BREATHING EASIER: 1996
A REPORT ON AIR QUALITY
»
IN CALIFORNIA, ARIZONA, NEVADA, & HAWAII
September 1996
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION 9
Air Quality Trends 1980-95
LEAD (Pb) Concentrations
South Coast -97%
Phoenix -96%
Sacramento -97%
San Diego -97%
San Francisco Bay Area -97%
'80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91 '92 '93 '94 '95
EPA 909-R-96-001
September 1996
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BREATHING EASIER: 1996
A REPORT ON AIR QUALITY
IN CALIFORNIA, ARIZONA, NEVADA, & HAWAII
September 1996
Prepared by:
U.S. Environmental Protection Agency
Region 9
Air and Toxics Division
75 Hawthorne Street (A-2-4)
San Francisco, CA 94105
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Table of Contents
Executive Summary. ES-1
Introduction i
Ozone 1-1
Particulate Matter 2-1
Carbon Monoxide 3-1
Nitrogen Dioxide 4-1
Sulfur Dioxide 5-1
Lead 6-1
Air Emissions Sources 7-1
PAMS Program 8-1
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EXECUTIVE SUMMARY
WE'RE BREATHING EASIER:
LONG-TERM PROGRESS
TOWARD CLEANER AIR IN
THE WESTERN STATES
A year ago, U.S. EPA published the
first Breathing Easier report. This update
provides evidence that the long-term trend
toward cleanerair in the western region is
continuing, though trouble spots remain.
There has been a substantial
improvement in air quality in U.S. EPA's
western region -- California, Arizona,
Nevada, and Hawaii -- over the last ten
years. Despite an increase in auto travel
of almost 50% over the past decade, air
pollutant levels have decreased overall
by about one-third. Both the number of
days on which air pollution has exceeded
federal air quality standards and the air
pollutant concentration levels have
decreased for the six major air pollutants
targeted for reduction under the federal
Clean Air Act.
Of the six pollutants, the greatest
reductions have been recorded for lead
(86%), followed by carbon monoxide
(35%), and particulate matter (26%). The
tremendous reduction in lead levels has
resulted mostly from the phase-out of
lead in gasoline. Particulate matter,
carbon monoxide, and smog-forming
ground-level ozone present the most
serious remaining challenges. However,
all six pollutants are being steadily
reduced.
Long-Term (1986-95)
Air Quality Trends
Ten-yeartrends show that air quality
has improved for ozone, carbon
monoxide, nitrogen dioxide, sulfurdioxide,
and lead. Although particulate matter
has only been monitored for eight years,
levels have decreased during that period.
Changes in air pollutant levels
between 1986 and 1995 (the most recent
year for which complete data are
available) forall long-term monitoring sites
in California, Arizona, Nevada, and Hawaii
are as follows:
Lead (Pb): 86% decrease
Carbon Monoxide (CO): 35%
decrease
Particulate Matter (PM.J: 26%
decrease
Sulfur Dioxide (SOJ: 21%
decrease
Nitrogen Dioxide (NO2): 15%
decrease
Ozone (O3): 12% decrease
Most Improved Areas
Many of the geographic areas that
failed to meet federal air quality standards
when the Clean Air Act Amendments were
passed in 1990 have improved enough to
meet the standards based on data from
ES- 1
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more recent years (1993, 1994, and 1995).
Areas in this "most improved" category,
for each of the six pollutants, are:
Ground-level Ozone (O3): Reno,
Monterey Bay, Chico, and Yuba
City areas.
Particulate Matter (PM10):
Sacramento, Mojave Desert,
and Mono Lake, California; Ajo,
Bullhead City, Douglas, Hayden,
Miami, Nogales, Paul Spur,
Payson, Rillito, and Yuma,
Arizona.
emissions at Hawaii Volcanoes
National Park.
Nitrogen Dioxide (NO2): All areas
met the federal standard. The
last violation of the standard was
in the South Coast Air Basin (Los
Angeles Area) in 1991 That area
met the standard from 1992
through 1995.
Lead (Pb): All areas met the
federal standard.
Where Problems Remain
Carbon Monoxide (CO): San
Francisco Bay Area, San Diego,
Sacramento, Fresno, Stockton,
Modesto, Bakersfield, Chico,
Lake Tahoe, Reno and Tucson.
Sulfur Dioxide (SO2): All areas
with man-made sources met the
federal standards. In earlieryears,
violations had occurred near
nonferrous metal (copper)
smelters in Arizona, but none have
been recorded recently. The only
recent violations were from
naturally-occurring volcanic
****,
C3
Ground-level Ozone (O3) violations
were recorded in most of Southern
California, the San Joaquin Valley,
San Francisco Bay Area,
Sacramento Area, and Phoenix.
Particulate Matter (PM10) violations
were recorded in the South Coast
AirBasin, Southeast Desert, Great
Basin Valley, San Joaquin Valley,
Reno, Las Vegas, and Phoenix.
Carbon Monoxide (CO) violations
occurred in the South Coast Air
Basin, Phoenix, Las Vegas, and
Calexico.
REGION 0
AIR MONITOUING STAIIONS
Figure ESa - Air Monitoring Stations. 1993-1995.
ES-2
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INTRODUCTION
This report presents air quality infor-
mation for areas within EPA Region 9,
consisting of Arizona, California, Hawaii,
Nevada, and the Pacific Islands. Current
air quality (through 1995) and ten-year
trends are presented forthe six air pollut-
ants for which National Ambient Air Qual-
ity Standards (NAAQS) have been devel-
oped. These air pollutants are carbon
monoxide (CO), ozone (O3), nitrogen di-
oxide (NO2), sulfur dioxide (SO2), lead
(Pb), and particulate matter with aerody-
namic size of 10 microns or less (PM10).
In addition to the 10 year (1986-1995) air
quality trend statistics, which are pre-
sented for comparison with the national
numbers, airquality graphs are presented
for the 16 year period from 1980 through
1995 to show long-term changes.
The Federal standards are presented
in Table 1. Although most of the stan-
dards are in units of parts per million
(ppm), some text and graphics in this
report use parts per billion (ppb) units.
The conversion factor is 1000 ppb equals
1 ppm. State air quality standards may
differ from the NAAQS.
The air quality data for this report
were collected from several hundred moni-
toring sites (see Figure ESa) throughout
Region 9 by local, state, and Federal
agencies and private organizations. Most
of the data are stored on EPA's Aerometric
Information Retrieval Systems (AIRS)
data base. The data, analysis methods,
and emissions estimates used in this re-
port are taken from EPA's annual "Na-
tional Air Quality and Emissions Trends
Report", but are tailored specifically to
EPA Region 9. The reader may refer to
that document for technical details and
for air quality information about areas
outside of Region 9.
The information presented here is
organized by pollutant and is intended to
show general air quality and trends for
areas within Region 9 and for the Region
as a whole. In most cases, air quality
information is not presented for individual
monitors.
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Table 1
National Ambient Air Quality Standards (NAAQS)
Pollutant
Primary
(Health Related)
Type ol Standard Level
Average Concentration'
Secondary
(Welfare Related)
Type of Standard Level
Average Concentration
CO
Pb
N02
03
PM-10
S02
B-hour"
1-hour*
Maximum
Quarterly
Average
Annual
Arithmetic
Mean
Maximum
Daily
1-hour
Average0
Annual
Arithmetic
Mean"
24-hour^
Annual
Arithmetic
Mean
24-hour6
9 ppm
(10 mg/m3)
35 ppm
(40 mg/m3)
1.5 pg/m3
0.053 ppm
(100pg/m3)
0.1 2 ppm
(235 pg/m3)
50 pg/m3
150pg/m3
80 pg/m3
(0.03 ppm)
365 pg/m3
0.14 ppm
No Secondary Standard
No Secondary Standard
Same as Primary Standard
Same as Primary Standard
Same as Primary Standard
Same as Primary Standard
Same as Primary Standard
3-hour* 1300 pg/m3
(0.50 ppm)
Parenthetical value is an approximately equivalent concentration.
Not to be exceeded more than once per year.
The standard is attained when the expected number ol days per calendar year with maximum hourly average con-
centrations above 0.12 ppm is equal to or less than one, as determined according toAppendix H ol the Ozone NAAQS.
Paniculate standards use PM-10 (particles less than \Q\j in diameter) as the indicator pollutant The annual stan-
dard is attained when the expected annual arithmetic mean concentration is less than or equal to 50 pg/m3; the
24-hour standard is attained when the expected number ol days per calendar year above 1 SO pq/m3 is equal to or
less than one; as determined according to Appendix K ol the PM NAAQS
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OZONE
BACKGROUND and HEALTH EFFECTS
Ground-level ozone (O3) is the major
component of smog. While ozone in the
upper atmosphere benefits life by shield-
ing the earth from the sun's harmful ultra-
violet radiation, high concentrations of
ozone at ground level are a major health
and environmental concern. Ozone is
not emitted directly into the air, but is
formed through complex chemical reac-
tions between precursor emissions of
volatile organic compounds (VOC) and
nitrogen oxides (NOJ in the presence of
sunlight. These reactions are stimulated
by sunlight and temperature, so that peak
ozone levels typically occur during the
warmer times of the year. Both VOC and
NOx are emitted by motor vehicles and
industrial sources.
The reactivity of ozone causes health
problems because it damages lung tis-
sue, reduces lung function, and sensi-
tizes the lungs to other irritants. Scien-
tific evidence indicates that ambient lev-
els of ozone not only affect people with
impaired respiratory systems, such as
asthmatics, but healthy adults and chil-
dren as well. Exposure to ozone for
several hours at relatively low concentra-
tions has been found to reduce lung func-
tion significantly in normal, healthy people
during exercise. This decrease in lung
function generally is accompanied by
symptoms including chest pain, cough-
ing, sneezing, and pulmonary conges-
tion. Ozone also damages agricultural
crops and forests.
REGION IX
AIR MONITORING STATIONS
FOR
OZONE
1993-95
Figure 1a
1 1
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The national health standard for O3
is defined in terms of the daily highest
(1-hour average) concentration. Ambi-
ent O3 concentrations should not exceed
120 ppb more than one day per year,
based on a three-year average.
RECENT OZONE AIR QUALITY
IN REGION 9
For the three-year period 1993-95,
O3 was monitored at 251 sites in Region
9. Figure 1 a shows the geographic distri-
bution of O3 monitors throughout the Re-
gion. In general, more monitors are lo-
cated in or near urban areas than in rural
areas.
The 81 monitoring stations where
ozone pollution exceeded the NAAQS dur-
ing 1993-95 are shown on the map in
Figure 1b as the vertical "spikes". The
height of each spike is proportional to the
number of days per year that the NAAQS
was exceeded. The most serious O3 prob-
lem in the Region (and in the nation) is in
the South Coast Air Basin (Los Angeles
area). Other areas that violated the O3
NAAQS include San Diego, Ventura, and
Santa Barbara counties, the California
Southeast Desert, San Joaquin Valley,
San Francisco Bay Area, Sacramento,
and Phoenix.
LONG-TERM OZONE TRENDS
With respect to ozone, air quality
has improved over the last ten years in
most areas of California, Arizona, Ne-
vada, and Hawaii. The exception is Phoe-
nix, the one urban area that has had an
increase in peak ozone concentrations
over the last ten years. Also, the number
of days per year above the ozone stan-
dard in Phoenix has been higherin recent
years than in the late 1980s.
The San Francisco Bay Area, which
typically exceeds the ozone standard two
to three days per year, had 1 3 days above
the standard in the latest year, 1995.
This unexpected increase in high ozone
days appears to be continuing into the
1996 ozone season.
For the Region as a whole, there
were 141 long-term monitors that oper-
ated forthe ten-year period. These moni-
tors, as a group, showed a 12% decrease
in O3 concentrations between 1986 and
1995 (based on the second highest daily
1-hour maximum concentration). This
compares to a 12% decrease at 549 sites
nationwide.
Figure 1c shows the number of days
that the O3 Stage 1 ("smog alert") level of
200 ppb was reached in the five most
serious O3 pollution areas of Region 9.
Ozone air quality measured by this air
quality indicator has improved remark-
ably over the last ten years. The South
Coast had 102 Stage 1 days in 1980
compared to 1 1 in 1995. Likewise, the
Southeast Desert has improved from a
high of 24 Stage 1 days in 1980 to one
day in 1995. Stage 1 days have not
occurred for several years in San Diego
or Ventura counties. Imperial County
reached Stage 1 levels in 1993 and 1995.
Figure 1d shows the number of days
in which ozone levels exceeded the O3
standard of 120 ppb for each year since
1980 in various areas of the Region. Note
that the number of days is a "basin-wide"
composite from all O3 monitors in an air
basin. It represents the number of days
during the year that the O3 standard was
exceeded at one or more monitors.
The largest reduction in ozone pollu-
tion has been in the California South
1 - 2
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EPA Region 9
Air Quality
OZONE
Frequency of
NAAQS Violations
Source - Aerooetrtc Information R«tr1«val Syrt«n (AIRS)
Air Quality Trends 1980-95
OZONE Stage 1 Days
Number of days 03 Stage 1 (200 ppb) reached.
South Coasl
S E Desert
Diego County
Ventura County
Stage 1 = 200 ppb (1-hour
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Air Quality Trends 1980-95
OZONE Exceedances
Number of days exceeding the 03 NAAQS.
co
TJ
I
o
X
ut
I
Areas Classified
Serious to
Extreme
South Coast
S E Desert Modified AQMA
San Joaquin Valley
San Diego County
Ventura County
Sacramento Metro
'80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91 '92 '93 '94 '95
180
150
120
90
60
30
0
Areas Classified
Attainment to
Moderate
Imperial County
Santa Barbara County
Phoenix
San Francisco Bay Area
Monterey Bay
Reno
/ / /"/-/ Las Vegas
'80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91 '92 '93 '94 '95
Figure 1d
1-4
Number of days exceeding the
NAAQS at one or more
locations.
NAAQS = 120ppb(1-hour
concentration).
NAAQS = National Ambient Air
Quality Standard.
8-12-96
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Coast Air Basin. The standard was ex-
ceeded in the Basin on 184 days at its
worst in 1981. In 1995, it was exceeded
on 107 days. The second-largest im-
provement occurred in the California
Southeast Desert area, where the number
of exceedances decreased from 123 days
in 1988 to 56 days in 1995.
The trend toward fewer days above
the O3 NAAQS and Stage 1 smog alert
level has been accompanied by a trend in
lower O3 concentrations.
Peak O, con-
o
centrations in most areas of Region 9 that
had several long-term monitors showed
improving air quality. The percent de-
creases in peak O3 concentration between
1986 and 1995 were as follows:
Although Figure 1d shows overall
improvement for ozone, some areas have
shown recent degradation, such as Phoe-
nix, San Francisco Bay Area, San Joaquin
Valley, Imperial County, and Ventura
County. It is important to note that ozone
levels can fluctuate from year to year and
these changes may not be indicative of
long-term trends.
% Decrease
In Peak
Concentration
Area
-28% San Diego County
-27% South Coast
-20% Southeast
Desert, CA
18% Ventura County
16% Monterey Bay
13% Sacramento Metro
13% Santa Barbara Co.
8% San Joaquin Valley
4% San Francisco Bay
+ 11% Phoenix
The South Coast Air Basin had the
second largest decrease in peak O3 con-
centrations. There were 27 long-term O3
monitors in the South Coast and the aver-
age (second highest daily 1-hour) con-
centration at those sites decreased from
227 ppb in 1986 to 164 ppb in 1995.
1 -5
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PARTICULATE MATTER
BACKGROUND and HEALTH EFFECTS
Air pollutants called "particulate mat-
ter" include dust, dirt, soot, smoke, and
liquid droplets directly emitted into the air
by sources such as factories, power plants,
transportation sources, construction ac-
tivity, fires, and windblown dust. Particu-
lates are also formed in the atmosphere
by condensation ortransformation of emit-
ted gases such as sulfur dioxide, nitrogen
oxides, and volatile organic compounds
into tiny droplets.
Based on studies of human popula-
tions exposed to high concentrations of
particles (often in the presence of sulfur
dioxide) and on laboratory studies of ani-
mals and humans, the major concerns for
human health include effects on breathing
and respiratory functions, aggravation of
existing respiratory and cardiovasculardis-
ease, alterations in the body's defense
systems against foreign materials, dam-
age to lung tissue, carcinogenesis and
premature death. The majorsubgroups of
the populations that appear likely to be
most sensitive to the effects of particulate
matter include individuals with chronic ob-
structive pulmonary cardiovascular dis-
ease, individuals with influenza, asthmat-
ics, the elderly, and children. Particulate
mattermay injure crops, trees and shrubs,
and may cause damage to metal surfaces,
fabrics, etc. Fine particulates also impair
visibility by scattering light and reducing
the visual range in urban, rural, and wil-
derness areas. The haze caused by fine
particles can diminish crop yields by re-
ducing sunlight.
The current NAAQS for particulate
matter was established in 1987 The par-
ticulate size measurement used, known
as PM10, includes particles with an aero-
dynamic diameter of less than 10 microns.
These smaller particles are most likely
responsible for the adverse health effects
on humans, because particles so small
can reach the thoracic or lower regions of
the respiratory tract. The PM10 annual
mean standard is 50 micrograms per cu-
bic meter of air (ug/m3). The 24-hour
standard is attained when the expected
number of days per calendar year above
150 ug/m3 is no more than one. EPA is
currently reviewing recent health effects
studies on fine particulates, and may re-
vise the PM10 NAAQS to focus on particles
smaller than ten microns, possibly at 2.5
microns. In addition, EPA is considering
standards for visibility impairment and re-
gional haze, which may be part of the
revised PM NAAQS orseparate standards.
A proposal is expected in November 1996
with final promulgation in June 1997
RECENT PMin AIR QUALITY IN REGION 9
Hj
For the three-year period 1993-95,
PM10 was monitored at 298 sites in Region
9. Figure 2a shows the geographic distri-
bution of PM10 monitors throughout the
Region.
The 42 PM_ sites that violated the
10
NAAQS during 1993-95 are shown on the
map in Figure 2b. The "spikes" represent
monitors with PM10 levels in violation of
the annual standard, and the height of
each spike shows the annual mean con-
centration for the site. The triangles on
the map show monitors that attained the
annual standard but exceeded the 24-
hour standard. The more serious PM,
problem areas in Region 9 are in the South
2 1
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Figure 2a
REGION IX
AIR MONITORING STATIONS
FOR
ARTICULATES (PM
Coast Air Basin (Los Angeles area), San
Joaquin Valley, Southeast Desert, and
Great Basin Valley of California^ addi-
tion to Reno, Las Vegas, Phoenix, and
areas near the Mexican border.
LONG-TERM PM^ TRENDS
PM.n is the newest NAAQS pollut-
annual PM
10
wise, Paul Spur, a
town in Arizona, im-
proved from 1 1 days
above the standard
in 1989 to none in
1995. Although Fig-
ure 2c shows gen-
eral improvement in
particulate trends,
some areas have
shown more bad-air
days in 1995. It is
important to note
that daily particulate
levels can fluctuate
and these increases
may not be indica-
tive of longer term
trends.
Figure 2d
shows the trend in
concentrations since 1988.
For all areas, the trend is positive -- the
annual mean particulate concentration has
decreased. The nonattainment areas (with
several long-term monitors) that had the
largest percentage reduction in their an-
nual mean concentration are:
ant to be measured, with data going back
only to 1988 in most areas. Overall, PM10
annual mean concentrations have de-
creased by 26% in Region 9, based on
156 monitoring sites operating from 1988
through 1995. This compares to a 20%
decrease at 748 sites nationwide.
Figure 2c shows the PM10trends for
22 areas in Region 9 from 1988 through
1995. For most of the areas, the number
of days with high particulate pollution has
decreased over time. For example, the
number of days with excess pollution in
the San Joaquin Valley decreased from
14 days in 1990 to 3 days in 1995. Like-
2
% Decrease in
Concentration
-49%
-36%
-34%
-33%
-28%
-24%
-23%
-14%
Area
Sacramento County
Coachella Valley, CA
South Coast
San Joaquin Valley
Las Vegas
Reno
Searles Valley. CA
Phoenix
California's South Coast Air Basin
has the largest long-term PM10 monitoring
network, with 14 sites, and has shown an
overall 34% reduction in annual mean con-
centrations between 1988 and 1995.
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A= Site exceeds only the 24-hour NAAQS
Figure 2b
EPA Region 9
Air Quality
PARTICULATES
( PM10 )
Severity of Annual NAAQS Violations
1993-95
2-3
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Air Quality Trends 1988-95
PARTICULATE MATTER (PM10) Exceedances
Number of days exceeding the 24-hour PM NAAQS.
Arizona and
Nevada
Nonattainment
Areas
Paul Spur
Reno
Payson
Vegas
Phoenix
Nogales
Rillrto
Yuma
Hayden/Miami
Bullhead City
Douglas
Ajo
'88
'89
'90
'91
'92
'93
'94
'95
NAAQS = 150ng/m3
(24-hour average
concentration).
Number of days
exceeding the NAAQS
at one or more
locations.
NAAQS = National
Ambient Air Quality
Standard.
15
o
<5
12
S" 9
a
a>
c
1 6
a>
o
x
LU
2. 3
Q
California
Nonattainment
Areas
San Joaquin Valley
South Coast
Owens Valley
Coachella Valley
Imperial Valley
San Bernardino County Desert
Searles Valley
, Mammoth Lakes
30"- Sacramento County
Mono Basin
'88
'89
'90
'91
'92
'93
'94
'95
2-4
Figure 2c
8-12-96
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Air Quality Trends 1988-95
PARTICULATE MATTER (PM10) Concentrations
Composite annual mean concentrations.
Arizona and Nevada
Nonattainment Areas
Paul Spur -75%
Payson -72%
Nogales -45%
Rillito -67%
1 Douglas -47%
Phoenix -13%
Yuma -43%
Las Vegas -28%
Hayden/Miami -55%
Reno -23%
Bullhead City -27%
A|0 -55%
'88 '89 '90 '91 '92 '93 '94 '95
NAAQS = 5
(annual mean
concentration)
Percent change in
concentration
between 1988 and
1995 is based on
linear regression
analysis.
NAAQS = National
Ambient Air Quality
Standard
California
Nonattainment
Areas
O)
a
c
o
*-*
a
E
8
c
o
O 125
O
a 100
S 75
50
09
O
§ 25
o
0 n
Imperial Valley -33%
South Coast -34%
San Joaqum Valley -33%
Coachella Valley -36%
San Bernardino County Desert -40%
Sacramento County -49%
Mammoth Lakes -13%
Searles Valley -23%
'88 '89 '90 '91 '92 '93 '94 '95
Owens Valley -62%
Mono Basin -12%
:' '-''-' :
2-5
Figure 2d
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CARBON MONOXIDE
BACKGROUND and HEALTH EFFECTS
Carbon monoxide (CO) is a color-
less, odorless, and poisonous gas pro-
duced by incomplete combustion of car-
bon in fuels. Two-thirds of the nationwide
CO emissions are from transportation
sources, with the largest contribution com-
ing from highway motor vehicles.
Carbon monoxide enters the blood-
stream and reduces the delivery of oxy-
gen to the body's organs and tissues.
The health threat is most serious forthose
who suffer from cardiovascular disease,
particularly those with angina or periph-
eral vascular disease. Exposure to el-
evated CO levels is associated with im-
pairment of visual perception, manual
AIR MONITORING STATIONS
CARBON MONOXIDE
994-95
dexterity, learning ability, and perfor-
mance of complex tasks.
The national health standard for am-
bient CO specifies upper limits for both 1-
hour and 8-hour average levels that are
not to be exceeded more than once per
year. The 1-hour level is 35 ppm, and the
8-hour average level is 9 ppm. This re-
port focuses on the 8-hour standard be-
cause the 1-hour standard is rarely ex-
ceeded.
RECENT CARBON MONOXIDE
AIR QUALITY IN REGION 9
Forthetwo-year period 1994-95, CO
was monitored at 141 sites in Region 9.
Figure 3a shows the geographic distribu-
tions of CO monitors
throughout the Re-
gion. In general,
more monitors are lo-
cated in or near ur-
ban areas than in ru-
ral areas.
The eight CO
monitoring sites that
violated the health
standard during
1994-95 are shown
on the map in Figure
3b. The vertical
"spikes" represent
CO monitors in viola-
tion, and the height
of each spike shows
the number of viola-
tions. The four areas
with violations were
the South Coast Air
Basin (Los Angeles
Figure 3a
3 1
-------
area), Phoenix, Las Vegas, and Calexico.
LONG-TERM CO TRENDS
Air quality with respect to carbon
monoxide has greatly improved over the
last ten years in all areas of Region 9.
Overall, CO concentrations (second high
8-hour average) have decreased by 35%
in the Region, based on 84 sites operat-
ing from 1986 through 1995. This com-
pares to a 28% decrease at 328 sites
nationwide. Much of the CO air quality
improvement can be attributed to newer,
cleaner-burning vehicles and fuels, and
state smog check programs.
Figure 3c shows the number of days
with CO pollution above the standard since
1980 for 14 areas of the Region. Note
that the number of days over the health
standard is a composite from all CO moni-
tors in an air basin. It represents the
number of days during the year that the
CO standard was exceeded at one or
more monitors.
Several areas have shown remark-
able reductions in CO exceedances since
1980. The CO exceedances in Phoenix
decreased from 99 days in 1984 to seven
days in 1995. The South Coast decreased
from 93 days in 1 980 to 1 7 days in 1 995.
Las Vegas decreased from 76 days to
four. Lake Tahoe decreased from 55
days in 1982 to none.
Peak CO concentrations (8-hour av-
erage) have also decreased substantially
during the last ten years in seven areas
that have several long-term monitors. The
percent decreases in CO concentrations
between 1986 and 1995 were as follows:
% Decrease
in Peak
Concentration
-54%
-39%
-39%
-35%
-33%
-32%
-27%
Area
Lake Tahoe
S.F Bay Area
Phoenix
Tucson
Sacramento
San Diego
South Coast
Figure 3b
EPA Region 9
Air Quality
CARBON MONOXIDE
Frequency of 8-hour
NAAQS Vio. itiOMs
ing.i 9:'
3-2
-------
Air Quality Trends 1980-95
CARBON MONOXIDE Exceedances
Number of days exceeding the 8-hour CO NAAQS.
100
"S 80
o
2
CO
O
u
O)
.£
o
X
LU
ra
O
40
20
.
Stockton
Modesto
San Diego County
Imperial County
Chico
Tucson
Bakerstield
South Coast
Phoenix
Las Vegas
Lake Tahoe
Sacramento
Reno
Fresno
San Francisco Bay Area
'80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91 '92 '93 '94 '95
NAAQS = 9 ppm (8-hour average concentration)
Number of days exceeding the NAAQS at one or more locations.
NAAQS = National Ambient Air Quality Standard
Figure 3c
8-12-96
3-3
-------
NITROGEN DIOXIDE
BACKGROUND and HEALTH EFFECTS as electric utilities and industrial boilers.
Nitrogen dioxide (NO2) is a brown-
ish, highly reactive gas which is present
in urban atmospheres. NO2 is formed in
the atmosphere from emissions of oxides
of nitrogen (NOJ. NOx plays a major role,
together with volatile organic compounds,
in the atmospheric reactions that produce
ozone. Although NOxactually scavenges
ozone at close range, it is a precursor
pollutant to ozone formation when it re-
acts with other compounds in the atmo-
sphere in the presence of sunlight, over
longer periods of time. Oxides of nitro-
gen are "transport pollutants" in ozone
formation in downwind areas.
NOx forms when fuel is burned at
high temperatures. The two major NOx
emission categories are transportation
sources (primarily motor vehicles) and
stationary fuel combustion sources, such
The NAAQS is based on nitrogen
dioxide (NO2) because it is known to be
highly toxic to humans. Nitrogen dioxide
can irritate the lungs, cause bronchitis
and pneumonia, and lower resistance to
respiratory infections. Nitrogen oxides
are an important precursor to both ozone
and acidic precipitation, which harm both
terrestrial and aquatic ecosystems. The
NAAQS for NO2 is 53 ppb annual mean
concentration.
RECENT NCL AIR QUALITY IN REGION 9
t
Forthe two-year period 1994-95, NO2
was monitored at 143 sites in Region 9.
Figure 4a shows the geographic distribu-
tion of NO2 monitors throughout the Re-
gion. In general, more monitors are lo-
cated in or near urban areas than in rural
areas.
Rl GION IX
AIR MONITORING STATIONS
fO~,
NITROGEN DIOXIDE
1994-95
4 1
Figure 4a
-------
There were no sites that violated the
N02 NAAQS in 1994 or 1995. In fact,
there were no violations anywhere in the
United States during this period. The
most recent violation occurred in the South
Coast Air Basin (Los Angeles area) in
1991.
For the Region as a whole, there
were 81 long-term monitors that operated
for the 10-year period. These monitors,
as a group, showed a 15% decrease in
their annual mean NO2 concentrations
between 1986 and 1995. This compares
to a 9% decrease at 205 sites nationwide.
LONG-TERM NO. TRENDS
Air quality with respect to nitrogen
dioxide has improved over the last ten
years in Region 9. Even with dramatic
increases in vehicle growth during this
period, the overall air quality improve-
ment has been largely due to newer,
cleaner-burning vehicles and stationary
source controls.
Figure 4b shows the change in an-
nual mean concentration for five areas
since 1980. The values are a composite
of the annual mean concentrations of all
long-term NO2 monitors in each area. Note
that all areas have been well below the
standard, except for the South Coast Air
Basin, which has shown the most im-
provement, with a 19% drop in NO2 con-
centrations from its peak in 1980.
Air Quality Trends 1980-95
NITROGEN DIOXIDE (NO2) Concentrations
Annual mean concentrations.
so
NAAQS = 53ppb (annual
mean concentration)
NAAQS = National Ambient
Air Quality Standard
South Coast
San Joaquin Valley
San Diego County
San Francisco Bay Area
Sacramento County
'80 '81 '82 83 84 85 86 87 '88 '89 '90 '91 92 93 94 '95
Figure 4b
4-2
-------
SULFUR DIOXIDE
BACKGROUND and HEALTH EFFECTS
Ambient sulfur dioxide (SO2) results
largely from stationary sources that burn
coal and oil, refineries, pulp and paper
mills, and from nonferrous metal smelt-
ers.
High concentrations of SO2 affect
breathing and may aggravate existing res-
piratory and cardiovascular disease.
Sensitive populations include asthmat-
ics, individuals with bronchitis or emphy-
sema, children, and the elderly. SO2 also
produces leaf damage to trees and agri-
cultural crops.
Sulfur dioxide and other oxides of
sulfur combine with oxygen to form sul-
fates and with water vapor to form aero-
sols of sulfurous and sulfuric acid. These
acid mists can irritate the respiratory sys-
tems of humans and animals and injure
plants. Particulate sulfates also reduce
visibility.
There are three national health stan-
dard for SO2: an annual arithmetic mean
of 80 micrograms per cubic meter of air
(pg/m3), a 24-hour level of 365 ug/m3 and
a 3-hour level of 1300 pg/m3 The first
two standards are primary (health-related)
standards, while the 3-hour NAAQS is a
secondary (welfare-related) standard. For
an air basin to be classified as having
attained the SO2 standard, the annual
mean standard is not to be exceeded,
while the short-term standards are not to
be exceeded more than once per year.
REGION IX
AIR MONITORING STATIONS
ron
SULFUR DIOXIDE
1994-95
5 1
Figure 5a
-------
RECENT SO. AIR QUALITY IN REGION 9
For the two-year period 1994-95, SO2
was monitored at 81 sites in Region 9.
Figure 5a shows the geographic distribu-
tion of SO2 monitors throughout the Re-
gion. The only site in Region 9 which
violated the NAAQS during this period
was one monitor at Hawaii Volcanoes
National Park, which exceeded both the
24-hour and 3-hour standards. The
exceedances were due to natural SO2
emissions from volcanoes. The annual
standard was not violated at any monitor-
ing site although the National Park site in
Hawaii came close.
LONG-TERM SO. TRENDS
There have been no exceedances of
the annual SO2 standard in Region 9 since
1984, and the trend in SO2 concentra-
tions has been downward since 1980.
Forthe Region as a whole, there were 41
long-term monitors during the ten year
period from 1986 to 1995. These moni-
tors, as a group, showed a 21% decrease
in annual S02 concentrations over ten
years. This compares to a 25% decrease
at 475 sites nationwide.
Until the mid-1980's, the SO2 NAAQS
was exceeded at sites near nonferrous
metal smelters in Arizona. See Figure 5b
forthe trends since 1980 for both the 24-
hour and 3-hour standards. During the
last ten years, several smelters have
ceased operations. The currently operat-
ing smelters near the towns of Hayden,
Miami, and San Manuel have substan-
tially reduced their SO2 emissions, and
consequently the number of NAAQS vio-
lations has declined. For example, the
Miami area went from 22 exceedances of
the 24-hour standard in 1982 to none in
recent years. Likewise for the 3-hour
standard, Miami went from 48
exceedances in 1982 to none in recent
years.
5-2
-------
Air Quality Trends 1980-95
SULFUR DIOXIDE Exceedances
Number of exceedances of the SO- NAAQS.
40
24-hour Primary Standard
= 365jig/m3)
Hawaii Volcanoes N P
- Morenci. AZ
Miami, AZ
Hayden, AZ
Douglas, AZ
Ajo, AZ
San Manuel. AZ
'80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91 '92 '93 '94 '95
Number of exceedances of
the NAAQS at one or more
locations.
NAAQS = National Ambient
Air Quality Standard.
3-hour Secondary Standard
(NAAQS = 1300 jig/m3)
Hawaii Volcanoes N.P
Morenci, AZ
Miami, AZ
Hayden, AZ
Douglas. AZ
Ajo, AZ
San Manuel, AZ
'80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91 '92 '93 '94 '95
Figure 5b
8-1296
5-3
-------
LEAD
BACKGROUND and HEALTH EFFECTS
Since the mid-1970's, lead (Pb) emis-
sions have been reduced over 95% -- the
most dramatic success thus far in the
nation's struggle for cleaner air. This has
been mainly the result of eliminating lead
from gasoline sold in the U.S. The elimi-
nation of lead emissions from transporta-
tion sources has changed the nature of
the ambient lead problem in the United
States from vehicle-related to one asso-
ciated with point stationary sources such
as smelters, battery plants, and solid
waste disposal. There are few such lead
point sources in Region 9.
Exposure to lead can occur through
multiple pathways, including inhalation of
air and ingestion of lead in food, water,
soil, or dust. Excessive lead exposure
can cause seizures, mental retardation,
and/or behavioral disorders. Fetuses,
infants, and children are especially sus-
ceptible to low doses of lead, resulting in
central nervous system damage. The
national health standard for lead is 1.5
micrograms per cubic meterof air (ug/m3)
average concentration over a three-month
period.
RECENT Pb AIR QUALITY IN REGION 9
Forthe two-year period 1994-95, lead
was monitored at 60 sites in Region 9.
Figure 6a shows the geographic distribu-
ii-VYA-,
REGION IX
AIR MONITORING STATIONS
FOR
LEAD
1994-95
6- 1
Figure 6a
-------
tion of the lead monitors throughout the
Region.
There were no violations of the na-
tional health standard at any sites during
1994-95. Lead concentrations are now
typically 5% of the Federal standard or
less. The only lead violation in the last
ten years was measured at a special pur-
pose monitor in 1991. The monitor is
sited near a lead smelter in Commerce,
located in the South Coast Air Basin.
Anti-pollution measures were subse-
quently put into place at this source, and
emissions were greatly reduced.
LONG-TERM LEAD TRENDS
For the Region as a whole, there
were 24 long-term monitors that operated
for the past ten years. These monitors,
as a group, showed an astounding 86%
decrease in maximum quarterly mean Pb
concentrations between 1986 and 1995.
This compares to an equally notable 86%
decrease at 197 sites nationwide.
Figure 6b shows the change in lead
concentrations for five areas of Region 9
since 1980. All five areas had a dramatic
96% to 97% reduction in lead concentra-
tions since 1980.
Air Quality Trends 1980-95
LEAD (Pb) Concentrations
Composite maximum quarterly mean concentrations.
NAAQS = 1.5
(highest quarterly mean
concentration).
NAAQS = National
Ambient Air Quality
Standard
Soulh Coast -97%
Phoenix -96%
Sacramento -97%
San Diego -97%
San Francisco Bay Area -97%
'80 '81 '82 '83 '84 '85 '86 '87 '88 '89 '90 '91 '92 '93 '94 '95
12-96
-------
AIR EMISSIONS SOURCES
Air Pollution Emissions
Human activity is responsible for
most air pollution. This chapter is a broad
overview of the pollution sources that con-
tribute to higher concentrations of carbon
monoxide, nitrogen dioxide, particular mat-
ter, and ground-level ozone. The emission
sources of two other air pollutants, sulfur
dioxide and lead, are not included here,
since ambient levels are very low through-
out our region.
The air pollution emissions in figure
7a are for the South Coast Air Basin (Los
Angeles area) for 1993, the most recent
year for which emissions have been esti-
mated. The South Coast was selected
because it represents an urban area with
high ambient concentrations of several air
pollutants. Other areas may have a some-
what different emissions mix.
The "pie charts" show emission
sources for volatile organic compounds
(VOC) and oxides of nitrogen (NOx), the two
ozone-forming pollutants, as well as emis-
sion sources for carbon monoxide (CO) and
particulate matter (PM10). The three pre-
dominant types of emissions are described
below.
Mobile Source (Vehicle) Emissions
This category is represented by the
magenta and red "pie slices" in figure 7a. It
is the largest emission source category for
three of the four pollutants presented. Mo-
bile sources include "on-road" motor ve-
hicles and "off-road" vehicles, such as trains
and ships. Total mobile sources account for
about 63 percent of VOC emissions, 84
percent of N0x emissions, and 99 percent
of CO emissions. The "on-road" portions
are 53, 64, and 82 percent, respectively.
Point Source Emissions
Point sources are generally large
emitters, such as manufacturing, chemical,
and petroleum production facilities, and
electric utilities. Point source emission
categories include petroleum processing,
storage and transfer, fuel combustion,
industrial processes, etc. The contribution
of point sources to the air pollution problems
is significant but smaller than the contribu-
tion from mobile sources.
Area Source Emissions
Area sources generally include many
small sources, such as residential water
heaters, architectural coatings, and travel-
related road dust (for PM10), etc. Area
sources account for 83% of the PM10 emis-
sions and a substantial part of the VOC
emissions.
7 1
-------
Figure 7a
AIR EMISSIONS ESTIMATES - South Coast Air Basin, CA
Relative Contribution by Source Category - 1993
Fuel Combustion 1 %
Solvent Usage,
27%
Petroleum
psr 4%
Other 5%
Off-Road
Dn-Road
53%
10%
voc
(Volatile Organic Compounds)
Fuel Combustion
11%
Other
1%
Other
1%
Off-Road
24%
Off-Road
17%
-Road
64%
NOx
(Nitrogen Oxides)
On-Roa
82%
Fuel Combustion 3%
On-Road Exhaust 6%
ff-Road Exhaust 4°,
Other 4%
CO
(Carbon Monoxide)
Area &
Road Dust
83%
* PST = Process, Storage & Transfer
7-2
PM10
(Particulate Matter)
-------
Enhanced Ozone Monitoring: PAMS Program in Region 9
REGULATORY BACKGROUND
The Clean Air Act Amendment
182(c)(1) requires States to promulgate
rules for enhanced monitoring of ozone
and its precursors, oxides of nitrogen, and
volatile organic compounds (VOC). These
rules are incorporated into the Code of
Federal Regulations (CFR). Title 40 CFR
Part 58 required Photochemical Assess-
ment Monitoring Stations (PAMS) as part
of State Implementation Plan monitoring
networks in ozone (O3) nonattainment ar-
eas classified as serious, severe, and ex-
treme. The principal reasons for PAMS
are to augment regional air and meteoro-
logical monitoring due to nonattainment
status of the NAAQS, and to satisfy the
need for a comprehensive database for
Region IX PAMS Networks
Area
South Coast
/Southeast
Desert
Class
Site Name
Extreme Pico Rivera Type #2
/Severe Upland Type #4/#1
Azusa Type #3
Banning - Type #2
Hawthorne - Type #1
San Diego Severe
Ventura
Severe
Sacramento Severe
San Joaquin Serious
Valley
El Cajon - Type #2
Overland - Type #2A
Alpine Type #3
Camp Pendleton Type #1
El Rio Type #2
Simi Valley - Type #3
Emma Wood Type #1
Del Paso - Type #2A
Folsom - Type #3
Elk Grove-Type #1
Golden State - Type #2
Clovis Type #2
Arvin Type #3
Parlier - Type #3
O3and precursors.
CALIFORNIA PAMS
For Region 9, PAMS networks exist
only in the State of California. The Cali-
fornia Air Resources Board (CARB) coor-
dinates the PAMS program in five areas,
namely Sacramento Metro, San Joaquin
Valley, Ventura County, South Coast/
Southeast Desert, and San Diego. Begin-
ning in 1993, these Districts were required
to measure speciated VOCs/carbonyls,
O3, NOX, and surface and upper air
meteorology. The table to the left lists the
existing PAMS by California District. Nine-
teen PAMS sites are in operation at this
time.
Each PAMS Network will consist of
as many as five stations, with the excep-
tion of the San Joaquin Valley and South
Coast/Southeast Desert consolidated ar-
eas which have proposed six PAMS by
1997 and 1998, respectively. Each PAMS
network will consist of four kinds of sta-
tions, designated as Type #1, #2, #3, and
#4, to fulfill specific data collection objec-
tives. The Type #1 site is located upwind
of the metropolitan area to measure O3
and precursors being transported into the
area. TheType #2 sites are located down-
wind of the central business district and
their main objective is to collect O3 precur-
sor emissions. At these sites, 56 hydro-
carbons and three carbonyls are the tar-
geted VOCs to be collected. The Type #3
stations measure maximum (^concentra-
tions and are sited downwind of the urban
area. And finally the Type #4 site is
located farther downwind of tho
nonattainment area. The primary pur-
pose of Type #4 sites is to measure O .md
8 1
-------
precursor concentrations exiting the area. Analysis of collected PAMS data is a
The figure below identifies general PAMS primary focus of the PAMS program. Ex-
network design requirements and visually ploratory analysis is already underway,
depicts the location of the different PAMS but comprehensive results will not be
sites. available until completed networks are
installed by 1998.
PAMS Network Design Q
Extreme Downwind
Required only for serious,
severe, and extreme areas
Requirements based on population
Ozone, NOx, and VOC monitoirng
required at each site
Monitoring season: (June-July-August)
(Calif: July-Aug-Sept)
©
Maximum Ozone
Secondary
Morning Wind
Five-year phase-in
Alternative networks allowed
Meteorological monitoring
* Surface - each site
* Upper air - 1 site/area
o
Upwind/Background
Primary
Morning Wind
Urbanized
Fringe
, f Primary
\ Attcrnnon Wind
8-2
**RNMENT PRINTING OFFICE 1996 -787-168
------- |