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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-600/4-79-046
September 1979
RELATIONSHIPS BETWEEN TOTAL SUSPENDED PARTICIPATE,
SULFATE, AND RESPIRABLE SUSPENDED PARTICULATE CONCENTRATIONS
Analysis of Data Collected in New York City
by
Gerard A. DeMarrais and Dale H. Coventry
Meteorology and Assessment Division
Environmental Sciences Research Laboratory
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 Environmental Sciences Research
Laboratory, U. S. Environmental Protection Agency, and approved for public-
cation. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use.
AFFILIATION
Messrs. DeMarrais and Coventry are presently meteorologists in the
Meteorology and Assessment Division, Environmental Sciences Research
Laboratory, U.S. Environmental Protection Agency, Research Triangle Park,
North Carolina, 27711. They are on assignment from the National Oceanic
and Atmospheric Administration, U. S. Department of Commerce.
n
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ABSTRACT
Two years of data for daily total suspended particulate, sulfate, and
respirable suspended particulate concentrations measured at four stations
in the New York City area are statistically analyzed. To show the varia-
bility of each pollutant data set, the mean, median, and 16th and 84th
percentile values of concentration of each pollutant are summarized. To
demonstrate the spatial representativeness of the concentrations of indi-
vidual pollutants, the daily (24-hour) concentrations at pairs of stations
were compared and correlation coefficients determined. Results indicated
that sulfate concentrations varied on an area-wide basis while the concen-
tration of respirable suspended particulates at the four stations appeared
to depend on local conditions.
m
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CONTENTS
Abstract iii
Figures vi
Tables., vii
1. Introduction 1
2. Conclusions 2
3. Source of Sampling Data, Instruments, Sites, Records, and
Analyses 4
4. Results 8
Annual and quarterly average, median, and 16th and 84th
percentile of 24-hour concentrations 8
Spatial agreement in concentration variations 12
Interrelationships of pollutant concentrations at
individual sites 16
5. Summary 19
References 23
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FIGURES
Number Page
1 CHAMP stations in the New York City area 5
2 CHAMP stations in New York City 6
vi
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TABLES
Number Page
1 Average 24-Hour Concentrations, TSP (yg/m3) and Percent!les
(16th/50th/84th), CHAMP Stations, New York City Area,
July 1974-June 1976 8
2 Average 24-Hour Concentrations, SO.* (yg/m3) and Percent!les
(16th/50th/84th), CHAMP Stations, New York City Area,
July 1974-June 1976 10
3 Average 24-Hour Concentration, RSP (yg/m3) and Percentiles
(16th/50th/84th), CHAMP Stations, New York City Area,
July 1974-February 1976 11
4 Correlation Coefficients of TSP Concentrations (yg/m3),
New York City Area Stations, July 1974-June 1976 13
5 Correlation Coefficients of SC\ Concentrations (yg/m3),
New York City Area Stations, July 1974-June 1976 15
6 Correlation Coefficients of RSP Concentrations (yg/m3),
New York City Area Stations, July 1974-February 1976 16
7 Correlation Coefficients, TSP Versus SCU Concentrations,
New York City Area Stations, July 1974-June 1976 17
8 Correlation Coefficients, TSP Versus RSP Concentrations,
New York City Area Stations, July 1974-February 1976 18
9 Correlation Coefficients, RSP Versus S04 Concentrations,
New York City Area Stations, July 1974-February 1976 18
vn
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SECTION 1
INTRODUCTION
Measurements of the concentrations of air pollutants are generally
made at widely separated sampling sites and it is assumed that each sample
is representative of a large area surrounding the sampling site. To those
trying to correlate variations in meteorological phenomena with variations
in concentrations, the spatial representativeness of the pollutant concen-
tration is significant. The reason for the significance is that the meteoro-
logical observations are frequently taken at sites which are not in the
same general area as the sampling site; for any pollutant-meteorological
correlations to be meaningful both sets of observations must represent
conditions in a common area.
In order to obtain an estimate of the spatial representativeness of
measurements of total suspended particulate (TSP), sulfates (S04), and
respirable suspended particulates (RSP), two years of daily air quality
data from a four-station network in the New York City area have been
analyzed in detail. Since all of these pollutants are particulates and
could be interrelated, the correlation coefficients of pairs of pollutants
were also determined. The concentration data are summarized for the entire
sampling period (annual = 2-year composite) and for the calendar quarters
for the year (first quarter includes January, February, and March).
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SECTION 2
CONCLUSIONS
Analyses of the TSP, SO., and RSP data of July 1, 1974 to June 30, 1976,
for four stations in the New York City area, were used to determine the
distribution of the pollutant concentrations. The correlation coefficients
of pairs of pollutants were also determined.
Sulfate concentrations, even though they showed large differences in
average concentrations and in the distribution of concentrations among the
stations, varied on an area-wide basis (the largest separation between
stations was 125 km). An SO^ observation at one site was generally repre-
sentative of the area.
Respirable suspended particulate concentrations among the four sites,
even though two of them were only 10 km apart, varied independently. High
RSP concentrations were more dependent on local rather than distant or
regional sources; the concentrations would have varied more uniformly if
distant or regional sources were the cause of the RSP concentrations.
The variations in TSP concentrations among the four sites were more
consistent than those shown in RSP concentrations and less consistent than
those shown in SO., concentrations. However, there was no obvious indication
that either local or distant sources were important in determining when
high TSP concentrations would occur.
At the individual sites, on an annual basis, TSP and SO., were fair
surrogates of one another (correlation coefficients of 0.75). Total
suspended particulate and RSP, and RSP and SO., were not as good of substi-
tutes for one another (correlation coefficients near 0.65) as were TSP
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and S0i+. In the second and third quarters the average concentrations of
TSP, S0i», and RSP were higher than they were for the year; in those quarters
all three pollutants were better surrogates for one another than they were
on an annual basis.
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SECTION 3
SOURCE OF SAMPLING DATA, INSTRUMENTS, SITES, RECORDS, AND ANALYSES
From January 1974 through June 1976 the Community Health Air Monitoring
Program (CHAMP) of the United States Environmental Protection Agency (EPA)
operated a four-station air quality sampling network in the New York City
area. Among the data collected were daily 24-hour samples of TSP, S0i», and
RSP. Each 24-hour sample was collected and analyzed in accord with the
*#f - i
recommended procedures of EPA , but the filters were changed at 11 a.m.
Eastern Standard Time (normally 24-hour samples are collected from midnight
to midnight). The TSP and SO* were collected with high volume air sampling
equipment and the RSP samples utilized a device known as a "cyclone" .
The locations of the four sampling sites are shown in Figure 1. A
more precise location of each of the stations in New York City is shown in
Figure 2. The shortest distance between sites was 10 km (between Brooklyn
and Queens), while the Riverhead site was 125 km east of New York City.
The Queens and Brooklyn sites were near the southern edge of the metropo-
litan area (a short distance from the Atlantic Ocean) while the Bronx site
was surrounded by an extensive built-up area. The Riverhead site was
considered a relatively clean site outside the major influence of New York
City.
The listings of the data were supplied by the Health Effects Research
Laboratory of EPA. The listings show the 24-hour concentration of each
pollutant for the day on which the sample was removed from the collector.
About 80 percent of the data for June 1974 were missing, so the period
selected for analysis was July 1, 1974 through June 30, 1976. There were
occasional days after June 30, 1974 when data for one or more pollutants
were missing and the cyclone instrument went out of service in late
4
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Figure 2. CHAMP stations in New York City.
6
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February 1976. Sulfate and TSP data were available for all stations for
more than 90 percent of the days and RSP data were available for more than
85 percent of the days.
In order to characterize the population distribution of concentrations
of the individual pollutants at each site, the concentrations of each
pollutant at each site were statistically analyzed. There are many ways
of summarizing the information contained in a data set. The two most widely
used in a statistical analysis are the mean and a measure of the variability
p
of the probability distribution . For this report the mean (average),
median (50th percentile), and 16th and 84th values of concentrations were
determined for the entire period and each quarter of the year. When the
distribution for values is normal the mean and median are approximately
the same, and the 16th and 84th percentiles are each one standard deviation
from the median. To demonstrate the spatial representativeness of the
concentrations of individual pollutants, the daily concentrations at pairs
of stations were compared and correlation coefficients for the entire sampling
period and each quarter of the year were calculated. To show the interre-
lationship of the concentrations of the particulate pollutants, pairs of
observations at the individual sites were compared and annual and quarterly
correlation coefficients calculated.
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SECTION 4
RESULTS
ANNUAL AND QUARTERLY AVERAGE, MEDIAN, AND 16TH AND 84TH PERCENTILE OF
24-HOUR CONCENTRATIONS
Total Suspended Particulate Concentrations
The average (mean), median, and 16th and 84th percentile values of
24-hour TSP concentrations for each of the four sites for the year and
each quarter are listed in Table 1. The primary 24-hour National Ambient
Air Quality Standard (NAAQS) for TSP is 260 yg/m3 (not to be exceeded more
than once a year). The value 260 yg/m3 was exceeded on only one occasion
at only one site during the two years.
TABLE 1. AVERAGE 24-HOUR CONCENTRATIONS, TSP (yg/m3) AND PERCENTILES
(16TH/50TH/84TH), CHAMP STATIONS, NEW YORK CITY AREA, JULY
1974-JUNE 1976
Period
of
Year
Annual Average
Percen tiles
1st Quarter Average
Percen tiles
2nd Quarter Average
Percentiles
3rd Quarter Average
Percentiles
4th Quarter Average
Percentiles
Station
Riverhead
35
18/30/50
32
18/29/43
37
19/32/53
38
20/33/53
30
15/27/44
Queens
51
28/45/73
46
29/43/63
51
29/43/71
56
27/50/88
51
28/45/74
Brooklyn
59
35/53/81
51
33/47/70
58
34/53/79
68
42/62/95
56
34/49/76
Bronx
60
29/54/90
57
28/46/88
66
33/60/94
62
35/58/88
56
25/49/86
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The annual average 24-hour TSP concentrations (Table 1) show that the
Riverhead concentrations were considerably lower than those at the three
New York City sites. The annual averages and medians show that the Brooklyn
and Bronx sites had comparable concentrations but the 16th and 84th percen-
tiles disclose that the concentrations had a much larger range at the Bronx
site. Although the Brooklyn site had a higher annual average concentration
than the Queens site, the range of values between the 16th and 84th percen-
tiles was practically the same; the distribution patterns were similar but
centered on different medians. The data for the quarters show that the
Riverhead site consistently had the lowest average concentrations, and in
the City the Queens site had the lowest average concentrations. In three
of the four quarters the Bronx had the highest average 24-hour concentration
while the Brooklyn site had the highest average concentrations in the third
quarter. Three of the four sites had their highest concentrations in the
third quarter and the second highest concentrations in the second quarter
at the Bronx site the highest average concentrations occurred in the second
quarter. The percentile data for the quarters show that the smallest
difference between the 16th and 84th percentiles was 25 yg/m3 (Riverhead in
the first quarter) and the highest was 61 yg/m3 (Queens in the third and
the Bronx in the second and fourth quarters). The differences were always
25 yg/m3 or greater and were frequently twice as great at sites in the City.
Sulfate Concentrations
The 24-hour average, median, and 16th and 84th percentile values of
SOi, concentrations for each site for the year and each quarter are listed
in Table 2. There is no NAAQS for SC\ but concentrations as low as 10 yg/m3
(24-hour average) have been associated with adverse health effects in pre-
3
liminary epidemeo logical studies . Since there is no other documentation
on possible hazardous SOi* concentrations, 10 yg/m3 is used as a reference
value. The annual average concentration at all three New York City sites
exceeded 9 yg/m3 and the 84th percentile for the year exceeded 10 yg/m3 at
all four sites; 24-hour SO.* concentrations exceeding 10 yg/m 3 occurred fre-
quently.
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TABLE 2. AVERAGE 24-HOUR CONCENTRATIONS, S(U (yg/m 3) AND PERCENTILES
(16TH/50TH/84TH), CHAMP STATIONS, NEW YORK CITY AREA,
JULY 1974-JUNE 1976
Period
of
Year
Annual Average
Percentiles
1st Quarter Avg.
Percentiles
Station
Riverhead
7 5
3.6/b.4/10.7
7.0
4.3/6.6/9.4
Queens
9.2
4.7/7.7/13.2
8.3
5.3/7.9/11.6
Brooklyn
9.7
5.2/8.4/13.5
8.8
5.5/8.4/12.5
Bronx
9.4
4.7/8.0/14
8.7
5.2/7.9/12
.0
.5
2nd Quarter Avg.
Percentiles
3rd Quarter Avg.
Percentiles
4th Quarter Avg.
Percentiles
7.9
3.8/6.3/11.3
9.1
3.2/6.7/15.3
6.2
3.4/5.5/9.0
9.5
4.8/7.9/13.6
10.7
4.3/8.7/16.5
8.1
4.5/7.1/11.7
9.5
5.2/8.1/13.5
11.8
5.2/10.2/16.8
8.7
5.0/7.9/12.6
10.0
4.9/8.1/14.6
11.0
4.7/9.6/18.4
8.0
4.2/7.1/12.0
The lowest 24-hour average concentrations on an annual basis and in
each quarter, as shown in Table 2, occurred in Riverhead. The Brooklyn
site had the highest average SO^ concentrations on an annual basis and in
all quarters but the second, when the highest concentrations occurred at
the Bronx site. Even though the Brooklyn site usually had the highest
average and median concentrations, the Bronx site showed the largest range
of values between the 16th and 84th percentiles on an annual basis and in
each quarter; the concentrations at the Bronx site varied over the widest
range. The Queens site showed a wider range of concentrations between the
16th and 84th percentiles than the Brooklyn site on an annual basis and
during the second and third quarters. Even the Riverhead site in the third
quarter had a larger range of concentrations than the Brooklyn site (the
Brooklyn site at this time had the highest average concentration shown in
Table 2). The S04 average 24-hour concentrations showed an obvious change
with quarter: the highest concentrations occurred in the third quarter, the
next highest in the second quarter, the third highest in the first quarter
and the lowest concentrations occurred in the fourth quarter.
10
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Respirable Suspended Particulate Concentrations
The average, median and 16th and 84th percentile values of 24-hour
RSP concentrations for the four sites for the year and each quarter are
listed in Table 3. There is such a scarcity of information on RSP concen-
trations in the ambient air that there are no indications of concentrations
that might constitute a health hazard. However, because of this lack of
A
knowledge about RSP, Congress has directed that studies of the pollutant
and its effects be conducted by EPA. Due to the lack of a reference value
for the RSP concentrations, discussions are limited to how they compare to
one another.
TABLE 3. AVERAGE 24-HOUR CONCENTRATIONS,RSP (yg/m 3) AND PBRCENTILES
(16TH/50TH/84TH), CHAMP STATIONS, NEW YORK CITY AREA,
JULY 1974-FEBRUARY 1976
Period
of
Year
Annual Average
Percent! les
1st Quarter Average
Percent! les
2nd Quarter Average
Percent! les
3rd Quarter Average
Percentiles
4th Quarter Average
Percent! 1 es
River head
24
12/22/36
22
10/20/31
21
12/21/30
29
16/26/41
22
10/21/30
Station
Queens
32
17/29/47
28
14/26/40
30
18/30/40
37
18/33/54
31
12/29/45 .
Brooklyn
32
17/29/46
29
15/27/39
28
18/28/38
35
19/32/52
32
16/30/45
Bronx
37
18/34/55
33
16/29/49
35
17/31/48
42
23/40/60
36
15/32/55
The average concentrations for the year and in each quarter (Table 3)
show that Riverhead had the lowest and the Bronx had the highest RSP concen-
trations. The average RSP concentrations at the Queens and Brooklyn sites
were practically the same at all times and these were generally 5 or 6 yg/m3
less than those at the Bronx site. The average concentrations for the
11
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quarters show that the third quarter had the highest concentrations at all
four sites. At the three New York City sites the fourth quarter had higher
average concentrations than the first and second quarters. The Bronx
had the largest range of concentrations between the 16th and 84th percentiles
on an annual basis and in each of the quarters. The relatively small
differences between the Queens and Brooklyn sites in average percentile
concentration indica'.e that distributions at these two sites were similar
at all times of year.
Distributions of Total Suspended Particulate, Sulfate, and Respirable
Suspended Particulate
The average concentrations in Tables 1, 2, and 3 are higher than the
median concentration in practically all cases. Furthermore, in all three
tables the range of concentrations between the 16th percentile and the
median is nearly always less than that between the median and the 84th
percentiles. Both of these comparisons demonstrate that the distribution
of each of the pollutants - TSP, SO*, and RSP - are not normal. While reducing
the distribution arrays of the three pollutants to normal distributions
would provide data for more detailed analyses, this reduction was not
c
attempted because recent evidence has shown that determining such a normal
"")
distribution is frequently a major undertaking; VJhitby has shown that
the distributions of sulfur containing aerosols were characterized by a
trimodal model consisting of three additive log-normal distributions.
SPATIAL AGREEMENT IN CONCENTRATION VARIATIONS
The spatial agreement in TSP concentration patterns among the four
sites, determined by calculating the correlation coefficients of the daily
observation at pairs of sites, is shown in Table 4. Since there were
obvious differences among the quarters of the year in the concentrations
(Table 1), quarterly as well as annual correlation coefficients were cal-
culated. The annual summary shows that the correlation coefficients among
the paired sites ranged from 0.67 to 0.74; the variance explained by one
variable in place of the other among the four concentrations patterns
12
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TABLE 4. CORRELATION COEFFICIENTS OF TSP CONCENTRATION (yg/m3),
NEW YORK CITY STATIONS, JULY 1974-JUNE 1976
Station
Riverhead
Queens
Brooklyn
Riverhead
Queens
Brooklyn
Riveinhead
Queens
Brooklyn
Riverhead
Queens
Brooklyn
Riverhead
Queens
Brooklyn
Queens Brooklyn
Annual Average
.71 .72
.74
1st Quarter
.65 .56
.67
2nd Quarter Average
.77 .81
.74
3rd Quarter Average
.72 .71
.77
4th Quarter Average
.67 .71
.73
Bronx
.70
.67
.71
.63
.57
.62
.76
.66
.82
.69
.75
.75
.70
.73
.66
13
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averaged 0.50. On an annual basis, the highest correlation of TSP concen-
trations was between the closest station, Brooklyn and Queens. However,
the poorest correlation was between Queens and the Bronx, not Riverhead
and one of the distant sites. The quarterly correlations show that the
coefficients changed markedly with time-of-year. The poorest correlations
occurred in the first and the best occurred in the second quarter. Generally,
the correlations in th,j second and third quarters were better and those in
the fourth and first quarters poorer than the annual correlations. Thus,
the correlations were better than average when the concentrations (Table 1)
were higher than average. The best correlations occurred in the second
quarter between Riverhead and Brooklyn and between Brooklyn and the Bronx.
It should be noted that the correlation coefficient for Brooklyn and Queens
(the stations with the smallest separation) was considerably less than that
for Brooklyn and Riverhead (the pair of sites with the largest separation)
in the second quarter; the correlation was not in proportion to the sepa-
ration of the stations.
The spatial agreement in SOi* concentration patterns at the four stations
is shown in Table 5. On an annual basis the correlation coefficients are
very high and markedly higher than those shown in the TSP comparisons
(Table 4). The best correlation - 0.93 - on an annual basis was between Brooklyn
and Queens. Probably the most significant feature of the quarterly corre-
lations is the high coefficients of the Brooklyn-Queens pairings in all
quarters. The indication is that a 10-km separation did not cause much of
a difference in SOi* concentrations at any time during the year. The
high correlation coefficients between Riverhead and all three City sites in
all quarters indicate that the S04 variations were consistent over most
of the area a very large portion of the time; the 125-km separations allowed
for differences in actual concentrations (Table 2), but most of the time all
of the stations showed the same relative concentrations. Considering the
four sites as a group, the highest correlation coefficients occurred in the
second and lowest in the first quarter (but there was no coefficient less
than 0.74). These high correlations among the paired sites indicate that
a S04 observation from one of these sites was representative of the area
14
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and appear to confirm the deductive reasoning that most of the SOi* comes
from the oxidation of sulfurous gases in the atomsphere. These gases were
emitted upwind of the New York City area and in the combined processes of
oxidation and dispersion became uniformly mixed SOi* by the time they were
transported to the New York City area.
TABLE 5. CORRELATION COEFFICIENTS OF SO* CONCENTRATIONS (yg/m 3),
NEW YORK CITY AREA STATION, JULY 1974-JUNE 1976
Station
Queens
Brooklyn
Bronx
River head
Queens
Brooklyn
Riverhead
Queens
Brooklyn
Riverhead
Queens
Brooklyn
Riverhead
Queens
Brooklyn
Riverhead
Queens
Brooklyn
Annual Average
.87 .88
.93
1st Quarter Average
.82 .81
.89
2nd Quarter Average
.94 .93
.97
3rd Quarter Average
.85 .88
.92
4th Quarter Average
.80 .86
.92
.86
.85
.86
.74
.75
.77
.88
.89
.90
.88
.85
.87
.84
.82
.86
The spatial agreement in RSP concentration patterns at all four
stations is shown in Table 6. On an annual basis, particularly when
these correlation coefficients are compared to those for TSP and SO^, the
correlations are poor. The best correlation was between the closest
stations, Brooklyn and Queens, but this was only 0.60. The overall indi-
15
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cation of these annual coefficients is that the concentration patterns were
highly variable and that a RSP measurement represented a very small area.
The seasonal correlations show that there was a marked change with time
of year. The best correlations occurred for the most part in the third
quarter and the poorest generally occurred in the first quarter.
TABLE 6. CORRELAuON COEFFICIENTS OF RSP CONCENTRATIONS
NEW YORK CITY AREA STATIONS, JULY 1974-FEBRUARY 1976*
Station
Queens
Brooklyn
Bronx
Riverhead
Queens
Brooklyn
Riverhead
Queens
Brooklyn
Riverhead
Queens
Brooklyn
Riverhead
Queens
Brooklyn
Riverhead
Queens
Brooklyn
Annual Average
.55 .49
.60
1st Quarter Average
.25 .30
.45
2nd Quarter Average
.51 .50
.59
3rd Quarter Average
.66 .59
.68
4th Quarter Average
.59 .43
.53
.54
.59
.56
.39
.55
.51
.63
.68
.58
.68
.64
.60
.46
.53
.52
* No RSP data available after February 1976.
INTERRELATIONSHIPS OF POLLUTANT CONCENTRATIONS AT INDIVIDUAL SITES
The correlation coefficients based on the comparison of daily TSP
and SOit concentrations at the individual sites are shown in Table 7.
On an annual basis the correlations coefficients were practically the same
16
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at all sites. The quarterly correlations show that the coefficients of the
second and third quarters were generally higher than the annual coefficients.
The poorest correlations occurred in the first quarter, generally a period
with low concentrations of TSP (Table 1) and SOU (Table 2). Riverhead showed
the extremes in correlation; the highest of all coefficients occurred at
Riverhead in the second quarter and the lowest occurred at Riverhead in the
first quarter. The Bronx site showed the most consistency from quarter-to-
quarter; the relationship between TSP and SOi, changed very little at the
Bronx, the site which generally had high concentrations in every quarter.
TABLE 7. CORRELATION COEFFICIENTS, TSP VERSUS SO* CONCENTRATIONS,
NEW YORK CITY AREA STATIONS, JULY 1974-JUNE 1976
Station
Period
Annual Average
1st Quarter Average
2nd Quarter Average
3rd Quarter Average
4th Quarter Average
Riverhead
.77
.56
.84
.80
.72
Queens
.75
.64
.75
.82
.76
Brooklyn
.75
.70
.77
.79
.70
Bronx
^5
.74
.79
.77
.79
The correlation coefficients based on the comparison of the daily RSP
and TSP concentrations at the indivudual sites are shown in Table 8. The
annual coefficients are less than those for TSP and S0.» concentrations
(Table 7) and show much more variation among the sites. The highest annual
coefficient was at the Bronx site, 0.71. The quarterly coefficients showed
fairly good correlations in the quarter which had both high RSP and TSP
concentrations (Tables 2 and 3); in the third quarter the correlation co-
efficients were 0.70 or greater. In the first quarter the Brooklyn, Queens,
and Riverhead sites showed correlations between RSP and TSP of less than
0.43. The Bronx site showed the most quarter-to-quarter consistency and in
the second quarter had a coefficient of 0.85. Riverhead, as it did with
the TSP-SOit comparison, showed the largest quarterly variation, with the
third quarter having the highest coefficient and the first quarter the
lowest coefficient.
17
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TABLE 8. CORRELATION COEFFICIENTS, TSP VERSUS RSP CONCENTRATIONS,
NEW YORK CITY AREA STATIONS, JULY 1974-FEBRUARY 1976
Station
Period
Annual Average
1st Quarter Average
2nd Quarter Average
3rd Quarter Average
4th Quarter Average
Riverhead
.65
.33
.74
.78
.61
Queens
.63
.41
.64
.70
.67
Brooklyn
.65
.42
.64
.71
.68
Bronx
.71
.71
.85
.82
.61
The correlation coefficients based on the comparison of the daily SOn
and RSP concentrations are shown in Table 9. The annual coefficients are
comparable to those for RSP versus TSP but lower than those for TSP versus
SOi*. The highest coefficients, on an annual basis, were at Queens and
Riverhead sites but the correlation coefficients were 0.67 or less. The
quarterly .results were very similar to those for the TSP-RSP comparisons
with the second and third quarters showing better correlations than the
fourth and first quarters. A second similarity was that the first quarter
showed Riverhead, Queens, and Brooklyn had very low coefficients. As with
both the RSP-TSP and TSP-SOi* comparison, the Bronx site showed the most
consistent pattern through the year and Riverhead showed the largest quar-
terly variation.
TABLE 9. CORRELATION COEFFICIENTS, RSP VERSUS SO., CONCENTRATIONS,
NEW YORK CITY AREA STATIONS, JULY 1974-FEBRUARY 1976
Station
Period
Annual Average
1st Quarter Average
2nd Quarter Average
3rd Quarter Average
4th Quarter Average
Riverhead
.66
.30
.77
.81
.48
Queens
.67
.33
.72
.77
.63
Brooklyn
.61
.51
.61
.69
.56
Bronx
.64
.67
.76
.73
.52
18
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SECTION 5
SUMMARY
On the basis of the statistical analyses of 24-hour concentrations of
TSP, SOij, and RSP, the distribution of the concentrations could be charac-
terized as follows:
The TSP concentrations were not normally distributed on an annual basis
nor in any quarter of the year. Among the four sites, Riverhead, the
site 125 km from New York City, had the lowest average (mean) concen-
trations on an annual basis and in each quarter. The highest average
concentrations in any quarter were at either the Brooklyn or the
Bronx site, and on an annual basis the average concentrations at these
sites were almost identical. For the year and in each quarter, the
Riverhead site showed the smallest range of concentrations and the
Bronx site, except for one quarter, had the largest range of concentra-
tions between the 16th and 84th percentiles. Average concentrations
of TSP among the four sites were relatively high in the second and
third quarters and low in the first and fourth quarters.
The SOi, concentrations were not normally distributed on an annual
basis nor in any quarter of the year. Of the four sites, that at River-
head had the lowest average concentration for the year and in each
quarter and the Brooklyn site had the highest average concentration on
an annual basis and in three of the four quarters. Even though the
Brooklyn site usually had the highest average concentration, all of the
other sites in one quarter or another had a larger range of concentrations
between the 16th and 84th percentiles than the Brooklyn site. The
largest range of concentrations on an annual basis and in each quarter
was at the Bronx site. The order of decreasing concentrations among
19
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the quarters was third, second, first, and fourth.
The RSP concentrations were not normally distributed. Among the four
sites the average concentrations for the year and in each quarter were
highest at the Bronx site and lowest at the Riverhead site. At the
Brooklyn and Queens sites, the average concentrations and average percen-
tile concentrations for the year and in each quarter differed very little;
the distributions at these two sites were similar throughout the year.
The Bronx site had the largest range of concentration on an annual basis
and in all four quarters. At the three city sites the fourth quarter
average concentrations were higher than those in the first and second
quarters.
Spatial correlation analyses of the 24-hour concentrations of the
individual pollutants among the four sites showed that:
The concentrations of TSP showed fairly consistent annual correlation
coefficients (averaging 0.71) among the individual pairs of sites in spite
of the large differences in annual average concentrations among the four
sites. The highest correlation on an annual basis was between the closest
stations and the two which showed the most similar distribution patterns,
Brooklyn and Queens, and not between the stations which observed similar
high average concentrations, Brooklyn and the Bronx. The poorest corre-
lation on an annual basis was between adjacent sites in the City, not a
City site and the distant Riverhead site; the correlation coefficients did
not vary in direct proportion to the spatial separation. The best corre-
lations on a quarterly basis occurred in the second and third quarters,
the periods when the concentrations were the highest.
The correlation coefficients for S04 concentrations between pairs of
stations, on an annual basis, ranged from 0.85 to 0.93. This indicates
that the correlations were extremely high even though the average concen-
tration at the individual sites differed by as much as 20 percent. The
highest quarterly correlations (averaging 0.92) among the four sites
occurred in the second quarter, the quarter with the second highest
20
-------
average concentrations and the second highest range of concentrations
between the 16th and 84th percentiles. The third quarter, that with
the highest average concentrations, showed correlation coefficients
only a little bit better than those for the year. With the exception
of the coefficients associated with the Bronx site in the first quarter,
all quarterly correlation coefficients between pairs of sites exceeded
0.80. The overall indication was that SO^ concentrations typically
increased or decreased on an area-wide basis.
The RSP correlation coefficients on an annual basis ranged from 0.49
to 0.60 between the pairs of stations; these correlations were much
lower than those for TSP and S0i» concentrations. On the basis of the
distribution patterns shown at the sites this was not anticipated.
This is particularly true with regard to the Brooklyn-Queens sites.
The RSP distribution patterns for these two stations were very similar
yet they show quarterly correlation coefficients as low as 0.49 and
0.53. The overall indication is that in spite of some marked simila-
rities in distribution patterns, increases and decreases in concentrations
frequently occurred independently at each site. An RSP measurement
appeared to be generally representative of a very small (less than
10 km diameter) area.
The analysis of the interrelationship of the pollutant concentrations,
based on the comparison of simultaneous observations of 24-hour concentration
of TSP, SOi* and RSP at the individual sites showed that:
The TSP and SO^ concentrations on an annual basis had correlation
coefficients that averaged 0.75 at three sites and 0.77 at the River-
head station. These correlations indicate good agreement. The highest
quarterly correlations (averaging approximately 0.79) occurred in the
second and third quarters, the two quarters that had relatively high
concentrations of both pollutants. In these two quarters the River-
head site had the best correlations while in the first and fourth
quarters the same site had the poorest correlations. The site which
showed the most consistency in correlation coefficients from quarter-
21
-------
to-quarter was the Bronx. The Bronx had the highest annual average
TSP and the second highest S04 concentrations, and usually had the
largest range of SOi* and TSP concentrations between the 16th and 84th
percentiles in eadh quarter. The correlation coefficients for the
comparison of TSP and RSP concentrations were lower and more wide-
ranging than those for the TSP-SCU comparisons; the coefficients at the
individual sites ranged from 0.63 to 0.71. Since RSP concentrations
appear to depend on local conditions, these correlation coefficients
were fairly good. In the first quarter of the year, that with relatively
low TSP and RSP concentrations, the coefficients were very low (0.42 or
less) at three of the four stations. The most consistent correlations
through the quarters were at the Bronx, the site which usually had the
highest annual average TSP and RSP concentrations and the largest range
of concentration between the 16th and 84th percentiles for both pollu-
tants. The Bronx site had the highest coefficient in the second and
third quarters while Riverhead had the second highest coefficients.
Since Riverhead had the lowest average concentrations, the coefficients
were not proportional to the relative concentrations.
The annual and quarterly coefficients for the RSP-SOi* comparisons at
the individual sites were similar in value to those for the TSP-RSP
comparisons. Because RSP concentrations tended to depend on local con-
dition, these correlation coefficients were fairly good. The third
quarter had relatively high RSP and SO^ concentrations and it showed
the best correlations with coefficients ranging from 0.69 to 0.81. The
highest coefficient for any quarter occurred at Riverhead in the third
quarter; this site had the lowest average concentration in that quar-
ter. The first quarter had shown relatively low average concentrations
of RSP and S(K and the correlations for the period were very low (0.51
or less) at three of the four sites. Again the Bronx site had the
most consistency in correlation coefficients from quarter-to-quarter.
22
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REFERENCES
1. Exposure Assessment Branch (W. F. Barnard, ed.) Community Health
Environmental Surveillance Studies (CHESS) Air Pollution Monitoring
Handbook: Manual Methods. EPA-600/1-76-011, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, 1976 131 pp.
2. Chapman, D. 6. Elementary Probability Models and Statistical Inference.
Xerox College Publishing Company, Waltham, Massachusetts, 1970 358 pp.
3. Human Studies Laboratory. Health Consequences of Sulfur Oxides:
A Report from CHESS, 1970-1971. EPA-650/1-004. U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, 1974 368 pp.
4. United States Congress. Clean Air Act Amendments of 1977. Provisions
of Public Law 95-95, Sec 403d, (42 USC 1857 et.seq). Washington,
District of Columbia, August 7, 1977.
5. Whitby, K. T. The Physical Characteristics of Sulfur Aerosols.
Atmos. Environ. 12:135-159, 1978.
6. Hidy, G. M., P. K. Mueller, and E. Y. Tong. Spatial and Temporal
Distributions of Airborne Sulfate in Parts of the United States.
Atmos. Environ. 12':735-752, 1978.
23
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-6QQ/4-79-Q46
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
RELATIONSHIPS BETWEEN TOTAL SUSPENDED PARTICULATE,
SULFATE, AND RESPIRABLE SUSPENDED PARTICULATE CONCEN-
TRATIONS. Analysis of Data Collected in New York City
5. REPORT DATE
September 1979
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Gerard A. DeMarrais
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
(Same as Block '.<_.)
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 7/78-6/79
14. SPONSORING AGENCY CODE
EPA/600/9
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Two years of data for daily total suspended participate, sulfate, and respirable
suspended participate concentrations measured at four stations in the New York City
area are statistically analyzed. To show the variability of each pollutant data
set, the mean, median, and 16th and 84th percentile values of concentration of
each pollutant are summarized. To demonstrate the spatial representativeness of
the concentrations of individual pollutants, the daily (24-hour) concentrations
at pairs of stations were compared and correlation coefficients determined.
Results indicated that sulfate concentrations varied on an area-wide basis while
the concentration of respirable suspended particulates at the four stations
appeared to depend on local conditions.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
* Air pollution
* Particles
* Sulfates
* Relations (Mathematics)
Data
New York City
13B
07B
12A
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
32
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
24
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