OCR error (C:\Conversion\JobRoot\0000062J\tiff\2000MD7M.tif): Unspecified error
-------
Accession Number
Main Title
publisher
Year Published
OCLC Number
Report Number
Holdings
Population exposure to oxidants and nitrogen
^rEnvlronrentafprotection Agency,
1977
EPA-l50/3-77-004a EPA-450/3-77-004b
EPA-450/3-77-004C 68-02-2318
EMAD
EMAD
EMAD
EPA-450/3-77-004a
EPA-450/3-77-004b
EPA-450/3-77-004C
v.1-3
-------
EPA-450/3-77-004c
POPULATION EXPOSURE
TO OXIDANTS AND NITROGEN DIOXIDE
IN LOS ANGELES
VOLUME III: LONG-TERM TRENDS,
1965-1974
by
Yuji Horie and Anton S. Chaplin
Technology Service Corporation
2811 Wilshire Boulevard
Santa Monica, California 90403
Contract No. 68-02-2318
Project No. DU-76-C190
Program Element No. 2AF643
EPA Project Officer: Neil H. Frank
Prepared for
ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
January 1977
-------
This report is issued by the Environmental Protection Agency to report
technical data of interest to a limited number of readers. Copies are
available f.-ee of charge to Federal employees, current contractors and
grantees, and nonprofit organizations - in limited quantities - from the
Library Services Office (MD-35), Research Triangle Park, North Carolina
27711; or, for a fee, from the National Technical Information Service,
5285 Port Royal Road, Springfield, Virginia 22161.
This report was furnished to the Environmental Protection Agency by
Technology Service Corporation, 2811 Wilshire Boulevard, Santa Monica,
California 90403, in fulfillment of Contract No. 68-02-2318, Project No.
DU-76-C190, Program Element No. 2AF643. The contents of this report
are reproduced herein as received from Technology Service Corporation.
The opinions, findings, and conclusions expressed are those of the author
and not necessarily those of the Environmental Protection Agency. Mention
of company or product names is not to be considered as an endorsement
by the Environmental Protection Agency.
Publication No. EPA-450/3-77-004c
u
-------
TABLE OF CONTENTS
Section
LIST OF FIGURES 1^
LIST OF TABLES v1
1. INTRODUCTION ]
2. OVERVIEW OF POPULATION AND AIR QUALITY IN THE
LOS ANGELES BASIN 5
2.1 Population Profile 8
2.2 Air Pollution Profile 12
2.3 Interfacing Population and Air Quality Data -|9
3. TRENDS IN OXIDANT AIR QUALITY AND POPULATION EXPOSURE . . 29
3.1 Spatial Change in 0 Air Quality 30
3.2 Regionwide Trend in Population Exposure to QX .... 34
4. TRENDS IN N02 AIR QUALITY AND POPULATION EXPOSURE .... 45
4.1 Spatial Change in NO? Air Quality 46
4.2 Regionwide Trend in Population Exposure to N02 ... 5<
4.3 Trend in N02 Annual Mean Concentration 62
5. CONCLUDING REMARKS 67
REFERENCES 70
Appendices
A. POPULATION DATA FOR THE LOS ANGELES AQCR A-l
B. AIR QUALITY DATA FOR 0Y AND N09 IN THE LOS ANGELES AQCR . B-l
A, £.
C. MONITORING STATIONS AND RECEPTOR POINTS C-l
D. ISOPLETH MAPS OF RISK FREQUENCY, MEAN DURATION, AND
ANNUAL MEAN CONCENTRATION D-l
E. METHODOLOGY TO CHARACTERIZE POPULATION EXPOSURE E-l
-------
LIST OF FIGURES
TITLE
2.1 TOPOGRAPHICAL FEATURES OF THE LOS ANGELES BASIN .... 6
2.2 LOCATION OF MONITORING STATIONS USED FOR 10 YEAR
TREND ANALYSIS 7
2.3 BOUNDARIES SHOWING TREND ANALYSIS AREAS AND
LOS ANGELES AQCR 9
2.4 REGIONAL STATISTICAL AREAS DEVELOPED BY SOUTHERN
CALIFORNIA ASSOCIATION OF GOVERNMENTS 10
2.5 POPULATION DENSITY IN PERSONS PER SQUARE MILE IN 1970 . 13
2.6 PERCENT CHANGE IN POPULATION 1965 TO 1975 15
2.7 DIAGRAM OF CREATING A DEMOGRAPHIC NETWORK FOR
METROPOLITAN LOS ANGELES AQCR 24
2.8 LOCATIONS OF THE 58 RECEPTOR POINTS ASSIGNED TO THE
STUDY REGION 25
3.1 PERCENT OF DAYS ON WHICH THE NAAQS FOR OXIDANT WAS
EXCEEDED DURING FIVE 2-YEAR PERIODS 31
3.2 AVERAGE DURATION (HOURS) ON DAYS WHEN THE NAAQS FOR
OXIDANT WAS EXCEEDED DURING FIVE 2-YEAR PERIODS .... 33
3.3 CHANGES IN POPULATION EXPOSURE TO 0 DURING FIVE
2-YEAR PERIODS 35
3.4 POPULATION EXPOSED TO 0Y DAILY MAXIMUM HOURLY
CONCENTRATION ABOVE THEXNAAQS MORE OFTEN THAN
STATED FREQUENCY DURING THE FIVE 2-YEAR PERIODS .... 36
3.5 POPULATION-AT-RISK DISTRIBUTION FOR 0 DURING 1965/66,
1969/70, AND 1973/74 FOR TOTAL SCHOOL-AGE, ELDERLY (3),
AND NON-WHITE POPULATION 37
3.6 EXPOSURE OF NON-WHITE AND TOTAL POPULATION TO 0
ABOVE THE NAAQS DURING 1965/66, 1969/70, AND 1973 ... 39
3.7 OXIDANT TRENDS AT THE 50th, 90th, AND 99th
PERCENTILE IN THREE AVERAGE CONCENTRATIONS 40
iTT
-------
LIST OF FIGURES (Cont'd)
TITLE PAGE
3.8 OXIDA.U TREND IN POPULATION EXPOSURE INDEX WITH THE
THRESHOLD EQUAL TO NAAQS, ZxNAAQS, and SxNAAQS 42
4.1 THE AVERAGE VALUE AND THE RANGE OF VALUES FOR ^IGHT
MONITORING STATIONS SHOWING NO? TRENDS IN ANNUAL MEAN
CONCENTRATIONS AND IN 99th PERCENTILE CONCENTRATIONS . . 47
4.2 PERCENT OF DAYS ON WHICH THE CALIFORNIA 1-HR STANDARD
FOR N02 WAS EXCEEDED DURING FIVE 2-YR PERIODS 48
4.3 AVERAGE DURATION (HOURS) ON DAYb WHEN THE CALIFORNIA
1-HR STANDARD WAS EXCEEDED DURING FIVE 2-YEAR PERIODS. . 49
4.4 CHANGES IN POPULATION EXPOSURE TO N09 DURING FIVE
2-YEAR PERIODS * 52
4.5 POPULATION EXPOSED TO NO- DAILY MAXIMUM HOURLY
CONCENTRATION ABOVE THE CALIFORNIA 1-HR STANDARD
MORE OFTEN THAN STATED FREQUENCY DURING THE FIVE
2-YEAR PERIODS 54
4.6 POPULATION-AT-RISK DISTRIBUTION FOR N09 DURING 1965/66
AND 1973/74 FOR TOTAL POPULATION . . / 56
4.7 POPULATION-AT-RISK DISTRIBUTION FOR N09 DURING 1969/70
FOR TOTAL POPULATION * 57
4.8 N09 TRENDS AT THE 50th, 9 M;h, AND 99th PERCENTILE IN
THREE AVERAGE CONCENTRATIONS 58
4.9 N0? TREND IN POPULATION EXPOSURE INDEX WITH THE
THRESHOLD EQUAL TO THE CALIFORNIA 1-HR STANDARD .... 60
4.10 N09 ANNUAL MEAN CONCENTRATION (yg/m3) FOR FIVE 2-YEAR
PERIODS 63
4.11 CHANGES IN THE TOTAL POPULATION EXPOSURE TO N09
DURING FIVE 2-YEAR PERIODS * 65
4.12 N09 TREND IN THRtE SPACE AVERAGES OF ANNUAL ARITHMETIC
MEAN CONCENTRATION 66
IV
-------
TITLE
LIST OF FIGURES (Cont'd)
PAGE
D-l OXIDANT AIR QUALITY IN PERCENT OF DAYS ON WHICH THE
NAAQS WAS EXCEEDED DURING FIVE 2-YEAR PERIODS D-l
D-2 OXIDANT AIR QUALITY IN MEAN DURATION (HRS/DAY) IN
NAAQS VIOLATIONS DURING FIVE 2-YEAR PERIODS D-7
D-3 NO? AIR QUALITY IN PERCENT OF DAYS ON WHICH THE CALIFORNIA
1-HR STANDARD WAS EXCEEDED DURING FIVE 2-YEAR PERIODS . . D-l2
D-4 NO? AIR QUALITY IN MEAN DURATION (HRS/DAY) OF CALIFORNIA
STANDARD VIOLATIONS DURING FIVE 2-YEAR PERIODS D-l7
D-5 NO? ANNUAL ARITHMETIC MEAN CONCENTRATION (yg/m3) DURING
FIVE 2-YEAR PERIODS °-2Z
-------
LIST OF TABLES
TITLE PAGE
2.1 CHARACTERISTICS OF THE TWO STUDY AREAS 14
2.2 TOTAL POPULATION IN THE TWO STUDY AREAS IN 1965,
1970, AND 1975 14
2.3 PERCENT OF DAYS THE NAAQS FOR Oy WAS EXCEEDED AND
THE MEAN DURATION IN HOURS (x,x) IN EACH OF THE FIVE
2-YEAR PERIODS 18
2.4 PERCENT OF DAYS THE CALIFORNIA STANDARD FOR NO? WAS
EXCEEDED AND THE MEAN DURATION IN HOURS (x,x) IN EACH
OF THE FIVE 2-YEAR PERIODS 20
2.5 ANNUAL ARITHMETIC MEAN CONCENTRATIONS FOR N02 IN EACH
OF THE FIVE 2-YEAR PERIODS . . . i 21
3.1 REGIONWIDE TREND IN # DAYS NAAQS FOR Ox WAS EXCEEDED
FOR THE AVERAGE PERSON AND THE MEAN DURATION IN HOURS
PER DAY 44
4.1 REGIONWIDE TREND IN # DAYS THE CALIFORNIA ONE-HOUR
STANDARD FOR N02 WAS EXCEEDED AND THE MEAN DURATION
IN HOURS 61
A-l SCAG ESTIMATE OF TOTAL POPULATION A-2
A-2 1970 CENSUS DATA OF VARIOUS SUBPOPULATIONS A-4
B-l CORRECTED 0Y DAILY MAXIML ', HOURLY AVERAGE CONCENTRA-
TIONS IN 1965 TO 1974 B-2
B-2 CORRECTED Ov HOURLY AVERAGE CONCENTRATIONS IN
1965 to 197$ B-4
B-3 N09 DAILY MAXIMUM HOURLY AVERAGE CONCENTRATIONS
iri965'TO 1974 B-6
B-4 N02 HOURLY AVERAGE CONCENTRATIONS IN 1965 TO 1974 . . . B-8
C-l LOCATIONS AND ADDRESSES OF AIR MONITORING STATIONS . . C-2
C-2 RECEPTOR POINTS ASSIGNED TO THE LOS ANGELES AQCR ... C-3
VI
-------
1. INTRODUCTION
This report represents one of three volumes on the subject of
population exposure to photochemical air pollution in the Los Angeles
Basin. Volume I is an executive summary which highlights the important
results described in detail in Volumes II and III. Volume II, entitled
"Population Exposure to Oxidants and Nitrogen Dioxide in Los Angeles --
Weekday/Weekend and Population Mobility Effects," focuses on these
aspects of the overall study.
The purpose of this volume is to report upon the trends in photochemical
air pollution in the Los Angeles Air Basin from two new aspects, characteriza-
tion of air quality relative to the standards and quantification of population
exposure to air pollution. Most of the past analyses of air quality data are
3
expressed in concentration units such as ppm (parts per million) and yg/m
(micrograms per cubic meter). In this report, emphasis is placed on quantifi-
cation of excessive air pollution (above the air quality standards) during the
10-year period, 1965-1974.
The air quality standards have been set to protect the public health
(primary standards) or the public welfare (secondary standards). Quantifi-
cation of the observed air quality in relation to the primary standard
should indicate explicit adverse impacts with respect to public health.
Therefore, hourly 0 air quality data are examined in relation to the
/\
primary National Ambient Air Quality Standard (NAAQS, 160 yg/m3 or approxi-
mately 8 pphm for one-hour average concentration). Annual average N02 con-
centrations are compared to the primary NAAQS (100 yg/m3). Because there
-------
exists no NAAQS for short-term N02 concentrations, hourly N02 air quality
data are examined in relation to the California Ambient Air Quality Standard
(CAAQS, 470 ug/m3 or approximately 25 pphm for one-hour average concentration).
Short-term NO- and 0 air quality are expressed in percentage of the time
C~ J\
the standard was exceeded and in mean duration of the excess air pollution
in hours per day.
Air quality data collected at ten air monitoring stations measuring
oxidants and eight measuring nitrogen dioxide were examined together with
population statistics prepared by tne Southern California Association of
Government (SCAG). A population of 8.6 million was associated with the
oxidant monitoring data, and the nitrogen dioxide monitoring network was
judged to represent 6.9 million people.
The air quality and population data were interfaced by using a grid
network of 58 receptor points for the oxidant analysis and 45 receptor
points for the nitrogen dioxide analysis. The receptor network provides
complete area coverage, but more detail is given to areas of high popula-
tion density. The oxidant and nitrogen dioxide air quality of each grid
point of the receptor network was 3Stimated from the actual monitoring
data by spatial interpolation. Thus, each receptor point represents a
local population as well as its air quality. The estimates of population
and air quality were then used to characterize the air pollution of the
region.
The estimates of population exposure were determined for the total
population as well as subpopulations consisting of the elderly, school-
age, and non-white.
The ten years of QX and N02 data were examined in terms of five 2-year
periods: 1965 and 1966, 1967 and 1968, 1969 and 1970, 1971 and 1972, and
-------
1973 and 1974. The spatial variations of short-term QX and NOo air quality
during each of the five 2-year periods are presented in isopleth maps of
the percentage of days the standard was exceeded and of the mean duration
of excess air pollution in hours per day. The spatial variations of long-
term N02 air quality are similarly presented in terms of isopleth maps of
annual average concentration.
The population exposure for total population and subpopulations are
examined by the use of population-at-risk distributions for short-term Ox
and N02 and population dosage distributions for long-term N02, as well as
aggregated indices of regionwide exposure for both pollutants. The popu-
lation-at-risk distribution describes the percentages of the population
exposed to a concentration above the standard for a given fraction of time.
The population dosage distribution describes percentages of the population
exposed to various concentration levels of air pollution.
-------
2. OVERVIEW OF POPULATION AND AIR QUALITY IN THE LOS ANGELES BASIN
Among the nation's 247 Air Quality Control Regions (AQCR's), the Los
Angeles AQCR is special in that it is defined by its geographical boundaries
(mountains and ocean), whereas the great majority of AQCR's are defined by
their administrative boundaries (state and county lines). Figure 2.1 depicts
the topographical features of the Los Angeles Basin. The AQCR (the area
surrounded by solid lines) covers six different counties: all of Orange and
Ventura counties, and part of Santa Barbara, Los Angeles, San Bernardino,
and Riverside Counties.
The difference between the AQCR boundaries and the county boundaries
makes it difficult to obtain the demographic data specific to the AQCR. In
the analysis of population exposure to air pollution, the spatial distribution
of population as well as the population size must be known. During our
search for the population data to be used for the population exposure
analysis, we found that the Regional Statistical Areas (RSA's) developed
by the Southern California Association of Governments (SCAG) were a proper
spatial unit for aggregating the population data.
Figure 2.2 depicts the location of air monitoring stations that were
used for the present study. For oxidants (0 ), 10 air monitoring stations
^
whose data quality met the EPA recommended criteria of at least 75% of the
total number of possible observations were used for the 10-year (1965-1974)
trend analysis of air quality and population exposure, while for nitrogen
dioxide (N02), eight air monitoring stations were used. Considering the
-------
Figure 2.1. TOPOGRAPHICAL FEATURES OF THE LOS ANGELES BASIN.
-------
/ SAN BERNARDINO COUNTY
LOS ANGELES I COUNTY
STATIONS FOR Ox ONLY
0 STATIONS FOR Ox AND N02
Miles
SANTA
BARBARA
COUNTY
1. Anaheim
2. Azusa
3. Burbank
4. Lennox
6. Los Angeles
7. Pomona
0. Reseda
9. San Bernardino
RIVERSIDE COUNTY
~
5. Long Beach 10. West Los Angeles
Figure 2.2 LOCATION OF 'KL'ITORING STATIONS USED FOR 10 YEAR TREND ANALYSIS
-------
area coverage at these stations, the study area for the 0 trend analysis
/\
was determined as shown in Figure 2.3. Because fewer stations are used for the
N02 trend analysis, only the Los Angeles County portion is used in the Ox study
area. As seen from Figure 2.3, the two study areas are considerably smaller
than the Los Angeles AQCR. However, the resident population is not much
smaller than that of the AQCR.
2.1 POPULATION PROFILE
The Southern California Association of Governments (SCAG) provides survey
statistics of total populations for 1960, 1970, and 1975, and the projected
population to 1980 (Table Al). All of the statistics are aggregated into
each of 55 Regional Statistical Areas (RSA's) which cover the six counties
of Ventura, Los Angeles, Orange, San Bernardino, Riverside, and Imperial
(Figure 2.4). Of the 55 Regional Statistical Areas, 25 RSA's were used for the
Ox trend analysis, and 17 RSA's for the N02 trend analysis (Figure 2.3).
Assuming that an air monitoring station represents an area circumscribed
by half of the distance to a neighboring station, inclusion (or exclusion)
of peripheral RSA's in (or from) the study region was determined by consider-
ing the distance between the outer-most station and the center of each of
those RSA's. As a result, the study region for 0 covers the southern
A
portion of Los Angeles county and western portions of Orange and San Bernardino
counties. The study region for N02 covers only the southern portion of Los
Angeles county.
-------
San Bernardino
County
Santa
Barbara
County
Ov Trend Analysis Area
A
' County 'Boundary
AQCR_Boundary
///// N0 irend Analysis Area
Figure 2.3 BOUNDARIES SHOWING TREND ANALYSIS AREAS
AND LCS ANGELES AQCR.
-------
'9 .88 ^ 37
REGIONAL STATISTICAL AREAS
Soi/l/itrn C0/ifor/>'o JSSKK//O/I of Carernmen/s
Figure 2.4. REGIONAL STAT.LSIKAL.AREAS DEVELOPED BY SOUTHERN CALIFORNIA
ASSOCIATION OF GOVERNMENTS
-------
n
Because we also need to know the number of people in each sub-population for
each 2-year period, the aggregated statistics of School-age (5-17 years old),
Elderly (>65 years old), Non-white, and Worker population for each RSA were
computed from the 1970 census tract data by using the conversion table pre-
pared by SCAG, which provided the number of census tracts belonging to each
RSA (Table A2).
It is found that there is a slight discrepancy between SCAG's estimates
2
of total population and those computed from the 1970 census tract data.
Because of the greater reliability in SCAG's estimates for this particular
region than our estimates computed from the census data, we decided to
use the SCAG's figures of total population. The size of total population
in each RSA for each 2-year period was estimated by interpolating those
of SCAG's estimates in 1960, 1970, and 1975 into the middle of the 2-year
period. For example, the total population in the 1967/68 period was
estimated by interpolating those in 1960 and 1970 into 1967.5. The size
of each sub-population in each RSA was then computed by multiplying the
total population of that 2-year period with the percentage of that sub-
population to the total population in that RSA in 1970.
The characteristics of the two study areas are given in Table 2.1. The
sizes of total population in the Los Angeles AQCR, the Ov trend analysis
A
area, and the N02 trend analysis area are 9.8, 8.5, and 6.9 million people,
respectively. School-age population constitutes about 24% of the total popu-
lation and Elderly population about 9% of the total population in the two
-------
12
study areas. Non-white population constitutes about 13% of the total
population in the 0Y trend analysis area and 15% of the total population in
/>
the N02 trend analysis area.
The spatial distribution of total population density is shown in Figure
2.5. A high population density area centers at the Los Angeles CBD and ex-
tends to the southern half of the Los Angeles County and portions of Orange
and San Bernardino Counties. The lowest population density if found in
the mountainous areas (Figs. 2.1 and 2.5).
Table 2.2 presents the summary of Total Population in the two study
areas during the 10-year (1965-1975) period. It can be seen that the popu-
lation growth in Total Population was slower during the 1970-75 period than
during the 1965-70 period. In particular, the N02 trend study area, i.e.,
Los Angeles County experienced a negative growth in both Total Population
and All Workers during the 1970-75 period. The spatial variations of
change in population during the 10-year period are shown in Figure 2.6.
It can be seen that the growth In total population is more pronounced in
the fringe areas than the urban core areas consisting of Los Angeles and
Long Beach cities.
2.2 AIR POLLUTION PROFILE
A percentile concentration distribution is used in this study to
characterize annual short-term (one hour) exposures of the population to
0Y and N0? air pollution. The short-term exposure of the population is
J\ L~
characterized by two parameters: (1) the frequency with which ambient
-------
miles
LOS ANGELES AIR BASIN
I I °-10
m;::m 10 -100
100-1,000
1,000 - 10,000
> 10,000
Figure 2.5. POPULATION DENSITY IN PERSONS PER SQUARE MILE IN 1970.
-------
14
Table 2.1 Characteristics of the Two Study Areas'
Study
Area
0Y Trend
A
Analysis
N02 Trend
Analysis
Land Area
(Sq. Miles)
2,316
1,509
Total
Population
8,548,431
6,858,390
School -Age
(5-15 years)
2,110,291
1,626,711
Elderly
(>65 years)
761,027
642,152
Non- White
I r
1,084,202
1,018,418
a: 1969-1970 population estimates
Table 2.2 Total Population in the Two Study Areas in
1965, 1970, and 1975.
Study Area
Ox Trend Analysis
N02 Trend Analysis
Total Population
1965
7,798,629
6,431,723
1970
8,631,745
6,905,798
1975
8,742,324
6,869,628
-------
en
LOS ANGELES AIR BASIN
Figure 2.6. PERCENT CHANGE IN POPULATION 1965 TO 1975.
-------
16
concentrations exceed the air quality standard or a multiple of the
standard, and (2) the mean duration of the excess air pollution above
the threshold in hours per day. Annual average concentrations are used
to characterize the long term exposure to NC^.
For the trend analyses of air quality and population exposure, the
"Ten-Year Summary of California Air Quality Data 1963-1972" and its sup-
3 4
plement for the 1973-1974 periods were used. * In an attempt to minimize
meteorological effects on the trends in air quality and population exposure,
a long period, 1965 to 1974, was chosen. However, this extended study period
left us very few air monitoring stations that had reported statistically
valid air quality data (75% or more of the possible observations) continu-
ously over that period. In order to pressure historical continuity at a
minimum number of monitoring stations, the data were examined in five 2.year
periods: 1965/66, 1967/68, 1969/70, 1971/72, and 1973/7*.
For a station that reported statistically valid air quality data for
both of the two years, the two-year average air quality is given by an
arithmetic average of the two annual statistics (percentile concen-
tration for analysis of short-term exposures to Ox and N02, and annual
arithmetic mean concentrations for analysis of long-term exposure to N02).
For a station that reported statistically valid air quality data for only
one of the two years, the two-year average air quality is given by the annual
concentration of the valid year. In this manner, 10 stations were saved for
the ten-year trend analysis for QX and eight stations for N02.
-------
17
The percent!le concentration statistics for each of the trend stations
are all presented in Appendix B (Tables Bl through B4). Tables Bl and B2
summarize Ox hourly concentrations and Ox daily maximum hourly concentrations
as percentile concentration distributions. The percentile concentrations of
stations outside the Los Angeles county, i.e., Anaheim and San Bernardino,
were corrected by multiplying their values with the correction factor of
0.80^ This factor has been recommended by the California Air Resources
Board in order to account for differences in California QX measurement
techniques outside of LA county. The percentile concentration statistics
of Tables Bl and B2 are further compacted in Table 2.3 which presents
characteristics of the air quality observed at each air monitoring station
in terms of the percent of days on which the NAAQs for QX was violated, and
of the mean duration in hours of such violations. It can be seen from the
table that all the trend stations show air quality improvement for oxidant
over the 10-year period. The coastal stations (Anaheim, Lennox, Long Baach,
West. L.A.) show a greater reduction in the percent of days exceeded than
the inland stations (Azusa, Burbank, Pomona, Reseda, San Bernardino).
-------
Table 2.3 Percent of Days the NAAQS for 0 was Exceeded and the Mean
/\
Duration in Hours (x.x) in Each of the Five 2-Year Periods
NU,
1
2
3
5
6
7
8
1 f)
SI AT IONJ
ANAHFJM
A4UI5A
BUKBAMKwPALM
LUNG BEACH
L , A , DOWNTOWN
PUMUNA
REStOA
wtsT L.A.-.WSTWOQ
1965/66
69.8
61 .0
22 I 3
62.1
6«,7
ID 53J3
(7^6)
(6. a)
(3.5)
(3.6)
(5.R)
(6,6)
(7.5)
( 5 '. 1 )
1967/68
35.4
63,7
I7!o
55,1
60,0
/ 1 1 hi
« I « O
(3,8)
(7,0)
C6.5)
( 3 , tt )
(2,7)
(6J9)
(7,2)
(5f,aj
1969/70
2S,0
68,7
60,0
25,0
5o!o
61,0
59,7
fl
-------
19
Table B3 and B4 summarize NCL hourly concentrations and N02 daily
maximum hourly concentrations in a percentile concentration distribution
for each of the two-year periods. These percentile concentration statistics
are further compacted in Table 2.4 which presents characteristics of the
air quality observed at each trend station in terms of the percent of days
on which the California standard for N02 hourly concentrations was violated,
and of the mean duration in hours of such violations. There is no obvious
trend in both percent of days exceeded and mean duration at any station
except Azusa which shows a steady increase in the percent of days exceeded.
The stations in the urban core areas (Burbank, Long Beach, L.A. Downtown,
West L.A.) appear to have a greater percent of days exceeded ,than those in
the fringe areas (Azusa, Pomona, and Reseda).
The annual arithmetic mean concentrations of N02 at each of the eight
trend stations are presented in Table 2.5. Again, there is no obvious trend
in annual mean concentration at any station except Azusa which shows a
steady increase in the annual arithmetic mean concentration. The West I.A.
station also shows somewhat of an increasing trend. For the rest of the
stations, the first and last two-year periods had a lower value in the
annual mean concentration than the three two-year periods in between. It
should be noted that except for the Azusa station in 1965/66 and 1967/68, all
o
the stations violated the NAAQS for N02 (100 yg/m or approximately 5
pphm) over the entire 10-year period.
2.3 INTERFACING POPULATION AND AIR QUALITY DATA
The task of interfacing the population data and the air quality data
starts with a search for a proper regional map on which the monitoring
-------
Table 2.4 Percent of Days the California Standard for N02 was Exceeded and the Mean
Duration in Hours (x.x) in Each of the Five 2-Year Periods
NO, STATION 196b/f»6 1967/68 1969/70 1971/72 1973/7
1
2
3
4
^
(j
7
6
AZUSA
HUHtJANK-"PALM
U.NNDX
LUNG UEACH
L f A » DDrtNTUWN
PUMQNA
Rfc Stn ft
WEST L.A.-WSTWOOO
.8
7, '4
5,0
5.0
U.6
1,3
2. S
y'.s
(2.0)
(3,6)
(2.3)
(2,9)
(2.S)
(1.1)
(2.1)
(2.7)
2.3
20,8
1^,4
1 1 ,4
10,9
4 , 7
b , 4
1 0,0
(1,7)
(4.5)
( U , 3)
(3, a)
( 2 , 8)
(3,0)
( ? , A )
(2,4)
2,3
H.9
5 , b
10,7
7 , 6
a, 6
3,0
7,1
(3,2)
t3,9)
(2,3)
(3.2)
(3,0)
(3, a)
(2,9)
(2,3)
3,9
11,8
-------
Table 2.5 Annual Arithmetic Mean Concentrations for N09 in Each of the
Five 2-Year Periods. ;
« , I ^
6,65
5,70
9, '40
6,75
7,70
7,00
8,05
6, *55
6,65
6 , 8 S
7,' 75
7,00
6,00
6 . ?5
1 ' f * ^
6,75
7,05
7, Ob
6,05
7,05
-------
22
stations and the receptor points can be located.6 A receptor point is
used to aggregate the local populations in the areas in which they reside.
For the Los Angeles AQCR, a regional map showing the boundaries of the
Regional Statistical Areas (RSA's) was available (Fig. 2.4). A number
of receptor points were assigned to each RSA according to the size of
the population and the land area. The criteria used for determining the
number of receptor points assigned to each RSA is as follows:
1. Regardless of the size of the population and/or the land area,
each RSA is represented by at least one receptor point.
2. An additional receptor point is assigned for each increment of
area by 200 square miles or each increment of resident population by 200,000.
For example, an RSA having a resident population of 500,000 and a land area
of 70 square miles is represented by 3 receptor points (1 for RSA and 2 for
population of 400,000), while another RSA having a population of 150,000 and
an area of 300 square miles is represented by 2 receptor points (1 for RSA
and 1 for land area of 200 square miles).
The number of people at eac receptor point is computed in the following
manner: the total population in each RSA is computed by making a linear
interpolation between the SCAG estimates for two time points. For the study
year 1971/72, the interpolation is made of 1970 and 1975 data into 1971.5.
Then, the number arrived at by interpolation is divided by the number of
receptor points in that RSA and the result is assigned to each receptor
point. For subpopulations such as school-age, elderly, and non-white popu-
lation, the number of people of a given subpopulation at each receptor point
-------
23
are given by the product of (total population) x (percent of subpopulation)
where the percentage is computed from the 1970 census data for the RSA to
which the receptor point belongs.
A diagram of how to create a demographic network is shown in Figure 2.7.
The regional map of RSA's prepared by SCAG is stored numerically on a tape through
the use of a digitizer. Using the UTM coordinates given in SAROAD format or the
site addresses (Appendix C, Table Cl) the air monitoring stations are located
on the digitized map through a coordinate transformation (Fig.2.2). In
order to determine a scale factor for the coordinate transformation, the
locations of the Los Angeles Downtown station and the Azusa station are
determined from their site addresses. The receptor points are located
at their proper places within the corresponding RSA. The receptor loca-
tions are shown in Fig. 2.8 and their X-Y coordinates are found in Appendix
C, Table C2.
To know the exposure of a person to air pollution, the spatial location
of the person and the air quality of his location must be known as a function
of time. In the present study, however, we are not interested in the actual
exposures of individual persons to air pollution, but rather in the ensemble
of potential exposures of a large population, say 10,000 people. For this
purpose, an appropriate estimate of air quality at each receptor point
should be sufficient to make an estimate of population exposure at that
particular locale, if the assumption is made that the population size and
sub-population composition will be quasi-stationary over each of the five
study periods. This assumption should be best for the analysis of exposure
-------
24
SEARCH FOR POPULATION DATA AND REGIONAL MAP
r,
POPULATION DATA
AGGREGATED INTO
RSA's
JL
ADDITIONAL DEMOGRAPHIC
DATA AGGREGATED INTO
RSA's THROUGH PRO-
CESSING THE CENSUS
DATA
1.
CREATE THE POPULATION !
DATA SET FOR RSA's
ASSIGN THE NUMBER OF
RECEPTORS TO EACH RSA
ACCORDING TO SOME RE-
CEPTOR PLACEMENT CRI-
TERIA
CREATE THE POPULATION
DATA SET FOR RECEPTORS
"T '
JL
MAP OF REGIONAL
STATISTICAL
AREAS (RSA)
I
DIGITIZE THE
BOUNDARIES
OF RSA's
PLACE THE MONI-
TORING STATIONS
ON THE MAP
PLACE THE RECEPTOR
POINTS ON THE MAP
DETERMINE THE GEO-
GRAPHICAL BOUNDARY
OF THE STUDY AREA
PREPARE 1HE COMPUTER-READY DATA
SETS OF POPULATION, AIR QUALITY,
MONITOR LOCATION AND RECEPTOR
LOCATION
Figure 2.7 Diagram of Creating a Demographic Network
for Metropolitan Los Angeles AQCR.
-------
r>o
in
Figure 2.8 Locations of the 58 Receptor Points Assigned to the Study Region.
-------
26
of elderly and school-age populations because these populations tend to
be locationally fixed, i.e., stay close to their resident locations most
of the time. While the stationary assumption is not strictly valid for
populations such as workers who spend a substantial part of their time at
places where the air environment may be quite different from that of their
residential locations, a special analysis for 1973 air quality and popula-
tion data8 has found that these effects can be largely ignored.
As mentioned earlier, the spatially distributed population is aggregated
at each receptor point. The air quality at a receptor point was estimated
by interpolating the observed air quality at the three nearest neighboring
monitoring stations to that point as
Ci ~ c-i for d. = 0
j « . .
(2.1)
where C. is the concentration estimated at j-th receptor point (x^.y^),
J
C.(i-l,2,3) are the concentrations observed at the three nearest neighboring
stations, i-th (1=1,2,3) air monitoring stations (x^,yi) around the j-th
receptor point, and di is the distance between the i-th monitoring station
and the j-th receptor point, i.e.,
/ 7 5- (2-2)
d. « /(x - x r + (v - v )
*! .r \f*» A j ' VJF v / .
i 1 J 1J
-------
27
Using the above interpolation formula repeatedly, the bi-annual
statistics of percentile concentrations for analysis of short-term exposures
to 0 and N0? and of arithmetic mean concentrations for analysis of long-
X £
term exposure to N02 were computed for every receptor point from the bi-
annual statistics of air quality data observed at the air monitoring
stations. By comparing the percentile concentrations with the NAAQS, a risk
frequency that indicates a percentage of the time the NAAQS was exceeded was
determined at each receptor point. An isopleth map of the risk frequency
is used in this report to describe a spatial change in short-term population
exposures to 0 and N09 over the study region during the 10 year period.
A £
A spatial change in long-term population exposure to N02 is expressed by an
isopleth map of the annual mean concentration.
By stratifying the population according to the magnitude of risk
frequency, the short-term exposures of the population to Ox and N02 are
summarized in a population-at-risk distribution that describes percentages
of the population exposed to a concentration above the NAAQS for a giver,
fraction of time. The long-term exposure of the population to N02 is
summarized in a population dosage distribution that describes percentages
of the population exposed to various levels of an annual mean concentration.
Finally, the regional index of short-term exposures to QX and N02 is
given by the population weighted average of a risk frequency while that of
long-term exposure to N02 by the population weighted average of an annual
mean concentration. In actual computations, however, these regional indices
were computed by numerically integrating the corresponding distribution
functions. A mathematical definition and/or derivation of each quantity used
in this report is presented in Appendix E.
-------
29
3. TRENDS IN OXIDANT AIR QUALITY AND POPULATION EXPOSURE
Trends in 0 air pollution in the Los Angeles AQCR are analyzed
/\
in this section with respect to the spatial patterns, the population
exposure distributions, and the aggregated indices of air quality and
population exposure. The air quality data used for the analysis were
obtained from the summary statistics of the following ten monitoring
stations: Anaheim, Azusa, Burbank, Lennox, Long Beach, L.A. downtown,
o n
Pomona, Reseda, San Bernardino, and West L.A. (Fig. 2.2). '
As shown in Figure 2.3, the trend study area consists of the
heavily populated portion of three counties: Los Angeles, Orange,
and San Bernardino. Although the land area of the QX trend study regions
1s only a quarter of the Los Angeles AQCR, the population of the trend
study areas is more than 70% of the AQCR population (Table 2.1).
The population size of every Regional Statistical Area (RSA) was
computed for each two-year period by interpolating the SCAG estimates
of RSA population in 1960, 1970, and 1975 into the midpoint of the two-
year period (e.g., 1965/66 as 1965.5). Sizes of subpopulations (elderly,
school-age, and non-white) at every receptor point were computed by
taking the product of the local total population at that receptor point
and the percentage of the subpopulation to the total population in 1970
(Table A2). During the 10-year period, some RSA's in Los Angeles county
lost a part of their population while RSA's in Orange County gained a
substantial number of people.
-------
30
3.1 SPATIAL CHANGE IN QX AIR QUALITY
The spatial variation of oxidant air quality and its change with
time were examined by computing isopleths of risk frequency. Figure 3.1
shows the spatial variation of daily risk frequency (i.e., percent of
days the NAAQS was exceeded) and the changes in the spatial variation
pattern over the ten-year period (see also Fig. Dl in Appendix D). It
can be seen that improvement in oxidant air quality took place everywhere
in the study area. A careful observation of the figure shows that there
were two stages in the air quality improvement.
The earlier stage of the improvement appears to have taken place
during the period from 1965 to 1970 and is characterized by the emergence
of the area where the NAAQS was exceeded less than 20% of the days. This
lower pollution area appeared in the 1967/68 period around Long Beach and en-
larged considerably in the 1969/70 period. The later stage of the
improvement appears to have taken place during the period from 1971 to
1974 and is characterized by th: shrinkage of the area where the NAAQS
was exceeded more than 50% of the days. This most polluted area remained
around Azusa. In this later stage, the area where the NAAQS was violated
less frequently than every five days covered the southern half of the
study area.
A possible explanation of these observations is as follows: The
emission control strategy implemented during the period from 1965 to
1970 reduced hydrocarbon emissions significantly in the study area but
Q
at the same time increased NO emissions significantly. As a
A
-------
1965/1966
1967/1968
1969/1970
1971/1972
CO
1973/1974
Figure 3 1 PERCENT OF DAYS ON WHICH THE NAAQS
FOR OXIDANT WAS EXCEEDED DURING
FIVE 2-YEAR PERIODS.
[ | < 20%
20 - 50%
> 50%
-------
32
result of these emission changes, the HC/NOX ratio should have acted to
delay 0 formation and pushed the GX maxima further inland. Therefore,
the significant improvement in QX air quality was observed in the coastal
region but not so in the inland region downwind of the urban area of the
cities of Los Angeles and Long Beach. During the pericd from 1971 to 1974,
the increase in the N0₯ emissions was slowed because new car emission
A
standards for NO took effect in 1971. The decline in hydrocarbon emissions
/\
continued during this later period. The compounded effects of the slowed
growth in NO emissions and the continued reduction in HC emissions were
A
probably responsible for the moderate and uniform improvement in QX air
quality throughout the study region.
The air quality improvement also accompanied a reduction in daily
exposure of the population on days when the standard was violated. Mean
duration of violations per day was computed by taking a ratio of the
daily risk frequency to the hourly risk frequency. The isopleths of
mean duration in hours per day are shown In Fig. 3.2 for each of the
five two-year periods. A more derailed isopleth map is presented in
Figure D2 in Appendix D. The first half of the ten-year period, i.e.,
1965/66 to 1969/70 showed a reduction in average duration around Long
Beach. However, the second half of the ten-year period, i.e., 1969/70
to 1973/74 did not show any substantial change in mean duration. The
mean durations in the inland areas are persistently longer than five
hours per day during the entire ten-year period.
-------
1965/1966
1971/1972
1967/1968
1973/1974
Figure 3.2. AVERAGE DURATION (HOURS) ON DAYS
WHEN THE NAAQS FOR OXIDANT WAS
EXCEEDED DURING FIVE 2-YEAR PERIODS.
GO
< 3 HRS
3- 5 HRS
> 5 HRS
-------
34
3.2 REGIONWIDE TREND IN POPULATION EXPOSURE TO QX
The implications of the air quality improvements on population exposure
to 0 in the Los Angeles Basin are summarized in Fig. 3.3 by the percentages
A
of the population exposed to Ov above the NAAQS at various percents of
A
time. The reduction in population exposure to oxidani air pollution is
greatest at a high exposure level. For example, the percentage of the
population exposed more than 50% of the time dropped from 53 percent in
1965/66 to a mere 5 percent in 1973/74. The resident locations of these
people are found in Fig. 3.1. The percentage of the population who were
exposed less than 20% of the time was zero percent in 1965/66 but increased
to 35 percent in 1973/74. Figure 3.3 also shows a similar reduction in
population exposure to higher oxidants concentrations (above the level of
twice and three times the standard).
The improvement in oxidant air quality during the ten-year period is
shown in Figure 3.4 in the form of a population-at-risk distribution. The
numerals 1, 2, 3, 4, and 5 indicate, respectively, the 1965/66, 67/68,
69/70, 71/72, and 73/74 periods. The reduction in population exposure
to 0 is demonstrated in the figure by the shift of curves toward the
A
lower left corner. The population-at-risk distribution for subpopulations:
school-age (2), elderly (3), and non-white (4) are shown in Fig. 3.5.
These figures show that the exposure patterns of school-age and elderly
populations are similar to that of total population which is designated
by numeral 1. However, the exposure pattern of non-white population is
somewhat different from those of other populations.
-------
ID CO O CVJ «d"
io UD r^. r^ r^
in r cr> i co
vo
vo
ur>
oo
vo
o
r~.
cr>
ID
c\j *
r~.r~-
i co
t P-«
ID OO
tO VD
to r~-
<*D VD
en
TOO
80
g 60
o
Q.
<
H-
O
U_
o 40
UJ
O
20
m
P IN PERCENT
Example: In 1965/1966 about 53% of the
total population was exposed to 03
levels above the NAAQS (8 pphm for one
hour) more than 50% of the days per year.
In the same period about 44% of the total
population was exposed to 03 levels at
twice the NAAQS for at least 20% of the
days per year, but less than 50% of the
days per year.
co
en
1 x standard
2 x standard
3 x standard
Figure 3.3. CHANGES IN POPULATION EXPOSURE TO 0 DURING FIVE 2-YEAR PERIODS.
a x
-------
36
o
c
o>
3
or
(U
Oi
c
-------
Fraction of population exposed more often than stated frequency
.01
.1
.01
(Q
C
n>
co
en
m > -o
i «r> o
o en -o
m *o c:
?o \ i
co
j> _i i
Z iD 73
3
n>
co co
o
I
m
TJ
o
13
S o
rI *
o>
cr
o
n>
0
73
3> co o 4>
-H o x ^
ooo00
z o cz
t~ 73
m
CT>
en
en
en
I I
.1 1
_L-.L_Li_i_i_l_. -I I I -Ii--l-i-j-i
-f-
UD
en
VO
--J
o
fcfc
t 9
r ~" r "r "i "r r'rn ~ ~Tv
I i I I i I n[ I [
-------
38
In order to examine the difference in population exposure between
non-white population and other populations, the histograms of population
exposure to 0 above the NAAQS ware obtained from Figure 3.5 for non-white
r*
population and total population. It can be seen from Figure 3.6 that
the percentage of non-white population exposed at the highest and the
lowest risk frequency is lower than those of other populations while
its percentage exposed at a risk frequency in the middle range is higher
than those of other populations. This is due to the higher density of non-
white populations in the central portions of the Los Angeles region where
0 concentrations are intermediate. This difference in exposure pattern
X
between non-white population and other populations increased from
1965/66 to 1973/74. This discovery of a subtle difference in exposure of
different populations could not be made by the method used by other
researchers who computed only a long-term pollution dosage or an
average concentration for a variety of social classes such as those
by income level and those by race.10»H .12
The regionwide trend of oxide t air quality is shown in Fig. 3.7
by using three different indices: population weighted average con-
centration, area weighted average concentration, and station average
concentration. At the higher percentile concentrations (99th and 90th
percentile), there is a strong downward trend in all three indices.
This is contrasted to a flat trend at the 50th percentile concentrations.
Figure 3.7 also shows that the population weighted average concentration
is persistently lower than the area weighted average concentration.
This indicates that oxidant concentration levels are not positively correlated
with population density. Because emissions of precursor pollutants such
-------
i I i
39
o
c
0)
3
O"
-------
-t
J
m
CO _
-J
in
CM
CM
0.
CL
c
o
to
o
c
o
o
«u
O)
<0
-------
41
as hydrocarbons and oxide of nitrogen are positively correlated with
population density in most urbanized areas, the above finding serves
as evidence that oxidants within an air shed may be poorly correlated
with local emission levels.
It should also be noted in Fig. 3.7 that the station average con-
centration is located between the population weighted average concen-
tration and the area weighted average concentration. This is evidence
that the ten monitoring stations used for the trend analysis are properly
arranged in space to report, without a particular bias, the air environ-
ment of people at various locations within the study area.
The regionwide trend in population exposure to Ox is shown in
Fig. 3.8 by the average hourly risk frequency. The average hourly risk
frequency was computed for three different thresholds:
CS = 1 x NMQS, CS = 2 x NAAQS, and CS = 3 x NAAQS. Figure 3.8 shows
that the percentage of hours at which an average person was exposed to
0 above the NAAQS dropped from about 12% in 1965/66 to about 6% in
A
1971/72 and 73/74, while that exposed to QX three times the NAAQS dropped
from about 0.7% in 1965/66 and 67/68 to about 0.15% in 1973/74. Therefore,
it can be said that-the rate of improvement in population exposure is
greater for the higher concentration threshold than for the lower con-
centration threshold (factor of 7 vs. factor of 2), while the absolute
improvement is greater for the lower threshold than for the higher
threshold (6% vs. 0.45%).
-------
42
100
00
-------
43
The reglonwlde trend 1n population exposure to Ox is summarized in
Table 3.1 by the number of days the NAAQS was exceeded and by the mean
duration of standard violations in hours per day. The number of days
on which an average person in the study area was exposed to DX above
the NAAQS decreased from 176 days per year in 1965/66 to 144 days per
year in 1969/70, and to 105 days per year in 1973/74. The mean duration
of such exposure of the average person also decreased from 5.1 hours
per day in 1965/66 to 4.6 hours per day in 1969/70, and to 4.3 hours
per day in 1973/74. The regdonwide trend in population exposure to Ox
above twice the standard is also found in Table 3.1. The average number
of days on which the threshold of twice the standard was exceeded de-
creased markedly from 70 days per year in 1965/66 to 45 in 1969/70, and
to 26 in 1973/74. However, the average mean duration decreased only a
little from 3.1 hours per day in 1965/66 to 2.9 hours per day in 1973/74.
-------
44
Table 3.1 Regionwide Trend in # Days NAAQS for Ov was Exceeded
J\
for the Average Person and the Mean Duration in Hours
per day
Threshold
1 X STD
160 yg/m
(8 pphm)
Index
# Days Exceeded
Per Year
Mean Duration
in Hours
1965/66
176
5.1
1967/68
162
4.8
1969/70
144
4.6
1971/72
109
3.8
1973/74
105
4.3
2 X STD # Days Exceeded 70 59 45 26 26
3 Per Year
320 yg/nT
(16 pphm) Mean Duration 3.1 3.1 .2.8 2.1 2.9
. in Hours
-------
45
4. TRENDS IN N02 AIR QUALITY AND POPULATION EXPOSURE
The National Ambient Air Quality Standard (NAAQS) for N02 is given
only for an annual arithmetic mean concentration. There is no NAAQS for
a short-term (hourly or daily) average concentration of N02- However,
recent epidemiological studies indicate that there are some adverse
effects on the public health of short-term exposure to high ambient N02
concentrations. The adverse effects suspected are increased
susceptibility and severity of acute respiratory disease such as in-
creased coughing and Klebsiella pneumonia.
Therefore, the trends of N02 air pollution are analyzed for both
annual arithmetic mean concentrations and hourly average concentrations.
The analysis of population exposure to annual mean concentrations is
made with respect to "dose rate" defined by Eq. E-3 (Appendix E). As seen
from the defining equation, the dose rate of a person is given by the annual
arithmetic mean concentration at his residence location (static population
assumption). To make an analysis of population exposure to hourly N02 con-
centrations, a threshold(s) has to be determined. The California standard
for a N02 hourly average concentration, C$ = 470 yg/m3 or approximately
25 pphm was chosen for the threshold.
The trend study area for N02 is smaller than that for 0 and is
confined to the heavily populated southern half of Los Angeles County.
Over this study area, there are only eight monitoring stations that provide
air quality data usable for the analysis of trends in N02 air quality and
in population exposure to N02-
-------
46
Figure 4.1 depicts the mean and the range of concentrations measured
at the eight stations during the ten-year period. A comparison between
the NAAQS for N02 and the range of annual mean concentrations indicates
that almost all the stations violated the national standard, particularly,
since 1969. In both the annual mean concentrations ani the 99th percentile
concentrations, the middle years 1967/78 to 1971/72 were more polluted than
the two end years 1965/66 and 1973/74.
4.1 SPATIAL CHANGE IN SHORT-TERM N02 AIR QUALITY
The spatial variation of NO,, air quality and the change of the spatial
pattern with time are depicted in Figure 4.2 (also in Figure D3) by the
percentage of days on which the California standard was exceeded and
Figure 4.3 (also in Figure D4) by the mean duration of concentrations
above the standard in hours per day. The area exceeding the California
standard more frequently than 6% of the days was approximately matched
with the area of Downtown Los Angeles in 1965/66, extended to almost
the entire study are in 1967/68, o9/70, and 71/72, and was confined
to the San Fernando Valley in 73/74 (Figure 4.2).. The area with a
mean duration longer than three hours per day was confined to the
north-central part of the San Fernando Valley in 1965/66, extended to
the majority of the study region in 1967/68, 69/70, and 71/72, and then
-------
30 -
CALIFORNIA 1-HR
STANDARD ,
25pphm = 470yg/nr
20 -
n:
D-
OJ
O
10 -
EPA STANDARD
ANNUAL AVERAGE
100ug/m3 = 5.3pphm
47
-1- o
I 1 J
-600
-500
-400
-300
.200
150
100
50
65/66 67/68 69/70 71/72 73/74
CT)
CVJ
o
Figure 4.1. THE AVERAGE VALUE AND THE RANGE OF VALUES FOR EIGHT MONITORING
STATIONS SHOWING N02 TRENDS IN ANNUAL MEAN CONCENTRATIONS (LOWER
SEGMENT) AND IN 99th PERCENTILE CONCENTRATIONS'(UPPER SEGMENT).
-------
1965/1956
1967/1968
1969/1970
1971/1972
1973/1974
Figure 4 2 PERCENT OF DAYS ON WHICH THE
CALIFORNIA 1-HR ofANDARD FOR NO-
WAS EXCEEDED DURING FIVE 2-YEAR
PERIODS.
< 6%
6 - 12%
> 12%
-------
1965/1966
1971/1972
1967/1968
1973/1974
Figure 4.3. AVERAGE DURATION (HOURS) ON DAYS
WHEN THE CALIFORNIA 1-HR
STANDARD WAS EXCEEDED DURING
FIVE 2-YEAR PERIODS.
[ | < 2 HRS
2 - 3 HRS
> 3 HRS
1969/1970
-------
50
shrank to the Los Angeles downtown area in 1973/74. A more detailed
isopleth map of percentage of days exceeded during each of the five
2-year periods is presented in Figure D3, Appendix D while in Figure D4,
an isopleth map of mean duration is shown.
Figure 4.2 and Figure D3 show that N02 air quality deteriorated
significantly during the middle year period 1967/68-1971/72 throughout
the study area, i.e., Southern half of Los Angeles County. N02 air
quality during the first and last two year periods, i.e., 1965/66 and
1973/74 was considerably better than that during the middle year period.
A comparison between N02 air quality in 1965/66 and that in 1973/74 shows
that the latter is distributed more uniformly over the study area than
the former. On the other hand, Figure 4.3 and Figure D4, which show mean
duration of the excess NOp concentration above the California standard
per day, do not show such a marked difference in mean duration between
1965/66 and 1973/74. In terms of mean duration, N02 air quality in
1973/74 has a measurable spatial gradient.
Although it is not the purpose of this study to find causes of the
air quality changes, the increases in N02 air pollution during the middle
year period 1967/68-1971/72 were probably due to the air pollution con-
trol strategy rather than the meteorology during that period. According
to an EQL report,"-9^ although hydrocarbon emissions decreased by 24% in
Los Angeles county during the period 1965-1974, emissions of oxides of
nitrogen increased by 25% during the same period. Table 2.2 shows that
-------
51
the population in the N02 study area increased from 6.43 million in
1965 to 6.91 million in 1970 and then declined to 6.87 million in
1975. Considering the population trend above and the fact that the NOX
emission standard for new cars became effective in 1971, we can expect
that most of the 25% increase in NOX emissions occurred during the
period 1965 to 1970 or to 1971. This increased NOX emission is the most
likely cause of the increases in N02 air pollution during the middle
year period 1967/68-1971/72.
As to the sudden improvement of N02 air quality in 1973/74, there is
no satisfactory explanation. However, a part of the cause may be found
in the facts that NOV emission standard for new cars became effective after
A
1971 and that the population in Los Angeles County declined sliahtly
from 6.91 million people in 1970 to 6.87 million people in 1975. Meteorology
may also be an important factor during this period.
4.2 REGIONWIDE TREND IN POPULATION EXPOSURE TO SHORT TERM NOg
The implications of the air quality changes with time and space on
population exposure to N02 are summarized in Fig. 4.4 by the percentages
of the population exposed to N02 above the California standard at various
percents of time. The N02 air quality deterioration during the middle
years 1967/68 to 1971/72 shown in Figs. 4.2 and 4.3 resulted in an in-
crease of the population exposed more frequently than 12% of days and
in a decrease of the population exposed less frequently than 6% of days
during the same period. These increases in N02 air pollution and in
-------
PERCENT OF TOTAL POPULATION
-n
_j*
c.
ro
o
CO
o
en
o
00
o
o
o
O
m
co
-a
o
x
o
o>
a
Q.
Ol
Q.
o
00
o
ro
ro
IA
a
cr>
| A
-a
A
T3
A
T3
n
o
ro
ro
i
3>
"U
O
o
oo
OO
OO
g
o
a
m
x
o
o
m
o
-------
53
population exposure to N02 during the middle years 1967/68 to 1971/72
are quite a contrast with the continuous decreases in Ox air pollution
and in population exposure to QX which have been observed in the Ox
trend analysis.
Population-at-risk distributions for N02 during the five two-year
periods are shown in Fig. 4.5. The high population exposure to N02
during the middle years, 1967/68, 69/70, and 71/72 is depicted by the
crowded curves 2, 3, and 4 at the upper right corner of the figure.
The difference in population exposure during the two lowest pollution
periods 1965/66 and 1973/74 is seen clearly from the population-at-risk
distributions of those two periods. Note that the slope of a curve
at a given risk frequency indicates the probability density of the popu-
lation exposed at that risk frequency. We thus know from the two dis-
tributions, that the great majority of the population was exposed over a
narrow range of risk frequency, say, 3% to 7.5% in 1973/74 while in
1965/66 over a wide range of risk frequency, say, 1% to 15%. The popula-
tion was also exposed over a wide range of risk frequency during the
middle year periods. Therefore, it can be said that the population
exposure to N02 in 1973/74 is unique and quite different from those in
the other periods. This peculiarity might be explained by the year-to-year
variation of meteorology. An emission control strategy that tends to
suppress the peak concentration of N02 might also be responsible for this
change in population exposure distribution.
-------
54
O
C
OJ
3
-O
0)
+J
-------
55
Population-at-risk distributions for three subpopulations, school-age
(2), elderly (3), and non-white (4) as well as total population (1) are
shown in Figs. 4.6 and 4.7. As seen from Figure 4.6, during the two
2-year periods, 1965/66, and 73/74, the school-age population was exposed
to the least N02. The non-white population was exposed most among the
four populations during the same two 2-year periods. However, as seen
from Figure 4.7, these relations were reversed during the middle year
period, 1969/70. The non-white population is more concentrated in the
urban core areas than the surrounding areas. It is difficult to explain
the reasons for the peculiar behavior of the population exposure of the
non-white population, which was less exposed than the other populations
when NOp air pollution got worse and was more exposed when N02 air
pollution improved.
The regionwide trend of N02 air quality is shown in Fig. 4.8 by using
three different indices; population weighted average concentration, area
weighted average concentration, and station average concentration. Although
there is no obvious trend at any percentile, there seems to exist a some-
what downward trend at the 99th percentile concentration while at the
50th percentile concentration a slightly upward trend. Figure 4.8 also
shows that the population weighted average concentration is persistently
higher than the area weighted average concentration at each of. the three
different percentiles. This indicates that N02 concentration levels are
positively correlated with population density. This interpretation is
partly verified by comparing the population density map (Fig. 2.5) to
-------
56
«
o>
o>
o
"O
0)
(/>
o
Q.
X
D
1
.5
1.5
0 .5 1 1.5
Percent of hours above the California 1-hr standard
Figure 4.6 POPULATION-AT-RISK DISTRIBUTION FOR N02 DURING 1965/66
AND 1973/74 FOR TOTAL (1), SCHOOL-AGE (2), ELDERLY (3),
AND NON-WHITE (4) POPULATION.
-------
0)
3
O"
OJ
s-
57
(O
(->
1/1
c
1C
c
0)
-------
o
ID
a.
a.
o»
o
o
o
-------
59
the NOg risk frequency map (Fig. 4.2). Knowing that levels of primary
pollutants such as particulates, SCL, and CO are strongly (positively)
correlated with population density in urban air pollution, the spatial
variation pattern of N02 behaves similarly to those of primary pollutants
in spite of the fact that the ambient N02 concentration is mostly due to
oxidation of the primary pollutant NO. It should also be noted that the
station average concentration gives slightly lower values at higher per-
centiles than the population weighted average concentration whose value
would be most representative for the air environment of an average person.
The regionwide trend in population exposure to N02 is shown in
Figure 4.9 by the average hourly risk frequency that has been computed
by using the concentration threshold equal to the California standard for
hourly average N02 concentration. There is a slightly downward trend in
the average hourly risk frequency although the higher values during the
middle-year periods obscure any trend in the population exposure index.
The regionwide trend in population exposure to NOp is also summarized
in Table 4.1 by using the average daily risk frequency and the average
mean duration of California standard violations in hours per day. An
average person in the study area was exposed to hourly NOp concentration
above the California standard on 25 days in 1965/66, 27 days in 1969/70,
and 18 days in 1973/74. The average duration of such high exposure changed
from 2.6 hours per day in 1965/66 to 3.0 hours per day in 1969/70, and
to 2.5 hours per day in 1973/74.
-------
ro
-O
C
ro
4->
I/)
s_
.c
i
s-
o
60.
100
ro
O
CD
10
O
J2
fO
CM
O
CD
to
O
a.
x
l/l
fO
at
a.
CD
CD
ra
S-
O)
>
ro
CS=1 STD
1
3
O
c
CD
U
ai
Q-
1965/66
67/68
69/70
71/72
73/74
Figure 4.9 N02 TREND IN POPULATION EXPOSURE INDEX WITH THE THRESHOLD
EQUAL TO THE CALIFORNIA 1-hr STANDARD.
-------
61
Table 4.1 Regionwide Trend in # Days the California One-Hour Standard
for N02 was Exceeded and the mean Duration in Hours
ThresholdInHex1965/661967/68 1969/70 1917/72 1973/74
1 X STD # Days Exceeded 25 40 27 33 18
470 tf/m Per Year
(25 pphm) Mean Duration 2.6 3.3 3.0 3.0 2.5
Hours
-------
62
4.3 TREND IN N02 ANNUAL MEAN CONCENTRATION
This section compares ambient N02 levels to the annual arithmetic
mean National Ambient Air Quality Standard (100 yg/m or approximately
5 pphm) for NOp. Figure 4.10 depicts the spatial and temporal variations
of N02 annual mean concentration. We see that almost the entire study
area exceeded the N02 standard during the ten-year period, 1965 to 1974.
However, notice that the small area around Azusa met the NAAQS for
oxidant during the early years (1965/66 and 67/68) even though in the
later years this area had the highest oxidant air pollution readings.
In the later years 1969/70, 71/72, and 73/74, the entire study area
exceeded the NAAQS.
A more detailed isopleth map of N02 annual mean concentration is
presented in Appendix D, Figure D5. A closer look at Figures 4.10 and
D5 reveals that the spatial gradient of N02 annual mean concentration diminishes
with time. A similar reduction in the spatial gradient was also found in
N02 daily risk frequency iscpleth maps (Figs. 4.2 and D3). A possible
explanation of the decrease in ti.e N02 spatial gradient with time may
be the more uniform distribution of NOY emissions over the Los
A
Angeles Basin in recent years. As discussed in Section 2.1, considerable
population growth took place in the suburban areas surrounding downtown
Los Angeles during the 10 year period, 1965 to 1974, while almost no
population growth in the downtown area itself. The population shift
toward the surrounding areas certainly would have brought the spread of
automobile traffic that, in turn, resulted in more uniform NOX emissions
through the basin.
-------
1965/1966
1971/1972
1973/1974
1969/1970
Figure 4.10. N02 ANNUAL MEAN CONCENTRATION
(yg/m3) FOR FIVE 2-YEAR PERIODS,
I ]
< 100
100 - 130
> 130
CTv
CO
-------
64
The population exposure to N02 annual mean concentration was determined
by computing the population dosage distribution which describes the fraction
of the population exposed to a concentration above the stated value.
Figure 4.11 was obtained from the computed population dosage distribution
to illustrate the distribution of the population at three annual N02 dose
levels; less than 100 vg/m3, between 100 and 130, and greater than 130
vg/m3 in annual mean concentration. These are comparable with the shaded
areas in the maps of Figure 4.10. In 1965/66, there were about 10% of
the population who lived in areas where the N02 air quality was better than
the NAAQS. Since 1969/70 even this small percentage has disappeared com-
pletely.
Regionwide trends in N02 annual mean concentrations are shown in
Fig. 4.12 by the three different indices; population weight average con-
centration (3), ar^a weighted average concentration (2), and station
average concentration (1). All the indices show that there is an apparent
upward trend in N02 annual mean concentration until 1973. These curves
are in agreement with the 50th percentile of the hourly concentrations
displayed in Figure 4.8.
-------
1.0
Q.
O
g
UJ
t
o
0.8
0.6
0.4
0.2
N02 ANNUAL MEAN CONCENTRATION
in yg/m3
[N02] < 100
100 < [N02] < 130
130 <_ [N02]
Example: During 1965/66 about 91% of the population
was exposed to N02 concentration between 100 and
130 yg/m3. About 19% were exposed to N02 concen-
trations above 130 yg/m3. The NAAQS is 100 yg/mj
annual average.
en
en
Figure 4.11. CHANGES IN THE TOTAL POPULATION EXPOSURE TO N02 DURING FIVE 2-YEAR PERIODS.
-------
Q.
Q.
C.
o
CO
s_
cu
o
c
o
o
O)
0>
-------
67
5. CONCLUDING REMARKS
Population exposure methodology was applied to analyze the 10-year
trends in two photochemical pollutants, QX and N02 in the Los Angeles
Basin. The following paragraphs summarize the findings and conclusions
reached in this report.
Trends in 0 Air Quality and Population Exposure to QX
There has been a regionwide downward trend in both QX
air pollution and population exposure to GX above the
NAAQS during the 10-year study period.
There were two stages in the Ox air quality improvement
over that period. The earlier stage (1965 to 1969) is
characterized by a sharp improvement in Ox air pollution
in the coastal areas around the city of Long Beach. The
later stage (1970 to 1974) is characterized by the Ox
air quality improvement in the inland areas.
The reduction in population exposure to Ox air pollution
is greatest at high exposure levels. The percentage of the
population exposed more than 50% of the time dropped from
53% in 1965/66 to a mere 5% in 1973/74. The percentage
of the population exposed less than 20% of the time was
zero percent in 1965/67 but increased to 35% in 1973/74.
-------
68
Trends in N02 Air Quality and Population Exposure to N02
During the 10-year study period, practically the entire
population in the study area, the southern half of Los
Angeles county, has been exposed to NCL annual mean con-
centration above the NAAQS.
There is no clear trend in either N02 air quality or
population exposure to NOp. However, there seems to
exist somewhat a downward trend at the 99th percentile
concentration while at the 50th percentile concentration
and/or in annual mean concentration, a slightly upward
trend is observed.
The N02 air quality deterioration and the accompanied
increase of population exposure to N02 during the middle
years from 1967/68 to 1971/72 appear to correspond to the
increased NOX emissions during that period.
There is a marked shift in the spatial distributions of
N02 air pollution and population exposure to N02 during
the 10-year period. N02 air pollution and population
exposure to N02 appear to be spread more uniformly in
recent years (1973/1974) than in earlier years
(1965/1966). In 1973/1974 the population was
-------
69
exposed to NOp above the California standard over a small
range of daily risk frequency from 3% to 7.5% while in
1965/66 over a wide range of daily risk frequency from
n to 15%.
For NOp, the station average concentration gives lower
values at higher percentile concentrations than the
population weighted average concentrations whose value
would be most representative for the air environment of an
average person in the study area. Therefore, the station
average concentration of NOp and probably those of the
primary pollutants should be used with caution because the
station average may tend to underestimate the regional
average concentration to which an average person is exposed.
-------
70
REFERENCES
1. "Suggested Revision of SCAG Growth Forecast Policy (June 1975), as
Modified (Der ?mber 1975), " Southern California Association of
Governments, LOb Angeles, California, April 1976.
2 "Census Tracts," Bureau of the Census, U.S. Department of Commerce,
Series PHC(l), May 1972.
3. "Ten-Year Summary of California Air Quality Data 1963-1972," California
Air Resources Board, Division of Technical Services, January 1974.
4. "Annual and Quarterly Statistics for South Coast Basin 1973-1974,"
California Air Resources Board, Division of Technical Services,
May 14, 1975.
5. Letter dated April 15, 1976, John Kinosian , Chief Division of Technical
Services, Air Resources Board, State of California.
6. Horie, Y., and A.C. Stern, "Analysis of Population Exposure to
Air Pollution in New York-New Jersey-Connecticut Tri-State Region,"
USEPA, OAQPS, EPA-450/3-76-027, March 1976.
7. "Directory of Air Qaulity Monitoring Sites - Active in 1973,"
USEPA, OAQPS, EPA-450-2-75-006, March 1975.
8. Horie, Y., A. S. Chaplin, and E. D. Helfenbein, "Special Features of
Population Exposure to Photochemical Air Pollution in the Los Angeles
Basin," Interim Report Volume I for the EPA Project #DU-75-C190,
Technology Service Corporati >n, November 30, 1976.
9. Trijonis, J.C., ejt a]_., "Emissions and Air Quality Trends in the
South Coast Air Basin," Environmental Quality Laboratory, California
Institute of Technology, EQL Memo No. 16, January 1976.
10. Zupan, J. M., "The Distribution of Air Quality in the New York Region,"
Resources for the Future, Inc., Washington, D.C., 1973.
11. Anderson, S. J., et al., "Correlation between Air Pollution and
Socio-Economic Factors in Los Angeles County," Paper submitted to
Urban Ecology, University of California at San Diego, January 1976.
12. Kuzmack, A. M., and R. E. McGaughy, "Quantitative Risk Assessment for
Community Exposure to Vinyl Chloride," Paper presented at the EPA
Conference on "Environmental Modeling and Simulation," Cincinnati, Ohio,
April 19-22, 1976. The outline appearing in the Proceedings of the
Conference, EPA 600/9-76-016, pp. 736-739, July 1976.
-------
71
13. Shy, C. M., J.P. Creason, M.E. Pearlman, K.E. McClain, and F.B. Benson,
"The Chattanooga Schoolchildren Study: Effects of Community Exposure
to Nitrogen Dioxide, II. Incidence of Acute Respiratory Illness,"
Journ. Air Pol. Cont. Assoc. 70:582-588, September 1970.
14. Gardner, D.E., "Time/Dose Response for Nitrogen Dioxide Exposure in
Air Infective Model System," Scientific Seminar on Automotive
Pollutants, EPA-600/9-75-003.
15. Jeffries, H., D. Fox, and R. Kames, "Outdoor Smog Chamber Studies-
Effect of Hydrocarbon Reduction on Nitrogen Dioxide," EPA-650/3-75-011,
USEPA, Office of Research and Development, Washington, D.C., June 1975.
-------
A-l
APPENDIX A
POPULATION DATA FOR LOS ANGELES AQCR
Table AT. SCAG estimate of total population.
Table A2. 1970 Census data of various subpopulations.
-------
A-2
Table Al. SCAR estimate of total population,
RSA
No.
1
2
3
4
5
6
RSA
Name
Ventura Co.
LOSPADS
VENTURA
OXNARD
SIMI
THSOAKS
FILLMOR
1960
329
78,443
90,658
11,012
9,941
8,755
1970
375
112,165
136,430
67,756
51,542
10,229
1975
347
115,854
155,400
77,291
72,602
10,913
COUNTY TOTAL 199,138 378,497 432,407
Los Anaeles Co.
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
CALABAS
NEWHALL
LANCAST
PALMDAL
S G MTS
S W SFV
BURBANK
N E SFV
MALIBU
SMONICA
WCENTRL
SO BAY
PALVRDS
L BEACH
E CENTRAL
MOR-WHI
LA CBD
GLENDAL
WSANGAB
ESANGAB
POMONA
5,410
14,987
41,979
23,579
2,612
391,057
249,337
205,990
6,486
275,921
866,053
471,185
276,350
423,023
808,521
508,130
96,854
376,581
594,212
303,966
98,572
18,935
48,078
51,446
31,429
2,013
539,935
264,922
267,158
11,709
304,380
934,831
531,318
413,506
435,416
828,311
592,502
90,416
412,626
669,136
441 ,043
149,654
27,898
60,035
55,762
33,541
1,806
564,005
256,791
269,745
15,478
313,121
908,068
515,515
429,159
415,387
774,927
615,645
83,102
404,766
655,161
470,628
150,232
COUNTY" TOTAL 6,040,805 7,038,764 7,020,772
San Bernardino Co.
28
29
30
31
32
33
34
WESTEND
EASTEND
SB MTS
BAKER
RARSTOW
TWPALMS
NEEDLES
159,735
250,086
9,454
8,177
54,192
15,691
6,256
233,386
312,097
20,374
9,700
76,701
24,103
5,872
251,316
299,019
23,693
6,696
81 ,502
27,931
5,907
COUNTY TOTAL 503,591 682,233 696,064
-------
A-3
Table Al. SCAG estimate of total population
(Continued).
RSA
No.
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
RSA
Name
Oranne Co.
,1-BUPK
A-FULTN
H-ANAHM
I-W CST
F-C CST
D-C CST
B-CANYN
Q-S ANA
C-TRABU
E-TORO
COUNTY TOTAL
Riverside Co.
JURUPA
RVSIDE
PERRIS
HEMET
MURRIET
BANNING
IDYWILD
PALM SP
COACHEL
CHUCKAW
COUNTY TOTAL
Imperial Co.
1960
68,193
101,673
225,637
54,574
80,353
15,443
7,462
140,505
1,897
8,188
703,925
25,357
154,049
9,783
17,352
7,969
20,764
1,842
26,723
27,265
15,087
306,191
1970
160,903
170,787
307,729
240,377
161,253
38,834
34,390
266,278
18,306
21,529
1,420,386
37,095
219,750
22,564
34,368
12,001
26,852
3,048
48,588
38,411
16,397
459,074
1975
172,496
185,292
324,251
285,100
199,710
60,570
55,386
299,836
29,389
33,046
1,655,076
40,251
247,929
28,300
44,541
14,356
27,999
3,903
65,903
41 ,969
16,528
531,679
55 IMPERL72,105 74,492 83,250
REGION 7,825,755 10,053,446 10,419,248
-------
Table A2. 1970 Census data of various subpopulations.
RSA
No.
1
2
3
4
5
6
Location
VENTURA COUNTY
LOSPADS
VENTURA
OXNARD
SIMI
THOUSAND OAKS
FILLMORE
COUNTY TOTAL
Total School Age
Population (5-17 years)
Number Number Percent*
Percent of total population
375
110690
136545
66588
52003
10229
376430
80
28423
40122
23987
17115
2797
1125:3
21.3
25.7
29.4
36.0
32.9
27.3
29.9
Elderly
(=>65)
Number Percent*
40
12386
7170
1945
2027
979
24547
10.7
11.2
5.3
2.9
3.9
9.6
6.5
Nonwhite
Number Percent*
9
2128
11098
868
741
225
15069
2.4
1.9
8.1
1 .3
1.4
2r\
.2
4.0
LOS ANGELES COUNTY
7
8
9
10
11
I I
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
CALABASAS
NEWHALL
LANCASTER
PALMDALE
S G MTS
VAN NUYS
BURBANK
NE SFV
MALIBU
SANTA MONICA
CULVER CITY
INGLEWOOD
SAN PEDRO
LONG BEACH
SOUTH GATE
DOWNEY
CBD
GLENDALE
PASADENA
COVINA
POMONA
COUNTY TOTAL
18935
47241
48035
32723
2015
539935
254922
267294
11709
309278
923817
531 1 38
413510
437186
835683
592297
90416
417901
657320
458691
132029
703207.5
5863
13918
13756
9779
380
139506
51236
83714
2911
53773
154867
120752
114717
83967
227786
166719
9884
84611
148176
152320
36124
1674759
31.0
29.5
28.6
29.9
18.9
25.8
19.3
31.3
24.9
17.4
17.2
22.7
27.7
19.2
27.3
28.1
10.9
20.2
22.5
33.2
27.4
23.8
732
2224
3725
2509
175
34289
26891
14076
634
34203
134335
36845
22933
54631
69859
34006
14843
54149
79017
19706
12615
652397
3.9
4.7
7.8
7.7
8.7
6.4
10.2
5.3
5.4
11.1
14.5
6.9
5.5
12.5
8.4
5.7
16.4
13.0
12.0
4.3
9.6
9.3
273
1328
2304
1691
122
8332
5342
22724
206
26476
365531
74967
35800
31368
304852
11922
15145
28466
60445
16410
11872
25576
1.4
2.8
4.8
5rt
.2
6T
.1
1.5
2.0
8.5
1.8
8.6
39.6
14.1
8.7
7.2
36.4
2.0
16.8
6.8
9.2
3.6
i?:8
-------
Table A3. 1970 Census data of various subpopulations (Continued),
RSA
No.
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
Location
SAN BERNARDINO
ONTARIO
SAN BERNARDINO
SB MTS
BAKER
BARSTOW
TWPALMS
NEEDLES
COUNTY TOTAL
ORANGE COUNTY
J-BUPK
FULLERTON
ANAHEIM
HUNTINGTON
BEACH
LAGUNA BEACH
SAN CLEMENTE
B-CANYN
SANTA ANA
C-TRABU
EL TORO
COUNTY TOTAL
Total School Age Elderly
Population (5-17 years) (=>65)
Number Number Percent* Number Percent*
Percent of total population
CO
233386
311654
20374
11982
76701
24103
5872
684072
161866
1 70784
307729
240357
160319
38834
34390
266272
18306
21529
1420386
67582
62965
5303
2563
21811
4201
1521
185946
53629
48475
87517
70093
34835
8828
11539
72331
5755
4328
397330
29.0
26.6
26.0
21.4
28.4
17.4
25.9
27.2
33.1
28.4
28.4
29.2
21.7
22.7
33.6
27.2
31.4
20.1
28.0
16754
34922
2055
358
5681
4861
669
65301
5445
9986
17406
16949
21127
5437
1116
18370
444
2151
98431
7.2
11.2
10.1
3.0
7.4
20.2
11.4
9.5
3.4
5.8
5.7
7.1
13.2
14.0
3.2
6.9
2.4
10.0
6.9
Nonwhite
Number Percent*
8481
25213
209
1177
6032
1006
473
42591
4057
4098
6969
5879
2745
947
602
11704
275
1369
38644
3.6
8.1
1.0
9.8
7.9
4.2
8.1
6.2
2.5
2.4
2.3
2.4
1.7
2.4
1.8
4.4
1.5
6.4
2.7
KIVER^DE COUNTY
f,
ti _
JIIRUPA
D1l'FRSIDE
S VALLEY
37095
221619
22414
34368
10?fi?
10500
62079
4531
6026
2282
28.3
28.0
20.2
17.5
22.2
3343
16578
6720
11016
2466
9.0
7.5
30.0
32.1
24.0
3299
14247
2486
750
832
8.9
6.4
11.1
2.2
8.1
-------
RSA
Location
Table A3. 1970 Census data of- various subpopulations (Continued)
Total
Population
Number
School Age
(5-17 years)
Number Percent*
Elderly
(=>65)
Number Percent*
Percent of total population
Nonwhite
Number Percent*
RIVERSIDE COUNTY
50 SAN GORGON10
PASS
51 IDYLLWILD
52 PALM SPRINGS
53 COACHELLA
54 CHUCKAWALLA
COUNTY TOTAL
IMPERIAL COUNTY
55 IMPERIAL COUNTY
TOTAL
26852
3048
48588
38411
16397
459074
6303
644
8410
11967
4885
117r27
74492
REGION TOTAL 10046529
23885
2512080
23.5
21.1
17.3
31.2
29.8
25.6
5959
530
10746
2101
1124
60583
32.1
25.0
5575
906834
22.2
17.4
22.1
5.5
6.9
13.2
2499
74
2471
3317
1574
31549
7.5
9.0
4570
1157999
9.3
2.4
5.1
8.6
9.6
6.9
6.1
11.5
(Ti
-------
B-l
APPENDIX B
AIR QUALITY DATA FOR DX AND N02 IN LOS ANGELES AQCR
Table Bl. Corrected 0 daily maximum hourly average concentrations
in 1965 to T974.
Table B2. Corrected 0₯ hourly average concentrations in 1965 to 1974.
/\
Table B3. N02 daily maximum hourly average concentrations in 1965 to
1974.
Table B4. NO, hourly average concentrations in 1965 to 1974.
-------
B-2
Table ei Corrected Ox daily maximum hourly average concentrations in
1965 to 1974. (all values in pphm)
No.
Station
Obs.
Max.
PERCENTILE
3% 5% 10%
25%
50% 75%
1
2
3
4
5
6
7
Anaheim
1965/66
1967/68
1969/70
1971/72
1973/74
Azusa
1965/66
1967/68
1969/70
1971/72
1973/74
Burbank
1965/66
1967/68
1969/70
1971/72
1973/74
Lennox
1965/66
1967/68
1969/70
1971/72
1973/74
Long Beach
1965/66
1967/68
1969/70
1971/72
1973/74
L.A. Downtown
1965/66
1967/68
1969/70
1971/72
1973/74
Pomona
1965/66
1967/68
19^9/70
1971/72
1973/74
351/356
356/360
345/325
349/359
361/363
365/365
365/365
363/365
365/362
365/365
365/365
364/365
365/365
365/363
365/365
324/365
364/366
359/363
358/366
365/364
362/364
364/365
359/362
365/366
364/361
365/365
364/365
365/357
365/363
365/361
if
192/365
365/366
365/365
364/366
364/365
36.0
29.2
29.2
30. d
25.2
53
54
56
48
42
36
44
36
29
32
34
28
24
19
19
30
27
20
22
18
54
41
31
24
38
44
46
46
36
31
.5
.5
.0
.5
.0
.0
.5
.5
.5
.0
.5
.3
.0
.0
.5
.5
.C
.0
.0
.5
.0
.0
.5
.5
.5
.0
.0
.5
.0
.5
28.8
24.8
20.8
19.2
18.0
41.0
44.0
47.0
37.5
34.5
31.5
39.5
32.5
26.5
26.0
24.5
21.0
19.0
16.0
12.0
24.5
15.5
15.0
15.5
14.0
38.0
30.5
25.5
22.6
27.0
38.0
39.5
40.5
29.0
30.5
25.2
20.0
17.2
15.2
16.0
36.5
36.5
41.0
32.5
29.0
27.7
34.5
28.5
23.5
22.0
18.0
16.5
14.0
11.5
9.0
18.5
13.5
12.0
10.5
9.5
31.5
26.5
20.5
19.5
20.0
35.0
35.1
35.0
25.0
25.5
21.2
17.2
15.2
12.8
14.0
33.5
34.0
37.0
29.5
27.5
26.0
32.5
25.5
21.0
20.0
15.0
14.0
12.0
10.5
8.0
16.0
11.0
10.0
9.0
8.5
26.0
24.0
19.0
17.5
18.0
30.0
32.0
32.5
24.0
24.0
17.2
16.8
12.8
10.0
10.0
31.0
30.0
32.5
25.5
24.5
24.0
26.5
21.5
19.0
17.0
12.0
11.5
9.5
8.0
6.0
11.5
9.0
8.0
8.0
7.0
22.5
19.5
16.0
14.0
15.0
28.0
28.0
28.0
20.0
20.5
11.2
10.0
8.0
6.4
6.4
24.0
23.0
23.5
18.5
17.5
17.5
19.5
16.5
13.0
12.5
-8.0
7.5
7.5
5.0
5.0
7;0
6.5
6.0
5.5
5.0
16.5
14.0
12.0
9.5
11.0
21.0
20.5
20.0
14.0
14.5
6.8
6.0
5.2
3.6
4.0
14.5
13.0
13.0
10.5
9.0
10.5
11.5
10.0
7.5
7.0
5.0
4.5
5.0
3.5
3.0
4.5
3.5
4.0
3.5
3.0
10.5
8.5
7.5
6.5
6.5
12.0
11.5
10.0
7.5
7.0
4.0
3.6
3.2
2.0
2.4
6.0
6.0
6.0
5.0
4.0
4.5
5.0
4.5
4.0
3.5
3.5
3.0
3.0
2.5
2.5
2.5
2.0
3.0
2.5
2.0
5.0
4.5
3.5
3.0
3.0
5.0
5.0
5.0
3.5
3.0
-------
B-3
Table BI .(Continued).
PERCENTILE
No
8
9
10
Station
Reseda
1965/66
1967/68
1969/70
1971/72
1973/74
San Bernardino
1965/66
1967/68
1969/70
1971/72
1973/74
West L.A.
1965/66
1967/68
1969/70
1971/72
1973/74
Obs.
291/365
365/365
363/365
360/366
365/365
360/355
365/362
363/363
364/363
353/193*
365/365
365/366
365/365
365/365
364/365
Max.
45.5
37.5
38.0
30.5
28.3
30.8
30.4
30.8
29.6
33.6
34.0
40.0
27.0
22.5
29.0
1%
34.0
34.5
31.5
25.5
23.6
25.2
24.0
28.4
26.6
28.8
29.0
26.0
22.5
18.0
18.5
3%
29.0
30.5
26.5
20.5
22.0
22.4
22.4
25.2
20.4
25.6
23.0
21.5
18.0
14.5
14.0
5%
26.5
28.5
24.5
19.5
19.5
21.2
20.0
23.2
18.8
23.2
20.5
19.5
16.0
13.0
12.5
10%
24.5
24.0
22.0
17.0
17.0
17.6
17.2
19.6
16.4
T9.2
16.5
16.5
14.0
10.5
10.5
25%
19.0
18.0
17.0
12.5
13.0
12.4
12.4
14.0
11.2
15.2
12.0
12.5
10.5
8.0
8.0
50%
12.
10.
9.
7.
7.
6.
6.
6.
5.
5.
8.
8.
7.
5.
5.
5
0
5
5
0
8
4
0
2
6
0
5
0
5
5
75%
5.0
4.5
5.0
4.0
3.5
2.8
3.2
2.8
2.5
2.4
5.0
5.0
4.0
3.0
3.5
A year has less than 75 percent of the possible observations.
-------
B-4
Table B2. Corrected Ox hourly average concentrations in 1965 to 1974.
(all values in pphm)
PERCENTILE
Obs.
Max. 1%
3%
5%
10%
25%
50% 75%
1
2
3
4
5
6
7
Anaheim
1965/66
1967/68
1969/70
1971/72
1973/74
Azusa
1965/66
1967/68
1969/70
1971/72
1973/74
Burbank
1965/66
1967/68
1969/70
1971/72
1973/74
Lennox
1965/66
1967/68
1969/70
1971/72
1973/74
Long Beach
1965/66
1967/68
1969/70
1971/72
1973/74
LA Downtown
1965/66
1967/68
1969/70
1971/72
1973/74
Pomona
1965/66
1967/68
1969/70
1971/72
1973/74
7645/7684
7737/8115
7678/7285
7714/8040
8173/8077
8206/8270
8040/8212
8195/8313
8260/8187
8162/8278
8180/8257
8015/8151
8193/8842
8218/8214
8315/8319
7191/8279
8220/8237
8072/8094
8072/8281
8316/8272
8101/8224
8214/8120
7852/8025
8303/8254
8201/8146
8221/8262
8202/8155
8224/7865
8230/8426
8357/8003
k
4282/8195
8305/8325
8201/8266
8171/8343
8253/8330
36.0
29.2
29.2
30.8
25.2
53.5
54.5
56.0
48.5
42.0
36.0
44.5
36.5
29.5
32.0
34.5
28.0
24.0
19.0
19.5
30.5
27.0
20.0
27.9
18.5
54.0
41.0
31.5
24.5
38.5
44.0
49.2
45.8
36.0
31.5
18.0
14.8
13.2
10.0
10.8
30.5
30.0
32.0
25.0
24.0
23.0
27.0
22.5
18.5
17.0
13.0
12.0
10.0
8.0
7.0
12.5
9.0
7.5
7.5
7.0
22.0
19.5
16.5
14.4
16.0
27.0
28.0
28.0
20.0
21.0
12.5
10.4
9.6
6.8
7.2
24.0
23.5
24.0
19.0
18.5
17.5
20.5
17.5
14.0
19.0
9.9
8.0
7.5
5.5
5.0
8.0
6.5
5.5
5.5
5.0
16.5
14.5
13.0
10.5
12.0
21.0
21.5
21.0
14.5
15.5
10.0
8.4
7.6
5.6
6.0
21.0
20.0
20.5
16.0
15.5
15.0
17.5
14.5
11.5
11.0
6.5
6.5
6.5
5.0
4.0
6.0
5.0
5.0
4.5
4.0
14.0
12.0
10.5
8.5
10.0
18.0
18.0
17.5
12.0
13.0
7.2
6.0
5.2
3.6
4.0
15.0
14.0
14.0
11.5
10.5
11.0
12.0
10.5
8.0
8.0
5.0
5.0
5.0
3.5
3.0
4.0
3.5
3.5
3.5
3.0
10.0
8.6
7.5
6.5
6.5
12.0
12.5
12.0
8.0
8.5
3.6
3.2
2.8
2.0
2.4
6.3
5.5
5.5
4.5
4.0
4.5
4.5
4.0
3.0
3.5
3.0
3.0
3.0
2.5
2.0
2.0
2.0
2.0
2.0
2.0
4.5
4.0
3.4
3.0
3.5
5.0
5.0
4.5
3.5
3.0
1.6
1.6
0.8
0.4
0.8
2.0
2.0
2.0
2.0
2.0
1.5
2.0
2.0
1.0
1.0
1.0
1.0
1.5
1.0
1.0
1.0
1.0
1.0
1.0
1.0
2.0
1.5
1.5
1.0
1.0
2.0
2.0
2.0
1.5
1.0
0.
0.
0.
0.
0.
1.
1.
1.
1.
1.
1.
1.
1,
1,
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
8
8
0
0
0
0
0
0
0
0
,0
,0
,0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
.0
-------
B-5
Table B2 (Continued).
PERCENTILE
No.
8
9
10
Station
Reseda
1965/66
1967/68
1969/70
1971/72
1973/74
San Bernardino
1965/66
1967/68
1969/70
1971/72
1973/74
West L.A.
1965/66
1967/68
1969/70
1971/72
1973/74
Obs0
*
6530/8232
8291/8055
8221/8097
8241/8383
8350/8347
8058/7955
8320/8229
7909/7845
7882/7904
7682/4139
8203/8121
8255/8204
8160/8246
8118/8337
8222/8193
Max.
44.0
37.5
38.0
30.5
28.0
30.8
30.4
30.8
29.6
30.0
34.0
40.0
27.0
22.5
29.0
1%
23.
25.
22.
17.
17.
18.
17.
20,
16.
19.
17.
17.
14.
10.
10.
0
0
5
0
5
0
6
0
4
2
5
0
0
5
5
3%
19.0
19.5
18.5
13.0
14.0
13.6
13.6
15.2
12.8
14.8
12.5
12.5
11.0
8.0
8.5
5%
17.0
16.5
15.5
11.5
12.2
12.0
12.0
12.8
10.4
12.4
10.5
11.0
9.5
6.5
7.0
10%
13.0
12.0
11.0
8.5
9.0
8.4
8.4
9.6
7.6
8.8
8.0
8.5
7.5
5.0
6.0
25%
6.0
5.0
5.0
4.0
4.0
3.6
3.6
3.6
2.8
3,6
4.5
4.5
4.0
3.3
3.5
50%
2.0
2.0
2.0
2.0
2.0
0.8
0.8
0.8
0.8
1.2
2.0
2.0
2.0
1.0
1.5
75%
1.0
1.0
1.0
1.0
1.0
0.0
0.0
0.0
0.0
0.0
1.0
1.0
1.0
1.0
1.0
A year has less than 75 percent of the possible observations.
-------
B-6
Table B3.
N02 daily maximum hourly average concentrations in 1965 to 19", 4.
(all values in pphm)
1 Anaheim
1965/66
1967/68
1969/70
1971/72
1973/74
2 Azusa
1965/66
1967/68
1969/70
1971/72
1973/74
3 Burbank
1965/66
1967/68
1969/70
1971/72
1973/74
4 Lennox
1965/66
1967/68
1969/70
1971/72
1973/74
5 Long Beach
1965/66
1957/68
1969/70
1971/72
1973/74
6 L.A. Downtown
1965/66
1967/68
1969/70
1971/72
1973/74
7 Pomona
1965/66
1967/68
1969/70
1971/72
1973/74
Obs.
Max. 1%
PERCENTILE
3% 5% 10%
25%
* *
226/257
314/337
-c 0/335
359/358
329/360
300/363
364/362
365/354
364/361
361/364
365/365
363/363
364/362
362/364
364/363
324/360
364/358
365/364
359/366
363/361
361/362
365/355
360/365
364/362
361/358
365/365
365/358
355/361
359/361
353/363
*
187/363
363/365
365/365
365/363
365/364
30.5
34.5
43.5
43.0
30.5
33.0
39.0
40.5
38.5
43.5
55.0
49.0
51.0
36.5
41.5
62.0
40.0
41.0
41.0
44.0
58.0
52.5
50.5
36.0
75.0
50.5
75.5
56.5
61.0
29.0
39.5
44.0
41.5
35.0
28.0
26.0
35.5
33.5
24.0
29.0
31.0
32.0
30.5
36.5
45.5
45.0
37.5
34.0
34.0
54.5
32.5
35.0
34.0
34.5
42.5
40.5
40.0
32.0
45.5
42.0
43.0
46.5
39.0
26.0
33.0
33.0
32.5
27.0
23.5
20.5
22.5
26.0
19.0
23.5
23.0
26.5
26.5
29.5
39.5
36.0
34.0
29.5
29.0
43.0
28.0
30.0
29.0
28.5
38.0
35.0
32.5
29.0
35.5
36.5
33.5
39.5
30.5
22.0
28.5
27.5
27.0
24.0
21.5
18.5
21.0
22.5
17.5
21.0
21.5
23.5
23.0
27.0
35.5
34.0
30.0
26.0
25.0
37.0
25.5
26.0
23.0
25.0
34.0
31.0
27.5
26.0
32.0
31.5
28.0
34.5
26.0
21.0
24.5
24.5
23.0
21.0
18.5
15.0
16.5
17.5
14.5
17.0
17.5
19.0
19.0
23.5
31.0
29.0
26.0
22.5
21.5
29.0
22.0
22.5
19.0
20.0
29.0
25.5
24.0
20.0
27.5
26.0
23.0
28.5
22.5
17.0
20.5
21.5
20.5
19.0
12.0
11.0
10.5
11.5
11.0
12.5
13.5
14.0
14.0
17.0
23.5
22.0
20.5
16.5
15.5
19.0
15.5
15.5
14.0
14.5
19.0
18.5
15.5
14.5
20.0
15.5
16.0
20.0
16.0
14.0
15.5
17.0
15.5
14.5
8.0
8.0
7.5
8.0
7.5
8.0
9.0
10.0
10.0
11.0
15.5
14.5
14.0
11.5
10.0
12.5
11.5
10.5
10.0
9.5
13.0
12.5
10.0
10.0
12.5
11.0
10.5
13.5
10.5
10.0
11.5
12.5
11.0
10.0
5.5
6.0
5.0
6.0
5.5
5.0
6.0
7.5
7.5
7.5
10.0
9.5
9.5
7.5
7.0
8.0
7.?
7.5
7.0
6.5
8.0
9.0
7.5
7.0
8.5
7.5
7.5
9.5
7.5
7.0
8.5
9.5
8.0
8.0
-------
B-7
IdDie DO IVAJML "
No. Station
8 Reseda
1965/66
1967/68
1969/70
1971/72
1973/74
9 San Bernardino
1965/66
1967/68
1969/70
1971/72
1973/74
10 West L.A.
1965/66
1967/68
1969/70
1971/72
1973/74
mcu; .
Obs.
292/365
363/361
362/364
359/364
365/364
HO*/ 303
313/292
169*/203*
321/341
356/351
358/365
364/362
364/365
362/357
358/363
Max
34.
45.
37.
40.
33.
25.
23.
28.
32.
50.
48.
50.
51.
61.
0
0
0
0
5
0
5
0
0
0
5
0
0
5
1%
28.5
36.5
29.5
34.5
30.0
21.0
20.5
22.0
18.5
42.5
40.5
37. 5
42.0
38.5
PERCENTILE
3% 5% 10%
23.5
28.5
25.0
28.5
24.0
18.0
17.5
19.0
16.0
3205
33.5
29.5
33.5
32.5
21.5
25.5
23.5
25.5
22.0
16.0
15.5
16.5
14.5
29.5
30.0
27.5
30.0
29.0
17.0
20.5
20.5
21.5
18.5
12.0
13.0
14.5
13.0
24.0
25.0
22.5
25.0
23.5
25%
12.5
15.0
15.5
16.5
14.5
9.0
10.0
11.0
11.0
16.5
16.5
16,0
17.0
16.5
50%
9.
10.
11.
12.
10.
7.
7.
8.
7.
10.
11.
10.
11.
11.
0
0
0
0
5
0
0
0
5
0
0
5
5
5
75%
5.5
6.5
7.0
8.0
7.0
5.0
4.5
6.0
5.0
7.0
8.0
7.5
7.5
8.0
A year has less than 75 percent of the possible observations,
-------
B-8
Table B4. NOo hourly average concentrations in 1965 to 1974,
All values in pphm. PERCENTILE
No.
Station
Obs.
Max
V
3%
5%
10% 25% 50% 75%
1
2
3
4
5
6
7
Anaheim
1965/66
1967/68
1969/70
1971/72
1973/74
Azusa
1965/66
1967/68
1969/70
1971/72
1973/74
Burbank
1965/66
1967/68
1969/70
1971/72
1973/74
Lennox
1965/66
1967/68
1969/70
1971/72
1973/74
Long Beach
1965/66
1967/68
1969/70
1971/72
1973/74
L.A. Downtown
1965/66
1967/68
1969/70
1971/72
1973/74
Pomona
1965/66
1967/68
1969/70
1971/72
1973/74
475^/5381
6749/7356
7985/7429
7875/8004
7340/7993
*
6119/7736
7690/7622
7853/7311
7998/8081
8096/8269
7674/7736
7682/7583
7753/7683
7833/8467
8462/8280
6452/^7397
7521/7351
7676/8065
8030/8338
8294/8254
7914/7306
7505/7992
7827/8073
8087/8183
8108/7890
7616/7817
7781/7623
7399/7902
8017/8215
7717/7959
*
3813/7634
7685/7848
7936/7930
8120/8231
8353/8270
30.5
34.5
43.5
43.0
31.0
33.0
39.0
40.5
38.5
43.5
55.0
49.0
51.0
36.5
40.0
62.0
40.0
41.0
41.0
44.0
58.0
52.5
50.5
36.0
75.0
50.5
75.5
56.5
61.0
29.0
39.5
44.0
41.5
35.0
19.0
17.0
19.5
21.0
16.0
19.5
20.0
21.5
20.5
25.5
33.5
30.5
27.0
23.0
22.0
34.0
22.5
24.0
20.5
22.5
29.5
27.0
25.5
22.0
26.5
26.5
24.5
29.0
23.5
18.0
23.0
23.0
22.5
19.5
15.0
13.0
14.0
15.5
12.0
19.5
15.5
16.5
16.0
20.5
27.0
24.5
22.0
18.5
17.0
23.5
17.5
17.5
16.0
17.0
22.5
21.0
19.0
16.5
21.5
19.5
18.5
22.5
18.5
15.0
17.0
19.0
17.5
15.5
13.0
11.0
12.0
13.0
11.0
12.5
13.5
14.0
14.0
17.0
23.0
21.5
19.5
16.0
15.0
19.5
15.5
15.0
13.5
14.5
19.5
18.0
16.0
14.5
18.0
16.5
16.0
19.0
15.5
13.0
15.0
16.5
15.5
14.5
10.0
9.0
9.0
9.5
9.0
10.0
11.0
11.0
11.5
13.0
18.5
17.0
15.5
13.0
12.0
14.5
12.0
11.5
11.0
11.5
15.0
14.0
12.0
12.0
14.0
12.5
12.5
14.5
12.0
11.0
12.5
13.5
13.0
11.5
6.0
6.0
6.0
6.5
6.0
6.5
7.5
8.0
8.0
9.0
12.0
12.0
11.0
9.0
7.0
9.0
8.5
8.0
8.0
7.5
10.0
9.5
8.5
8.0
9.5
8.5
8.5
10.5
8.5
8.0
9.5
10.5
10.0
9.0
4.0
4.0
4.0
4.5
4.0
3.5
4.5
5.5
5.5
6.0
8.0
8.0
7.5
6.0
5.0
6.0
6.0
5.5
5.5
4.5
6.0
6.5
5.5
6.0
6.0
5.5
6.0
7.5
6.0
6.0
6.5
7.5
7.0
6.0
2.5
3.0
3.0
3.0
2.0
1.5
2.5
3.0
3.5
3.5
5.5
5.5
5.0
4.0
3.0
4.0
4.0
4.0
4.0
3.0
4.0
4.0
4.0
4.0
4.0
4.5
4.0
5.5
4.0
4.0
4.5
5.0
5. 0
4.5
-------
B-9
Table B4 (Continued).
No. Station
8 Reseda
1965/66
1967/68
1969/70
1971/72
1973/74
9 San Bernardino
1965/66
1967/68
1969/70
1971/72
1973/74
10 West L.A.
1965/66
1967/68
1969/70
1971/72
1973/74
Obs.
if
5939/7729
7565/7558
7683/7764
7881/8318
8506/8390
* *
211 1*1 591 3
617375808^
3105*/3820
6575/6891
7408/8058
7282/7779
7632/7798
8103/8008
7918/8042
8207/8184
Max
35.0
45.0
37.0
40.0
33.5
28.0
32.0
50.0
48.5
50.0
51.0
61.5
1%
19.0
24.0
21.5
23.5
20.0
15.5
13.0
25.0
25.0
22.5
25.0
23.5
PERCENTILE
3% 5% 10%
14.0
17.5
17.5
18.0
15.5
12.0
11.0
18.5
19.0
17.0
19.0
18.5
12.0
15.0
15.5
16.0
13.5
11.0
9.5
15.5
16.5
15.0
16.0
15.5
10.0
12
12
13
11
8
7
12
12
11
12
12
.0
.5
.0
.0
.5
.5
.0
.5
.5
.5
.5
25%
7.0
8.0
8.5
9.0
7.5
6.0
5.5
7.5
8.0
8.0
8.5
8.5
50%
4.
5
5
6
5
4
4
5
5
5
5
6
,0
.0
.5
.0
.5
.0
.0
.0
.5
.5
.5
.0
75%
3.0
3.0
3.0
3.5
3.5
3.0
2.0
3.0
3.5
4.5
3.5
4.0
*: A year has less than 75 percent of the possible observations.
-------
C-l
APPENDIX C
MONITORING STATIONS AND RECEPTOR POINTS
Table Cl. Locations and addresses of Air Monitoring Stations,
Table C2. Receptor points assigned to the Los Angeles AQCR.
-------
C-2
Table C1. Locations and Addresses of Air Monitoring Stations
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Anaheim #050230001101 (30176)
1010 S. Harbor Blvd., Anaheim, Orange County
Azusa #050500002101 (7GJ50)
803 Loren Ave., Azusa, Los Angeles County
Burbank #050900002101 (70069)
228 W. Palm, Burbank, Los Angeles County
Lennox #053900001101 (70076)
11408 La Cienega Blvd., Lennox, LA County
Long Beach #054100002101 (70072)
3648 N. Long Beach Blvd., Long Beach, LA Cty.
L.A. Downtown #054180001101 (70001)
434 S. San Pedro St., Los Angeles County
Pomona #056040001101 (70075)
924 N. Garey Ave., Pomona, Los Angeles County
Reseda #054200001101 (70074)
18330 Gault St., Reseda, Los Angeles County
San Bernardino #056680001101 (36151)
172 W. 3rd St., San Bernardino, S.B. Cty.
West L.A. #054180002101 (70071)
2351 Westwood Blvd., Los Angeles County
UTM
N =
E =
N =
E =
N =
E =
N =
E =
N =
E=
N =
E =
N =
C
N =
E =
N =
E =
N =
E =
3,742,467
415,477
3,777,371
414,892
3,782,904
379,355
3,755,070
373,477
3,743,190
390,007
3,767,650
385,310
3,767,844
430,882
3,785,129
358,851
3,773,634
473,637
3,767,403
368,178
X-Y
Y =
X =
Y =
X =
Y =
X =
Y =
X =
Y =
X =
Y =
X =
Y =
X =
V "
x =
Y =
X =
Y =
X =
Coord.
1340
1824
1634
1819
1681
1520
1446
1470
1346
1610
1552
1570
1554
1900
1699
1347
1602
2315
1550
1426
-------
C-3
Table C2. Receptor Points Assigned to the Los Angeles AQCR
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
County
Los Angeles
Los Angeles
ii
ii
Los Angeles
ii
Los Angeles
H
Los Angeles
Los Angeles
n
Los Angeles
n
n
n
n
Los Angeles
n
n
Los Angeles
II
Los Angeles
Los Angeles
n
n
Los Angeles
n
n
n
n
RSA #
7
12
12
12
13
13
14
14
15
16
16
17
17
17
17
17
18
18
18
19
19
19
20
20
20
21
21
21
21
21
Code #
2071
2121
2122
2123
2131
2132
2141
2142
2151
2161
2162
2171
2172
2173
2174
2175
2181
2182
2183
2191
2192
2193
2201
2202
2203
2211
2212
2213
2214
2215
X-Coord.
1285
1361
1351
1400
1485
1521
1421
1510
1221
1380
1430
1521
1521
1521
1480
1480
1521
1475
1500
1505
1505
1545
1595
1650
1625
1565
1565
1565
1610
1610
Y-Coord.
1610
1670
1720
1630
1645
1650
1730
1710
1550
1570
1465
1510
1550
1590
1530
1580
1440
1460
1410
1320
1365
1350
1330
1320
1390
1420
1470
1520
1520
1470
-------
Table C2 (Continued).
C-4
No.
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
S5
,56
57
58
County
Los Angeles
H
M
Los Angeles
Lob Angeles
it
H
Los Angeles
M
it
H
Los Angeles
Los Angeles
n
Los Angeles
Orange
Orange
Orange
n
Orange
n
Orange
Orange
it
San Bernardino
n
San Bernardino
n
RSA =
22
22
22
23
24
24
24
. 25
25
25
25
26
26
26
27
35 .
36
37
37
38
38
41
42
42
28
28
29
29
Code #
2221
2222
2223
2231
2241
2242
2243
2251
2252
2253
2254
2261
2262
2263
2271
3351
3361
3371
3372
3381
3382
3411
3421
3422
4281
4282
4291
4292
X-Coord.
1660
1690
1725 .-
1555
1561
1561
1595
1641
1660
1710
1730
1765
1810
1840
'1900
1710
1800
1765
1785
1708
1750
1911
. 1825
1840
1960
2000
2190
2335
Y--Coord.
1420
1480
1435 '
1545
1585
1640
1595
1625
1560
1555
1620
1520
1595
1500
1580
1355
1410 '
1320
1355
1280
1250
1390'
1285
1335
1490
1590
1625 .
1555
-------
D-l
APPENDIX D
ISOPLETH MAP OF RISK FREQUENCY, MEAN DURATION,
AND ANNUAL MEAN CONCENTRATION
Figure Dl. Oxidant Air Quality in Percent of Days on which the
NAAQS was Exceeded During Five 2-Year Periods.
Figure D2. Oxidant Air Quality in Mean Duration (Hrs/Day) in
NAAQS Violations During Five 2-Year Periods.
Figure D3. NO? Air Quality in Percent of Days on which the
California 1-Hr Standard was Exceeded During
Five 2-Year Periods.
Figure D4. NO? Air Quality in Mean Duration (Hrs/Day) of
California Standard Violations During Five
2-Year Periods.
o
Figure D5. N02 Annual Arithmetic Mean Concentration (yg/m )
During Five 2-Year Periods.
-------
n>
i
01
o
X
_J.
QL
fa
o*
3
TJ
3
o>
o
=J
o
CO
O>
in
m
x
o
(0
(D
Q.
n>
o.
3
(O
CT>
tn
-------
Figure Dl-b. Oxidant Air Quality in Percent of Days on Which the NAAQS Was Exceeded During 1967/68
-------
Figure Dl-c. Oxidant Air Quality in Percent of Days on Which the NAAQS Was Exceeded During 1969/70
-------
Figure Dl-d. Oxidant Air Quality in Percent of Days on Which the NAAQS Was Exceeded During 1971/72
-------
I
Figure Dl-e. Oxidant Air Quality in Percent of Days on Which the NAAQS Was Exceeded During 1973/74
-------
Figure D2-a. Oxidant Air Quality in Mean Duration (Mrs/Day) of NAAQS Violations During 1965/66
-------
I
00
Figure D2-b. Oxidant Air Quality in Mean Duration (Hrs/Day) of NAAQS Violations During 1967/68
-------
IQ
Figure D2-c. Oxidant Air Quality in Mean Duration (Hrs/Day) of NAAQS Violations During 1969/70
-------
Figure D2-d. Oxidant Air Quality in Mean Duration (Hrs/Day) of NAAQS Violations During 1971/72
-------
Figure D2-e. Oxidant Air Quality in Mean Duration (Hrs/Day) of NAAQS Violations During 1973/74
-------
0
I
ro
Figure D3-a. N02 air quality in percent of days on which the California 1-hr standard was exceeded during 1965/66.
-------
Figure D3-b. N02 air quality in percent of days on which the California 1-hr standard was exceeded during 1967/68.
-------
I
-p>
Figure D3-c. N02 air quality in percent of days on which the California 1-hr standard was exceeded during 1969/70.
-------
'ZZ/LZ6L 6uiunp papaaoxa SBM puepueis uq-L BLUJO^LLBQ aq^ LJDLMM uo s/Cep ^o ;uaouad UL /C^iLenb uie 2QN 'P-CQ
IT)
I
Q
-------
Figure D3-e. N02 air quality in percent of days on which the California 1-hr stnadard was exceeded during 1973/74.
-------
*,
o
I
Figure D4-a. N02 air quality in mean duration (hrs/day) of California standard violations during 1965/66.
-------
00
Figure D4-b. N02 air quality in mean duration (hrs/day) of California standard violations during 1967/68.
-------
<£>
Figure D4-c. N02 air quality in mean duration (hrs/day) of California standard violations during 1969/70.
-------
o
I
ro
o
Figure D4-d. N02 air quality in mean duration (hrs/day) of California standard violations during 1971/72.
-------
/ -r 2.0 -
Figure D4-e. N02 air quality in mean duration (hrs/day) of California standard violations during 1973/74.
-------
I
ro
ro
3
Figure D5-a. N0? Annual Arithmetic Mean Concentration (yg/m ) During 1965/66.
-------
a
i
(N5
00
o
Figure D5-b. HQ2 Annual Arithmetic Mean Concentration (yg/m ) During 1967/68.
-------
o
ro
Figure D5-c. N0? Annual Arithmetic Mean Concentration (ug/m ) During 1969/70.
-------
i
ro
o
Figure D5-d. N02 Annual Arithmetic Mean Concentration (ug/m ) During 1971/72.
-------
o
I
ro
en
Figure D5-e. N02 Annual Arithmetic Mean Concentration (yg/m ) During 1973/74.
-------
E-l
APPENDIX E
METHODOLOGY TO CHARACTERIZE
POPULATION EXPOSURE
-------
E-2
FORMULATION OF POPULATION EXPOSURE PARAMETERS
Suppose a person stays at a place where the air quality is continously
monitored. Then, the pollution "dose" of that person over a time period T
can be given by
T.
DOSE = f C(t) dt (E-l)
o
where C(t) is the concentration reading at time t. A pollutant concentra-
tion is usually measured at a constant time interval, say, every hour.
Monitored concentrations are often sorted in ascending order and summarized
to percentile concentration statistics. In this case, Eq. (E-l) reduces to
1
DOSE =T/*C(f) df (E-2)
o
where C(f) is the concentration at the f percentile.
From the quantities in Eq. (E-2) we will derive the three exposure
parameters: "dose rate," "risk frequency," and "mean duration". The dose
rate is the average concentration with respect to a subject person and is
given, for the above example, as
D
"o
Namely, the dose rate is equal to the artihmetic mean concentration averaged
over the time period T, i.e., a year in this study. The risk frequency is the
-------
E-3
percentage of time that a subject person is exposed to a concentration
2
above a given concentration threshold C<..
R(CS) = 1 - f.
(E-4)
where f is the percentile given by a solution to C(f) = C<.. The mean
s j
duration can be determined when the percentile concentration statistics
are available for both hourly average concentrations and daily maximum
hourly average concentrations. It is given by
24
where R. is the risk frequency for hourly average concentrations (hourly
risk frequency) and R. the risk frequency for daily maximum hourly average
concentrations (daily risk frequency).
Using an indicator step function U(x) that assumes the value one for
positive arguments and zero elsewhere, the distribution function for each
of the three population exposure parameters D, R(C<.), and T(CS) is given
as3:
S(D*) = I P U(0. - D*)/Pn ' (E-6)
* I I \J
S(R*) = I P1 U[R.(CS) - R*]/PQ (£-7)
i
S(T*) = I P1 U[Ti(Cs) - T*]/PQ (E-8)
-------
E-4
where P.. is the size of the local population at the i-th receptor point, P
the total number of people of the population, and D*, R*, and T* are,
respectively, the threshold values of D, R(CS) and T(CS).
Once the distribution function is determined for a parameter D, R, or
T, the mean value of that parameter over the entire population is given by
the integral of the distribution function with respect to the threshold of
that parameter . The average dose rate "D, the average risk frequency R^C$)
and the average mean duration T(CS) over the entire population are given as
S(0*) dO*
=/
o
(Cc) = /SCr
5 -
tC = r dr* (E-ll)
-
The actual computation of D, R^(CS) and T(CS) was done by numerically
integrating the distribution functions S(D*), S(R*), and S(T*), respectively.
-------
E-5
REFERENCES TO APPENDIX E
1. Craw, A. R., "A Contribution to the Problem of Placement of Air Pollution
Samplers," U.S. Dept. of Commerce, National Bureau of Standards, NBS
Report #10-284, May 1970.
2. Brasser, L. J., "A New Method for the Presentation of a Large Number of
Data Obtained from Air Pollution Survey Networks," Paper #SU-18B, Pro-
ceedings of the Second International Clean Air Congress, IUAPPA, Washington,
D.C., USA, December 6-11, 1970.
3. Csanady, G. T., "The Dosage-Area Problems in Turbulent Diffusion,"
Atmospheric Environment, Vol. 1, 1967, pp. 451-459.
4. Horie, Y., and A. C. Stern, "Analysis of Population Exposure to Air
Pollution in New York - New Jersey - Connecticut Tri-State Region,1 U.S.
EPA, OAQPS, EPA-450/3-76-027, March 1976.
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-450/3-77-004C
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Population Exposure to Oxidants and Nitrogen Dioxide
in Los Angeles Volume III: Long-Term Trends,
1965-1974
5. REPORT DATE
.lanuarv 1Q77
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Yuji Horie and Anton S. Chaplin
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park. North Carolina 27711
10. PROGRAM ELEMENT NO.
2AF643
11. CONTRACT/GRANT NO.
68-02-2318
12. SPONSORING AGENCY NAME AND ADDRESS
Technology Service Corporation
2811 Wilshire Boulevard
Santa Monica, California 90403
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A population exposure methodology was applied to trend analyses of photochemical
air pollution and population exposure to Ox and N02 in the Los Angeles Basin. The
analyses were made on the air quality and population data during the five 2-year
periods from 1965/66 to 1973/74 to determine the 10-year trends in air quality and
in population exposure to the two pollutants.
Oxidant air quality improved throughout the region during the 10-year period.
The improvement appeared first in the coastal region and thereafter proceeded toward
the inland region. The extent of Ox air quality improvement was greater in the
coastal region than in the inland region. As a result, population exposure to Ox
above the standard was also diminished. The decrease in population exposure to Ox
was pronounced more at higher exposure levels than at lower exposure levels.
There was no obvious trend in N0£ air quality and population exposure to N02-
The middle years 1967/68-1971/72 were more polluted than the end years 1965/66 and
1973/74. The spatial gradient of NO? air pollution became smaller in recent years
and consequently, the population received more uniform exposure to N0£. The NAAQS
for N02 annual mean concentration was violated practically everywhere in the region
during the entire period.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Photochemical Air Pollution
Air Quality Trend
Population Exposure
Data Analysis
Control Strategy
18. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
129
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
------- |