York City
13B
07B
04B
14B
8. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
43
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
35
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