FINAL 

2003 AQMP APPENDIX II 

CURRENT AIR QUALITY 

AUGUST 2003 
SOUTH COAST AIR QUALITY MANAGEMENT DISTRICT 

GOVERNING BOARD 

Chairman: WILLIAM A. BURKE, Ed.D. 

 Speaker of the Assembly Appointee 

 

Vice-Chair: S. ROY WILSON, Ed.D. Supervisor, Fourth District 

Riverside County Representative 

Members:

FRED AGUIAR 

Supervisor, Fourth District 

San Bernardino County Representative 

MICHAEL D. ANTONOVICH 

Supervisor, Fifth District 

Los Angeles County Representative 

HAL BERNSON 

Councilmember, City of Los Angeles 

Cities Representative, Los Angeles County/Western Region 

JANE W. CARNEY 

Senate Rules Committee Appointee 

WILLIAM CRAYCRAFT 

Councilmember, City of Mission Viejo 

Cities Representative, Orange County 

BEATRICE LAPISTO-KIRTLEY 

Councilmember, City of Bradbury 

Cities Representative, Los Angeles County/Eastern Region 

RONALD O. LOVERIDGE 

Mayor, City of Riverside 

Cities Representative, Riverside County 

LEONARD PAULITZ 

Mayor Pro-Tem, City of Montclair 

Cities Representative, San Bernardino County 

CYNTHIA VERDUGO-PERALTA 

Governor’s Appointee 

JAMES W. SILVA 

Supervisor, Second District 

Orange County Representative 

EXECUTIVE OFFICER

Barry R. Wallerstein, D.Env. 
CONTRIBUTORS

Barry R. Wallerstein, D.Env. 

Executive Officer 

Elaine Chang, DrPH 

Deputy Executive Officer 

Planning, Rule Development and Area Sources 

Laki Tisopulos, Ph.D., P.E. 

Assistant Deputy Executive Officer 

Planning, Rule Development and Area Sources 

Zorik Pirveysian 

Planning and Rules Manager 

Planning, Rule Development and Area Sources 

Authors: With the Assistance of:

Planning & Rules 

Joe Cassmassi 

Shoreh Cohanim 

Information Technology 

Curt Miller 

Tom Parsons 

Sandra Hom 

Production: U. S. Environmental Protction Agency:

Planning & Rules 

Patti Whiting 

Faye Thomas 

Region IX 

Coe Owen 

Table Of Contents 

i

Table of Contents 

SUMMARY 

Summary .................................................................................................................II-S-1 

South Coast Air Basin..................................................................................II-S-1 

Riverside County Salton Sea Air Basin.......................................................II-S-2 

Seasonal, Day-of-Week and Diurnal Variations .........................................II-S-2 

CHAPTER 1 INTRODUCTION 

Introduction.............................................................................................................II-1-1

Air Quality Overview ..................................................................................II-1-1 

Air Quality Standards and Episode Levels..................................................II-1-2 

South Coast Air Quality Management District............................................II-1-3 

South Coast, Salton Sea and Mojave Desert Air Basins .............................II-1-4 

Weather ........................................................................................................II-1-4 

Emissions. ....................................................................................................II-1-5 

Air Quality Trends .......................................................................................II-1-6 

Air Quality in the District Compared to Other Areas of the U.S. ...............II-1-6 

CHAPTER 2 AIR QUALITY IN THE SOUTH COAST AIR BASIN 

Air Quality in the South Coast Air Basin ...............................................................II-2-1 

Ozone (O3) ...................................................................................................II-2-1 

Carbon Monoxide (CO)...............................................................................II-2-9 

Suspended Particulate Matter (PM10) ........................................................II-2-14 

Suspended Particulate Matter (PM2.5)........................................................II-2-19 

Nitrogen Dioxide (NO2).............................................................................II-2-22 

Sulfur Dioxide (SO2) .................................................................................II-2-24 

Sulfate (SO4

=

).............................................................................................II-2-25 

Lead (Pb)....................................................................................................II-2-26 

CHAPTER 3 AIR QUALITY IN THE RIVERSIDE COUNTY SSAB 

Air Quality in the Riverside County SSAB............................................................II-3-1 

Ozone (O3) ...................................................................................................II-3-2 

Suspended Particulate Matter (PM10) ..........................................................II-3-2 

Suspended Particulate Matter (PM2.5)..........................................................II-3-3 

Carbon Monoxide (CO)...............................................................................II-3-4 

Nitrogen Dioxide (NO2)...............................................................................II-3-4 

Sulfur Dioxide (SO2) ...................................................................................II-3-4 
Final 2003 AQMP Appendix II: Current Air Quality 

ii

Sulfate (SO4

=

)...............................................................................................II-3-4 

Lead (Pb)......................................................................................................II-3-5 

ATTACHMENT 

LIST OF FIGURES: 

Figure 1-1: 2001 Maximum Pollutant Concentrations As 

Percent of Standards ....................................................................................II-1-1 

Figure 1-2: South Coast Air Quality Management District...................................II-1-3 

Figure 1-3: 1997 Average Daily Emissions...........................................................II-1-5 

Figure 1-4: Percent Basin-Days Exceeding the Federal Satandard, 

1976-2001 ....................................................................................................II-1-6 

Figure 1-5: Ozone - 1998-2000, Average Number of Days 

Exceeding Federal Standard ........................................................................II-1-7 

Figure 2-1: Monthly Number of Days Exceeding Federal Standards in 2001 ......II-2-2 

Figure 2-2: Ozone - 2001, Number of Days Exceeding 1-Hour 

Federal Standard ..........................................................................................II-2-4 

Figure 2-3: Ozone - 2001, Number of Days Exceeding 8-Hour 

Federal Standard ..........................................................................................II-2-5 

Figure 2-4: 5-Year Average Number of Days Per Month Exceeding 

Federal Ozone Standard in the Basin...........................................................II-2-6 

Figure 2-5: Ozone, Diurnal Variation, May-October 2001, Maximum 

Concentration for Each Hour.......................................................................II-2-7 

Figure 2-6: Ozone, Day-of-Week Variation, 1999-2001, Exceedances 

of the Federal Standard by Day of Week.....................................................II-2-8 

Figure 2-7: Carbon Monoxide - 2001, Maximum 8-Hour Average 

Concentration, ppm....................................................................................II-2-10 

Figure 2-8: Carbon Monoxide, Seasonal Variation, 1999-2001, Average 

Monthly Exceedances of Federal Standard ...............................................II-2-11 

Figure 2-9: Carbon Monoxide, Diurnal Variation, 2001, Maximum 

Concentration for Each Hour.....................................................................II-2-12 
Table Of Contents 

iii

Figure 2-10: Carbon Monoxide, Day-of-Week Variation, 1999-2001, 

Average Concentrations by Day of Week .................................................II-2-13 

Figure 2-11: Chemical Composition of PM10, 1995............................................II-2-15 

Figure 2-12: Suspended Particulate Matter (PM10) - 2001, Annual 

Arithmetic Mean, μg/m3............................................................................II-2-17

Figure 2-13: Basin-Days Exceeding State PM10 Standard by 

Month, 1999-2001 .....................................................................................II-2-18 

Figure 2-14: Monthly Average PM10 Concentration, 1999-2001........................II-2-18 

Figure 2-15: Day-of-Week Variation, 1999-2001, Average PM10 

Concentration by Day of Week .................................................................II-2-19 

Figure 2-16: Suspended Particulate Matter (PM2.5) - 2001, Annual 

Arithmetic Mean, μg/m3............................................................................II-2-20

Figure 2-17: PM2.5 Seasonal Variation, 1999-2001, Average Number 

of Basin-Days Exceeding Federal Standard by Month .............................II-2-21 

Figure 2-18: PM2.5 Day-of-Week Variation, 1999-2001, Basin-Days 

Exceeding the Federal Standard by Day of Week.....................................II-2-22 

Figure 3-1: Maximum Pollutant Concentrations as Percent of 

Standards, Riverside County SSAB ............................................................II-3-1 

LIST OF TABLES: 

Table 1: 2001 Maximum Annual Average Nitrogen Dioxide 

Concentrations ...........................................................................................II-2-23 

Table 2: 2001 Maximum 24-Hour Average Sulfur Dioxide 

Concentrations ...........................................................................................II-2-25 

Table 3: 2001 Maximum 24-Hour Average Sulfate Concentrations...................II-2-26 

Table 4: 2001 Maximum Quarterly Average Lead Concentrations ....................II-2-27 
Final 2003 AQMP Appendix II: Current Air Quality 

iv

ATTACHMENT LIST: 

Table A-1: Ambient Air Quality Standards 

Table A-2: Episode Criteria 

Table A-3: Air Monitoring Stations and Source/Receptor Areas 

Figure A-1:South Coast Air Basin and Adjoining Areas of SaltonSea Air Basin 

Table A-4: Ozone - Number of Days Exceeding the Federal Standard 

Table A-5: Ozone, 1976 - 2001, Annual Number of Days of First/Second Stage 

Episodes 

Table A-6: Ozone - Annual Maximum 1-Hour, ppm, 1955-2001 

Table A-7: Carbon Monoxide - Number of Days Maximum 8-Hour Average 

Exceeded the Federal Standard 

Table A-8: Carbon Monoxide - Number of Days Maximum 8-Hour Average 

Exceeded the Federal Alert Level 

Table A-9: Carbon Monoxide, Annual Maximum 8-Hour Average, ppm, 

1976-2001 

Table A-10: Suspended Particulates (PM10), Annual Arithmetic Mean, 

μg/m3

, 1985-2001 

Table A-11: Suspended Particulates (PM10), Annual Geometric Mean, 

μg/m3

, 1985-2001 

Table A-12: Suspended Particulates (PM10) - Percent of Sampling Days 

 Exceeding State Standard and Federal Standards, 1985-2001 

Table A-13: Suspended Particulates (PM10), Annual Maximum 24-Hour 

Average, μg/m3, 1985-2001 

Table A-14: Nitrogen Dioxide - Annual Average of All Hours, pphm, 

1976-2001 

Table A-15: Nitrogen Dioxide - Number of Days 1-Hour Average Exceeded 

the State Standard, 1976-2001 

Table A-16: Nitrogen Dioxide, Annual Maximum 1-Hour, ppm, 1976-2001 
Table Of Contents 

v

Table A-17: Sulfur Dioxide - Annual Average, pphm, 1976-2001 

Table A-18: Sulfur Dioxide, Annual Maximum 1-Hour Average, ppm, 

1976-2001 

Table A-19: Sulfate - Percent of Sampling Days Exceeding the State 

Standard, 1976-2001 

Table A-20: Sulfate - Maximum 24-Hour Averages, 1976-2001 

Table A-21: Lead - Highest Calendar Quarter Mean, μg/m3

, 1976-2001 

Table A-22: Lead - Highest Monthly Averages, μg/m3

, 1976-2001 
CHAPTER 1 

INTRODUCTION 

Chapter 1 Introduction 

II-1-1

INTRODUCTION 

Air Quality Overview 

In 2001, the South Coast Air Quality Management District (District) monitored 

ambient air quality for criteria pollutants (ozone, carbon monoxide, nitrogen dioxide, 

sulfur dioxide, particulate matters, lead and sulfate) at 32 locations in Southern 

California’s South Coast Air Basin (Basin) and in the neighboring areas of the 

Salton Sea Air Basin (SSAB) that are within the District's jurisdiction. Pollutant 

concentrations exceeded federal and/or state standard(s) for ozone and particulate 

matters (PM10 and PM2.5). Figure 1-1 shows the maximum pollutant 

concentrations for 2001 as a percentage of the federal standards. 

 * There is no federal standard for sulfate. 

** Higher measurements were recorded at special monitoring sites immediately adjacent to sources. 

FIGURE 1-1 

2001 Maximum Pollutant Concentrations as Percent of Standards 

Maximum 1-hour average and 8-hour average ozone concentrations in 2001 (0.190 

ppm and 0.144 ppm) were 152% and 169% of the federal 1-hour and 8-hour 

standards, respectively. Maximum 24-hour average and annual average PM10 

concentrations (219 μg/m3

 and 63.1 μg/m3) were 146% and 125% of the federal 24-

Percent of Standard

0

50

100

150

200

250

Ozone Ozone Carbon Nitrogen Sulfur PM2.5 PM10 Sulfate* Lead**

Monoxide Dioxide Dioxide

(1-Hour) (8-Hour) (8-Hour) (Annual) (Annual) (Annual) (Annual) (24-Hour) (Quarter)

STANDARD
Final 2003 AQMP Appendix II: Current Air Quality 

II-1-2

hour and annual standards, respectively. Maximum 24-hour average and annual 

average PM2.5 concentrations (98.0 μg/m3

 and 31.1 μg/m3) were, respectively, 

150% and 201% of the federal 24-hour and annual standards. Carbon monoxide 

concentration did not exceed the standards in 2001. The highest 8-hour average 

carbon monoxide concentration of the year (7.71 ppm) was 81% of the federal 

standard. 

In 2001, the federal nitrogen dioxide standard was not exceeded, with a maximum 

concentration (0.0419 ppm) which was 78% of the federal standard. The maximum 

1-hour average nitrogen dioxide concentration (0.25 ppm) was 96% of the state 

standard. The maximum 24-hour sulfate concentration (20.6 μg/m3

) was 82% of the 

state standard. (There is no federal sulfate standard.) Sulfur dioxide and lead 

concentrations continued to remain well below the federal and state standards in 

2001. 

Air Quality Standards and Episode Levels 

Both the federal and state governments have adopted ambient air quality standards, 

which define the concentration below which long-term exposure to a pollutant is not 

expected to cause adverse effects to public health and welfare. Episode levels have 

also been established, below which short-term exposures are not expected to be 

injurious to health. The standards and episode levels are summarized in Tables A-1 

and A-2 in the Attachment. 

Both standards and episode levels are periodically reviewed to incorporate the 

findings from the most current research available on effects of pollutants. In 1997, 

the U.S. EPA adopted new federal air quality standards for particulate matter and 

ozone. The 8-hour average ozone standard (0.08 ppm) would protect the public 

health against the effects of prolonged exposure and represents a tightening of the 1-

hour ozone standard. For particulate matter, annual and 24-hour standards for the 

finest fraction of particulate, PM2.5 (particles less than 2.5 micrometer), was 

established to complement the PM10 federal and state standards that target a full 

range of inhalable particulate matter. PM2.5 is estimated to be the most injurious to 

health and causes the greatest visibility reduction. The form of the 24-hour PM10 

standard was also revised. The 1-hour average ozone standard and the annual PM10 

standard are retained. 
Chapter 1 Introduction 

II-1-3

South Coast Air Quality Management District 

California’s first local air pollution control agency, the Los Angeles County Air 

Pollution Control District (LAAPCD), was formed in 1947 and APCDs were formed 

in Orange, Riverside, and San Bernardino counties not long afterward. These four 

agencies combined in 1976 to form the Southern California APCD, which was later 

replaced by the South Coast Air Quality Management District and the Mojave 

Desert APCD. 

The South Coast Air Quality Management District was established by state 

legislation effective February 1, 1977, and was assigned jurisdiction over air quality 

in the South Coast Air Basin. The District is also responsible for air quality in the 

Riverside county area of the Salton Sea Air Basin (SSAB), by contract with the 

county. The South Coast Air Quality Management District is the name applied both 

to the agency and to the geographic jurisdiction which region it serves. The region 

encompassed by the District is shown in Figure 1-2. In 2001, the District 

maintained a network of 30 air monitoring stations in the Basin and an additional 

two in the District portions of SSAB (shown in Figure A-1 and Table A-3 in the 

Attachment). 

Antelope Valley 

COUNTY

MDAB

South Coast

Air Quality Management District

0 50

SOUTH C OAST

AIR B ASIN (SOCA B)

MOJAV E DE SE RT AIR

BASIN (M DAB)

SCA QMD J URISDIC TION

J UN E 1996 R EVISION

MILES

LOS ANGELES COUNTY

RI VER SIDE C OUNT Y

KE RN C OUNTY

IMPERIAL COUNT Y

SAN DIEGO COUNTY BOUNDAR IES COUN TY

Antelope Valley

SCAQM D AIR

MONITOR ING STATION

SOCAB SAN BERNARDINO COU NTY

ORANGE

COUNTY

Coachella

Valley

SSAB

SA LTON SEA

AIR B ASIN (SSAB)
Final 2003 AQMP Appendix II: Current Air Quality 

II-1-4

FIGURE 1-2 

South Coast Air Quality Management District 

South Coast, Salton Sea and Mojave Desert Air Basins 

The South Coast Air Basin (Basin) has an area of 6800 square miles and the 

population was 15 million in 2001. It includes all of Orange county and the nondesert areas of Los Angeles, Riverside and San Bernardino counties. The Los 

Angeles urban area (the nation’s second largest) and the Anaheim-Fullerton and 

Riverside-San Bernardino urban areas lie within the Basin’s boundaries. About twothirds of the Basin’s population lives within Los Angeles county. 

The Salton Sea Air Basin and the Mojave Desert Air Basin (MDAB) have a 

combined area of approximately 32,200 square miles. The two Basins include the 

desert portions of Los Angeles, Riverside and San Bernardino counties as well as 

Imperial county and part of Kern county. 

The SSAB and MDAB were previously included in a single large Basin called the 

Southeast Desert Air Basin (SEDAB). The SEDAB also included the San Gorgonio 

Pass area. On May 30, 1996, the California Air Resources Board replaced the 

SEDAB with the SSAB and MDAB, and transferred the San Gorgonio Pass area to 

the Basin. In July 1997, the Antelope Valley area of MDAB was separated from the 

District and incorporated into a new air district under the jurisdiction of the newly 

formed Antelope Valley Air Pollution Control District (AVAPCD). 

The South Coast Air Quality Management District has the jurisdiction over the 

Coachella Valley portion of Riverside county in SSAB. The population in the 

SSAB portion under the jurisdiction of the District is about 300,000. The District 

also has the jurisdiction over a small portion of the MDAB in eastern Riverside 

county. The area is sparcely populated desert. 

Weather 

The South Coast Air Basin is arid, with virtually no rainfall and abundant sunshine 

during the summer months. It has light winds and poor vertical mixing compared to 

the other large urban areas in the U.S. The combination of poor dispersion and 

abundant sunshine provide conditions especially favorable to the formation of 

photochemical smog. The Basin is also bounded to the north and east by mountains 

with maximum elevations exceeding 10,000 feet. The unfavorable combination of 

meteorology, topography, and emissions from the nation’s second largest urban area 

result in the Basin having the worst air quality in the U.S. More detailed 

information on Basin climatology appeared in a previous District publication. 
Chapter 1 Introduction 

II-1-5

Emissions 

The amount of each of the major pollutants emitted into the atmosphere of the Basin 

in 1997 is shown in Figure 1-3. In 1997, approximately 7800 tons of carbon 

monoxide (CO), 1400 tons of oxides of nitrogen (NOx), 1200 tons of volatile 

organic compounds (VOC), 80 tons of oxides of sulfur (SOx), 330 tons of directly 

emitted particulate (PM10), 120 tons of finer particlate (PM2.5), and 600 tons of 

total suspended particulate (TSP) were emitted into the Basin’s atmosphere each 

day. (Additional PM10 forms by chemical reaction of the gaseous pollutants.) 

Emissions vary relatively little by season, but there are large seasonal differences in 

the atmospheric concentrations of pollutants due to seasonal variations in the 

weather. (Details of the 1997 emissions inventory are contained in Appendix III.) 

Volatile organic compounds and oxides of nitrogen are precursors of ozone. Oxides 

of nitrogen and volatile organic compounds also react to form nitrates and solid 

organic compounds, which are a significant fraction of PM10. Sulfur dioxide reacts 

to form sulfates which are likewise significant contributors to the Basin’s PM10 and 

PM2.5. In addition to the PM10 formed by reaction of gaseous precursors, there is 

directly emitted PM10, most of which is attributed to fugitive dust sources such as 

re-entrained road dust, construction activities, farming operations and wind-blown 

dust. 

FIGURE 1-3 

1997 Average Daily Emissions in the Basin 

01234567

PM2.5

PM10

TSP

SOx

NOx

VOC

CO

Thousands Tons/Day
Final 2003 AQMP Appendix II: Current Air Quality 

II-1-6

Air Quality Trends 

In 2001, the SCAB locations exceeded one or more of the federal standards on 37 

days (excluding the recently adopted 8-hour ozone and PM2.5 standards 

exceedances). 

Figure 1-4 shows the long-term annual trend of percent "basin-days" exceedances of 

the federal standards. (A "basin-day" is recorded if any location in the South Coast 

Air Basin exceeds the standard. Multiple locations exceeding on the same day count 

as a single basin-day.) 

FIGURE 1-4 

Percent Basin-Days Exceeding the Federal Standards, 1976-2001 

Air Quality in the District Compared to Other Areas of the U.S. 

Despite the significant downtrend, the South Coast Air Basin still has some of the 

worst air quality in the nation in terms of the annual number of days exceeding the 

federal standards. In 2001, the highest U.S. location in terms of number of days 

over the federal ozone standard was located in the Basin (Central San Bernardino 

Percent Basin-Days

0%

25%

50%

75%

100%

76 78 80 82 84 86 88 90 92 94 96 98 00

All Standards O3 (1-Hour)

CO (8-Hour) PM10 (24-Hour)
Chapter 1 Introduction 

II-1-7

Mountains, 26 days). Other area with the greatest number of exceedances outside 

California was located in the Houston Metropolitan Area, Texas (10 days). Figure 

1-5 shows the average number of days on which the federal ozone standard was 

exceeded at U.S. locations for the years 1998-2000. 

Over the past decade, reductions in vehicular emissions have reduced carbon 

monoxide levels throughout the U.S., and many areas have ceased violating the 

standards. In 2001, the Basin continued to rank among the areas of the U.S. with 

high 8-hour average carbon monoxide concentration, although it did not exceed the 

standards. 

The Basin exceeded the federal 24-hour average and annual PM10 standards in a 

few areas in 2001. The highest 24-hour average PM10 concentration in the U.S. 

was recorded at a location in the Great Basin Valleys Air Basin in California. More 

detailed information on air quality in the U.S. is available in EPA's annual National 

Air Quality and Emissions Trend Report. 

FIGURE 1-5 

OZONE, 1998-2000 

Average Number of Days Exceeding the Federal Standard 
Final 2003 AQMP Appendix II: Current Air Quality 

II-1-8

The following two chapters of this report summarize current air quality in the 

District. Analyses are presented for: 

• Ozone (O3) 

• Carbon monoxide (CO) 

• Nitrogen dioxide (NO2) 

• Sulfur dioxide (SO2) 

• Particulate matter (PM10) 

• Particulate matter (PM2.5) 

• Lead (Pb) 

• Sulfate (SO4

=

) 

Chapters 2 and 3 contain summaries of air quality in the South Coast Air Basin, and 

the Riverside county portion of Salton Sea Air Basin, respectively. Salton Sea Air 

Basin includes Coachella Valley. For those pollutants still designated as 

nonattainment, maps are presented which show how air quality varies in different 

areas in the Basin. Detailed air quality statistics for each of the District’s monitoring 

locations in the Basin and SSAB are contained in the attachment to this report. 

A brief update of air quality trends through 2001 are presented in this report. 

Detailed analyses of air quality trends in the Basin are available in Appendix II of 

the 1997 AQMP and the December editions of the Air Quality Standards 

Compliance Reports (AQSCR's). 
CHAPTER 2 

AIR QUALITY IN THE SOUTH COAST AIR BASIN 

Chapter 2 Air Quality in the South Coast Air Basin 

II-2-1 

AIR QUALITY IN THE SOUTH COAST AIR BASIN 

The maximum pollutant concentrations recorded at District monitoring stations in 

2001 (Figure 1-1 in Chapter 1) were all recorded in the densely populated South 

Coast Air Basin. However, air quality in the Basin varies widely by season and by 

area. 

The prevailing daytime sea breeze tends to transport pollutants from coastal areas 

into the Basin’s inland valleys, and from there, still further inland into neighboring 

areas of Salton Sea Air Basin of the District as well as the MDAB. Concentrations 

of primary pollutants (those emitted directly into the air) are typically highest close 

to the sources which emit them. However, secondary pollutants (those formed in the 

air by chemical reaction of precursors) reach maximum concentrations some 

distance downwind of the sources that emit the precursors, due to the fact that the 

polluted air mass is moved inland many miles by the prevailing winds before 

maximum concentrations are reached. 

The Basin’s air quality varies with season due to seasonal differences in the weather. 

In Figure 2-1, the number of days exceeding federal standards for each criteria 

pollutant is shown for each month of 2001. All of the ozone exceedances occurred 

during the May to October “smog season.” Particulate matter (PM10 and PM2.5) 

standards are exceeded at times throughout the year and do not have a clear pattern 

like ozone and carbon monoxide. PM2.5 exceedances, however, typically occur 

more frequently during late fall and early winter months. The standards were 

exceeded on a total of 54 days in 2001 (37 days excluding PM2.5). 

Ozone (O3) 

Properties

The Basin's unique air pollution problem first began to be recognized in the 1940's. 

Unlike the smog in many other urban areas, the Los Angeles smog was worse in 

summer. Early research showed that ozone was being formed in the Basin's 

atmosphere from hydrocarbons and oxides of nitrogen being emitted into the air in 

the presence of steady sunshine. Regular monitoring of total oxidants was begun by 

the Los Angeles Air Pollution Control District (LAAPCD) in the 1950’s, and annual 

maximum 1-hour ozone concentrations in excess of 0.6 ppm were recorded at that 

time. 

Ozone (O3), a colorless gas with a sharp odor, is a highly reactive form of oxygen. 

High ozone concentrations exist naturally in the stratosphere. Some mixing of 

stratospheric ozone downward through the troposphere to the earth's surface does 

occur; however, the extent of ozone transport is limited. At the earth's surface in 
Final 2003 AQMP Appendix II: Current Air Quality 

II-2-2

sites remote from urban areas ozone concentrations are normally very low (0.03-

0.05 ppm). 

 * Basin-days represents the number of days a standard was exceeded anywhere in the Basin. 

** Number of exceedances due to PM10 may have been higher, since PM10 samples are collected every 6 

days (or every 3 days at a few sites). 

FIGURE 2-1 

Monthly Number of Days Exceeding Federal Standards in 2001 

In urban areas, ozone is formed by a complicated series of chemical and 

photochemical reactions between reactive organic compounds, nitrogen oxides, and 

the oxygen in the air. A decrease in ozone precursors may or may not give a 

decrease in ozone. Ozone concentrations are dependent not only on overall 

precursor emissions, but on the ratio of hydrocarbon concentration to oxides of 

nitrogen concentration, the reactivity of the specific hydrocarbons present, the 

spatial and temporal distribution of emissions, and weather. 

While ozone is beneficial in the stratosphere because it filters out skin-cancercausing ultraviolet radiation, it is a highly reactive oxidant. It is this reactivity which 

accounts for its damaging effects on materials, plants, and human health at the 

earth's surface. 

The propensity of ozone for reacting with organic materials causes it to be damaging 

to living cells, and ambient ozone concentrations in the Basin are frequently 

sufficient to cause health effects. Ozone enters the human body primarily through 

the respiratory tract and causes respiratory irritation and discomfort, makes 

breathing more difficult during exercise, and reduces the respiratory system's ability 

Basin-Days Exceeding*

0

2

4

6

8

10

12

14

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Ozone (1-Hour)

CO (8-Hour)

PM10 (24-Hour)**

PM2.5 (24-Hour)

2 or More Standards
Chapter 2 Air Quality in the South Coast Air Basin 

II-2-3 

to remove inhaled particles and fight infection. People with respiratory diseases, 

children, the elderly, and people who exercise heavily are more susceptible to the 

effects of ozone. 

Plants are sensitive to ozone at concentrations well below the health-based standards 

and ozone is responsible for significant crop damage. Ozone is also responsible for 

damage to forests and other ecosystems. 

Federal 8-Hour Ozone Standard

Studies have shown that even relatively low concentrations of ozone, if continued 

for several hours, can significantly reduce lung function in normal healthy people. 

In July 1997, the U.S. Environmental Protection Agency (U.S. EPA) adopted an 8-

hour average federal ozone standard with a level of 0.08 ppm. The new standard 

was based on exposure studies reporting health effects associated with long-term (6 

to 8 hours) exposures at levels below the level of the 1-hour standard. The 8-hour 

ozone standard is more stringent than the 1-hour standard and provides greater 

protection to public health than the 1-hour standard. It will help protect people who 

spend a significant amount of time working or playing outdoors -- a group that is 

particularly vulnerable to the effects of ozone. The federal 1-hour ozone standard 

continues to apply in non-attainment areas (including the District), where the 

standard is still violated. 

The effect of the adopted 8-hour ozone standard on this region's attainment of 

federal ozone standards has been evaluated by comparing the number of 

exceedances of the 1-hour standard (0.12 ppm 1-hour average) with the number of 

exceedances of 8-hour average concentrations of 0.08 ppm. The number of 

exceedances in different areas in the Basin and SSAB vary; however, there are a 

greater number of days exceeding the federal 8-hour ozone standard level in most 

areas, especially in the inland valleys and adjacent mountains where high ozone 

concentrations normally occur. 

Current Ozone Air Quality

In 2001, the District measured ozone concentrations at 28 regular ambient 

monitoring locations. The maximum 1-hour average and 8-hour ozone 

concentrations in the Basin in 2001 (0.190 ppm and 0.144) were 152% and 169% of 

the federal 1-hour and 8-hour standards, respectively, and 190% of the state 

standard. The federal 1-hour ozone standard was exceeded at one or more Basin 

locations on a total of 36 days, the 8-hour standard was exceeded on 100 days. The 

California state standard was exceeded on 121 days, and the health advisory level on 

15 days. The stage 1 episode level (1-hour average ≥ 0.20 ppm) was not exceeded 

anywhere in the Basin for the third consecutive year. 
Final 2003 AQMP Appendix II: Current Air Quality 

II-2-4

Figure 2-2 is a contour diagram of the number of days exceeding the 1-hour federal 

ozone standard in different areas of the Basin in 2001. The standard was exceeded 

most frequently in the Basin's Central San Bernardino Mountains and adjacent 

valleys. The coastal areas of Los Angeles and Orange counties and areas near the 

boundary between the Basin and San Diego county did not exceed the 1-hour federal 

ozone standard. 

The more stringent state standard was exceeded almost everywhere in the Basin with 

the greatest number of exceedances occuring in the Central San Bernardino 

Mountains and adjacent valleys (not shown). 

A decade ago, only the coastal areas of the Basin did not record exceedances of the 

stage 1 episode level (1-hour average O3 greater than or equal to 0.20 ppm). In 

2001, stage 1 episodes were not recorded anywhere in the Basin. In addition, there 

have been no exceedances of the stage 2 episode level (1-hour average O3 greater 

than or equal to 0.35 ppm) since 1988 and the stage 3 episode level (1-hour average 

O3 greater than or equal to 0.50 ppm) has not been exceeded since 1974. 

FIGURE 2-2 

OZONE - 2001 

Number of Days Exceeding 1-Hour Federal Standard 

(1-hour average ozone > 0.12 ppm) 
Chapter 2 Air Quality in the South Coast Air Basin 

II-2-5 

Figure 2-3 shows the number of days exceeding the 8-hour federal standard in the 

Basin in 2001. The 8-hour federal ozone standard was also exceeded most 

frequently in the Basin's Central San Bernardino Mountains and adjacent areas. The 

federal standards were not exceeded in the coastal areas. 

FIGURE 2-3 

OZONE - 2001 

Number of Days Exceeding 8-Hour Federal Standard 

(8-hour average ozone > 0.08 ppm) 

Table A-4 in the Attachment shows the number of exceedances of the 1-hour federal 

ozone standard at all District air monitoring sites, for all years for which data was 

available during the period 1976-2001. Tables A-5 and A-6 show the number of 

days exceeding stage 1 and stage 2 episode levels and the maximum1-hour ozone 

concentrations. 
Final 2003 AQMP Appendix II: Current Air Quality 

II-2-6

Seasonal Variation

Because photochemical reactions require sunlight to proceed, ozone formation is 

favored by strong solar radiation. Solar radiation is more intense and of longer 

duration, and temperature inversions are stronger and more persistent, in summer 

than in winter. This causes ozone concentrations to be higher in summer than in 

winter. Peak ozone concentrations generally occur near the middle of the day during 

the period May through October. 

Figure 2-4 shows the 5-year average of number of days per month exceeding the 

federal ozone standard for the period 1976-2000. Up until the late 1980's it was 

common to have days exceeding the federal ozone standard as early as February and 

as late as November and December. In late 1990's (since 1996) there have been no 

federal standard exceedances recorded in the months of January-March and 

November-December. Also, the frequency of exceedances in fall (September and 

October) has been reduced significantly in the recent years. 

FIGURE 2-4 

5-Year Average of Number of Days Per Month 

Exceeding Federal Ozone Standard in the Basin 

0

5

10

15

20

25

30

35

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Days Exceeding

76-80

81-85

86-90

91-95

96-00
Chapter 2 Air Quality in the South Coast Air Basin 

II-2-7 

Diurnal Variation

Because time and sunlight are required for the precursor organic gases and nitrogen 

oxides to react to form ozone, peak ozone concentrations usually occur from 

afternoon to early evening. By this time, the prevailing sea breeze has moved the 

polluted air mass miles inland from the major sources of precursor emissions. 

Figure 2-5 illustrates the maximum ozone concentrations for each hour of the day 

for the smog season (May-October) of 2001 at three representative areas in the 

Basin. The diurnal pattern in these areas, coastal area of Los Angeles county, inland 

valley area and San Bernardino mountain area, depicts diurnal formation and impact 

of ozone transport. 

Ozone concentrations in the Basin are typically low during early morning hours, 

increasing rapidly after sunrise and peaking in the afternoon. However, peak 

concentrations occur earlier in the day for coastal areas and later in the day for 

locations further downwind. Examining diurnal variation throughout the District, 

the time of the peak concentration was found to vary from noon - 1 p.m. PST in 

coastal-central Los Angeles county, to 4 - 7 p.m. in the farthest inland Basin and 

SSAB locations. 

FIGURE 2-5 

OZONE 

Diurnal Variation, May-October 2001 

Maximum Concentration for Each Hour 

0

5

10

15

20

25

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

HOUR, PST

Concentration, ppm

East San Gabriel Valley

South Coastal Los Angeles County

Central San Bernardino Mountains
Final 2003 AQMP Appendix II: Current Air Quality 

II-2-8

In East San Gabriel Valley, an area typical of the inland valley areas of the Basin 

where high ozone concentrations occur, concentrations are usually low at night and 

remain relatively low until mid-morning, reaching peak concentrations in the 

afternoon around 1 - 3 p.m. Diurnal variation in the South Coastal Los Angeles 

county area where ozone concentrations are typically low, show a similar pattern 

except that the peak concentrations are lower. In the mountain area where the 

Basin's highest concentrations have been recorded in recent years, concentrations are 

usually higher all the times and the peak is reached later in the afternoon around 4 - 

5 p.m. and remains relatively high through out the evening hours during the smog 

season. 

Day-of-Week Variation

Since the mid-1970s, it has been documented that ozone concentrations in the Basin 

are higher on weekends than on weekdays, in spite of the fact that ozone pollutant 

precursors are lower on weekends than on weekdays. Similar effects have been 

observed in some other metropolitan areas in the nation such as San Francisco, 

Washington D.C., Philadelphia and New York. 

Figure 2-6 shows the three-year average number of exceedances of the federal 1-

hour ozone standard for each day of the week in the Basin for the period 1999-2001. 

The number of exceedances was higher on Sundays followed by Saturdays. Fridays 

FIGURE 2-6 

OZONE 

Day-of-Week Variation, 1999-2001 

Exceedances of the Federal Standard by Day of Week 

Average Number of Exceedances

0

2

4

6

8

10

12

Mon Tue Wed Thu Fri S at S un
Chapter 2 Air Quality in the South Coast Air Basin 

II-2-9 

exceeded least. Average ozone concentrations also show a pattern similar to the 

average number of exceedances, with weekends tending to be higher than weekdays. 

The California Air Resources Board (ARB) has sponsored several research projects 

to study the causes of elevated ozone levels on weekends in the Basin. Changes in 

daily patterns that impact the quantity and temporal loading of emissions have been 

suggested as strongly contributing to observations. Carryover of matured precursor 

from weekdays to weekends is also suggested as contributing factor. 

Carbon Monoxide (CO) 

Properties

Carbon monoxide (CO) is a colorless, odorless, relatively inert gas. It is a trace 

constituent in the unpolluted troposphere, and is produced by both natural processes 

and human activities. In remote areas far from human habitation, carbon monoxide 

occurs in air at an average background concentration of 0.04 ppm, primarily as a 

result of natural processes such as forest fires and the oxidation of methane. Global 

atmospheric mixing of CO from urban and industrial sources creates higher 

background concentrations (up to 0.20 ppm) near urban areas. The major source of 

CO in urban areas is incomplete combustion of carbon-containing fuels, mainly 

gasoline. In 1997, 97% of the CO emitted into the Basin's atmosphere was from 

mobile sources. Consequently, CO concentrations are generally highest in the 

vicinity of major concentrations of vehicular traffic. 

Carbon monoxide is a primary pollutant, meaning that it is directly emitted into the 

air, not formed in the atmosphere by chemical reaction of precursors, as is the case 

with ozone and other secondary pollutants. Ambient concentrations of CO in the 

Basin exhibit large spatial and temporal variations, due to variations in the rate at 

which CO is emitted, and in the meteorological conditions that govern transport and 

dilution. Unlike ozone, CO tends to reach high concentrations in the fall and winter 

months. The highest concentrations frequently occur on weekdays at times 

consistent with rush hour traffic and late night during the coolest, most stable 

portion of the day. 

When carbon monoxide is inhaled in sufficient concentration, it can displace oxygen 

and bind with the hemoglobin in the blood, reducing the capacity of the blood to 

carry oxygen. Individuals most at risk from the effects of CO include heart patients, 

fetuses (unborn babies), smokers, and people who exercise heavily. Normal healthy 

individuals are affected at higher concentrations, which may cause impairment of 

manual dexterity, vision, learning ability, and performance of work. The results of 

studies concerning the combined effects of CO and other pollutants in animals have 

shown a synergistic effect after exposure to CO and ozone. 
Final 2003 AQMP Appendix II: Current Air Quality 

II-2-10

Current Carbon Monoxide Air Quality

The District currently monitors carbon monoxide air quality at 23 of its 32 air 

monitoring stations. The highest CO concentrations are found in coastal and central 

Los Angeles county. The highest 8-hour average CO concentration in 2001 (7.71 

ppm) was recorded in South Central Los Angeles county and was 81% of the federal 

standard and 85% of the state standard. This was the lowest concentration recorded 

in the Basin since carbon monoxide monitoring began in this region. The highest 1-

hour average concentration in 2001 (12.0 ppm) was 33% of the federal and 57% of 

the state 1-hour standards. Concentrations in the less urbanized areas of the Basin 

and in the SSAB were well below the standards. 

In 2001, for the first time since montoring began, carbon monoxide standards were 

not exceeded anywhere in the Basin. The Basin, however, continued to rank in the 

nation among the locations with the highest carbon monoxide concentrations. 

Figure 2-7 shows the distribution of maximum 8-hour average carbon monoxide 

concentrations in the Basin in 2001. Highest concentrations were recorded in Los 

Angeles county areas, in the areas of South Central Los Angeles county and West 

San Fernando Valley. There have been no exceedances of the stage 1 episode 

(federal alert) level (8-hour average CO greater than or equal to 15 ppm) since 1994. 

FIGURE 2-7 

CARBON MONOXIDE - 2001 

Maximum 8-Hour Average Concentration, ppm 
Chapter 2 Air Quality in the South Coast Air Basin 

II-2-11 

The annual number of days exceeding the federal carbon monoxide standard at all 

monitoring sites during the period 1976-2001 is given in Table A-7 in Attachment. 

Tables A-8 and A-9 show the annual number of federal alerts and maximum CO 

concentrations for all sites for the years 1976-2001. 

Seasonal Variation 

Carbon monoxide concentrations in the Basin tend to be highest in the late fall and 

winter months. This is due mainly to meteorological conditions which occur more 

frequently in late fall and winter; specifically, light winds and late night and early 

morning radiation inversions, which inhibit the vertical dispersion of pollutants. 

Also, mobile sources produce more CO emissions in colder temperatures. Figure 2-

8 shows the three-year average monthly number of exceedances of the federal CO 

standard for the years 1999-2001 in the Basin. In the late fall and winter months, the 

actual number of exceedances for each of the three years 1999-2001 ranged from 

one day to four days per month in January and December. No exceedances of the 

CO standards were recorded during February through November of the years 1999-

2001. 

FIGURE 2-8 

CARBON MONOXIDE 

Seasonal Variation, 1999-2001 

Average Monthly Exceedances of Federal Standard

Average Number of Exceedances

0

1

2

3

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Final 2003 AQMP Appendix II: Current Air Quality 

II-2-12

Diurnal Variation 

Figure 2-9 shows the maximum concentration of carbon monoxide for each hour of 

the day for the winter months (January, February, November and December) of 

2001 in the Basin areas where typically higher CO concentrations are recorded, all 

located in Los Angeles county. On average, the CO concentration exhibits two 

peaks: first at around 7 - 8 a.m., the time of morning rush traffic congestion. A 

second peak is typically observed at 10 - 11 p.m. after the evening commute. 

Hourly concentrations during the summer months were relatively low at all hours, 

with the peak concentration for winter averaging more than two times higher than 

the average peak concentration for summer. The seasonal and diurnal patterns in 

these Los Angeles county areas are typical of those found at most locations in the 

District. 

FIGURE 2-9 

CARBON MONOXIDE 

Diurnal Variation, 2001 

Maximum Concentration for Each Hour 

0

5

10

15

20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

HOUR, PST

Concentration, pp

m

South Central Los Angeles County

Southwest Coastal Los Angeles County

West San Fernando Valley
Chapter 2 Air Quality in the South Coast Air Basin 

II-2-13 

Day-of-Week Variation 

Concentrations of carbon monoxide and exceedances of the carbon monoxide 

standards have been found to vary significantly with day of week. This is due to 

variation in vehicular traffic and CO emissions by day of week. Figure 2-10 shows 

the three-year average maximum hourly concentrations for each day of the week in 

the South Central Los Angeles county area during the period 1999-2001. The 

average concentration for weekends (due primarily to Sunday) was lower than the 

average concentration for weekdays (Monday to Friday). A similar pattern has been 

observed for day-of-week variation at most locations in the District. 

FIGURE 2-10 

CARBON MONOXIDE 

Day-of-Week Variation, 1999-2001 

Average Concentrations by Day of Week 

Average Concentration, ppm

0.0

5.0

10.0

15.0

20.0

Mon Tue Wed Thu Fri Sat Sun

South Central Los Angeles County
Final 2003 AQMP Appendix II: Current Air Quality 

II-2-14

Suspended Particulate Matter 

Total suspended particulate (TSP) is the name applied to the complex mixture of solid 

material suspended in the atmosphere. TSP is collected on a glass fiber filter by means 

of a high volume sampler. Samples are collected for a 24-hour period every sixth day, 

and then returned to the District laboratory for chemical analysis to determine the 

relative concentrations of sulfate, nitrate and lead. The federal and state standards for 

lead and sulfate are based on analyses of TSP samples. In 2001, TSP samples were 

collected by the District at 13 sites. These samples were analyzed for sulfate and nitrate 

and were found to contain an average of from 5 to 19 percent sulfate and 5 to 21 percent 

nitrate, depending on location. Lead concentrations were determined for 9 of the sites, 

and the average lead concentration ranged from 0.03 to 0.06 percent of the TSP. 

The fine fraction of TSP has greater effects on health and visibility than the coarse 

fraction. In 1987 EPA adopted PM10 standards, which replaced the earlier TSP 

standards. PM10 samples are collected on quartz filters with a size selective inlet high 

volume sampler. The District began PM10 monitoring in late 1984. 

In 1997, the U.S. EPA adopted new federal air quality standards for finer particulate 

matter, PM2.5, to complement existing PM10 standards that target the full range of 

inhalable particulate matter. In compliance with the adopted standard, the District 

monitored PM2.5 concentrations at 18 sites in 2001. 

Suspended Particulate Matter (PM10) 

Properties

Of greatest concern to public health are the particles small enough to be inhaled into the 

deepest parts of the lung. Respirable particles (particulate matter less than about 10 

micrometers in diameter) can accumulate in the respiratory system and aggravate health 

problems such as asthma, bronchitis and other lung diseases. Children, the elderly, 

exercising adults, and those suffering from asthma are especially vulnerable to PM10's 

adverse health effects. 

PM10 particles are both directly emitted or formed from diverse emission sources. Major 

sources of directly emitted (primary) PM10 include re-suspended road dust or soil 

entrained into the atmosphere by wind or activities such as construction and agriculture. 

Other components of PM10 form in the atmosphere (secondary PM10) from precursor 

emissions of the gaseous pollutants. 

In 2001, the District measured PM10 concentrations at 18 locations. At the 7 locations 

where both PM10 and TSP were monitored, PM10 averaged 50 to 76% of TSP. PM10
Chapter 2 Air Quality in the South Coast Air Basin 

II-2-15 

samples are routinely analyzed for sulfate and nitrate, and in 2001 sulfates constituted an 

average of 7 to 18% of PM10, and nitrates constituted 4 to 18% of PM10. 

An intensive study of PM10 was conducted at six locations in 1995, using special 

samplers designed to allow detailed chemical analyses of PM10. The study sites included 

five Basin locations in Central Orange county (CEOC), Central Los Angeles county 

(CELA), Pomona/Walnut Valley (PWV), Central San Bernardino Valley (CSBV), and 

Metropolitan Riverside county (MRIV) areas and one remote area in San Nicolas Island 

(SANI). 

Figure 2-11 shows the average amounts of sulfate (SO4

=

), nitrate (NO3

-

), ammonium 

(NH4

+

), organic carbon (OC), elemental carbon (EC), sodium (Na+), chloride (Cl-), and 

other materials such as soil components in the PM10 samples which were collected 

during 1995. Sulfates, nitrates, and organic carbon are typically formed in the air by 

reaction of gaseous precursors such as oxides of nitrogen, oxides of sulfur, volatile 

organic compounds (hydrocarbons and related compounds) and ammonia, which are 

emitted by a variety of sources. Soil-related materials tend to be larger particles which 

are suspended in the air by human activity or by wind. 

FIGURE 2-11 

Chemical Composition of PM10, 1995 

0

20

40

60

80

100

SANI CEOC CELA PWV CSBV MRIV

SO4= NO3- NH4+ OC EC Na Cl Others

μg/m3
Final 2003 AQMP Appendix II: Current Air Quality 

II-2-16

San Nicolas Island, 80 miles offshore and remote from the Basin’s urban areas, recorded 

a very low average PM10 (18 μg/m3

), which contained a relatively large fraction of Na 

and Cl (25% of the PM10). The relatively high Na and Cl is due to the influx of sea salt 

from the surrounding ocean. The concentrations of, and in most cases percentages of, 

the other components (NH4

+

, NO3

-

, SO4

=

, OC, EC, crustal material) were low compared 

to mainland Basin sites. 

PM10 annual concentrations measured at the five Basin locations recorded PM10

concentrations from 42 μg/m3

 to 78 μg/m3. These Basin sites contain relatively high 

proportions of sulfates (6-11%), nitrates (22-26%), organic carbon(15-20%), and 

elemental carbon (5-8%). These materials derive from stationary or mobile sources of 

pollution in the Basin. The amount of soil-related material in the air is also greater (17% 

to 31%), due to suspension of soil in the air by human activities such as re-entrainment 

of road dust and construction. 

Current PM10 Air Quality

In 2001, the District measured PM10 concentrations at 18 locations throughout the South 

Coast and Salton Sea Air Basins. Figure 2-12 shows for 2001 the annual average 

(arithmetic mean) PM10 concentrations in the Basin. The area which exceeded the 

federal standard (inside the dashed line) is limited to the areas of Riverside and San 

Bernardino counties close to Metropolitan Riverside county. The maximum annual 

average recorded (63.1 μg/m3

 in the Metropolitan Riverside county area) was 125% of 

the federal standard. 

The federal 24-hour standard was exceeded at two Basin locations in the inland valley 

areas 2001 (not shown). The maximum 24-hour average concentration (219 μg/m3

recorded in Metropolitan Riverside county) was 146% of the federal 24-hour standard. 

The more stringent state annual standard was exceeded in a much larger area than the 

federal annual standard, with most of the Basin and part of the Riverside county SSAB 

recording annual average concentrations above the standard. The maximum annual 

average (annual geometric mean PM10 54.3 μg/m3

, recorded at Metropolitan Riverside 

county) was 180% of the state annual standard. 

The state 24-hour PM10 standard was exceeded at all locations monitored in the District. 

The standard was exceeded most frequently in the Basin’s inland valleys, centering in 

Metropolitan Riverside county. The maximum 24-hour average was 429% of the state 

24-hour standard. 

The annual arithmetic and geometric mean, the percent of days exceeding state and 

federal standards, and the maximum 24-hour average concentration for the years 1985 - 

2001 are given in Tables A-10 to A-13 in Attachment. 
Chapter 2 Air Quality in the South Coast Air Basin 

II-2-17 

FIGURE 2-12 

Suspended Particulate Matter (PM10) - 2001 

Annual Arithmetic Mean, μg/m3

 

Seasonal and Day-of-Week Variation in PM10

PM10 samples are only collected every sixth day (or third day at sites where an intensive 

monitoring schedule has been adopted) and exceedances of the federal standard are 

relatively infrequent in recent years. As a consequence, seasonal and day-of-week 

variations in exceedances of the federal standard for the last few years cannot be 

determined accurately. However, if exceedances of the state standard are considered, 

seasonal and day-of-week patterns do emerge. 

Previous analyses of seasonal variations in PM10 show that the monthly average PM10

concentration and the monthly average number of days exceeding the state standard tend 

to peak in summer and fall in the inland valley area of the Basin where PM10

concentrations are highest. However, in the South Coastal Los Angeles county area, 

monthly average PM10 concentrations and the average number of days exceeding the 

state standard are highest in late fall and winter months. 

Figure 2-13 shows the average number of days in each month exceeding the state 

standard at one or more Basin locations over the period 1999-2001. The greatest 

number of state standard exceedances occurred in the summer and fall months. Due to 

higher number of exceedances in the inland valleys, the pattern for the Basin is more 
Final 2003 AQMP Appendix II: Current Air Quality 

II-2-18

similar to those for individual sites in the inland valley areas. Figure 2-14 shows the 

monthly average PM10 concentrations for the two sites, Metropolitan Riverside county in 

inland valleys and South Coastal Los Angeles county. In the inland valley areas, PM10

concentrations are higher in the summer and fall months while in the coastal areas higher 

concentrations are recorded in the late fall and winter months. 

FIGURE 2-13 

Basin-Days Exceeding State PM10 Standard by Month, 1999-2001 

FIGURE 2-14 

Monthly Average PM10 Concentration, 1999-2001 

0

2

4

6

8

10

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Basin-Days > 50 μg/m3

0

20

40

60

80

100

Jan Feb Mar Apr May Jun Juy Aug Sep Oct Nov Dec

Concentration, ug/m3

Metropolitan Riverside County

South Coastal Los Angeles County
Chapter 2 Air Quality in the South Coast Air Basin 

II-2-19 

Day-of-week variations have also been examined, and it was found that the average 

weekend concentrations were lower than the weekday average at all sites monitored in 

the Basin and SSAB locations. Figure 2-15 shows the average PM10 concentrations by 

day of week at three representative monitoring sites in the Basin for the period 1999-

2001, based on the Beta Attenuation Monitor (BAM) and Tapered Element Oscillating 

Microbalance (TEOM) data. 

Diurnal variations proved to be complex and location dependent. 

FIGURE 2-15 

Day-of-Week Variation, 1999-2001 

Average PM10 Concentration by Day of Week 

Suspended Particulate Matter (PM2.5) 

Properties

PM2.5, the fine sized particles less than 2.5 micrometers in diameter, are small enough to 

penetrate the defenses of the human respiratory system and lodge in the deepest recesses 

of the lung, causing adverse health impacts. The health effects include increased 

respiratory symptoms and diseases such as ashma, bronchitis, acute and chronic 

respiratory problems like shortness of breath and painful breathing (in children, the 

elderly and sensitive people), and premature deaths (mainly in the elderly due to a 

weaker immune system). The sources of PM2.5 include diesel-powered vehicles such as 

0

20

40

60

80

Mon Tue Wed Thu Fri Sat Sun

Concentration, ug/m3

Metropolitan Riverside County

Central Los Angeles

South Coastal Los Angeles County
Final 2003 AQMP Appendix II: Current Air Quality 

II-2-20

buses and trucks, fuel combustion from automobiles, power plants, industrial processes, 

and wood burning. 

In the South Coast Air Basin, much of the PM10 fraction is actually finer in size than 2.5

micrometers, a condition which has major implications for both health and atmospheric 

visibility. Reducing PM2.5 concentrations will therefore not only reduce the threat to the 

health of the Basin's population, but will also improve visual air quality in this region. 

The District began monitoring PM2.5 regularly in 1999. In 2001, the District measured 

PM2.5 concentrations at 18 locations. Samples are collected for a 24-hour period every 3 

days at most locations except for a few sites with high PM2.5 levels where samples are 

taken every day. 

Current PM2.5 Air Quality

Figure 2-16 shows 2001 the annual average arithmetic mean PM2.5 concentrations in 

different areas of the Basin. Like PM10, PM2.5 concentrations were higher in the inland 

valley areas of San Bernardino county and Metropolitan Riverside county. However, 

PM2.5 concentrations were also high in the metropolitan areas of Los Angeles and 

Orange counties. The high PM2.5 concentrations in these areas are mainly due to the 

FIGURE 2-16 

Suspended Particulate Matter (PM2.5) - 2001 

Annual Arithmetic Mean, μg/m3

 
Chapter 2 Air Quality in the South Coast Air Basin 

II-2-21 

secondary formation of smaller-sized particulate resulting from mobile and stationary 

source activities. The maximum annual average recorded (31.1 μg/m3

 in the 

Metropolitan Riverside county area) was 201% of the federal standard. In 2001, the 

federal annual PM2.5 standard was exceeded everywhere in the District except for the 

San Bernardino Mountain area in the Basin and Coachella Valley area in SSAB. 

The federal 24-hour PM2.5 standard was exceeded likewise almost everywhere in the 

Basin in 2001. The standard was exceeded most frequently in the metropolitan areas of 

Los Angeles and Riverside counties. Maximum 24-hour average concentration (98.0 

μg/m3

 in Metropolitan Riverside county) was 150% of the federal 24-hour standard. 

Seasonal and Day of Week Variation in PM2.5

Evaluation of the available data for the past two years that PM2.5 has been monitored 

shows that the PM2.5 concentrations tend to peak during the late fall-winter months. 

Figure 2-17 shows the average number of days in each month exceeding the federal 

standard at one or more Basin locations over the years 1999-2001. The greatest number 

of exceedances occurred in January and October-December. 

FIGURE 2-17 

PM2.5 Seasonal Variation, 1999-2001 

Average Number of Basin-Days Exceeding Federal Standard by Month 

0

1

2

3

4

5

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Basin-Days > 65 μg/m3
Final 2003 AQMP Appendix II: Current Air Quality 

II-2-22

Because PM2.5 standards and monitoring requirements are of recent adaption, there is 

insufficient data accumulated thus far to accurately determine day-of-week trends in 

PM2.5 concentrations in the Basin. Preliminary analysis of available data shows slightly 

higher frequency of number of days exceeding the federal standard on Sundays and 

Mondays. No specific day-of-week pattern was found in the in PM2.5 concentrations in 

the Basin. Figure 2-18 the total number of days exceeding the federal standard in the 

Basin by day of week for the three-year period 1999-2001. 

FIGURE 2-18 

PM2.5 Day-of-Week Variation, 1999-2001 

Basin-Days Exceeding the Federal Standard by Day of Week 

Nitrogen Dioxide (NO2) 

Properties 

Nitrogen dioxide (NO2) is a reddish-brown gas with a bleach-like odor. Nitric oxide 

(NO) is a colorless gas, formed from the nitrogen (N2) and oxygen (O2) in air under 

conditions of high temperature and pressure which are generally present during 

combustion of fuels; NO reacts rapidly with the oxygen in air to give nitrogen dioxide 

(NO2). NO2 is responsible for the brownish tinge of polluted air. The two gases, nitric 

oxide and nitrogen dioxide, are referred to collectively as oxides of nitrogen (NOx). In 

the presence of sunlight, nitrogen dioxide reacts to give nitric oxide and an oxygen atom. 

The oxygen atom can react further to give ozone, via a complex series of chemical 

0

5

10

15

Mon Tue Wed Thu Fri Sat Sun

Basin-Days
Chapter 2 Air Quality in the South Coast Air Basin 

II-2-23 

reactions involving hydrocarbons. Nitrogen dioxide may also react to give nitric acid 

(HNO3) which reacts further to give nitrates, which are a component of PM10. 

Nitrogen dioxide is a respiratory irritant and reduces resistance to respiratory infection. 

Children and people with respiratory disease are most susceptible to its effects. 

Current Nitrogen Dioxide Air Quality

In 2001, the District monitored nitrogen dioxide concentrations at 23 locations. Federal 

and state standards for nitrogen dioxide were not exceeded at any location. The federal 

standard has not been exceeded in the Basin since 1991. 

Table 1 below shows the 2001 maximum annual average nitrogen dioxide 

concentrations by Basin and county. The maximum annual average nitrogen dioxide 

concentration (0.0419 ppm recorded in the East San Fernando Valley area of Los 

Angeles county) was 78% of the federal standard. Concentrations in the downwind 

SSAB areas were much lower. The maximum 1-hour average concentration in the Basin 

(0.25 ppm in East San Fernando Valley) was 96% of the state standard. 

The annual averages, number of days exceeding the state standard, and maximum 1-hour 

average concentrations for each individual area of the District for the years 1976-2001 

are given in Tables A-14 to A-16 in Attachment. 

TABLE 1 

2001 Maximum Annual Average Nitrogen Dioxide Concentrations* 

Maximum Percent 

Basin/County Annual Avg. Federal Area

 ppm Standard

South Coast Air Basin

Los Angeles 0.0419 78% East San Fernando Valley

Orange 0.0293 55% Central Orange County

Riverside 0.0247 46% Metropolitan Riverside County

San Bernardino 0.0384 72% Northwest San Bernardino Valley

Salton Sea Air Basin

Riverside 0.0175 33% Coachella Valley

 * Federal standard = 0.0535 ppm
Final 2003 AQMP Appendix II: Current Air Quality 

II-2-24

Though the state and federal standards were not exceeded in 2001, nitrogen dioxide is 

still a concern since it is a precursor to both ozone and particulate matter. Further 

control of oxides of nitrogen will be required to attain the ozone and particulate 

standards. 

Sulfur Dioxide (SO2) 

Properties

Sulfur dioxide (SO2) is a colorless gas with a sharp odor. It reacts in the air to form 

sulfuric acid (H2SO4), which contributes to acid precipitation, and sulfates, which are a 

component of PM10 and PM2.5. Most of the SO2 emitted into the atmosphere is produced 

by the burning of sulfur-containing fuels. 

At sufficiently high concentrations, sulfur dioxide affects breathing and the lungs’ 

defenses, and can aggravate respiratory and cardiovascular diseases. Asthmatics and 

people with chronic lung disease or cardiovascular disease are most sensitive to its 

effects. Sulfur dioxide also causes plant damage, damage to materials, and acidification 

of lakes and streams. 

Current Sulfur Dioxide Air Quality

In 2001, sulfur dioxide was measured at seven Basin locations. No violations of federal 

or state standards occurred. The federal standards were last exceeded in the 1960’s and 

the state standard was last exceeded in 1990. 

The maximum 24-hour average SO2 concentrations recorded in the District in 2001 are 

shown in Table 2. The highest 24-hour average SO2 concentration (0.012 ppm in South 

and Southwest Coastal Los Angeles county areas) was 8% of the federal 24-hour 

standard. The highest 1-hour average (0.05 ppm in South Coastal Los Angeles county) 

was 19% of the state standard. The maximum annual average concentration (0.0041 

ppm in the Southwest Coastal Los Angeles county area) was 13% of the federal 

standard. 

Detailed statistics including annual average and maximum 1-hour average SO2

concentrations for each location monitored for the years 1976-2001 are given in in 

Attachments A-17 and A-18. 

While sulfur dioxide concentrations in the Basin no longer exceed standards, SO2 is a 

precursor of PM10 and sulfate. 
Chapter 2 Air Quality in the South Coast Air Basin 

II-2-25 

TABLE 2 

2001 Maximum 24-Hour Average Sulfur Dioxide Concentrations* 

Maximum Percent 

Basin/County 24-hr Avg. Federal Area

 ppm Standard

South Coast Air Basin

Los Angeles 0.012 8% Southwest Coastal LA County

Orange 0.007 5% North Coastal Orange County

Riverside 0.011 8% Metropolitan Riverside County

San Bernardino 0.010 7% Central San Bernardino Valley

Salton Sea Air Basin

Riverside N.D.

N.D. = No Data. Historical measurements indicate concentrations are below standard.

* Federal standard = 0.14 ppm

Sulfate (SO4

=

) 

Properties

Sulfates are chemical compounds which contain the sulfate ion (SO4

=

), and are part of 

the mixture of solid materials which make up PM10 and TSP. Most of the sulfates in the 

atmosphere are produced by oxidation of sulfur dioxide. Oxidation of sulfur dioxide 

yields sulfur trioxide (SO3) which reacts with water to give sulfuric acid (H2SO4), which 

contributes to acid precipitation. The reaction of sulfuric acid with basic substances 

such as ammonia yields sulfates, a component of PM10. 

Current Sulfate Air Quality

In 2001 sulfate concentrations were measured at 13 Basin locations. Table 3 shows the 

2001 maximum 24-hour average concentrations in the District by Basin and county. The 

maximum sulfate concentration (20.6 μg/m3

) recorded in the District was 82% of the 

state standard. 

The percent of days exceeding the standard and the maximum 24-hour average 

concentration at each monitoring location for the years 1976-2001 are given in Tables 

A-19 to A-20 in Attachment. 
Final 2003 AQMP Appendix II: Current Air Quality 

II-2-26

TABLE 3 

2001 Maximum 24-Hour Average Sulfate Concentrations 

Maximum Percent 

Basin/County 24-hr. Avg. State Area

 μg/m3 Standard

South Coast Air Basin

Los Angeles 20.6 82% Southwest Coastal LA County

Orange N.D.

Riverside 10.7 43% Metropolitan Riverside County

San Bernardino 11.5 46% Central San Bernardino Valley

Salton Sea Air Basin

Riverside N.D.

N.D. = No Data. Historical measurements indicated concentrations were below standard.

* State standard = 25 μg/m3

Lead (Pb) 

Properties

Lead in the atmosphere is present as a mixture of a number of lead compounds. Leaded 

gasoline and lead smelters have been the main sources of lead emitted into the air. Due 

to the phasing out of leaded gasoline, there was a dramatic reduction in atmospheric lead 

in the Basin over the past two decades. However, lead concentrations in excess of the 

standards have been recorded since 1990 in very localized areas near stationary sources 

of lead. 

Current Lead Air Quality

In 2001 lead concentrations were measured at nine Basin air monitoring stations, none of 

which exceeded the state or federal standards. Table 4 shows the maximum quarterly 

average lead concentrations in the District by Basin and county in 2001. The maximum 

quarterly average lead concentration (0.12 μg/m3

) was 8% of the federal standard. The 

maximum monthly average lead concentration (0.23 μg/m3

) was 15% of the state 

standard. 
Chapter 2 Air Quality in the South Coast Air Basin 

II-2-27 

TABLE 4 

2001 Maximum Quarterly Average Lead Concentrations 

Maximum Percent 

Basin/County Qtr. Avg.* Federal Area

 μg/m3 Standard

South Coast Air Basin

Los Angeles 0.12 8% South Central LA County

Orange N.D. 

Riverside 0.03 2% Metropolitan Riverside County

San Bernardino 0.04 3% Multiple Sites

Salton Sea Air Basin

Riverside N.D.

N.D. = No Data. Historical measurements indicated concentrations were below standard.

* Higher concentrations (0.49 μg/m3) were measured in localized areas near sources.

 

In addition to lead measurements at District air monitoring stations, special monitoring 

was done in the immediate vicinity of several stationary sources of lead. Data from the 

special monitoring sites showed that higher concentrations were reached in very 

localized areas near sources, with a maximum quarterly average (0.49 μg/m3

) 32% of the 

federal standard, and a maximum monthly average (0.57 μg/m3

) 38% of the state 

standard. 

Maximum quarterly average and monthly average lead concentrations at each of the 

regular monitoring sites for the years 1976-2001 are given in the Attachment, Tables A21 and A-22 in Attachment. 
CHAPTER 3

AIR QUALITY IN THE RIVERSIDE COUNTY SSAB

Chapter 3 Air Quality in the Riverside County SSAB

II-3-1

AIR QUALITY IN THE RIVERSIDE COUNTY SSAB

In 2001, the District monitored air quality at two locations in the Riverside county portion 

of the Salton Sea Desert Air Basin (SSAB), both in the Coachella Valley. One monitoring 

station was located immediately downwind of the densely populated Basin, and the other 

was located further downwind in the Coachella Valley. The maximum concentrations 

recorded at these locations in 2001 are shown in Figure 3-1.

In 2001, pollutant concentrations in the Riverside county SSAB exceeded standards for 

ozone and PM10. The maximum 1-hour average ozone concentration (0.137ppm) was 

137% and 110% of the state and federal standards, respectively. The maximum 8-hour 

average ozone concentration (0.114 ppm) was 134% of the 8-hour federal ozone standard. 

The maximum annual average PM10 concentration (50.2 μg/m3) was 99% of the federal 

annual PM10 standard. (The annual average PM10 does not include the data for the 

samples collected on high-wind days in accordance with EPA's Natural Event Policy.) The 

maximum annual average PM2.5 concentration (12.2 μg/m3) was 79% of the standard. 

FIGURE 3-1

2001 Maximum Pollutant Concentrations as Percent of Standards

Riverside County SSAB

Percent of Federal Standard

0

50

100

150

Ozone Ozone PM10 PM2.5 Carbon Monoxide Nitrogen Dioxide

(1-Hour) (8-Hour) (Annual) (Annual) (8-Hour) (Annual)

Coachella Valley

Federal Standard
Final 2003 AQMP Appendix II: Current Air Quality

II-3-2

Federal and state standards for carbon monoxide and nitrogen dioxide were not exceeded. 

The highest 8-hour average carbon monoxide concentration (1.75 ppm) was 16% of the 

federal standard. The maximum annual average nitrogen dioxide concentration recorded 

(0.0175 ppm) was 33% of the federal NO2 standard. No measurements of sulfur dioxide, 

sulfate or lead were made in the Riverside county SSAB area of the District in 2001. 

Historical measurements in this area showed concentrations of these pollutants to be well 

below the state and federal standards and monitoring was discontinued. Detailed

information on historical air quality and trends in air quality in this area was presented in a 

previous report.

Ozone (O3)

Ozone in the atmosphere of the Riverside county portion of SSAB is both directly

transported from the Basin and formed principally from precursors emitted upwind. These 

precursors are emitted in greatest quantity in the coastal and central Los Angeles county 

areas of the Basin. The Basin’s prevailing sea breeze causes polluted air to be transported 

inland. As the air is being transported inland, ozone is formed, with peak concentrations 

occurring in the inland valleys of the Basin in an area extending from eastern San Fernando 

Valley through the San Gabriel Valley into the Riverside-San Bernardino area and the 

adjacent mountains. As the air is transported still further inland into the desert areas, 

ozone concentrations decrease.

The 1-hour federal ozone standard level was exceeded on a maximum of six days in 

Coachella Valley in 2001. The more stringent 8-hour federal standard was exceeded on 42 

days. Ozone concentrations and the number of days exceeding the federal ozone standard 

are greatest in summer. There are typically no exceedances during the winter months.

The 1-hour state ozone standard was exceeded on a maximum of 53 days in Coachella 

Valley in 2001. The health advisory level has not been exceeded in the Coachella Valley 

area since 1999. No stage 1 episode level has been recorded in the Riverside county SSAB 

areas since 1989.

Number of days exceeding the 1-hour federal ozone standard and episode levels and the 

maximum 1-hour ozone concentrations for the years 1976-2001 are given in the

Attachment, in Tables A-4 through A-6.

Particulate Matter (PM10)

Although exceedances of the ozone standard in the Coachella Valley area are due to the 

transport of ozone from the densely populated areas of the Basin upwind, the same cannot 

be said for PM10 exceedances. PM10 exceedances in the Coachella Valley are primarily 

due to locally generated sources of fugitive dust (e.g. construction activities, re-entrained 
Chapter 3 Air Quality in the Riverside County SSAB

II-3-3

dust from paved road travel, and natural wind-blown sources) and not as a result of 

secondary PM10 generated from precursor gaseous emissions. In addition, the Riverside 

county SSAB is subject to frequent high winds which generate wind-blown sand and dust 

that can cause high levels of PM10. PM10 is the only pollutant which has sometimes 

reached higher concentrations in SSAB than in the densely populated Basin.

In 2001, the federal 24-hour PM10 standard was exceeded in Coachella Valley on a 

maximum of five days (4% of sampling days). All samples which exceeded the standard 

were collected on high-wind days which resulted in windblown dust. The data for these 

samples are excluded from the data base in accordance with the EPA's Natural Event 

Policy. The federal annual PM10 standard level was not exceeded in the Riverside county 

part of SSAB in 2001. The maximum annual average PM10 concentration (50.2 μg/m3) 

was 99% of the standard. 

The maximum annual average PM10 concentrations in the western portion of the Coachella 

Valley area, as well as the San Gorgonio Pass area at the eastern edge of the Basin, 

remained well below the federal PM10 standards in 2001.

In 2001, the state 24-hour PM10 standard was exceeded on a maximum of 50 days (45% 

of sampling days) in Coachella Valley. The state annual standard was also exceeded. The 

maximum annual average (44.3 μg/m3, annual geometric mean) was 147% of the state 

standard.

Analyses of the seasonal distribution of exceedances of the PM10 standards showed a 

pattern similar to the inland valleys with a peak in summer and falling to a minimum in 

winter. 

Variation in average concentration by day-of-week in Coachella Valley also shows the 

same pattern as other areas in the Basin, with concentrations lower on weekends than on 

week days. 

Annual average, percent number of days exceeding standards and maximum 24-hour 

average concentrations for the years 1985-2001 for the Riverside county SSAB and other 

District air monitoring stations are presented in the Attachment, in Tables A-10 to A-13.

Particulate Matter (PM2.5)

PM2.5 has been measured in Coachella Valley since 1999 when the District began PM2.5 

monitoring. In 2001, federal PM2.5 standards were not exceeded at either of the two 

Riverside county SSAB air monitoring sites. The maximum 24-hour average and annual 

average concentrations recorded in 2001 (44.7 μg/m3 and 12.2 μg/m3) were, respectively, 

68% and 79% of the federal 24-hour and annual standards. 
Final 2003 AQMP Appendix II: Current Air Quality

II-3-4

Carbon Monoxide (CO)

Carbon monoxide was measured at one of the Riverside county SSAB air monitoring 

stations in 2001. Neither the federal nor state standards were exceeded. The maximum 8-

hour average CO recorded in 2001 (1.75 ppm) was 16% of the federal and 19% of the state 

standards. Historical carbon monoxide air quality and trends in the Riverside county SSAB 

area shows that the area has not exceeded the federal standard over the last two decades. 

Summary statistics for carbon monoxide in the Riverside county SSAB as well as other 

District areas are given in the Attachment, in Tables A-7 to A-9. 

Nitrogen Dioxide (NO2)

Nitrogen dioxide was measured at one of the stations in the Riverside county SSAB in 

2001. The maximum annual average nitrogen dioxide concentration (0.0175 ppm) was 

33% of the federal standard and the maximum 1-hour average (0.08 ppm) was 31% of the 

state 1-hour standard.

Table 1 (Chapter 2) and Tables A-15 to A-17 in the Attachment contain nitrogen dioxide 

summary statistics for the Riverside county SSAB and other District monitoring stations 

for the year 2001 and earlier years.

Sulfur Dioxide (SO2)

Sulfur dioxide concentrations were not measured in the Riverside county SSAB in 2001. 

Measurements made in past years have shown concentrations to be well below the standard.

Tables A-17 and A-18 in the Atthachment contain annual average and maximum 1-hour 

averages for available years for the period 1976-2001 at Riverside county SSAB and other 

District monitoring stations.

Sulfate (SO4

=

)

No measurements of sulfate concentrations were made in 2001 at the two monitoring 

stations in the Riverside county SSAB. Historical monitoring has shown concentrations to 

be less than the state standard.

The percent of days exceeding the standard, and the maximum 24-hour average and annual 

average sulfate concentrations at each monitoring location for past years are presented in 

the Attachment, in Tables A-20 to A-22. 
Chapter 3 Air Quality in the Riverside County SSAB

II-3-5

Lead (Pb)

Lead concentrations were not measured at the two Riverside county SSAB stations in 

2001. Measurements made in past years have shown concentrations to be less than the 

state and federa standards.

Maximum quarterly average and monthly average concentrations for past years are given in

Tables A-23 and A-24 in the Attachment.
SUMMARY 

Summary 

II-S-1

SUMMARY 

This report contains a summary of the year 2001 air quality in the South Coast Air Basin 

and the portion of Salton Sea Air Basin monitored by the South Coast Air Quality 

Management District. For those pollutants for which the Basin is in nonattainment of 

the federal standards, an updated air quality trends through the year 2001 are presented.1 

In 2001 the South Coast Air Quality Management District monitored concentrations of 

air pollutants at 32 locations in Southern California’s Los Angeles, Orange, Riverside 

and San Bernardino counties. Pollutant concentrations exceeded the federal and state 

standards for ozone and particulate matter (PM10, PM2.5). Standards for carbon 

monoxide, nitrogen dioxide, sulfur dioxide, sulfate and lead were not exceeded. 

In the year 2001, the U.S. location with the highest number of days exceeding the federal 

ozone standard was located in the South Coast Air Basin (Orange county and the nondesert portions of Los Angeles, Riverside and San Bernardino counties). The Basin also 

continued to rank among the areas of the U.S. with high carbon monoxide and PM10 

concentrations in 2001. 

South Coast Air Basin (SCAB) 

In 2001, there were a total of 37 days on which the federal standards for 1-hour ozone 

and 24-hour PM10 were exceeded at one or more SCAB (Basin) locations. The recently 

adopted federal 24-hour PM2.5 standard was exceeded on 23 days in the Basin. 

The number of days exceeding the federal ozone standard varied widely by area, from 

zero to 26 exceedances, depending on location. Exceedances were fewest at the coast, 

increasing to a maximum in the Basin's Central San Bernardino Mountains and inland 

valleys, and then decreasing further downwind in the Basin’s far inland areas. The 

Central San Bernardino Mountains area exceeded the federal ozone standard most 

frequently (26 days). The more stringent state standard was exceeded on 88 days in the 

same area. The highest 1-hour average and 8-hour average ozone concentration 

recorded in 2001 (0.190 ppm and 0.144 ppm) were 152% and 169% of the federal 1-

hour and 8-hour standards, respectively. 

In 2001, carbon monoxide concentrations did not exceed the standards anywhere in the 

Basin. The highest carbon monoxide concentrations were recorded in coastal and central 

Los Angeles county areas. The maximum 8-hour average concentration of 7.71 ppm, 

recorded in South Central Los Angeles County, was 81% of the federal standard. 

 

1

 The current air quality analysis presented in this report is based on the data through the year 2001. Complete 

particulate data for the year 2002 is not available at this time. 
Final 2003 AQMP Appendix II: Current Air Quality 

II-S-2

Exceedances of the federal annual PM10 standard were confined to Riverside and San 

Bernardino counties, primarily in and around the Metropolitan Riverside county area. 

The more stringent state annual PM10 standard was exceeded in a much larger area, 

covering most of the Basin. The federal 24-hour PM10 standard was also exceeded at a 

few locations in the inland valley areas in 2001. The state 24-hour standard, however, 

was exceeded at all locations monitored, with the Metropolitan Riverside county area 

exceeding most frequently (67% of sampling days). The maximum 24-hour average and 

annual PM10 concentrations (219 μg/m3 and 63.1 μg/m3

) were 146% and 125% of the 

federal 24-hour and annual standards, respectively. 

PM2.5 concentrations were monitored in the District in 2001 in accordance with the 

adopted federal PM2.5 standards. Maximum 24-hour average and annual average 

PM2.5 concentrations (98.0 μg/m3

 and 31.1 μg/m3) were 150% and 201% of the federal 

24-hour and annual standards, respectively, both recorded in the Metropolitan Riverside 

county area. 

Riverside County Salton Sea Air Basin (SSAB) 

Pollutant concentrations in the Riverside county portion of SSAB were monitored at two 

locations in the Coachella Valley in 2001, and exceeded the federal and state standards 

for ozone. No other standards were exceeded. 

The highest 1-hour and 8-hour ozone concentrations recorded in the Coachella Valley in 

2001 (0.137 ppm and 0.114 ppm) were 110% and 134% of the federal 1-hour and 8-hour 

standards, respectively. The federal 1-hour ozone standard exceeded on a maximum of 

six days in SSAB in 2001. The more stringent state standard was exceeded on 42 days. 

Both the state and federal 24-hour PM10 standards and the state and federal annual 

PM10 standards were exceeded in the Coachella Valley. However, the deletion of highwind day samples from consideration results in there being no exceedances of the federal 

standards in 2001. PM2.5 concentrations were below the federal 24-hour and annual 

PM2.5 standards. 

Seasonal, Day-of-Week and Diurnal Variations 

Concentrations of pollutants have been found to vary by season, day of week, and time 

of day, and these variations were examined for 1999-2001 for ozone, carbon monoxide 

and PM10. Ozone standard exceedances generally peak in summer, while carbon 

monoxide exceedances peak in late fall and winter, and federal 24-hour PM10 

exceedances peak in fall and winter. Ozone tended to be higher on weekends than on 

weekdays, while the opposite was true for carbon monoxide and PM10. The time of the 

day which averaged highest in ozone concentration was early afternoon in the peak 
Summary 

II-S-3

ozone area, while carbon monoxide averaged highest at the time of morning rush-hour 

traffic. 
ATTACHMENT
TABLE A-1

AMBIENT AIR QUALITY STANDARDS

CALIFORNIA FEDERAL

AIR POLLUTANT CONCENTRATION DISTRICT METHOD PRIMARY (>) SECONDARY (>) METHOD a)

Ozone b) 0.09 ppm, 1-hour average > U.V. Photometry 0.12 ppm, 1-hour average

0.08 ppm, 8-hour averageb)

Same as Primary 

Standrd

Chemiluminescence

Carbon Monoxide 9.0 ppm, 8-hour average > c)

20 ppm, 1-hour average > Gas Correlation

9 ppm, 8-hour average d)

35 ppm, 1-hour average None

Non-dispersive InfraRed Spectrophotometry

Nitrogen Dioxide 0.25 ppm, 1-hour average > e) Gas Phase 

Chemiluminescence

0.053 ppm, annual average f) Same as Primary 

Standrd

Gas Phase 

Chemiluminescence

Sulfur Dioxide 0.04 ppm, 24-hour average > g)

0.25 ppm, 1-hour average > h)

Ultraviolet 

PulseFluorescence

0.03 ppm, annua l average

0.14 ppm, 24-hour average

0.50 ppm, 3-hour 

average

Para-rosaniline

Suspended 

Particulate 

Matter (PM10)**

30 μg/m3, annual geometric mean >

50 μg/m3, 24-hour average > i), **

20 μg/m3, annual arithmetic mean > 

**

Size Segregation Inlet

High Volume Sampling

50 μg/m3, annual arithmetic mean

150 μg/m3, 24-hour average j)

Same as Primary 

Standrd

Inertial Separation and 

Gravimetric Analysis

Suspended 

Particulate 

Matter (PM2.5) k), **

12 μg/m3, annual arithmetic mean ** Inertial Separation and 

Gravimetric Analysis

15 μg/m3, annual arithmetic mean 

k) 

65 μg/m3, 24-hour average k)

Same as Primary 

Standrd

Inertial Separation and 

Gravimetric Analysis

Lead 1.5 μg/m3, 30-day average >= High Vol. Sampling

Atomic Absorption

1.5 μg/m3, calendar quarter Same as Primary 

Standrd

High Vol. Sampling

Atomic Absorption

Sulfates 25 μg/m3, 24-hour average >= High Vol. Sampling

Ion Chouromatography

Hydrogen Sulfide 0.03 ppm, 1-hour average >= Cadmium Hydroxide Stractan

Vinyl Chloride 0.010 ppm, 24-hour average >= Gas Chouromatography

Visibility Reducing

Particles

In sufficient amount to give an 

extinction coefficient > 0.23 inverse 

kilometers (visual range less than 10 

miles), with relative humidity <70%, 

8-hour average (10am-6pm, PST) l) .

Nephelometry and AISI 

Tape Sampler (COH)

NO

FEDERAL

STANDARDS

a) Reference method as described by the federal government. An equivalent method of measurement may be used as approved by the federal government.

b) Effective September 16, 1997, new federal 8-hour average standard was established.

c) Effective December 15, 1982. The previous standards were 10 ppm, 12-hour average and 40 ppm, 1-hour average.

d) Effective September 13, 1985, standard changed from >10 μg/m3 (>=9.3 ppm) to > 9 ppm (>=9.5 ppm).

e) Effective March 9, 1987, standard changed from >=0.25 ppm to > 0.25 ppm.

f) Effective July 1, 1985, standard changed from > 100 μg/m3 (>0.0532 ppm) to > 0.053 ppm (>= 0.0535 ppm).

g) Effective July 29, 1992. The previous standard was >= 0.05 ppm, 24-hour average with ozone >=0.1 ppm, 1-hour average or TSP >=100 μg/m3, 24-hour average.

h) Effective October 5, 1984. The previous standard was 0.5 ppm, 1-hour average.

i) Effective August 19, 1983**. The previous standards were annual geometric mean TSP > 60 μg/m3, and 24 hour average TSP > 100 μg/m3.

j) Effective July 1, 1987. The previous standards were annual geometric mean TSP > 75 μg/m3, and 24 hour average TSP > 260 μg/m3.

k) Effective September 16, 1997, new federal standards were established. There were no previous standards for PM2.5.
** The new PM2.5 annual average state standard of 12 μg/m3

 and revised PM10 annual average state standard of 20 μg/m3 (to replace AGM 30 μg/m3) recommended by 

the California Air Resources Board was approved by the state Office of Administrative Law effective July 5, 2003.

l) Effective October 18, 1989. The previous standard was “In sufficient amount to reduce the prevailing visibility to less than 10 miles at relative humidity Revised

less than 70%, 1 observation”, and was based on human observation rather than instrumental measurement. July 2003
TABLE A-2

Episode Criteria

SCAQMD AND CALIFORNIA FEDERAL

AIR POLLUTANT HEALTH ADVISORY (≥) STAGE I (≥) STAGE II (≥) STAGE III (≥) STAGE I (≥) 

(ALERT)

STAGE II (≥)

(WARNING)

STAGE III (≥)

(EMERGENCY)

Ozone 0.15 ppm, 1-hr. avg. 0.20 ppm, 1-hr. avg. 0.35 ppm, 1-hr. avg. 0.50 ppm, 1-hr. avg. 0.2 ppm, 1-hr. avg. 0.4 ppm, 1-hr. avg. 0.5 ppm, 1-hr. avg.

Carbon Monoxide 40 ppm, 1-hr. avg.

20 ppm, 12-hr. avg.

75 ppm, 1-hr. avg.

35 ppm, 12-hr. avg.

100 ppm, 1-hr. avg.

50 ppm, 12-hr. avg.

15 ppm, 8-hr. avg. 30 ppm, 8-hr. avg. 40 ppm, 8-hr. avg.

Nitrogen Dioxide 0.6 ppm, 1-hr. avg.

0.15 ppm, 24-hr. avg

1.2 ppm, 1-hr. avg.

0.30 ppm, 24-hr. avg.

1.6 ppm, 1-hr. avg.

0.40 ppm, 24-hr. avg.

Sulfur Dioxide 0.50 ppm, 1-hr. avg.

0.20 ppm, 24-hr. avg.

1.00 ppm, 1-hr. avg. 

0.70 ppm, 24-hr. avg.

2.00 ppm, 1-hr. avg.

0.90 ppm, 24-hr. avg.

0.3 ppm, 24-hr. avg. 0.6 ppm, 24-hr. avg. 0.8 ppm, 24-hr. avg.

Suspended Particulate 

(PM10)

350 μg/m3, 24-hr. avg. 420 μg/m3, 24-hr. avg. 500 μg/m3, 24-hr. avg.

Suspended Particulate 

(PM2.5)

Sulfates* 25 μg/m3, 24-hr. avg. combined with ozone > 0.20 ppm, 1-hr. avg.

Actions to be Taken** Health Advisory to 

a) Persons with 

respiratory and

coronary disease, 

b) School officials in 

order to curtail students' 

participation in strenuous 

activities.

First steps in 

abatement plans. 

Health Advisory to 

a) Persons with 

respiratory and 

coronary disease, 

b) School officials

in order to curtail 

students' participation 

in strenuous activities.

Intermediate Steps. 

Abatement actions 

taken to reduce 

concentration of 

pollutant at issue.

Mandatory abatement 

measures. Extensive 

actions taken to 

prevent exposure at 

indicated levels. 

State can take 

action if local efforts 

failed.

Open burning 

prohibited. Reduction 

in vehicle operation 

requested. Industrial 

curtailment.

Incinerator use 

prohibited. Reduction

in vehicle operation 

required. Further 

industrial curtailment.

Vehicle use prohibited. 

Industry shut down or 

curtailment. Public 

activities ceased.

 * Episodes based upon these criteria are not classified according to stages.

** For ozone, actions a) and b) are taken at Health Advisory level. For all other pollutants, these actions are taken at Stage I Episode level.
TABLE A-3

Air Monitoring Stations and Source/Receptor Areas

AIR

SOURCE/RECEPTOR MON

AREA # AREA* STN #

LOS ANGELES COUNTY

 1 Central LA 087

 2 Northwest Coastal LA County 091

 3 Southwest Coastal LA County 094

 4 South Coastal LA County 072

 6 West San Fernando Valley 074

 7 East San Fernando Valley 069

 8 West San Gabriel Valley 088

 9 East San Gabriel Valley 1 060

 9 East San Gabriel Valley 2 591

10 Pomona/Walnut Valley 075

11 South San Gabriel Valley 085

12 South Central LA County 1 084

12 South Central LA County 2 801

13 Santa Clarita Valley 090

ORANGE COUNTY

16 North Orange County 3177

17 Central Orange County 3176

18 North Coastal Orange County 3195

19 Saddleback Valley 1 3186

19 Saddleback Valley 2 3812

RIVERSIDE COUNTY

22 Norco/Corona 4155

23 Metropolitan Riverside County 1 4144

23 Metropolitan Riverside County 2 4146

24 Perris Valley 4149

25 Lake Elsinore Area 4158

29 Banning Airport 4164

30 Coachella Valley 1** 4137

30 Coachella Valley 2** 4157

SAN BERNARDINO COUNTY

32 Northwest San Bernardino Valley 5175

33 Southwest San Bernardino Valley 5817

34 Central San Bernardino Valley 1 5197

34 Central San Bernardino Valley 2 5203

35 East San Bernardino Valley 5204

37 Central San Bernardino Mountains 5181

38 East San Bernardino Mountains 5818

* Source/Receptor areas and numbers are shown in detail on the map "South Coast Air Quality Management

 District and Air Monitoring Areas" which is available from SCAQMD Public Information.

**Salton Sea Air Basin.
Los Angeles County

Orange County

San Bernardino County

Riverside County

M I LES

0

25

19

21

25

22

26

24

23

32

36

37 38

30

28

29

27

20

18

33

34

35

17

4

16

10

11

5

1

2

3

9

8

6 7

12

13 15

14

##

SOUTH C OAST

AIR BASIN (SCAB)

COUNT Y LINES

AREA LINES

AIR MONITORING

STATION

AREA NUMBER

APR IL 1995 VERSION

SCAQMD

AIR MONITORING NETWORK

FIGURE A-1

South Coast Air Basin and Adjoining Areas of Salton Sea Air Basin
TABLE A-4 

Ozone - Number of Days Exceeding the 

Federal Standard (12 pphm, 1-Hour Average) 

STN# LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 199LOS ANGELES COUNTY:  060 East San Gabriel Valley 1 129 137 155 146 129 137 104 123 129 117 126 111 125 112 84 73 91 79 72 63  069 East San Fernando Valley 138 75 102 92 99 91 63 95 73 87 93 76 64 40 40 55 47 16 18 20  072 South Coastal Los Angeles County 3 4 8 12 6 13 6 16 13 11 10 4 7 3 0 0 6 1 1 0  074 West San Fernando Valley 122 126 68 103 98 96 66 67 78 75 72 60 71 54 41 53 25 32 7 8  075 Pomona/Walnut Valley 1 108 120 136 126 99 97 66 102 98 98 89 72 91 61 60 60 56 45 47 47  076 Southwest Coastal Los Angeles County 9 4 13 7 0 4 2 9 8 4* a) -- -- -- -- -- -- -- -- --  080 Southeast Los Angeles County 70 53 65* 47 40 56 44 67 60 58 39 40 29 37 21 23 32 12 -- --  084 South Central Los Angeles County 1 18* 3* 16 26 14* 15 13 27 22 16 16 11 12 7 3 1 4 0 0 0  085 South San Gabriel Valley 69* 130 120 110 107 94 66 98 92 79 79 63 67 61 43 48 45 33 21 20  087 Central Los Angeles 71 58 55 50* 59 74 48 69 53 56 48 36 24 34 32 23 23 8 14 5  088 West San Gabriel Valley 129 134 152 151 118 116 89 122 125 116 110 95 119 80 69 70 71 53 61 44  090 Santa Clarita Valley 120 132 121 140 96 123 94 85 86 93 87 67 107 71 62 65 71 44 66 26  091 Northwest Coastal Los Angeles County 32 14 34* 44 35 40 20 37 35 37 30 16 16 15 8 9 12 7 2 1  094 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- 8 3 5 3 0 0 1 1 0 0  108 Pomona/Walnut Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 44* 26 23  591 East San Gabriel Valley 2 -- -- -- -- -- 135 126 134 130* 141 148 135 148 121 103 91 118 96 88 73  801 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- ORANGE COUNTY: 3176 Central Orange County 1 26* 14* 51 27 39 32 28 40 37 35 28 25 19 13 11 11 22 3 5 2 3177 North Orange County 32 37 69 62 63 60 39 64 59 57 49 41 33 36 35 28 31 13 9 4 3186 Saddleback Valley 1 26 17* 33 24 25 18 18 24 26 30 12 16 18 7 11 10 9 7 5 1 3190 Central Orange County 2 20 18* 39 17 13 13 10 16 12 11 5 4 17 11 7 10 9 4 -- -- 3195 North Coastal Orange County 3 6* 25 16 5 6 6 15 7 17 10 2 1* -- 3 5 3 1 0 0 3812 Saddleback Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- RIVERSIDE COUNTY: 4137 Coachella Valley 1** 33* 51 57 49* 49 57 37 40 36 25 31 33 35 37 27 22 21* 20 13 9 4141 Hemet/San Jacinty Valley 17 31 20* -- -- -- -- -- -- 13 9 27 28 21 20 23 5 8 13 2 4144 Metropolitan Riverside County 141 152 139 151 132 127 96 121 127 125 106 113 123 112 90 79 75 71 77 52 4149 Perris Valley 109 132 109 118 103 118 90 88 75 96 79 82 82 78 62 71 83 73 59 36 4150 Banning/San Gorgonio Pass 37* 62 79 84 76 50 58 67 48 55 45 53 64 60 43 31 19 8 25 15 4155 Norco/Corona 102 116 113 114 99 101 67 97 85* 92 77 73 61 56 13 54 16 17 14 23 4157 Coachella Valley 2** -- 35 37 16 -- 30 18 33 19 16 -- -- -- 16 10 13 8 3 0 3 4158 Lake Elsinore 55 74 45* -- -- -- -- -- -- -- -- -- -- 62 36 45 24 27 27 23 4163 Temecula Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 2 1 0* 0 4164 Banning Airport -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 5175 Northwest San Bernardino Valley 139* 151* 138* 135 131 139* 113* 120 115 110 111 101 122 97 64 67 81 55 79 67 5181 Central San Bernardino Mountains 47* 142 123 139 125 131 121 117 139 114 117 119 128 127 103 90 103 88 107 65 5197 Central San Bernardino Valley 1 145 160 155 164 146 147 96 127 136 126 121 116 124 112 92 74 88 65 91 57 5203 Central San Bernardino Valley 2 112 139 138 140 130 134 111 117 125 111 108* 117 121 115 78 79 85 65 96 61 5204 East San Bernardino Valley 1 96 123 136 139 127 116 103 109 116 113 93 120 130 116 81 91 103 95 98 69 

District Maximum 145 160 155 164 146 147 126 134 139 141 148 135 148 127 103 91 118 96 107 73 

a) Station relocated in 1986. b) Station relocated in 1998. * Less than 12 full months of data ** Salton Sea Air Basin
TABLE A-5 

Ozone, 1976-2001 

Annual Number of Days of First/Second Stage Episodes 

(Days Maximum 1-Hour Average Ozone ≥ 0.20 ppm/≥ 0.35 ppm) 

STN# LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995  060 East San Gabriel Valley 1 47/1 64/0 76/5 71/10 74/7 65/2 40/1 63/3 55/0 48/1 45/0 26/0 33/0 30/0 13/0 12/0 16/0 11/0 2/0 3/0  069 East San Fernando Valley 43/1 11/0 30/0 26/2 30/1 18/0 12/0 34/0 5/0 17/0 14/0 6/0 4/0 5/0 1/0 4/0 8/0 0/0 0/0 0/0  072 South Coastal Los Angeles County 0/0 0/0 0/0 1/0 1/0 1/0 1/0 1/0 1/0 1/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0  074 West San Fernando Valley 33/0 37/0 16/0 24/0 36/1 12/0 4/0 11/0 6/0 9/0 5/0 2/0 4/0 5/0 0/0 2/0 0/0 0/0 0/0 0/0  075 Pomona/Walnut Valley 1 37/1 58/0 72/9 57/3 49/1 32/0 31/0 45/0 30/0 32/0 24/0 16/0 16/0 10/0 12/0 8/0 10/0 6/0 3/0 2/0 

 080 Southeast Los Angeles County 19/1 12/0 18/1* 16/0 5/0 18/0 7/0 23/0 17/0 11/0 4/0 4/0 5/0 4/0 0/0 0/0 1/0 0/0 -- -- 

 084 South Central Los Angeles County 2/0* 0/0* 0/0 6/0 0/0* 1/0 2/0 3/0 4/0 1/0 1/0 1/0 1/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0  085 South San Gabriel Valley 26/1* 52/0 48/5 38/3 38/1 28/0 18/1 35/0 24/0 19/0 18/0 7/0 12/0 16/0 0/0 6/0 5/0 0/0 2/0 0/0 

 087 Central Los Angeles 11/0 3/0 16/0 14/0 10/0 8/0 7/1 12/0 8/0 9/0 8/0 2/0 2/0 1/0 2/0 0/0 1/0 0/0 0/0 0/0  088 West San Gabriel Valley 51/0 55/0 85/8 78/11 56/3 48/0 33/1 59/0 49/0 41/1 33/0 15/0 18/0 17/0 7/0 10/0 10/0 5/0 2/0 1/0  090 Santa Clarita Valley 38/0 59/0 45/0 59/0 46/2 37/0 17/0 19/0 18/0 15/0 15/0 2/0 28/0 11/0 6/0 8/0 4/0 3/0 6/0 1/0 

 091 Northwest Coastal Los Angeles County 4/0 0/0 10/0* 7/0 3/0 3/0 3/0 6/0 5/0 4/0 1/0 1/0 2/0 1/0 0/0 0/0 0/0 0/0 0/0 0/0  094 Southwest Coastal Los Angeles County 1/0 0/0 2/0 0/0 0/0 0/0 0/0 0/0 1/0 0/0 0/0 1/0 1/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0  108 Pomona/Walnut Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3/0* 2/0 0/0  591 East San Gabriel Valley 2 -- -- -- -- 30/5* 61/2 62/2 74/2 67/0* 68/5 70/1 51/0 54/0 37/0 29/0 34/0 30/0 19/0 10/0 9/0 3176 Central Orange County 1 4/0* 0/0* 13/0 5/0 6/0 5/0 7/0 10/0 5/0 11/0 1/0 3/0 3/0 4/0 0/0 2/0 1/0 0/0 1/0 0/0 3177 North Orange County 15/0 8/0 24/1 21/1 14/0 15/0 12/0 15/0 15/0 13/0 8/0 6/0 3/0 5/0 4/0 1/0 1/0 0/0 2/0 0/0 

3186 Saddleback Valley 3/0 2/0* 10/0 6/0 3/0 5/0 3/0 10/0 3/0 7/0 1/0 1/0 2/0 2/0 0/0 1/0 0/0 0/0 0/0 0/0 3188 Capistrano Valley 2/0* 1/0 2/0* -- -- -- -- -- -- -- -- -- -- 0/0* -- -- -- -- -- -- 3190 Central Orange County 2 2/0 0/0* 5/0 2/0 3/0 0/0 2/0 2/0 0/0 0/0 0/0 0/0 1/0 0/0 0/0 0/0 0/0 0/0 -- -- 

3191 North Orange County 17/0 10/0 9/0 14/2 13/0 4/0* -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3195 North Coastal Orange County 0/0 0/0* 3/0 1/0 0/0 1/0 0/0 2/0 1/0 1/0 0/0 0/0 0/0* -- 0/0 0/0 0/0 0/0 0/0 0/0 4137 Coachella Valley 1** 3/0* 5/0 3/0 3/0* 4/0 0/0 0/0 0/0 1/0 2/0 0/0 0/0 1/0 0/0 0/0 0/0 0/0 0/0 0/0 0/0 4141 Hemet/San Jacinty Valley 0/0 2/0 2/0* -- -- -- -- -- -- 1/0 0/0 0/0 0/0 0/0 1/0 0/0 0/0 0/0 0/0 0/0 4144 Metropolitan Riverside County 46/2 66/1 62/2 55/0 67/4 34/0 26/0 42/1 29/0 35/1 19/0 20/0 16/0 18/0 15/0 17/0 6/0 5/0 2/0 3/0 

4149 Perris Valley 13/0 39/0 38/0 26/0 20/0 18/0 10/0 13/0 6/0 8/0 3/0 1/0 1/0 4/0 0/0 5/0 1/0 3/0 0/0 1/0 4150 Banning/San Gorgonio Pass 20/0* 13/0 22/0 22/0 13/0 7/0 3/0 12/0 5/0 8/0 1/0 3/0 7/0 6/0 4/0 1/0 0/0 0/0 1/0 0/0 

4155 Norco/Corona 26/0 31/1 34/2 24/0 32/0 24/1 15/1 29/1 19/0* 20/1 12/0 9/0 7/0 3/0 0/0 7/0 1/0 0/0 0/0 0/0 

4157 Coachella Valley 2** 0/0* 0/0 0/0 1/0 0/0 0/0 0/0 0/0 0/0 1/0 -- 0/0 -- 0/0 0/0 0/0 0/0 0/0 0/0 0/0 4158 Lake Elsinore 1/0 10/0 7/0* -- -- -- -- -- -- -- -- -- 0/0* 4/0 0/0 1/0 0/0 0/0 0/0 0/0 4163 Temecula Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0/0 0/0 0/0* 0/0 5175 Northwest San Bernardino Valley 61/1* 85/2* 68/2* 59/2 73/4 62/1 0/0* 59/1* 41/0 39/0 38/0 23/0 25/1 19/0 12/0 14/0 15/0 7/0 7/0 6/0 5181 Central San Bernardino Mountains 11/0* 63/0 73/0 80/3 54/0 49/1 29/0 48/0 49/0 41/0 34/0 22/0 38/0 30/0 16/0 15/0 22/0 5/0 12/0 6/0 5182 East San Bernardino Valley 2 28/0 39/0 56/0 0/0* 67/0 19/0* -- -- -- -- -- -- -- -- -- -- -- -- -- -- 5197 Central San Bernardino Valley 1 69/1 98/6 98/11 95/9 84/6 73/1 34/0 56/0 45/0 48/0 42/0 28/0 23/0 28/0 20/0 16/0 19/0 5/0 9/0 2/0 5198 Southwest San Bernardino Valley 39/1 42/3 22/2* -- -- -- -- -- -- 15/0 14/0 0/0 -- -- -- -- -- -- -- -- 5203 Central San Bernardino Valley 2 51/0 70/1 72/1 62/0 72/2 58/1 38/0 49/0 36/0 30/0 41/0* 27/0 31/0 22/0 8/0 9/0 17/0 4/0 7/0 4/0 

5204 East San Bernardino Valley 1 25/1 48/0 64/2 57/0 61/0 20/0 30/0 41/0 26/0 31/0 22/0 26/0 25/0 17/0 11/0 16/0 7/0 8/0 8/0 4/0 

 * Less than 12 full months of data. ** Salton Sea Air Basin.
TABLE A-6 

Ozone - Annual Maximum 1-Hour, ppm 1955-2001 

 LOCATION 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1

087 Central Los Angeles .68 .47 .53 .61 .61 .41 .45 .50 .50 .46 .58 .50 .36 .46 .30 .33 .24 060 East San Gabriel Valley 1 - - .42 .45 .56 .49 .45 .43 .34 .40 .54 .53 .65 .44 .54 .58 .48 

069 East San Fernando Valley .30* .33 .43 .39 .47 .33 .33/ .33 .38 .39 .40 .32 .47 .42 .38 .35 .31 

091 Northwest Coastal Los Angeles County - - - - - - - .40* .40 .32 .39 .29 .36 .44 .30 .24 .26 

072 South Coastal Los Angeles County - - - .37 .30 .37 .34 .33/ .28 .27 .34 .27 .21 .33 .22 .18 .27 

074 West San Fernando Valley - - - - - - - - - - .47 .44 .41 .34 .39 .37 .32 

075 Pomona/Walnut Valley 1 - - - - - - - - - - .44* .44 .43 .49 .45 .48 .35 

076 Southwest Coastal Los Angeles County - - - - - - - - - - .32 .37 .33 .23 .25 .23 .21 

094 Southwest Coastal Los Angeles County - - - - - - - - - - - - - - - - - 080 Southeast Los Angeles County - - - - - - - - - - - - - - .43* .36 .39 

090 Santa Clarita Valley - - - - - - - - - - - - - - .20 .41 .30 

088 West San Gabriel Valley - .46 .36/ .44* .47 .54 .44 .46 .41 .42 .46 .43 .40/ .48* .52 .51 .53 .

084 South Central Los Angeles County 1 - - - - - - - - - - - - - - - - 

801 South Central Los Angeles County 2 - - - - - - - - - - - - - - - - - 085 South San Gabriel Valley - - - - - - - - - - - - - - - - - 

591 East San Gabriel Valley 2 - - - - - - - - - - - - - - - - - 

3176 Central Orange County 1 -------- .27 .23 .41 .31 .30 .28 .30 .29 .34 3177 North Orange County 1 - - - - - - - - - - - - .23* .26 .43 .30 .34 

3195 North Coastal Orange County - - - - - - - - - - - - - - - - - 

3186 Saddleback Valley 1 - - - - - - - - - - - - - - - - - 

3812 Saddleback Valley 2 - - - - - - - - - - - - - - - - - 

3188 Capistrano Valley - - - - - - - - - - - - - - - - - 

3190 Central Orange County 2 - - - - - - - - - - - - - - - - - 

3191 North Orange County 2 - - - - - - - - - - - - - - - - - 

4137 Coachella Valley 1** - - - - - - - - - - - - - - - - .31 4157 Coachella Valley 2** - - - - - - - - - - - - - - - - .26 

4155 Norco/Corona - - - - - - - - - - - - - - - - .05* 4141 Hemet/San Jacinto Valley - - - - - - - - - - - - - - - - - 

4144 Metropolitan Riverside County 1 - - - - - - - - .28 .40 .29 .31 .40 .34* - - .45 .

4149 Perris Valley - - - - - - - - - - - - - - - - - 

4150 San Gorgonio Pass - - - - - - - - - - - - - - - .37 .19 

4164 BanningAirport - - - - - - - - - - - - - - - - - 

4163 Temecula Valley - - - - - - - - - - - - - - - - - 

4158 Lake Elsinore - - - - - - - - - - - - - - - - - 

5203 Central San Bernardino Valley 2 -------- .28 .32 .32 .31 .33 .28 .27 .36 .26 5204 East San Bernardino Valley - - - - - - - - - - - - .12* .32 .30 .42 .28 

5171 Southwest San Bernardino Valley - - - - - - - - - - - .32* .21 .21 .22 .08* - 

5175 Northwest San Bernardino Valley - - - - - - - - - - - - - - - - - 

5174 Northwest San Bernardino Valley (ARB) - - - - - - - - - - - - - - - - - 

5197 Central San Bernardino Valley 1 - - - - - - - - - - - - - - - - - 

5177 Central San Bernardino Mountains 2 - - - - - - - - - - - - - - - - - 5181 Central San Bernardino Mountains 1 - - - - - - - - - - - - - - - - - 

 District Maximum .68 .47 .53 .61 .61 .54 .45 .50 .50 .46 .58 .53 .65 .49 .54 .58 .53 

 * Incomplete data. / Station location change 

** Salton Sea Air Basin 
TABLE A-6 (continued) 

Ozone - Annual Maximum 1-Hour, ppm 1955-2001 

 LOCATION 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 

087 Central Los Angeles .30 .31/ .29 .32 .40 .26 .29 .30 .22 .22 .21 .25 .20 .19 .20 .16 .19 .17 060 East San Gabriel Valley 1 .40 .45 .41 .35 .36 .39 .31 .36 .31 .30 .30 .33 .23 .28 .27 .24 .25 .21 

069 East San Fernando Valley .30 .39 .35 .27 .25 .31 .26 .30 .28 .23 .24 .20 .20 .22 .22 .18 .17 .17 

091 Northwest Coastal Los Angeles County .24/ .26 .21 .23 .28 .23 .27/ .27 .20 .28 .24 .25 .16 .18 .17 .18 .16 .14 

072 South Coastal Los Angeles County .19 .21 .20 .23 .22 .30 .27 .23 .18 .17 .16 .16 .12 .11 .15 .14 .16 .11 

074 West San Fernando Valley .27 .33 .38 .25 .22 .26 .26 .25 .22 .22 .25 .23 .19 .22 .17 .19 .14 .15 

075 Pomona/Walnut Valley 1 .41 .35 .37 .33 .31 .34 .31 .33 .27 .29 .29 .25 .24 .24 .26 .21 .24 .22 

076 Southwest Coastal Los Angeles County .30 .19 .11 .19 .16 .18 .22 .17/ - - - - - - - - - 

094 Southwest Coastal Los Angeles County - - - - - - - - .19 .20 .22 .19 .10 .11 .15 .13 .11 .12 080 Southeast Los Angeles County .36 .32 .27 .27 .31 .32 .30 .32 .25 .23 .29 .26 .19 .19 .22 .19 - - 

088 West San Gabriel Valley .42 .44 .41 .33 .37/ .34 .30 .37 .26 .28 .29 .27 .26 .23 .27 .22 .26 .21 

090 Santa Clarita Valley .32 .32 .36 .29 .26/ .29 .27 .24 .24 .21 .30 .25 .23 .24 .22 .22 .26 .21 

084 South Central Los Angeles County 1 .18 .29 .18 .21 .26 .23 .27 .21 .20 .24 .21 .14 .15 .16 .17 .12 .12 .09 

801 South Central Los Angeles County 2 - - - - - - - - - - - - - - - - - - 085 South San Gabriel Valley .43 .39 .39 .35 .39 .33 .27 .31 .24 .28 .30 .26 .19 .26 .26 .19 .22 .18 

591 East San Gabriel Valley 2 - - .49 .39 .36 .38 .34 .39 .35 .33 .34 .34 .29 .32 .30 .28 .30 .22 

3176 Central Orange County 1 .29 .33 .28 .26 .26 .30 .25 .25 .20 .22 .27 .24 .18 .25 .22 .17 .21 .13 3177 North Orange County 1 .35 .38 .31 .27 .32 .27 .32 .34 .25 .24 .29 .26 .21 .21 .21 .19 .25 .16 

3195 North Coastal Orange County .22 .21/ .16 .20 .18 .25 .25 .21 .17 .16 .13 - .15 .17 .15 .13 .12 .11 

3186 Saddleback Valley 1 .34 .32 .34 .33 .27 .29 .30 .28 .23 .20 .21 .23 .19 .24 .16 .16 .18 .15 

3812 Saddleback Valley 2 - - - - - - - - - - - - - - - - - - 

3188 Capistrano Valley .32 - - - - - - .19 - - - .15* - - - - - - 

3190 Central Orange County 2 .27 .26 .22 .18 .23 .20 .19 .19 .15 .17 .23 .16 .17 .17 .18 .15 - - 

3191 North Orange County 2 .27 .39 .33 .23* - - - - - - - - - - - - - - 

4137 Coachella Valley 1** .20 .24 .21 .19 .19 .19 .20 .24 .18 .17 .20 .19 .17 .18 .15* .17 .17 .16 4157 Coachella Valley 2 ** .17 .21 .11 .18 .17 .18 .19 .20 - .16 - .16 .16 .18 .14 .16 .12 .14 

4155 Norco/Corona .40 .33/ .34 .37 .35 .35 .30 .35 .27 .24 .25 .23 .17 .22 .23 .16 .17 .19 

4141 Hemet/San Jacinto Valley .27 - - - - - .18* .23 .18 .18 .18 .19 .22 .19 .15 .18 .16 .15 

4144 Metropolitan Riverside County .39 .34 .37 .30 .31 .36 .32 .35 .25 .29 .28 .27 .29 .24 .26 .26 .25 .21 

4149 Perris Valley .32 .25 .29 .24 .28 .26 .22 .29 .22 .20 .23 .21 .19 .20 .21 .20 .18 .20 

4150 San Gorgonio Pass .30 .27 .26 .23 .24 .26 .25 .29 .22 .21 .26 .23 .22 .20 .16 .16 .20 .18 

4164 Banning Airport - - - - - - - - - - - - - - - - - - 

4163 Temecula Valley .23 - - - - - - - - - - - - .17* .13 .13 .10* .11 

4158 Lake Elsinore .30 - - - - - - - - - - .24 .19 .20 .17 .19 .19 .19 

5203 Central San Bernardino Valley 2 .36 .34 .36 .36/ .30 .32 .30 .27/ .30 .25 .28 .30 .29 .25 .28 .21 .25 .20 5204 East San Bernardino Valley .39 .34/ .32 .24 .29 .30 .29 .33/ .29 .24 .29 .27 .30 .25 .27 .27 .23 .24 

5171 Southwest San Bernardino Valley .36 - - - - - .32* .32 .25 - - - - - - - - - 

5175 Northwest San Bernardino Valley - - - - - .36 .32 .33 .29 .28 .35 .32 .29 .27 .28 .24 .25 .24 

5174 Northwest San Bernardino Valley (ARB) .35 .37 .44 .36 - - - - - - - - - - - - - - 

5197 Central San Bernardino Valley 1 .42 .42 .42 .35/ .31 .32 .32 .34 .31 .29 .29 .32 .27 .29 .28 .24 .25 .22 

5177 Central San Bernardino Mountains 2 .17 - - - - - - .26 - - - - - - - - - - 5181 Central San Bernardino Mountains 1 .33 .40 .31 .35 .32 .28 .34 .30 .26 .29 .29 .27 .33 .27 .28 .24 .27 .26 

 District Maximum .43 .45 .49 .39 .40 .39 .34 .39 .35 .33 .35 .34 .33 .32 .30 .28 .30 .26 

* Incomplete data. / Station location change ** Salton Sea Air Basin
TABLE A-7 

Carbon Monoxide - Number of Days Maximum 8-Hour Average 

Exceeded the Federal Standard (≥ 9.5 ppm) 

STN# LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1LOS ANGELES COUNTY:  060 East San Gabriel Valley 1 3 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0  069 East San Fernando Valley 100 72 54 54 60 48 36 21 18 18 16 14 15 21 10 8 3 0 5  072 South Coastal Los Angeles County 52 41* 31 20 8 3 4 8 1 5 4 0 1 2 0 0 0 0* 0  074 West San Fernando Valley 52 45 47 28 28 30 26 17 8 10 12 2 4 13 12 9 1 0 4  075 Pomona/Walnut Valley 6 9 6 1 4 3 0 0 0 0 0 1 0 0 0 0 0 0 0  076 Southwest Coastal Los Angeles County 83 62 62 50 67 46 44 40 58 45 a) -- -- -- -- -- -- -- --  080 Southeast Los Angeles County 41 33 28 18* 19 10 10 6 0 4 0 1 0 0 0 0 0 0 --  084 South Central Los Angeles County 1 107 83 79 64 65 54 44 29 49 32 43 38 55 61 42 37 31 22 22  085 South San Gabriel Valley 24* 41 39 26 19 6 4 5 0 4 1 1 1 1 0 0 0 0 0  087 Central Los Angeles 64 53 36 14 16 16 9 11 0 2 2 2 4 1* 2 0 2 0 0  088 West San Gabriel Valley 34 27 26 21 22 19 14 10 0 5 2 3 4 0 2 1 0 0 0  090 Santa Clarita Valley 0 2 0 0 -- -- -- -- -- -- -- -- -- 0* 0 0 0 0 0  091 Northwest Coastal Los Angeles County 53 33 19* 27 34 21 19 11 7 0 0 0 0 0 0 0 0 0 0  094 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- 16 15 25 24 10 7 7 3 5  801 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- ORANGE COUNTY: 3176 Central Orange County 60 30 21 31 44 17 1 4 4 3 1 0 5 6 2 0 0 0 0 3177 North Orange County 70* 50 17 18 19* 10 10 8 1 6 2 3 3 7 1 0 0 0 0 3186 Saddleback Valley 1 -- -- -- -- -- 0* 0 0 0 0 0 0 0 0 0 0 0 0 0 3195 North Coastal Orange County 55 15 7 16 6 5 2 1 1 5 3 0 2 6* 4 0 0 0 0 3812 Saddleback Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- RIVERSIDE COUNTY: 4137 Coachella Valley 1** 0* 0 0 0* 0 0 0 0 0 0 0 0 0 0 0 0 0* 0 0 4144 Metropolitan Riverside County 1 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 4146 Metropolitan Riverside County 2 1* -- -- -- -- -- -- 0 0 0 0 0 1 0 0 0 0 0 0 4149 Perris Valley 0* 0* 0 0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4150 San Gorgonio Pass 0* 0 0 0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4155 Norco/Corona 0 1* 0* 0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4157 Coachella Valley 2** 0* 0* 0 0* -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4158 Lake Elsinore -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 5175 Northwest San Bernardino Valley 0* 0* 0 0 0 0* -- 2 0 0 0 0 0 0 0 0* -- -- -- 5181 Central San Bernardino Mountains 0* 0* 0 0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 5197 Central San Bernardino Valley 1 0 0* 1 1 0* 0 0 0 0 0 0 0 0 0 0 0* -- -- -- 5203 Central San Bernardino Valley 2 0 2* 0 0 0 0 0 0 0 0* 0* 0 0 0 0 0 0 0 0 5204 East San Bernardino Valley 1 0 0 0 0 0 0 0 0 -- -- -- -- -- -- -- -- -- -- -- a) Station relocated in 1986.  * Incomplete data ** Salton Sea Air Basin 
TABLE A-8 

Carbon Monoxide - Number of Days Maximum 8-Hour Average 

Exceeded the Federal Alert Level (> 15 ppm) 

STN# LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1LOS ANGELES COUNTY:  060 East San Gabriel Valley 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  069 East San Fernando Valley 30 12 6 3 12 11 9 4 0 2 1 0 0 0 0 0 0 0 0  072 South Coastal Los Angeles County 0 1* 2 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0* 0  074 West San Fernando Valley 13 12 8 3 9 13 4 3 0 0 1 0 0 0 0 0 0 0 0  075 Pomona/Walnut Valley 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  076 Southwest Coastal Los Angeles County 28 14 9 8 18 7 3 7 7 9 a) -- -- -- -- -- -- -- --  080 Southeast Los Angeles County 0 0 1 0* 1 0 0 0 0 0 0 0 0 0 0 0 0 0 --  084 South Central Los Angeles County 1 37 21 17 12 25 10 7 7 7 10 7 7 14 13 4 3 3 0 0  085 South San Gabriel Valley 0* 0 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  087 Central Los Angeles 4 6 1 1 0 0 0 0 0 0 0 0 0 0* 0 0 0 0 0  088 West San Gabriel Valley 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  090 Santa Clarita Valley 0 0 0 0 -- -- -- -- -- -- -- -- -- 0* 0 0 0 0 0  091 Northwest Coastal Los Angeles County 6 2 1* 5 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0  094 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- 3* 1 0 2 1 0 0 0 0 0  801 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- ORANGE COUNTY: 3176 Central Orange County 5 3 1 0 11 0 0 0 0 1 0 0 0 0 0 0 0 0 0 3177 North Orange County 38* 7 0 0 0* 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3186 Saddleback Valley 1 -- -- -- -- -- 0* 0 0 0 0 0 0 0 0 0 0 0 0 0 3195 North Coastal Orange County 15 0 0 1 0 0 0 0 0 0 0 0 0 0* 0 0 0 0 0 3812 Saddleback Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- RIVERSIDE COUNTY: 4137 Coachella Valley 1** 0* 0 0 0* 0 0 0 0 0 0 0 0 0 0 0 0 0* 0* 0 4144 Metropolitan Riverside County 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4146 Metropolitan Riverside County 2 0* -- -- -- -- -- -- 0 0 0 0 0 0 0 0 0 0 0 0 4149 Perris Valley 0* 0* 0 0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4150 San Gorgonio Pass 0* 0 0 0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4155 Norco/Corona 0 0* 0* 0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4157 Coachella Valley ** 0* 0* 0* 0* -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 5175 Northwest San Bernardino Valley 0* 0* 0 0 0 0* -- 0 0 0 0 0 0 0 0 0* -- -- -- 5181 Central San Bernardino Mountains 0* 0* 0 0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 5197 Central San Bernardino Valley 1 0 0* 0 0 0* 0 0 0 0 0 0 0 0 0 0 0* -- -- -- 5203 Central San Bernardino Valley 2 0 0* 0 0 0 0 0 0 0 0* 0* 0 0 0 0 0 0 0 0 5204 East San Bernardino Valley 1 0 0 0 0 0 0 0 0 -- -- -- -- -- -- -- -- -- -- -- 

District Maximum 38 21 17 12 25 13 9 7 7 10 7 7 14 13 4 3 3 0 0 

a) Station relocated in 1986.  * Incomplete data. ** Salton Sea Air Basin 
TABLE A-9 

Carbon Monoxide 

Annual Maximum 8-Hour Average, ppm 

1976-2001 

STN# LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1LOS ANGELES COUNTY:  060 East San Gabriel Valley 10.6 10.8 8.6 9.0 8.8 9.5 6.9 6.6 4.6 4.9 5.5 6.0 6.0 5.8 5.1 5.9 4.9 4.0 4.5 6 069 East San Fernando Valley 26.3 21.9 16.8 15.4 24.8 21.1 16.4 16.6 12.0 16.1 16.4 12.5 11.9 13.9 13.0 10.6 10.5 8.4 10.7 1 072 South Coastal Los Angeles County 14.6 17.3 16.8 12.1 12.9 11.3 11.6 12.1 10.3 15.7 10.3 9.4 10.3 10.1 9.1 9.3 8.1 6.9 8.9 6 074 West San Fernando Valley 20.9 20.5 24.3 19.5 19.5 21.6 19.4 16.0 11.0 14.1 15.7 12.1 13.1 12.5 14.9 13.5 9.9 9.0 10.8 1 075 Pomona/Walnut Valley 11.7 12.6 12.0 9.6 10.8 9.6 9.1 8.0 7.3 7.4 8.7 10.0 8.6 7.4 7.5 7.1 8.3 5.5 6.8 6 076 Southwest Coastal Los Angeles County 25.3 20.4 24.3 21.4 21.6 19.2 19.2 18.4 19.7 24.0 a) -- -- -- -- -- -- -- --  080 Southeast Los Angeles County 14.4 13.6 15.5 14.1 15.8 13.7 12.7 13.6 9.4 14.6 8.7 9.7 7.3 8.8 9.0 7.5 9.37 5.86 7.7 

 084 South Central Los Angeles County 1 23.3 27.4 21.1 23.4 25.8 25.3 21.3 20.9 18.9 27.7 19.7 19.6 27.5 21.8 16.8 17.4 18.75 14.63 18.10 13

 085 South San Gabriel Valley 14.9 14.8 18.3 12.1 14.5 11.9 11.9 10.9 8.7 13.1 10.7 10.0 9.9 10.7 9.4 9.1 8.62 6.43 9.29 7

 087 Central Los Angeles 17.0 21.3 15.4 15.7 14.0 14.9 11.9 13.1 9.1 9.9 11.6 10.9 11.4 9.8 9.9 9.0 9.50 6.75 8.43 8

 088 West San Gabriel Valley 12.4 16.6 13.3 12.5 13.6 11.8 12.9 12.3 8.0 11.3 10.1 11.3 10.6 8.4 10.0 9.5 7.25 6.25 8.50 9

 090 Santa Clarita Valley 6.8 10.8 5.8 6.4 4.5 -- -- -- -- -- -- -- -- 5.4 4.6 5.1 3.71 3.86 3.86 4

 091 Northwest Coastal Los Angeles County 17.3 16.1 15.5 19.3 16.3 14.8 14.6 12.9 11.6 10.7 8.6 7.5 8.6 8.0 8.0 6.1 5.87 5.43 6.00 5

 094 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- 15.0 14.1 15.9 16.4 12.7 11.3 12.29 10.71 12.00 8

 801 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 

ORANGE COUNTY: 

3176 Central Orange County 24.8 15.9 15.5 13.8 21.3 13.4 9.6 10.9 14.4 17.0 9.7 8.7 12.0 12.1 11.7 8.6 9.37 7.71 8.62 83177 North Orange County 24.0 21.6 13.5 13.0 13.8 13.0 11.9 11.7 9.6 14.0 10.3 10.6 9.9 10.7 9.6 8.0 9.14 6.00 8.75 6

3186 Saddleback Valley 1 -- -- -- -- -- 7.0 5.3 5.7 6.1 7.7 4.9 6.3 5.1 5.1 5.6 4.8 7.25 4.13 5.37 4

3195 North Coastal Orange County 20.6 12.4 12.8 15.9 13.9 11.7 10.4 10.6 9.6 13.3 10.4 8.4 11.6 12.7 10.7 8.1 9.14 7.33 7.86 6

3812 Saddleback Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- RIVERSIDE COUNTY: 

4137 Coachella Valley 1** 3.1 3.5 3.1 3.0 3.6 3.8 2.6 2.8 2.1 2.6 3.6 2.9 2.1 2.9 2.3 2.5 2.4 2.00 1.87 14144 Metropolitan Riverside County 1 8.6 9.5 7.6 8.1 7.4 7.5 6.4 6.3 6.3 5.7 6.0 6.1 6.8 10.3 6.3 7.4 5.25 7.13 5.75 5

4146 Metropolitan Riverside County 2 9.5 -- -- -- -- -- -- 7.9 8.9 9.1 8.3 7.6 10.0 8.5 7.3 6.9 6.12 6.25 7.25 6

4149 Perris Valley 7.6 6.5 5.1 5.0 4.8 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4150 San Gorgonio Pass 4.6 4.8 3.1 5.0 2.1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 

4155 Norco/Corona 8.0 11.1 7.5 6.6 9.3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4157 Coachella Valley 2** 7.1 6.0 6.5 4.8 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4158 Lake Elsinore -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 5175 Northwest San Bernardino Valley 6.8 5.4 6.4 6.3 9.0 6.6 1.9 12.5 5.6 6.3 6.6 5.1 5.0 5.4 6.6 4.6 -- -- -- 5181 Central San Bernardino Mountains 5.6 5.9 6.8 6.3 4.1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 5197 Central San Bernardino Valley 1 7.3 8.4 9.8 9.8 8.5 7.6 4.4 5.1 4.4 4.0 5.9 4.0 5.6 5.8 4.9 4.4 -- -- -- 5203 Central San Bernardino Valley 2 9.3 12.1 8.5 7.6 8.1 6.0 6.9 5.4 5.1 5.3 6.7 6.7 7.6 8.1 6.0 7.0 5.9 6.0 6.5 65204 East San Bernardino Valley 1 9.1 8.4 6.4 6.8 4.4 4.9 3.0 3.0 -- -- -- -- -- -- -- -- -- -- -- 

District Maximum 26.3 27.4 24.3 23.4 25.8 25.3 21.3 20.9 19.7 27.7 19.7 19.6 27.5 21.8 16.8 17.4 18.8 14.6 18.1 1

 a) Station relocated in 1986. ** Salton Sea Air Basin 
TABLE A-10 

Suspended Particulates (PM10) 

Annual Arithmetic Mean, μg/m3 

1985-2001 

STN# LOCATION 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 LOS ANGELES COUNTY:  060 East San Gabriel Valley 1 67 61 68 63 61 55 66 47 43 44 49 45 46  069 East San Fernando Valley 70 63 60 62 65 52 55 49 45 38 42 42 45  072 South Coast Los Angeles County 55 56 50 52 51 44 40 39 37 40 39 35 41  087 Central Los Angeles 70 59 57 58 61 53 57 48 47 45 43 41 43  090 Santa Clarita Valley -- -- -- -- 54 43 47 35 33 36 37 33 33  094 Southwest Coastal Los Angeles County -- -- -- -- 50 41 39 33 37 36 36 33 36  108 Pomona/Walnut Valley -- -- -- -- -- -- -- -- -- -- -- 37 40 ORANGE COUNTY: 3176 Central Orange County 1 -- -- -- -- -- 49 45 40 38 37 44 35 39 3186 Saddleback Valley 1 47 37 40 38 42 43 37 34 34 33 38 30 35 3190 Central Orange County 56 48 49 46 46 -- -- -- -- -- -- -- -- 3812 Saddleback Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- RIVERSIDE COUNTY: 4137 Coachella Valley 1** -- -- 33 29 45 35 43 30 27 28 27 29 26 4144 Metropolitan Riverside County 1 96 86 90 95 94 78 76 63 72 66 69 61 65 4149 Perris Valley -- -- 49 59 61 59 49 45 50 45 47 40 45 4150 San Gorgonio Pass 51 41 44 42 47 35 38 34 33 35 30 34 38 4155 Norco/Corona 45 -- -- -- -- -- -- -- 53 53 54 44 50 4157 Coachella Valley 2** 68 50 51 48 90 79 69 43 46 49 52 51 49 4163 Temecula Valley -- -- -- -- -- -- 38 31 27 22 -- -- -- 4164 Banning Airport -- -- -- -- -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 5171 Southwest San Bernardino Valley 1 74 76 70 78 79 72 68 79 58 50 54 51 51 5181 Central San Bernardino Mountains -- -- -- -- 39 37 39 33 31 26 20 24 24 5197 Central San Bernardino Valley 1 74 76 74 81 77 78 63 56 57 60 61 55 54 5203 Central San Bernardino Valley 2 -- 85 70 80 81 65 61 57 56 54 57 53 51 5204 East San Bernardino Valley -- -- -- -- -- -- -- -- 45 47 48 46 43 5817 Southwest San Bernardino Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- 

District Maximum 96 86 90 95 94 79 76 79 72 66 69 61 65 

** Salton Sea Air Basin 
TABLE A-11 

Suspended Particulates (PM10) 

Annual Geometric Mean, μg/m3 

1985-2001 

STN# LOCATION 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 LOS ANGELES COUNTY:  060 East San Gabriel Valley 1 59 54 59 56 54 48 60 40 36 38 41 39 41  069 East San Fernando Valley 65 57 54 57 60 48 49 42 39 34 37 42 42  072 South Coast Los Angeles County 52 51 46 47 46 41 37 37 34 37 32 31 38  087 Central Los Angeles 66 54 51 53 56 48 51 44 43 41 36 37 39  090 Santa Clarita Valley -- -- -- -- 49 39 43 31 28 32 31 30 31  094 Southwest Coastal Los Angeles County -- -- -- -- 45 38 35 30 33 33 31 29 34  108 Pomona/Walnut Valley -- -- -- -- -- -- -- -- -- -- -- 33 38 ORANGE COUNTY: 3176 Central Orange County 1 -- -- -- -- -- 43 40 37 34 34 36 32 36 3186 Saddleback Valley 1 43 34 36 35 38 40 34 32 30 30 32 27 33 3190 Central Orange County 2 52 44 42 40 42 -- -- -- -- -- -- -- -- 3812 Saddleback Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- RIVERSIDE COUNTY: 4137 Coachella Valley 1** -- -- 24 24 36 30 37 24 24 24 24 25 24 4144 Metropolitan Riverside County 1 81 74 73 81 81 67 65 52 58 56 52 52 56 4149 Perris Valley -- -- 32 52 52 50 43 38 41 39 37 35 39 4150 San Gorgonio Pass 40 33 34 34 37 29 31 29 26 27 25 27 30 4155 Norco/Corona -- -- -- -- -- -- -- -- 44 45 45 40 44 4157 Coachella Valley 2** 55 46 44 43 66 65 61 39 41 45 47 46 44 4163 Temecula Valley -- -- -- -- -- -- 36 28 24 19 -- -- -- 4164 Banning Airport -- -- -- -- -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 5171 Southwest San Bernardino Valley 1 65 65 60 67 70 61 60 62 37 45 44 46 45 5181 Central San Bernardino Mountains -- -- -- -- 36 31 35 30 25 22 18 20 21 5197 Central San Bernardino Valley 1 63 63 58 67 68 63 58 49 46 53 51 48 48 5203 Central San Bernardino Valley 2 -- 74 55 67 69 55 52 49 48 46 48 46 46 5204 East San Bernardino Valley -- -- -- -- -- -- -- -- 35 38 37 38 35 5817 Southwest San Bernardino Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- 

District Maximum 81 74 73 81 81 67 65 62 58 56 52 52 56 

** Salton Sea Air Basin 
TABLE A-12 

Suspended Particulates (PM10) - Percent of Sampling Days 

Exceeding State Standard (50 μg/m3) 

And Federal Standard (150 μg/m3), 

1985-2001 

STN# LOCATION 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 LOS ANGELES COUNTY:  060 East San Gabriel Valley 1 68/0 61/4 64/3 67/0 59/2 50/0 68/0 39/0 32/0 40/0 40/2 41/0 40/0  069 East San Fernando Valley 77/2 67/3 61/0 68/0 69/0 47/2 50/0 31/3 36/0 18/0 25/0 25/0 30/0  072 South Coast Los Angeles County 58/0 40/0 33/0 40/0 44/0 24/0 24/0 19/0 20/0 18/0 19/0 15/0 18/0  087 Central Los Angeles 85/0 66/2 62/2 57/0 57/0 52/2 54/2 36/0 43/0 33/0 23/0 18/0 25/0  090 Santa Clarita Valley -- -- -- -- 44/0 28/0 23/0 9/0 15/0 18/0 14/0 9/0 9/0  094 Southwest Coastal Los Angeles County -- -- -- -- 48/0 26/0 42/0 13/0 15/0 22/0 21/0 8/0 7/0  108 Pomona/Walnut Valley -- -- -- -- -- -- -- -- -- -- -- 18/0 18/0 ORANGE COUNTY: 3176 Central Orange County 1 -- -- -- -- -- 34/2 24/0 20/0 21/0 18/0 23/2 10/0 18/0 3186 Saddleback Valley 1 37/0 8/0 25/0 18/0 33/0 29/0 15/0 8/0 12/0 12/0 18/0 7/0 7/0 3190 Central Orange County 2 57/0 33/0 36/2 26/0 38/0 -- -- -- -- -- -- -- -- 3812 Saddleback Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- RIVERSIDE COUNTY: 4137 Coachella Valley 1** -- -- -- 13/0 28/3 15/0 25/2 7/2 2/0 3/0 4/0 3/0 2/0 4144 Metropolitan Riverside County 1 75/18 79/8 77/12 84/12 84/12 75/5 68/3 64/0 69/7 67/2 62/7 68/2 70/2 4149 Perris Valley -- -- 33/0 63/2 66/2 53/5 43/0 41/0 45/0 43/0 38/0 33/0 32/0 4150 San Gorgonio Pass 50/0 33/0 36/2 30/0 33/3 20/0 30/0 17/0 18/0 23/0 12/0 19/0 25/0 4155 Norco/Corona -- -- -- -- -- -- -- -- 51/2 58/0 47/3 33/0 42/2 4157 Coachella Valley 2** 67/5 45/0 41/0 36/0 67/7 70/7 63/5 31/0 41/0 38/0 44/2 50/0 43/0 4163 Temecula Valley -- -- -- -- -- -- 21/0 4/0 3/0 0/0 -- -- -- 4164 Banning Airport -- -- -- -- -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 5171 Southwest San Bernardino Valley 1 70/2 74/9 68/2 78/3 80/7 63/7 67/2 66/3 62/0 44/0 51/5 53/0 36/2 5181 Central San Bernardino Mountains -- -- -- -- 22/0 19/0 13/0 8/0 4/0 5/0 2/0 0/0 0/0 5197 Central San Bernardino Valley 1 60/7 68/7 63/5 77/7 77/3 73/5 65/0 59/0 57/0 63/0 57/3 57/0 48/0 

5203 Central San Bernardino Valley 2 -- 76/5 59/3 71/5 75/5 58/3 68/2 60/0 63/0 51/0 53/0 58/0 45/0 5204 East San Bernardino Valley -- -- -- -- -- -- -- -- 46/0 41/0 41/2 42/0 38/0 5817 Southwest San Bernardino Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- 

** Salton Sea Air Basin 
TABLE A-13 

Suspended Particulates (PM10) 

Annual Maximum 24-Hour Average, μg/m3 

1985-2001 

STN# LOCATION 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 LOS ANGELES COUNTY:  060 East San Gabriel Valley 1 149 183 188 127 172 127 137 107 101 127 157 100 116  069 East San Fernando Valley 165 211 147 138 133 161 133 222 93 114 135 110 92  072 South Coast Los Angeles County 106 136 113 149 119 119 92 67 86 97 146 113 87  087 Central Los Angeles 146 178 158 130 137 152 151 137 104 122 141 138 102  090 Santa Clarita Valley -- -- -- -- 100 93 81 84 75 66 87 91 67  094 Southwest Coastal Los Angeles County -- -- -- -- 133 127 79 67 91 81 136 107 79  108 Pomona/Walnut Valley -- -- -- -- -- -- -- -- -- -- -- 103 67 ORANGE COUNTY: 3176 Central Orange County 1 -- -- -- -- -- 158 146 88 92 106 172 101 91 3186 Saddleback Valley 1 100 109 107 97 88 88 94 83 115 91 122 79 86 3190 Central Orange County 2 144 124 163 132 138 -- -- -- -- -- -- -- -- 3812 Saddleback Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- RIVERSIDE COUNTY: 4137 Coachella Valley 1** -- -- 121 77 292 83 197 175 58 55 68 130 63 4144 Metropolitan Riverside County 1 208 294 219 252 252 207 179 126 231 161 219 162 163 4149 Perris Valley -- -- 187 164 187 250 113 115 131 112 145 87 139 4150 San Gorgonio Pass 135 135 163 113 194 89 87 89 87 96 138 122 227 4155 Norco/Corona -- -- -- -- -- -- -- -- 164 139 177 94 158 4157 Coachella Valley 2** 358 111 115 115 712 520 340 117 125 97 199 117 144 4163 Temecula Valley -- -- -- -- -- -- 66 88 105 48 -- -- -- 4164 Banning Airport -- -- -- -- -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 5171 Southwest San Bernardino Valley 1 157 272 182 192 254 185 158 649 138 138 167 129 208 5181 Central San Bernardino Mountains -- -- -- -- 87 88 105 62 73 67 53 45 47 5197 Central San Bernardino Valley 1 154 275 203 287 227 475 127 105 143 133 178 130 122 5203 Central San Bernardino Valley 2 -- 285 211 289 271 235 163 136 139 147 148 136 108 5204 East San Bernardino Valley -- -- -- -- -- -- -- -- 109 138 172 128 103 5817 Southwest San Bernardino Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- 

District Maximum 358 294 219 289 712 520 340 649 231 161 219 162 227 

** Salton Sea Air Basin 
TABLE A-14 

Nitrogen Dioxide - Annual Average of All Hours, pphm, 1976-2001a)

(To Be Compared to Federal Standard of 5.34 pphm, Annual Average of All Hours) 

STN# LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 19LOS ANGELES COUNTY:  060 East San Gabriel Valley 1 4.71 5.77 5.29 3.64 3.71 5.03 4.94 4.70 4.35 5.02 4.96 4.98 5.30 5.11 4.10 4.50 4.03 4.00 4.30 4. 069 East San Fernando Valley 6.31 6.58 7.18 6.86 7.06 7.13 6.15 5.57 5.60 5.71 5.74 5.16 5.28 5.07 4.79 4.68 5.01 4.40 4.97 4. 072 South Coastal Los Angeles County 6.50 6.34 5.81 6.04 4.87 5.38 5.12 4.56 4.98 4.99 5.29 4.32 4.75 4.28 3.93 4.11 3.89 3.57 3.46 3. 074 West San Fernando Valley 4.88 5.19 4.59 5.29 4.99 4.90 4.50 4.41 3.89 3.85 2.77 3.19 3.78 3.90 3.40 3.99 3.17 3.06 3.39 3. 075 Pomona/Walnut Valley 1 5.98 6.30 6.20 5.18 5.03 5.06 5.50 5.20 5.16 5.41 5.58 5.47 5.61 5.71 5.55 5.50 5.07 4.99 4.80 4. 076 Southwest Coastal Los Angeles County 6.36 6.08 5.49 5.75 5.79 5.90 5.27 4.44 4.61 4.32 c) -- -- -- -- -- -- -- -- - 080 Southeast Los Angeles County 6.36 6.49 6.13 6.04 5.10 5.48 5.35 5.16 4.48 4.79 5.04 4.86 4.98 4.44 4.28 3.94 3.76 3.76 -- - 084 South Central Los Angeles County 1 4.67 5.70 4.68 5.39 5.00 5.74 4.96 4.62 5.45 5.23 5.28 4.29 4.78 4.59 4.08 4.37 4.55 4.09 4.99 4. 085 South San Gabriel Valley 7.22 7.49 6.61 6.33 5.87 6.06 5.79 5.04 4.88 5.32 5.29 4.89 5.39 5.47 4.99 4.69 4.43 4.28 4.49 4. 087 Central Los Angeles 6.40 7.73 6.64 5.82 6.10 6.68 6.02 5.88 5.67 5.99 6.12 5.37 6.13 5.53 4.67 4.93 4.04 3.32 4.76 4. 088 West San Gabriel Valley 6.84 7.80 7.34 6.03 5.53 5.78 5.55 4.84 4.85 5.01 5.13 4.20 5.00 5.31 4.74 5.02 4.23 3.90 4.28 3. 090 Santa Clarita Valley 2.39 3.10 3.18 2.18 -- -- -- -- -- -- -- -- -- -- 3.16 3.24 2.76 2.89 3.27 3. 091 Northwest Coastal Los Angeles County 6.68 7.00 5.59 6.42 5.75 5.37 5.22 4.98 4.36 3.84 4.21 3.78 3.43 3.15 3.24 2.78 2.84 2.87 2.96 2. 094 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- 4.20 3.53 3.58 3.74 3.39 2.98 3.20 3.00 3.22 3. 108 Pomona/Walnut Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4.58 4. 591 East San Gabriel Valley 2 -- -- -- -- -- -- -- -- -- -- -- 3.77 4.39 3.89 3.77 4.30 3.53 3.39 3.62 3. 801 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -ORANGE COUNTY: 3176 Central Orange County 4.81 5.04 4.33 4.82 5.20 4.97 4.64 4.46 4.41 4.30 4.46 4.21 4.58 4.72 4.69 4.48 3.94 3.54 3.80 3.3177 North Orange County 4.32 5.43 5.31 5.30 5.13 5.26 4.78 4.55 4.63 4.26 4.21 3.82 4.24 4.28 4.47 4.26 3.79 3.87 4.14 3.3195 North Coastal Orange County 2.39 2.47 2.52 2.70 2.50 3.24 3.11 2.80 2.58 2.48 2.60 2.81 2.68 4.63 2.72 2.60 2.49 2.20 2.44 2.RIVERSIDE COUNTY: 4137 Coachella Valley 1** -- -- -- 1.84 1.89 1.87 2.45 2.73 1.43 1.96 1.86 1.90 2.20 2.39 2.06 2.08 2.10 1.95 2.19 2.4144 Metropolitan Riverside County 3.17 4.19 3.13 3.25 3.42 3.63 3.36 3.44 3.54 3.53 3.16 2.69 3.68 3.64 3.36 3.51 3.04 2.98 3.20 3.4149 Perris Valley -- -- -- -- -- -- -- -- -- -- -- -- 3.10 3.22 2.82 -- -- -- -- -4157 Coachella Valley 2** 1.99 1.75 1.52 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -4158 Lake Elsinore -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 2.12 2.4164 Banning Airport -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -SAN BERNARDINO COUNTY: 5175 Northwest San Bernardino Valley 4.07 6.10 4.42 6.11 4.88 4.90 -- 4.20 4.05 3.98 4.23 4.72 4.72 4.48 4.11 4.28 3.96 4.21 4.15 4.5197 Central San Bernardino Valley 1 3.53 3.40 4.25 3.39 3.90 4.24 3.68 3.36 3.78 3.73 4.18 3.83 3.69 3.63 3.43 3.77 3.44 3.72 4.03 4.5203 Central San Bernardino Valley 2 2.15 2.67 2.57 3.16 4.79 4.86 4.33 3.60 4.00 3.79 4.37 4.30 4.21 4.09 3.93 3.55 3.56 3.76 4.11 4.5204 East San Bernardino Valley 2.17 2.78 2.45 1.83 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -

District Maximum 7.22 7.80 7.34 6.86 7.06 7.13 6.15 5.88 5.67 5.99 6.12 5.47 6.13 5.71 5.55 5.50 5.07 4.99 4.99 4.

a) Data prior to 1980 have been multiplied by an adjustment factor of 0.877 to be made comparable to 1980-2001 data. b) 1982 annual averages are based on the arithmetic mean of the monthly averages and may differ slightly from the annual average of all hours. c) Station relocated in 1986. **Salton Sea Air Basin. 
TABLE A-15 

Nitrogen Dioxide - Number of Days 1-Hour Average 

Exceeded the State Standard (> .25 ppm), 1976-2001 

STN# LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1LOS ANGELES COUNTY:  060 East San Gabriel Valley 1 1 7 8 1 1 3 3 1 0 1 0 0 0 2 0 0 0 0 0  069 East San Fernando Valley 4 12 26 11 22 9 1 4 0 1 1 1 2 0 0 2 0 0 0  072 South Coastal Los Angeles County 25 14 4 7 4 10 3 3 5 3 1 1 1 1 1 2 0 0 0  074 West San Fernando Valley 1 5 5 3 2 0 0 0 3 0 0 0 0 0 0 0 0 0 0  075 Pomona/Walnut Valley 1 5 7 4 2 1 4 1 0 0 0 0 0 0 1 0 0 0 0 0  076 Southwest Coastal Los Angeles County 6 16 6 6 2 8 3 3 1 0 a) -- -- -- -- -- -- -- --  080 Southeast Los Angeles County 7 13 8 6 4 10 4 4 2 3 1 0 0 1 0 0 0 0 --  084 South Central Los Angeles County 1 3 4 0 4 1 5 0 1 2 1 1 1 1 2 1 2 0 0 0  085 South San Gabriel Valley 10 33 14 7 6 8 2 4 0 4 1 0 0 3 2 0 1 1 0  087 Central Los Angeles 16 42 15 8 15 16 8 4 0 2 6 4 6 1 3 5 1 0 0  088 West San Gabriel Valley 12 26 15 7 11 2 1 3 0 1 0 0 2 2 0 2 0 0 0  090 Santa Clarita Valley 0 0 0 1 0 -- -- -- -- -- -- -- -- 0 0 0 0 0 0  091 Northwest Coastal Los Angeles County 37 30 11 25 16 6 4 4 3 0 0 1 1 0 0 0 0 0 0  094 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- 0 0 1 0 0 0 0 0 0  108 Pomona/Walnut Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0  591 East San Gabriel Valley 2 -- -- -- -- -- -- -- -- -- -- 0 0 0 0 0 0 0 0 0  801 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- ORANGE COUNTY: 3176 Central Orange County 7 2 1 1 15 3 0 0 0 2 0 0 1 1 0 0 0 0 0 3177 North Orange County 0 1 3 0 5 7 1 3 0 2 0 0 0 0 0 0 0 0 0 3195 North Coastal Orange County 4 0 2 1 2 2 1 1 0 0 0 0 1 0 0 0 0 0 0 RIVERSIDE COUNTY: 4137 Coachella Valley 1** -- -- -- 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4144 Metropolitan Riverside County 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 4149 Perris Valley -- -- -- -- -- -- -- -- -- -- -- -- 0 0 0 -- -- -- -- 4157 Coachella Valley 2** 0 0 0 0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4158 Lake Elsinore -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0 4164 Banning Airport -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 5175 Northwest San Bernardino Valley 0 2 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5197 Central San Bernardino Valley 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5203 Central San Bernardino Valley 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5204 East San Bernardino Valley 0 0 0 0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 

 a) Station relocated in 1986. ** Salton Sea Air Basin 
TABLE A-16 

Nitrogen Dioxide 

Annual Maximum 1-Hour, ppma)

1976-2001 

STN# LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 199LOS ANGELES COUNTY:  060 East San Gabriel Valley 1 .27 .35 .38 .35 .27 .28 .30 .26 .16 .27 .21 .23 .24 .27 .21 .25 .15 .17 .19 .22  069 East San Fernando Valley .33 .40 .44 .31 .35 .37 .26 .30 .21 .31 .28 .26 .26 .25 .23 .29 .19 .17 .18 .18 

 072 South Coastal Los Angeles County .38 .38 .35 .41 .31 .37 .30 .37 .35 .35 .26 .26 .28 .27 .27 .28 .18 .20 .20 .21  074 West San Fernando Valley .26 .35 .46 .27 .32 .24 .24 .23 .21 .21 .22 .15 .20 .18 .19 .17 .17 .15 .17 .14  075 Pomona/Walnut Valley 1 .28 .31 .32 .30 .27 .31 .32 .21 .20 .23 .25 .22 .20 .26 .21 .22 .18 .20 .17 .18  076 Southwest Coastal Los Angeles County .34 .38 .34 .33 .38 .42 .34 .32 .27 .24 b) -- -- -- -- -- -- -- -- -- 

 080 Southeast Los Angeles County .46 .61 .44 .32 .47 .38 .30 .32 .29 .31 .28 .25 .22 .29 .23 .22 .21 .20 -- -- 

 084 South Central Los Angeles County 1 .34 .29 .23 .32 .29 .32 .24 .27 .27 .31 .26 .26 .31 .34 .26 .26 .25 .23 .20 .21 

 085 South San Gabriel Valley .46 .39 .40 .36 .54 .36 .29 .31 .25 .31 .26 .24 .24 .31 .27 .25 .27 .26 .24 .23  087 Central Los Angeles .46 .53 .37 .41 .44 .45 .41 .33 .23 .27 .33 .42 .54 .28 .28 .38 .30 .21 .22 .24  088 West San Gabriel Valley .33 .42 .52 .32 .35 .40 .34 .35 .21 .27 .24 .21 .27 .34 .23 .32 .22 .18 .18 .22  090 Santa Clarita Valley .11 .29 .18 .25 .10 -- -- -- -- -- -- -- -- .13 .15 .17 .11 .13 .12 .16 

 091 Northwest Coastal Los Angeles County .40 .49 .49 .40 .37 .40 .39 .47 .32 .23 .24 .27 .26 .22 .20 .25 .17 .17 .16 .20  094 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- .23 .23 .27 .24 .23 .21 .19 .16 .22 .18  108 Pomona/Walnut Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 22 .21  591 East San Gabriel Valley 2 -- -- -- -- -- -- -- -- -- -- .13 .17 .20 .22 .19 .23 .16 .16 .19 .20  801 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- ORANGE COUNTY: 3176 Central Orange County .40 .25 .26 .29 .43 .30 .20 .24 .24 .28 .21 .22 .28 .28 .21 .20 .21 .20 .19 .18 3177 North Orange County .25 .34 .33 .21 .42 .36 .28 .33 .25 .30 .20 .22 .24 .23 .22 .20 .17 .18 .23 .20 3195 North Coastal Orange County .30 .20 .26 .25 .31 .29 .23 .27 .22 .24 .20 .19 .26 .22 .22 .16 .15 .14 .16 .18 RIVERSIDE COUNTY: 4137 Coachella Valley 1** -- -- -- .09 .13 .09 .15 .16 .09 .08 .08 .08 .11 .09 .09 .09 .09 .15 .08 .09 4144 Metropolitan Riverside County .20 .24 .19 .18 .20 .32 .16 .19 .17 .16 .16 .21 .19 .16 .16 .16 .23 .14 .18 .15 

4149 Perris Valley -- -- -- -- -- -- -- -- -- -- -- -- .14 .14 .11 -- -- -- -- -- 4157 Coachella Valley 2** .08 .13 .11 .08 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4158 Lake Elsinore -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- .11 .21 4164 Banning Airport -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 

5175 Northwest San Bernardino Valley .11 .26 .24 .26 .35 .19 .20 .25 .15 .18 .24 .20 .21 .20 .19 .21 .14 .16 .17 .20 5197 Central San Bernardino Valley 1 .26 .20 .26 .16 .25 .19 .18 .16 .16 .14 .18 .18 .21 .18 .20 .19 .14 .16 .18 .17 5203 Central San Bernardino Valley 2 .11 .17 .12 .20 .25 .20 .19 .19 .20 .15 .18 .19 .19 .18 .20 .16 .13 .15 .16 .16 5204 East San Bernardino Valley .22 .21 .18 .17 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 

District Maximum .46 .61 .52 .41 .54 .45 .41 .47 .35 .35 .33 .42 .54 .34 .28 .38 .30 .26 .22 .24 

 a) Data prior to 1980 have been multiplied by an adjustment factor of 0.877 to be made comparable to 1980-2001 data.  b) Station relocated in 1986. ** Salton Sea Air Basin 
TABLE A-17 

Sulfur Dioxide - Annual Average, pphm 

1976-2001 

STN# LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 LOS ANGELES COUNTY:  060 East San Gabriel Valley 1 1.02 1.03 0.75 0.71 0.62 0.32 0.31 0.21 0.23 0.29 0.30 0.24 0.22 0.17 0.11 -- -- -- -- --  069 East San Fernando Valley 0.81 1.37 1.07 1.04 0.67 0.52 0.58 0.47 0.52 0.51 0.34 0.30 0.22 0.20 0.18 0.09 0.10 0.12 0.07 0.01  072 South Coastal Los Angeles County 1.51 1.45 1.33 0.90 1.08 0.95 1.07 0.89 0.98 0.81 0.84 0.58 0.68 0.46 0.31 0.43 0.37 0.36 0.31 0.23  074 West San Fernando Valley 0.77 0.95 0.47 0.33 0.48 0.44 0.45 0.43 0.41 0.25 0.33 0.26 0.17 0.18 0.15 -- -- -- -- --  075 Pomona/Walnut Valley 1 1.02 1.41 1.16 0.60 0.41 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --  076 Southwest Coastal Los Angeles County 1.70 1.78 0.64 0.81 1.14 1.05 1.06 0.95 1.04 0.74 a) -- -- -- -- -- -- -- -- --  080 Southeast Los Angeles County 1.88 1.73 1.30 2.33 0.99 0.70 0.80 0.58 0.60 0.43 0.43 0.42 0.55 0.36 0.16 0.16 0.08 0.07 -- --  084 South Central Los Angeles County 1 1.22 1.04 0.84 0.64 0.82 0.91 0.70 0.66 0.84 0.70 0.51 0.59 0.69 0.42 0.33 0.30 0.31 0.23 0.26 0.30  085 South San Gabriel Valley 0.77 0.80 0.63 0.76 0.55 0.55 0.54 0.56 0.70 0.50 0.34 0.36 0.48 0.45 0.43 -- -- -- -- --  087 Central Los Angeles 1.94 2.01 1.74 1.16 1.28 0.71 0.79 0.61 0.85 0.53 0.42 0.43 0.41 0.22 0.17 0.17 0.15 0.03 0.07 0.10  088 West San Gabriel Valley 1.52 1.53 1.48 1.05 0.61 0.38 0.47 0.35 0.33 0.25 0.19 0.28 0.23 0.22 0.15 -- -- -- -- --  090 Santa Clarita Valley 1.12 1.11 0.93 0.90 0.49 -- -- -- -- -- -- -- -- 0.09 0.09 -- -- -- -- --  091 Northwest Coastal Los Angeles County 0.79 0.87 1.12 0.88 0.66 0.40 0.28 0.23 0.27 0.32 0.33 0.28 0.22 0.24 0.21 -- -- -- -- --  094 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- 0.50 0.38 0.48 0.47 0.35 0.40 0.57 0.31 0.22 0.27 ORANGE COUNTY: 3176 Central Orange County 1 0.67 0.62 0.45 0.63 0.67 0.41 0.56 0.50 060 0.32 0.32 0.30 0.41 0.31 0.18 -- -- -- -- -- 3177 North Orange County 0.61 0.75 0.73 0.6 0.8 0.53 0.51 0.55 0.6 0.51 0.5 0.49 0.38 0.21 0.11 0.12 0.06 0.06 0.09 0.09 3186 Saddleback Valley 0.12 0.14 0.14 0.18 0.06 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3190 Central Orange County 2 0.96 0.88 0.66 0.76 0.90 0.46 0.45 0.36 0.40 0.30 0.27 0.30 0.29 0.27 0.19 0.11 0.11 0.08 -- -- 3195 North Coastal Orange County 0.63 0.59 0.42 0.42 0.54 0.34 0.35 0.25 0.29 0.28 0.15 0.20 0.18 0.15 0.07 0.07 0.06 0.05 0.07 0.07 RIVERSIDE COUNTY: 4137 Coachella Valley 1** -- -- -- 0.65 0.54 0.07 0.01 0.07 -- -- -- -- -- -- -- -- -- -- -- -- 4144 Metropolitan Riverside County 0.50 1.00 0.89 0.93 0.40 0.13 0.17 0.14 0.00 0.14 0.07 0.22 0.14 0.07 0.03 0.02 0.02 0.03 0.02 0.01 4157 Coachella Valley 2** -- 0.01 0.74 0.44 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 5175 Northwest San Bernardino Valley -- -- 0.75 0.85 0.49 0.51 0.65 0.25 0.16 0.08 0.07 0.14 0.17 0.14 0.12 -- -- -- -- -- 5197 Central San Bernardino Valley 1 2.71 2.60 0.98 0.85 0.53 0.47 0.51 0.21 0.11 0.10 0.14 0.18 0.16 0.05 0.01 0.05 0.12 0.00 0.02 0.06 5203 Central San Bernardino Valley 2 0.82 1.50 1.15 1.00 0.21 0.09 0.15 0.10 0.21 0.17 0.34 0.26 0.18 0.06 0.01 -- -- -- -- -- 

District Maximum 2.71 2.60 1.74 2.33 1.28 1.05 1.07 0.95 1.04 0.81 0.84 0.59 0.69 0.47 0.43 0.43 0.57 0.36 0.31 0.30 

 a) Station relocated in 1986. ** Salton Sea Air Basin 
TABLE A-18 

Sulfur Dioxide 

Annual Maximum 1-Hour Average, ppm 

1976-2001 

STN# LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 19LOS ANGELES COUNTY:  60 East San Gabriel Valley .10 .06 .05 .06 .05 .04 .06 .03 .04 .02 .03 .03 .03 .02 .03 -- -- -- --  69 East San Fernando Valley .09 .10 .06 .06 .04 .04 .09 .04 .05 .04 .02 .03 .02 .03 .02 .01 .03 .02 .03 . 72 South Coastal Los Angeles County .13 .13 .19 .13 .10 .14 .09 .12 .32 .08 .07 .06 .05 .11 .05 .14 .11 .05 .04 . 74 West San Fernando Valley .04 .06 .05 .03 .03 .03 .03 .03 .03 .02 .02 .02 .02 .02 .02 - -- -- --  75 Pomona/Walnut Valley .06 .08 .06 .05 .03 -- -- -- -- -- -- -- -- -- -- -- -- -- --  76 Southwest Coastal Los Angeles County .18 .30 .09 .10 .08 .07 .08 .09 .06 .06 a) -- -- -- -- -- -- -- --  80 Southeast Los Angeles County .15 .18 .10 .14 .16 .09 .09 .09 .06 .05 .06 .07 .10 .04 .04 .07 .03 .03 --  84 South Central Los Angeles County .09 .12 .13 .09 .08 .09 .06 .06 .07 .06 .13 .06 .06 .04 .04 .05 .06 .03 .02 . 85 South San Gabriel Valley .05 .08 .05 .10 .07 .05 .05 .08 .09 .07 .03 .09 .05 .04 .04 -- -- -- --  87 Central Los Angeles .12 .09 .09 .05 .06 .05 .05 .07 .07 .04 .03 .03 .04 .03 .02 .02 .05 .01 .02 . 88 West San Gabriel Valley .06 .07 .06 .06 .05 .04 .04 .05 .03 .03 .02 .02 .03 .02 .02 -- -- -- --  90 Santa Clarita Valley .10 .04 .05 .05 .03 -- -- -- -- -- -- -- -- .02 .01 -- -- -- --  91 Northwest Coastal Los Angeles County .07 .05 .08 .04 .04 .04 .03 .06 .05 .03 .02 .03 .03 .02 .02 -- -- -- --  94 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- .09 .03 .15 .09 .31 .12 .15 .07 .04 .ORANGE COUNTY: 3176 Central Orange County 1 .11 .09 .07 .07 .08 .04 .04 .05 .08 .03 .03 .09 .06 .03 .02 -- -- -- -- 3177 North Orange County .11 .12 .10 .09 .09 .04 .04 .05 .04 .05 .06 .05 .05 .03 .03 .04 .02 .02 .02 .3186 Saddleback Valley .05 .07 .10 .09 .06 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3190 Central Orange County 2 .25 .14 .16 .11 .14 .06 .08 .05 .06 .02 .03 .04 .04 .07 .03 .03 .10 .02 -- 3195 North Coastal Orange County .13 .10 .07 .07 .06 .08 .06 .04 .04 .05 .02 .03 .03 .03 .02 .04 .02 .01 .02 .RIVERSIDE COUNTY: 4137 Coachella Valley 1** -- -- -- .03 .03 .01 .01 .01 -- -- -- -- -- -- -- -- -- -- -- 4144 Metropolitan Riverside County .08 .12 .08 .08 .07 .02 .02 .02 .02 .02 .02 .04 .02 .02 .03 .02 .02 .02 .02 .4157 Coachella Valley 2** -- .02 .04 .04 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 5175 Northwest San Bernardino Valley -- -- .10 .08 .07 .04 .05 .03 .02 .02 .01 .03 .03 .03 .01 -- -- -- -- 5197 Central San Bernardino Valley 1 .25 .40 .12 .14 .11 .11 .14 .06 .03 .02 .02 .03 .04 .03 .01 .05 .02 .01 .03 .5203 Central San Bernardino Valley 2 .07 .35 .09 .08 .03 .02 .02 .02 .03 .02 .05 .07 .02 .03 .01 -- -- -- -- 

District Maximum .25 .40 .19 .14 .16 .14 .14 .12 .32 .08 .13 .09 .15 .11 .31 .14 .15 .07 .04 .

 a) Station relocated in 1986. ** Salton Sea Air Basin 
TABLE A-19 

Sulfate - Percent of Sampling Days Exceeding the State Standard 

(≥ 25 μg/m3, 24-hour Average) 

1976-2001a)

STN# LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1LOS ANGELES COUNTY:  60 East San Gabriel Valley 5 11 8 0 6 0 2 2 2 0 0 0 0 0 0 0 0 0 0  69 East San Fernando Valley -- -- -- -- -- -- -- -- 0 0 0 0 0 0 2 0 0 0 0  72 South Coastal Los Angeles County -- -- -- -- 10 2 2 2 0 2 2 0 2 0 0 0 0 0 0  74 West San Fernando Valley 2 5 7 0 5 0 5 0 0 0 0 -- -- -- -- -- -- -- --  75 Pomona/Walnut Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --  76 Southwest Coastal Los Angeles County 11 14 6 5 11 2 3 0 2 0 b) -- -- -- -- -- -- -- --  80 Southeast Los Angeles County -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --  84 South Central Los Angeles County 5 13 7 8 12 0 3 2 0 0 0 0 2 0 2 0 0 0 0  85 South San Gabriel Valley -- 13 8 5 12 2 3 2 0 0 0 0 2 2 0 0 0 0 2  87 Central Los Angeles 7 13 7 3 8 0 4 2 2 0 0 0 2 0 2 0 0 0 0  88 West San Gabriel Valley 8 11 8 2 7 2 4 2 2 0 0 0 0 0 2 0 0 0 0  90 Santa Clarita Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --  91 Northwest Coastal Los Angeles County 0 2 9 0 5 2 4 0 2 0 0 0 0 0 0 0 0 0 2  94 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- 2 0 0 0 0 0 0 0 2 ORANGE COUNTY: 3176 Central Orange County 1 5 5 3 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3177 North Orange County 2 5 8 3 8 2 2 0 0 0 0 -- -- -- -- -- -- -- -- 3186 Saddleback Valley -- 3 2 0 0 0 0 0 0 0 0 0 0 0 0 -- -- -- -- 3190 Central Orange County 2 3 7 5 2 4 2 0 2 0 0 0 0 2 0 0 0 0 0 -- 3195 North Coastal Orange County 2 5 3 0 0 -- -- -- -- -- -- -- -- -- -- -- -- -- -- RIVERSIDE COUNTY: 4137 Coachella Valley 1** -- -- 0 0 0 0 0 0 0 0 0 0 0 0 0 -- -- -- -- 4144 Metropolitan Riverside County 1 4 2 8 5 5 2 0 2 0 0 0 0 0 0 0 0 0 0 0 4146 Metropolitan Riverside County 2 -- -- -- -- -- -- -- 2 0 0 0 0 0 0 0 0 0 0 0 4149 Perris Valley -- -- -- -- -- -- -- 0 0 0 0 0 0 0 0 -- -- -- -- 4150 San Gorgonio Pass -- -- 0 0 0 0 0 0 0 0 0 0 0 0 0 -- -- -- -- 4155 Norco/Corona -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4157 Coachella Valley 2** -- -- 0 0 0 0 0 0 0 0 0 0 0 0 0 -- -- -- -- SAN BERNARDINO COUNTY: 5171 Southwest San Bernardino Valley -- -- -- -- -- -- -- 2 4 0 0 0 0 0 0 -- -- -- -- 5175 Northwest San Bernardino Valley 6 2 7 -- 8 2 -- 2 0 0 0 0 0 0 0 0 0 0 0 5181 Central San Bernardino Mountains -- -- 0 0 2 0 0 0 0 0 0 0 0 0 0 -- -- -- -- 5197 Central San Bernardino Valley 1 4 2 16 13 6 7 5 2 0 0 0 0 2 0 0 0 0 0 0 5203 Central San Bernardino Valley 2 3 2 8 8 10 0 3 2 0 0 0 0 0 0 0 0 0 0 0 5204 East San Bernardino Valley 0 0 5 0 5 2 2 0 0 0 0 -- -- -- -- -- -- -- -- a) Data from 1982 onward are based on new filter type. b) Station relocated in 1986. ** Salton Sea Air Basin 
TABLE A-20 

Sulfate - Maximum 24-Hour Averages, 1976-2001a)

(To Be Compared to State Standard of 25 μg/m3, 24-Hour Average) 

STN# LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 19LOS ANGELES COUNTY:  60 East San Gabriel Valley 29.8 38.3 36.7 24.5 38.2 23.0 26.2 25.8 27.6 15.4 14.6 15.4 23.6 16.9 16.0 19.2 16.8 19.1 17.5 1 69 East San Fernando Valley -- -- -- -- -- -- -- -- -- 21.6 19.1 17.5 33.6 22.1 25.9 18.6 12.9 20.1 18.3 1 72 South Coastal Los Angeles County -- -- -- -- 40.7 32.7 30.4 30.8 22.2 31.0 25.2 17.6 27.8 20.0 22.6 19.9 22.6 15.6 17.1 1 74 West San Fernando Valley 30.2 27.3 57.8 22.9 35.6 24.1 29.2 22.5 22.9 19.0 11.7 -- -- -- -- -- -- -- --  75 Pomona/Walnut Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --  76 Southwest Coastal Los Angeles County 37.2 43.6 44.4 36.1 34.0 26.2 37.3 24.8 26.7 24.4 b) -- -- -- -- -- -- -- --  80 Southeast Los Angeles County -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --  84 South Central Los Angeles County 42.4 38.0 38.1 28.1 34.2 24.0 36.8 27.6 24.9 24.0 22.4 18.2 27.1 19.6 28.1 22.4 18.7 13.7 23.1 1 85 South San Gabriel Valley -- 40.8 47.2 30.6 34.3 27.1 30.8 34.8 20.6 19.2 22.1 17.8 28.1 32.0 21.1 21.6 17.0 15.5 26.2 1 87 Central Los Angeles 34.4 47.2 45.0 29.7 32.8 23.7 27.7 25.7 27.4 20.0 20.4 14.5 26.6 23.0 25.3 23.1 19.4 17.6 21.7 1 88 West San Gabriel Valley 33.8 38.2 53.4 26.4 38.4 27.8 26.6 26.8 25.4 20.9 15.6 14.0 24.4 18.0 28.4 20.1 11.5 18.8 14.5 1 90 Santa Clarita Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --  91 Northwest Coastal Los Angeles County 22.6 28.7 41.2 23.5 34.9 25.3 26.0 20.0 26.4 22.5 16.9 15.2 17.4 19.6 24.8 20.9 12.3 18.1 26.8 1 94 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- 25.2 20.6 19.0 22.6 24.8 24.7 17.6 20.5 26.7 2

ORANGE COUNTY: 

3176 Central Orange County 1 29.3 37.7 30.7 24.4 37.2 24.7 22.6 24.4 20.1 19.4 18.5 14.6 23.1 17.7 18.3 20.6 16.0 15.3 14.5 13177 North Orange County 26.0 34.5 34.7 26.2 35.0 25.6 28.8 19.7 21.9 22.8 10.1 -- -- -- -- -- -- -- -- 3186 Saddleback Valley 22.6 32.9 26.7 21.5 21.2 20.0 13.4 21.2 14.9 21.2 14.9 14.3 16.2 16.5 13.4 -- -- -- -- 3190 Central Orange County 2 35.9 37.0 31.0 26.6 34.6 26.0 24.5 26.3 19.5 22.4 23.6 18.2 27.3 17.4 16.8 16.9 16.0 14.7 -- 3195 North Coastal Orange County 28.2 37.8 27.2 24.2 13.5 -- -- -- -- -- -- -- -- -- -- -- -- -- -- RIVERSIDE COUNTY: 4137 Coachella Valley 1** 16.7 12.1 13.9 12.0 11.9 12.8 11.4 13.3 8.9 9.1 8.8 10.4 11.2 12.1 5.6 -- -- -- -- 4144 Metropolitan Riverside County 1 44.3 33.4 55.9 28.1 39.2 30.4 23.1 27.7 22.8 21.0 18.4 16.1 23.6 16.9 19.9 14.8 12.3 13.7 20.4 2

4146 Metropolitan Riverside County 2 -- -- -- -- -- -- -- 27.5 22.6 21.1 18.5 19.7 19.0 16.6 19.3 12.8 12.1 15.1 15.7 24149 Perris Valley -- -- -- -- -- -- -- 17.9 15.9 14.1 14.0 15.6 11.5 15.9 12.9 -- -- -- -- 4150 San Gorgonio Pass 31.6 15.6 20.7 20.0 18.5 19.6 22.9 20.1 22.2 12.3 11.3 15.2 10.6 13.8 8.6 -- -- -- -- 4155 Norco/Corona -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4157 Coachella Valley 2** 19.9 10.6 11.4 13.9 16.9 13.5 11.7 12.3 11.7 8.4 7.9 10.3 8.4 18.3 7.0 -- -- -- -- SAN BERNARDINO COUNTY: 

5171 Southwest San Bernardino Valley 48.6 29.4 30.0 -- -- -- -- 27.2 28.3 18.5 19.8 17.8 21.1 16.4 19.9 -- -- -- -- 5175 Northwest San Bernardino Valley 34.0 64.7 37.0 32.0 -- -- -- 25.5 22.6 15.3 15.7 18.0 18.5 13.9 18.7 19.0 13.2 17.1 15.8 1

5181 Central San Bernardino Mountains 8.2 13.2 9.8 13.9 37.3 14.2 13.3 10.3 10.3 7.1 8.0 13.1 13.4 10.2 6.6 -- -- -- -- 

5197 Central San Bernardino Valley 1 32.7 30.2 51.7 32.8 40.0 42.4 32.5 33.1 23.8 16.4 18.1 18.7 28.1 14.9 18.3 20.2 13.4 16.7 15.5 1

5203 Central San Bernardino Valley 2 27.5 28.5 47.1 31.7 42.8 38.8 29.6 27.1 23.4 19.4 17.8 17.6 15.8 17.8 17.3 18.3 12.9 17.2 14.9 15204 East San Bernardino Valley 21.5 23.7 32.7 23.7 37.3 31.0 28.5 24.1 21.0 16.2 9.9 -- -- -- -- -- -- -- -- 

District Maximum 48.6 64.7 57.8 36.1 42.8 42.4 37.3 34.8 28.3 31 25.2 20.6 33.6 32 28.4 24.7 22.6 20.5 26.8 2

 a) Data from 1982 onward are based on new filter type.  b) Station relocated in 1986. ** Salton Sea Air Basin 
TABLE A-21 

Lead - Highest Calendar Quarter Mean, μg/m3 

(To Be Compared to Federal Standard of 1.5 μg/m3, Calendar Quarter Average) 

1976-2001 

STN# LOCATION 1976 1977 1978 1979 198 1981 1982 1983 1984 1985 1986 1987 1988 1989 199 1991 1992 1993 1994 19LOS ANGELES COUNTY:  60 East San Gabriel Valley 1.96 2.68 1.44 1.08 0.91 0.74 0.69 0.50 0.43 0.21 0.18 -- -- -- -- -- -- -- -- --  69 East San Fernando Valley -- -- -- -- -- -- -- -- 0.65 0.49 0.33 0.20 0.20 0.10 0.07 0.07 0.09 0.05 0.05 0.0

 72 South Coastal Los Angeles County -- -- -- -- -- 1.12 0.92 0.70 0.69 0.36 0.31 0.22 0.15 0.08 0.07 0.07 0.05 0.05 0.04 0.0 74 West San Fernando Valley 3.37 3.40 2.42 1.73 1.68 0.97 0.79 0.67 0.55 0.27 0.15 -- -- -- -- -- -- -- -- --  75 Pomona/Walnut Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- - -- -- --  76 Southwest Coastal Los Angeles County 7.52 5.34 4.06 3.21 2.55 1.57 1.63 1.03 1.02 0.60 a) -- -- -- -- -- -- -- -- -- 

 80 Southeast Los Angeles County -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --  84 South Central Los Angeles County 5.30 4.59 3.27 2.98 2.15 1.40 1.36 1.03 1.02 0.63 0.44 0.24 0.19 0.11 0.11 0.10 0.08 0.06 0.07 0.0

 85 South San Gabriel Valley -- 5.52 2.77 2.00 1.96 1.27 1.12 0.86 0.72 0.49 0.40 0.26 0.22 0.12 0.11 0.14 0.10 0.11 0.08 0.0 87 Central Los Angeles 3.76 4.46 2.38 2.69 2.04 1.30 1.04 0.80 0.72 0.47 0.28 0.18 0.14 0.12 0.09 0.14 0.11 0.07 0.07 0.0 88 West San Gabriel Valley 4.49 4.37 3.01 2.28 1.65 1.08 0.73 0.56 0.56 0.29 0.19 -- -- -- -- -- -- -- -- -- 

 90 Santa Clarita Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --  91 Northwest Coastal Los Angeles County 2.17 2.14 2.00 1.81 1.68 1.28 0.89 0.60 0.58 0.26 0.15 -- -- -- -- -- -- -- -- --  94 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- 0.25 0.17 0.11 0.07 0.06 0.06 0.05 0.04 0.04 0.0

ORANGE COUNTY: 

3176 Central Orange County 1 3.49 3.28 2.00 1.60 1.44 0.90 0.75 0.54 0.56 0.27 0.20 0.13 0.09 0.08 0.06 0.06 0.03 0.04 0.03 0.03177 North Orange County 3.46 3.20 2.11 1.67 1.34 0.97 0.88 0.59 0.58 0.33 0.18 -- -- -- -- -- -- -- -- -- 3186 Saddleback Valley -- 1.58 0.85 0.65 0.60 0.41 0.32 0.27 0.24 0.15 0.09 -- -- -- -- -- -- -- -- -- 3190 Central Orange County 2 4.57 3.25 2.70 2.08 1.52 0.85 0.97 0.55 0.60 0.31 0.22 -- -- -- -- -- -- -- -- -- 3195 North Coastal Orange County 3.39 2.66 2.00 1.38 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- RIVERSIDE COUNTY: 4137 Coachella Valley 1** -- -- 0.47 0.34 0.25 0.21 0.13 0.12 0.14 0.10 0.06 -- -- -- -- -- -- -- -- -- 4144 Metropolitan Riverside County 1 2.31 1.95 1.53 1.18 0.84 0.64 0.46 0.41 0.40 0.21 0.16 0.12 0.07 0.05 0.05 0.05 0.03 0.04 0.04 0.04146 Metropolitan Riverside County 2 -- -- -- -- -- -- -- 0.54 0.55 0.30 0.21 0.14 0.09 0.06 0.05 0.06 0.03 0.04 0.03 0.0

4149 Perris Valley -- -- -- -- -- -- -- 0.25 0.26 0.13 0.10 -- -- -- -- -- -- -- -- -- 4150 San Gorgonio Pass -- -- 0.50 0.49 0.27 0.23 0.23 0.17 0.18 0.09 0.08 -- -- -- -- -- -- -- -- -- 4155 Norco/Corona -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4157 Coachella Valley 2** -- -- 0.50 0.36 0.28 0.22 0.13 0.17 0.20 0.14 0.12 -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 

5171 Southwest San Bernardino Valley -- -- -- -- -- -- -- 0.36 0.50 0.26 0.17 -- -- -- -- -- -- -- -- -- 5175 Northwest San Bernardino Valley 2.07 1.84 1.35 1.09 -- -- -- 0.47 0.36 0.23 0.17 0.11 0.07 0.08 0.05 0.07 0.04 0.04 0.04 0.05181 Central San Bernardino Mountains -- 1.02 -- 0.35 0.26 0.19 0.15 0.13 0.13 0.07 0.05 -- -- -- -- -- -- -- -- -- 

5197 Central San Bernardino Valley 1 1.40 1.53 0.99 0.87 0.60 0.46 0.46 0.35 0.27 0.17 0.16 -- -- -- -- -- -- -- -- -- 5203 Central San Bernardino Valley 2 1.87 1.41 2.47 1.22 1.04 0.73 0.51 0.41 0.37 0.20 0.19 0.13 0.08 0.07 0.05 0.05 0.04 0.04 0.04 0.05204 East San Bernardino Valley 1.33 1.80 1.06 0.66 0.45 0.36 0.32 0.27 0.22 0.15 0.07 -- -- -- -- -- -- -- -- -- 

District Maximum 7.52 5.52 4.06 3.21 2.55 1.57 1.63 1.03 1.02 0.63 0.44 0.26 0.22 0.12 0.11 0.14 0.11 0.11 0.08 0

 a) Station relocated in 1986. ** Salton Sea Air Basin
TABLE A-22 

Lead - Highest Monthly Averages, μg/m3 

(To Be Compared to State Standard of 1.5 μg/m3, Monthly Average) 

1976-2001 

STN# LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 199LOS ANGELES COUNTY:  60 East San Gabriel Valley 2.27 3.06 1.59 1.48 1.45 0.92 0.72 0.55 0.45 0.25 0.19 -- -- -- -- -- -- -- -- --  69 East San Fernando Valley -- -- -- -- -- -- -- -- 0.90 0.60 0.41 0.29 0.35 0.20 0.08 0.10 0.16 0.05 0.06 0.05  72 South Coastal Los Angeles County -- -- -- -- 2.01 1.22 1.09 1.08 0.94 0.52 0.43 0.33 0.21 0.11 0.09 0.08 0.07 0.06 0.06 0.05 

 74 West San Fernando Valley 3.96 4.50 3.05 2.24 1.71 1.62 1.01 0.96 0.68 0.32 0.19 -- -- -- -- -- -- -- -- --  75 Pomona/Walnut Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --  76 Southwest Coastal Los Angeles County 10.04 6.77 5.48 3.91 3.44 1.91 1.70 1.29 1.38 0.90 a) -- -- -- -- -- -- -- -- -- 

 80 Southeast Los Angeles County -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --  84 South Central Los Angeles County 8.13 5.74 4.42 3.67 3.02 1.83 1.55 1.36 1.43 0.91 0.58 0.32 0.31 0.15 0.14 0.17 0.11 0.08 0.09 0.07 

 85 South San Gabriel Valley -- 6.68 4.02 2.24 2.34 1.59 1.18 1.14 0.93 0.65 0.57 0.31 0.29 0.19 0.13 0.19 0.15 0.15 0.10 0.07  87 Central Los Angeles 4.90 5.06 2.71 2.82 2.68 1.75 1.05 1.04 0.89 0.61 0.42 0.23 0.22 0.17 0.09 0.21 0.16 0.10 0.11 0.07  88 West San Gabriel Valley 5.61 4.73 4.16 2.54 1.72 1.43 0.90 0.84 0.73 0.38 0.24 -- -- -- -- -- -- -- -- -- 

 90 Santa Clarita Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --  91 Northwest Coastal Los Angeles County 2.98 2.63 2.90 2.17 2.02 1.83 1.00 0.82 0.78 0.33 0.23 -- -- -- -- -- -- -- -- --  94 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- 0.35 0.26 0.18 0.13 0.08 0.08 0.05 0.05 0.05 0.04 

ORANGE COUNTY: 

3176 Central Orange County 1 4.62 4.60 2.96 1.90 2.05 1.13 0.78 0.72 0.65 0.32 0.27 0.14 0.11 0.15 0.10 0.08 0.05 0.07 0.06 0.04 3177 North Orange County 4.55 4.07 3.20 1.89 1.72 1.31 0.96 0.95 0.71 0.44 0.23 -- -- -- -- -- -- -- -- -- 3186 Saddleback Valley 2.11 2.66 1.36 0.72 0.69 0.61 0.36 0.32 0.31 0.20 0.10 -- -- -- -- -- -- -- -- -- 3190 Central Orange County 2 6.38 4.68 4.04 2.71 1.88 1.14 1.08 0.93 0.86 0.39 0.28 -- -- -- -- -- -- -- -- -- 3195 North Coastal Orange County 4.16 3.63 3.11 1.90 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- RIVERSIDE COUNTY: 4137 Coachella Valley 1** -- -- 0.73 0.44 0.35 0.31 0.18 0.16 0.17 0.13 0.10 -- -- -- -- -- -- -- -- -- 4144 Metropolitan Riverside County 1 2.94 2.45 1.80 1.30 1.07 0.85 0.55 0.57 0.54 0.27 0.17 0.14 0.10 0.07 0.08 0.06 0.03 0.05 0.06 0.04 

4146 Metropolitan Riverside County 2 4.37 3.90 -- -- -- -- -- 0.77 0.65 0.37 0.24 0.18 0.12 0.07 0.08 0.08 0.03 0.04 0.04 0.05 

4149 Perris Valley -- -- -- -- -- -- -- 0.28 0.31 0.18 0.11 -- -- -- -- -- -- -- -- -- 4150 San Gorgonio Pass -- -- 0.59 0.61 0.31 0.27 0.27 0.24 0.21 0.10 0.10 -- -- -- -- -- -- -- -- -- 4155 Norco/Corona -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4157 Coachella Valley 2** -- -- 0.63 0.52 0.36 0.40 0.16 0.24 0.24 0.19 0.16 -- -- -- -- -- -- -- -- -- SAN BERNARDINO COUNTY: 

5171 Southwest San Bernardino Valley 5.30 -- -- -- -- -- -- 0.44 0.67 0.36 0.22 -- -- -- -- -- -- -- -- -- 5175 Northwest San Bernardino Valley 2.60 2.47 1.68 1.43 -- -- -- 0.54 0.43 0.26 0.20 0.13 0.10 0.11 0.07 0.08 0.04 0.05 0.05 0.06 5181 Central San Bernardino Mountains 0.30 0.78 0.36 0.48 0.31 0.29 0.18 0.17 0.14 0.12 0.08 -- -- -- -- -- -- -- -- -- 5197 Central San Bernardino Valley 1 2.10 3.15 1.19 1.20 0.86 0.52 0.53 0.39 0.34 0.22 0.17 -- -- -- -- -- -- -- -- -- 5203 Central San Bernardino Valley 2 2.40 1.83 3.33 1.49 1.30 1.01 0.62 0.52 0.47 0.31 0.23 0.15 0.12 0.09 0.07 0.06 0.05 0.05 0.04 0.05 5204 East San Bernardino Valley 1.80 1.59 1.25 0.82 0.57 0.47 0.34 0.32 0.30 0.19 0.10 -- -- -- -- -- -- -- -- -- 

Disctrict Maximum 10.04 6.77 5.48 3.91 3.44 1.91 1.70 1.36 1.43 0.91 0.58 0.33 0.35 0.20 0.14 0.21 0.16 0.15 0.11 0.0

 a) Station relocated in 1986. ** Salton Sea Air Basin