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
r—I  *—
    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— -I—i--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)

-------