Appendix II

Air Quality Management Plan

South Coast Air Quality Management District

Cleaning the air that we breathe...

®

AQMD

December 2012

TRAN

S

P

O

RTATION

AIR QUALITY

ENERGY

CLIMATE

2012

Current Air Quality
FINAL 2012 AQMP

APPENDIX II

CURRENT AIR QUALITY

DECEMBER 2012
SOUTH COAST AIR QUALITY MANAGEMENT DISTRICT

GOVERNING BOARD

CHAIRMAN: WILLIAM A. BURKE, Ed.D.

Speaker of the Assembly Appointee

VICE CHAIR: DENNIS YATES

Mayor, Chino

Cities of San Bernardino

MEMBERS:

MICHAEL D. ANTONOVICH

Supervisor, Fifth District

County of Los Angeles

JOHN J. BENOIT

Supervisor, Fourth District

County of Riverside

MICHAEL A. CACCIOTTI

Mayor, South Pasadena

Cities of Los Angeles County/Eastern Region

JOSIE GONZALES

Supervisor, Fifth District

San Bernardino County Representative

RONALD O. LOVERIDGE

Mayor, City of Riverside

Cities Representative, Riverside County

JOSEPH K. LYOU, Ph.D.

Governor's Appointee

JUDITH MITCHELL

Councilmember, Rolling Hills Estates

Cities of Los Angeles County/Western Region

SHAWN NELSON

Supervisor, Fourth District

County of Orange

CLARK E. PARKER, Ph.D.

Senate Rules Appointee

JAN PERRY

Councilmember, Ninth District

City of Los Angeles

MIGUEL A. PULIDO

Mayor, Santa Ana

Cities of Orange County

EXECUTIVE OFFICER: BARRY R. WALLERSTEIN, D.Env.
South Coast Air Quality Management District

Barry R. Wallerstein, D.Env.

Executive Officer

Elaine Chang, DrPH

Deputy Executive Officer

Planning, Rule Development, & Area Sources

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

Assistant Deputy Executive Officer

Planning, Rule Development, & Area Sources

Philip M. Fine, Ph.D.

Planning and Rules Manager

Planning, Rule Development, & Area Sources

Authors

SCAQMD - Planning, Rule Development, & Area Sources

Kevin Durkee, Senior Meteorologist

Shoreh Cohanim, Air Quality Specialist

Thomas Chico, Program Supervisor

Andrea Polidori, Ph.D., Air Quality Specialist

Contributors

Mark Bassett, Ph.D., Air Quality Specialist Dan Houghton, Sr. Air Quality Chemist

Sandra Hom, Sr. Air Quality Chemist Brian Vlasich, Sr. Air Quality Instrument Specialist

Chris Nelson, Sr. Staff Specialist Hanna Zhuang, Air Quality Data Translator

Henry Cheung, Student Worker

Reviewed By

Barbara Baird, District Counsel

Production

Arlene Martinez, Administrative Secretary
Table of Contents

II-i

Table of Contents

SUMMARY

SUMMARY ......................................................................................................................II-1

CHAPTER 1 - INTRODUCTION

AIR QUALITY SETTING ............................................................................................II-1-1

District Jurisdiction and Boundaries..........................................................................II-1-1

Weather Factors .........................................................................................................II-1-3

Emissions ...................................................................................................................II-1-4

AMBIENT AIR QUALITY STANDARDS..................................................................II-1-6

Design Values ............................................................................................................II-1-8

Summary of Criteria Pollutants and Air Quality Standards.....................................II-1-10

CHAPTER 2 - AIR QUALITY IN THE SOUTH COAST AIR BASIN

Violations of Standards....................................................................................II-2-1

Design Values and NAAQS Attainment Status ..............................................II-2-2

Air Quality Compared to Other U.S. Metropolitan Areas ..............................II-2-4

Air Quality Trends...........................................................................................II-2-7

Spatial and Temporal Variability ....................................................................II-2-8

Pollutant-Specific Air quality Discussion .........................................................II-2-10

Particulate Matter (PM).................................................................................II-2-10

Ozone .............................................................................................................II-2-28

Carbon Monoxide (CO).................................................................................II-2-37

Nitrogen Dioxide (NO2) ................................................................................II-2-38

Sulfur Dioxide (SO2) .....................................................................................II-2-39

Sulfate (SO4

2-

)................................................................................................II-2-40

Lead (Pb)........................................................................................................II-2-41

CHAPTER 3 AIR QUALITY IN THE RIVERSIDE COUNTY PORTION OF 

THE SALTON SEA AIR BASIN (COACHELLA VALLEY)

AIR QUALITY IN THE SSAB, RIVERSIDE COUNTY (Coachella Valley).............II-3-1

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

Particulate Matter (PM10) .........................................................................................II-3-6

Ozone (O3) .................................................................................................................II-3-8
Final 2012 AQMP Appendix II: Current Air Quality

II-ii

Carbon Monoxide (CO).................................................................................II-3-11

Nitrogen Dioxide (NO2)...........................................................................................II-3-12

Sulfur Dioxide (SO2)................................................................................................II-3-12

Sulfate (SO4

2-

)..........................................................................................................II-3-12

Lead (Pb)..................................................................................................................II-3-12

LIST OF FIGURES:

Figure 1-1: South Coast Air Quality Management District and Surrounding 

Jurisdictions.............................................................................................. II-1-1

Figure 1-2: South Coast Air Quality Management District Ambient Air 

Monitoring Stations in 2011..................................................................... II-1-3

Figure 1-3: 2008 South Coast Air Basin Average Daily Emissions 

(Thousand Tons per Day)......................................................................... II-1-5

Figure 1-4: 2008 Coachella Valley Average Daily Emissions (Tons per Day).......... II-1-5

Figure 1-5: Annual PM2.5 3-Year (2009-2011) Design Values by Station 

Compared to Current and Proposed Federal Standards.......................... II-1-14

Figure 2-1: 2011 South Coast Air Basin Maximum Pollutant Concentrations........... II-2-1

Figure 2-2: South Coast Air Basin and Coachella Valley 3-Year (2009-2011) 

Design Values........................................................................................... II-2-2

Figure 2-3: 2011 South Coast Air Basin Air Quality Compared to Other U.S. 

Urban Areas.............................................................................................. II-2-5

Figure 2-4: 2011 South Coast Air Basin Air Quality Compared to Other 

California Air Basins................................................................................ II-2-6

Figure 2-5: Trend of Basin-Days Exceeding Federal Standards, 1990-2011 ............. II-2-7

Figure 2-6: Trends of South Coast Air Basin Maximum Pollutant 

Concentrations.......................................................................................... II-2-8

Figure 2-7: Number of Basin-Days per Month Exceeding the Most Stringent State

or Federal Standards in 2011.................................................................... II-2-9

Figure 2-8: South Coast Air Quality Management District PM2.5 Air Monitoring . II-2-11

Figure 2-9: South Coast Air Quality Management District PM10 Air Monitoring .. II-2-11

Figure 2-10: Annual Average PM2.5 (μg/m3) in 2011 ............................................... II-2-15

Figure 2-11: 98th Percentile 24-Hour Average PM2.5 (μg/m3) in 2011 ..................... II-2-15

Figure 2-12: South Coast Air Basin PM2.5 Design Value Trends, 2001-2011 .......... II-2-16

Figure 2-13: 2011 PM2.5 Variation of Basin-wide FRM Monthly Average

Concentration......................................................................................... II-2-17

Figure 2-14: PM2.5 Basin-wide Day-of-Week Variation of 24-hour Average FRM 

PM2.5 Concentrations, 2009-2011......................................................... II-2-18
Table of Contents

II-iii

Figure 2-15: Diurnal Variation of Hourly FEM PM2.5, Averaged by Time of Day 

(2009-2011) ............................................................................................ II-2-19

Figure 2-16: South Coast Air Basin PM2.5 SASS Speciation Network Annual 

Trends 2004-2010................................................................................... II-2-20

Figure 2-17: 2010 PM2.5 Speciation for Annual Average and Highest Day.............. II-2-21

Figure 2-18: Annual Arithmetic Mean PM10 Particulate Matter (μg/m3) in 2011..... II-2-23

Figure 2-19: PM10 Particulate Matter Design Value Trend ....................................... II-2-24

Figure 2-20: Basin-Days Exceeding the State PM10 Standard (50 μg/m3) by Month, 

2009-2011............................................................................................... II-2-25

Figure 2-21: Number of Station Days Exceeding State PM10 Standard (50 μg/m3) 

by Month, 2009-2011 ............................................................................. II-2-26

Figure 2-22: PM10 Day-of-Week Variation, 2009-2011 ............................................ II-2-27

Figure 2-23: PM10 Diurnal Variation, 2011 ............................................................... II-2-28

Figure 2-24: Number of Days in 2011 Exceeding the 1979 1-Hour Ozone Federal 

Standard .................................................................................................. II-2-31

Figure 2-25: Number of Days in 2011 Exceeding the Current (2008) Federal 

8-Hour Ozone Standard.......................................................................... II-2-32

Figure 2-26: Trend of Annual Basin Days Exceeding Federal 8-Hour and 1-Hour 

Ozone Standards and Peak Concentrations............................................ II-2-33

Figure 2-27: South Coast Air Basin Ozone Design Value Trends, 1990-2011........... II-2-33

Figure 2-28: Monthly Distribution of Basin Days Exceeding the (2008) Federal 

8-hour Ozone Standard........................................................................... II-2-34

Figure 2-29: 8-Hour Ozone Day-of-Week Variation, 2011 ........................................ II-2-36

Figure 2-30: Diurnal Variation of Basin May-October 2011 Averaged Hourly 

Ozone Concentrations............................................................................. II-2-37

Figure 3-1: Location and Topography of the Coachella Valley.................................. II-3-1

Figure 3-2: Coachella Valley 2011 Maximum Pollutant Concentrations 

as Percent of State and Federal Standards................................................ II-3-2

Figure 3-3: Coachella Valley 3-Year (2009-2011) Design Values 

as Percent of Federal Standards................................................................ II-3-3

Figure 3-4: Trend of Annual Average PM2.5 and PM10, 1990-2011 ........................ II-3-6

Figure 3-5: Coachella Valley Federal and State Ozone Trends, 1990-2011............. II-3-10

Figure 3-6: Trends of Coachella Valley Maximum 1-hour and 8-hour Ozone 

Concentrations, 1990-2011..................................................................... II-3-11
Final 2012 AQMP Appendix II: Current Air Quality

II-iv

LIST OF TABLES:

Table 1-1: Historic Population and Projections for South Coast Air Basin 

and Coachella Valley...........................................................................II-1-2

Table 1-2: Current Primary Ambient Air Quality Standards and Health Effects.II-1-7

Table 1-3: Primary National Ambient Air Quality Standards (NAAQS) and 

Design Value Requirements................................................................II-1-9

Table 1-4: Summary of National Ambient Air Quality Standards (NAAQS) 

for Particulate Matter, 1971-Present (with Proposed).......................II-1-15

Table 2-1: National Ambient Air Quality Standards (NAAQS) Attainment Status, 

South Coast Air Basin .........................................................................II-2-3

Table 2-2: 2011 Maximum 24-hour Average PM2.5 Concentrations 

by Basin and County..........................................................................II-2-13

Table 2-3: 2011 Maximum Annual Average PM2.5 Concentrations 

by Basin and County..........................................................................II-2-14

Table 2-4: 2011 Maximum 24-hour Average PM10 Concentrations 

by Basin and County..........................................................................II-2-22

Table 2-5: 2011 Maximum Annual Average PM10 Concentrations 

by Basin and County..........................................................................II-2-23

Table 2-6: 2011 Maximum 1-Hour Average Ozone Concentrations 

by Basin and County..........................................................................II-2-30

Table 2-7: 2011 Maximum 8-Hour Average Ozone Concentrations 

by Basin and County..........................................................................II-2-30

Table 2-8: 2011 Maximum 8-Hour and 1-Hour CO Concentrations 

by Basin and County..........................................................................II-2-38

Table 2-9: 2011 Maximum 1-Hour and Annual Average NO2 Concentrations 

by Basin and County..........................................................................II-2-39

Table 2-10: 2011 Maximum 1-Hour Average SO2 Concentrations 

by Basin and County..........................................................................II-2-40

Table 2-11: 2011 Maximum 24-Hour Average Sulfate (PM10) Concentrations 

by Basin and County..........................................................................II-2-41

Table 2-12: 2011 Maximum 3-Month Rolling Pb Concentrations 

by Basin and County..........................................................................II-2-43

Table 3-1: National Ambient Air Quality Standards (NAAQS) Attainment Status, 

Coachella Valley Portion of the Salton Sea Air Basin........................II-3-4
Table of Contents

II-v

ATTACHMENT LIST:

Table A-1: Air Monitoring Stations and Source/Receptor Areas

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

Table A-2: Ozone – Number of Days Exceeding the 2008 Federal Standard (0.075 ppm, 

8-Hour Average), 1995-2011

Table A-3: Ozone – Number of Days Exceeding the Former (1979) 1-Hour Federal 

Standard (0.12 ppm, 1-Hour Average), 1995-2011

Table A-4: Ozone – Annual Maximum 4th Highest 8-Hour Average (ppb), 1995-2011

Table A-5: Ozone – Annual Maximum 1-Hour Average (ppm), 1976-2011

Table A-6: Particulate Matter (PM10) – Annual Arithmetic Mean (μg/m

3

), 

1995-2011

Table A-7: Particulate Matter (PM10) – Percent of Sampling Days Exceeding State (50 

μg/m

3

) and Federal (150 μg/m

3

) 24-Hour Standards, 1995-2011

Table A-8: Particulate Matter (PM10) – Annual Maximum 24-Hour Average (μg/m

3

), 

1995-2011

Table A-9: Fine Particle Matter (PM2.5) – Annual Arithmetic Mean (μg/m

3

), 

1999-2011

Table A-10: Fine Particulate Matter (PM2.5) – Percent of Sampling Days Exceeding the 

Federal Standard (35 μg/m

3

), 1999-2011

Table A-11: Fine Particulate Matter (PM2.5) – Annual Maximum 24-Hour Average 

(μg/m

3

), 1999-2011

Table A-12: Fine Particulate Matter (PM2.5) – Annual 24-Hour Average 98th Percentile 

Concentration (μg/ m

3

), 1999-2011

Table A-13: Carbon Monoxide – Annual Maximum 8-Hour Average (ppm), 

1995-2011

Table A-14: Nitrogen Dioxide – Annual Average (pphm), 1995-2011

Table A-15: Nitrogen Dioxide – Annual Maximum 1-Hour Average (ppm), 1995-2011

Table A-16: Sulfur Dioxide – Annual Maximum 1-Hour Average (ppm), 1995-2011

Table A-17: Sulfate (PM10) – Annual Maximum 24-Hour Average (μg/m3), 1995-2011

Table A-18: Lead (TSP) – Annual Maximum Calendar Quarter Mean (μg/m

3

), 1995-2011

Table A-19: Lead (TSP) – Annual Maximum Monthly Average (μg/m

3

), 1995-2011

Table A-20: Lead (TSP) – Annual Maximum 3-Month Rolling Average (μg/m

3

), 1995-

2011
SUMMARY
Summary

II-1

SUMMARY

This appendix contains a detailed summary of the air quality in 2011 and the prior year 

trends for the South Coast Air Basin (Basin) and the Coachella Valley portion of Salton 

Sea Air Basin (SSAB), under the jurisdiction of the South Coast Air Quality 

Management District (District). The Basin includes Orange County and the non-desert 

portions of Los Angeles, Riverside and San Bernardino counties. In 2011, the District 

measured concentrations of air pollutants at 35 routine air monitoring stations in 

Southern California’s Los Angeles, Orange, Riverside and San Bernardino counties, 

including two stations in the Coachella Valley. In addition, six source-specific lead (Pb) 

monitors were operated in 2011, near potential Pb emission sources.

Chapter 1 of this appendix presents descriptions of the air quality setting for the 

District’s jurisdiction, including the relevant boundaries, weather factors and emissions 

for both the Basin and the Coachella Valley. It also briefly describes the properties and 

health effects of each criteria pollutant and the state and federal ambient air quality 

standards, along with revisions to the standards, both adopted and currently proposed. 

Criteria pollutants are those which have associated health-based National Ambient Air 

Quality Standards (NAAQS). Chapters 2 and 3 present summaries of current air quality 

for each of the criteria pollutants in the Basin and the Coachella Valley, respectively. 

These chapters include comparisons of the current concentrations compared to the state 

and federal standards, along with spatial, seasonal, and diurnal variations. Air quality 

statistics and trends presented in this Appendix provide information on the recent history 

and current status and progress toward attainment of the NAAQS and state standards, 

providing a baseline for planning toward future attainment.

Ozone (O3) and fine particulate matter (PM2.5) are the main pollutants for which the U.S 

EPA has designated the Basin as nonattainment. The Coachella Valley is also a 

nonattainment area for ozone and PM10, but PM2.5 concentrations remain below the 

federal standards. PM2.5 concentrations in the Basin have improved considerably, with 

2010 and 2011 the cleanest years on record for the area. However, the Basin had the 

highest number of days exceeding the federal ozone standard of any urban area 

nationwide in 2011.

The Los Angeles County portion of the Basin is also currently nonattainment for the 

recently lowered federal lead standard, due to source-specific monitoring near a 

stationary Pb source, as required under the new U.S. EPA regulation. The remaining 

ambient Pb monitoring measurements throughout the Basin are below the current Pb 
Final 2012 AQMP Appendix II: Current Air Quality

II-2

NAAQS. Pb air quality and attainment has been addressed separately in the 2012 Lead 

SIP for Los Angeles County submitted to U.S. EPA in June 2012.

While the new federal 1-hour standard concentration level was exceeded on one day for 

nitrogen dioxide (NO2) in 2011, it should be noted that this does not include 

nonattainment. The Basin has not been designated as nonattainment of the NAAQS, 

since the Basin has not exceeded the design value1form of the revised NO2 standard 

(98th percentile concentration, averaged over 3 years).

Both the Basin and the Coachella Valley are currently listed as PM10 nonattainment 

areas by U.S. EPA, based on the current 24-hour PM10 NAAQS. However, all 

exceedances of the federal 24-hour PM10 NAAQS in recent years have been flagged in 

the U.S. EPA Air Quality System (AQS) database for exclusion based on the U.S. EPA 

Exceptional Events Regulation (due to high wind events and Independence Day 

fireworks displays). The District has requested that U.S. EPA consider redesignate both 

areas to attainment status. State and federal standards for carbon monoxide (CO), sulfur 

dioxide (SO2), and sulfate (SO4

2-

) were not exceeded in the District. 

 

1 A design value is a statistic that describes the air quality status of a given area relative to the level and form of the 

National Ambient Air Quality Standards (NAAQS). For most criteria pollutants, the design value is a 3-year average 

and takes into account the form of the short-term standard (e.g., 98th percentile, fourth high value, etc.)
CHAPTER 1

INTRODUCTION

Air Quality Setting

District Jurisdiction and Boundaries

Weather Factors

Emissions

Ambient Air Quality Standards

Design Values

Summary of Criteria Pollutants and Air Quality Standards
Chapter 1: Introduction

II-1-1

AIR QUALITY SETTING

District Jurisdiction and Boundaries

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 soon 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, the Mojave Desert AQMD, (which 

covers the Mojave Desert Air Basin except for the portion within the South Coast Air 

District in the eastern portion of Riverside County), and the Antelope Valley APCD 

(which covers portions of Los Angeles County not within the South Coast Air Basin). 

The South Coast Air Quality Management District (District) was established by state 

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

the South Coast Air Basin (Basin). The Basin includes all of Orange County and the 

non-desert areas of Los Angeles, Riverside, and San Bernardino Counties. The District 

is also responsible for air quality in the Riverside County portion of the Salton Sea Air 

Basin (SSAB), which is primarily the Coachella Valley. The region encompassed by the 

District is shown in Figure 1-1.

FIGURE 1-1

South Coast Air Quality Management District and Surrounding Jurisdictions

South Coast

Air Quality Management District

SCAQMD Jurisdiction

Mojave Desert

Air Basin

Salton Sea

Air Basin

San Diego

Air Basin

South

 Central

 Coast Air Basin

South Coast

 Air Basin

San Diego County

Imperial County

Riverside County

Los Angeles

 County

Kern County San Bernardino County

Orange

 County

Santa

 Barbara

 County

Ventura

 County

San Joaquin

 Valley

 Air Basin
Final 2012 AQMP Appendix II: Current Air Quality

II-1-2

The Basin has an area of 6,800 square miles with a population of approximately 16 

million people in 2011. The Los Angeles urban area (the nation’s second largest), the 

Anaheim-Fullerton urban area, and the Riverside-San Bernardino urban area lie within 

the Basin’s boundaries. About two-thirds of the Basin’s population lives within Los 

Angeles County. The 2011 population in the Riverside county portion of the SSAB 

portion under the jurisdiction of the District was approximately 450,000. The District 

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

(see Figure 1-1). The area is sparsely populated desert and contains a portion of Joshua 

Tree National Park. Table 1-1 summarizes the historic, current and future projections of 

the population of the Basin and the Coachella Valley.

TABLE 1-1

Historic Population and Projections for South Coast Air Basin and Coachella Valley

Area 1980 1990 2000 2010 2020 2030

South Coast Air Basin 10,500,000 13,022,000 14,681,000 15,759,412 16,901,492 18,129,690

Coachella Valley 139,000 267,000 320,892 439,357 558,321 710,430

The SSAB 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.

In 2011, the District maintained a network of 33 regular air monitoring stations2in the 

Basin and two in the Coachella Valley area. In addition, six monitors measure sourcespecific lead near emissions sources. Figure 1-2 shows the locations of the ambient air 

monitoring stations along with the District boundaries. PM2.5 monitoring has been 

significantly increased throughout the District in recent years, using both Federal 

Reference Method (FRM) filter measurements and continuous measurements for realtime data. Table A-1 and Figure A-1 in the Attachment to Appendix II also show the 

District’s current ambient air monitoring network.

 

2 Not all criteria pollutants are measured at every station.
Chapter 1: Introduction

II-1-3

FIGURE 1-2

South Coast Air Quality Management District Ambient Air Monitoring Stations in 2011

Weather Factors

The climate of the District varies considerably between the coastal zone, inland valleys, 

mountain areas and deserts. Most of the Basin is relatively arid, with very little rainfall 

and abundant sunshine during the summer months. It has light winds and poor vertical 

mixing compared to other large urban areas in the U.S. The combination of poor air 

dispersion and abundant sunshine provides conditions especially favorable to the 

formation of photochemical smog and the trapping of particulates and other pollutants. 

The Basin is 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 results in the Basin having some 

of the worst air quality in the U.S.

The prevailing daytime sea breeze tends to transport pollutants and precursor emissions 

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

neighboring areas of the SSAB, 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 

reactions, such as ozone and the majority of PM2.5) reach maximum concentrations 

some distance downwind of the sources that emit the precursors, due to the fact that the 
Final 2012 AQMP Appendix II: Current Air Quality

II-1-4

polluted air mass is moved inland by the prevailing winds many miles to areas where 

maximum concentrations are reached.

Emissions

The quantity of each of the major pollutants emitted into the atmosphere of the Basin in 

2008 is shown in Figure 1-3 (in thousands of Tons per Day). The year 2008 emissions 

are the base year emissions used for the Final 2012 AQMP. In that year, the Basin’s 

annual average daily emissions were approximately 2880 tons of CO, 593 tons of 

volatile organic compounds (VOC), 754 tons of oxides of nitrogen (NOx), 54 tons of 

oxides of sulfur oxides (SOx), 170 tons of PM10, and 80 tons of PM2.5. Figure 1-4 

shows the amount of each of the major pollutants emitted into the atmosphere in the 

Coachella Valley (in Tons per Day). These are much lower than those emitted in the 

Basin, by a factor of 10 to over 350, depending on the pollutant. The difference in local 

emissions between these two areas and the prevailing wind flows illustrate the 

importance of pollutant transport to the Coachella Valley’s air quality.

Additional PM10 and PM2.5 material forms through chemical reactions of gaseous 

precursor emissions. Most 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. VOCs and NOx are precursors of ozone, and they also react to 

form nitrates and solid organic compounds, which are a significant fraction of the 

ambient particulate matter. SO2 reacts to form sulfates which are also significant 

contributors to the Basin’s PM10 and PM2.5 levels. In addition to the particulates 

formed by the reaction of gaseous precursors, there is directly emitted PM10 and PM2.5, 

most of which is attributed to fugitive dust sources such as re-entrained road dust, 

construction activities, farming operations and wind-blown dust but also includes other 

directly-emitted substances such as diesel particulate. Details of the 2008 base year and 

future-year projected emissions inventories are contained in Chapter 3 and Appendix III.
Chapter 1: Introduction

II-1-5

0.0 1.0 2.0 3.0

PM2.5

PM10

SOx

NOx

VOC

CO

NH3

Emissions (Tons/Day x 1000)

FIGURE 1-3

2008 South Coast Air Basin Average Daily Emissions (Thousand Tons per Day)

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0

PM2.5

PM10

SOx

NOx

VOC

CO

NH3

Emissions (Tons/Day)

FIGURE 1-4

2008 Coachella Valley Average Daily Emissions (Tons per Day)
Final 2012 AQMP Appendix II: Current Air Quality

II-1-6

AMBIENT AIR QUALITY STANDARDS

Both the federal government and the State of California have adopted ambient air quality 

standards, which define the concentration below which long-term or short-term exposure 

to a pollutant is not expected to cause adverse effects to public health and welfare. The 

criteria pollutants, those that have health-based standards, are: ozone (O3), carbon 

monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), coarse and fine particulate 

matter (PM10 and PM2.5, respectively), lead (Pb), and sulfate (SO4

2-

, California only). 

California also has a welfare-based standard for visibly-reducing particles. In 2011, the 

District monitored ambient air quality for criteria pollutants at 35 routine monitoring 

sites throughout the Basin and in the neighboring Coachella Valley in the Riverside 

county portion of the Salton Sea Air Basin (SSAB), plus six additional source-specific 

lead monitors.

For several National Ambient Air Quality Standards (NAAQS), there are both primary 

and secondary standards. Primary standards provide public health protection, including 

protecting the health of "sensitive" populations such as asthmatics, children, and the 

elderly. Secondary standards provide public welfare protection, including protection 

against decreased visibility and damage to animals, crops, vegetation, and buildings. 

This document focuses on the primary federal standards. The federal and state primary 

standards are summarized in Table 1-2, along with a brief summary of health effects. 

Further discussion of the health effects of air pollutants is presented in Chapter 2 and 

more detailed health information is presented in Appendix I.
Chapter 1: Introduction

II-1-7

TABLE 1-2

Current Primary Ambient Air Quality Standards and Health Effects

Air 

Pollutant

State

Standard

Federal Standard

(NAAQS)

Relevant Health and Welfare Effects#

Concentration,

Averaging Time

Concentration,

Averaging Time

Ozone (O3)

0.09 ppm, 1-Hour

0.070 ppm, 8-Hour 0.075 ppm, 8-Hour

(2008)

0.08 ppm 8-Hour

(1997)

(a) Pulmonary function decrements and localized lung edema in 

humans and animals; (b) Risk to public health implied by alterations in 

pulmonary morphology and host defense in animals; (c) Increased 

mortality risk; (d) Risk to public health implied by altered connective 

tissue metabolism and altered pulmonary morphology in animals after 

long-term exposures and pulmonary function decrements in 

chronically exposed humans; (e) Vegetation damage; (f) Property 

damage

Carbon 

Monoxide

(CO)

20 ppm, 1-Hour

9.0 ppm, 8-Hour

35 ppm, 1-Hour

9 ppm, 8-Hour

(a) Aggravation of angina pectoris and other aspects of coronary heart 

disease; (b) Decreased exercise tolerance in persons with peripheral 

vascular disease and lung disease; (c) Impairment of central nervous 

system functions; (d) Possible increased risk to fetuses

Nitrogen Dioxide

(NO2)

0.18 ppm, 1-Hour

0.030 ppm, Annual

100 ppb, 1-Hour

0.053 ppm, Annual

(a) Potential to aggravate chronic respiratory disease and respiratory 

symptoms in sensitive groups; (b) Risk to public health implied by 

pulmonary and extra-pulmonary biochemical and cellular changes and 

pulmonary structural changes; (c) Contribution to atmospheric 

discoloration

Sulfur Dioxide

(SO2)

0.25 ppm, 1-Hour

0.04 ppm, 24-Hour 75 ppb, 1-Hour Bronchoconstriction accompanied by symptoms which may include wheezing, shortness of breath, and chest tightness during exercise or 

physical activity in persons with asthma

Suspended 

Particulate 

Matter (PM10)

50 μg/m3, 24-Hour

20 μg/m3, Annual

150 μg/m3, 24-Hour

(a) Exacerbation of symptoms in sensitive patients with respiratory or 

cardiovascular disease; (b) Declines in pulmonary function growth in 

children; (c) Increased risk of premature death Suspended 

Particulate 

Matter (PM2.5) 12.0 μg/m3, Annual

35 μg/m3, 24-Hour

15.0 μg/m3, Annual

Sulfates-PM10

(SO4

2-

)

25 μg/m3, 24-Hour N/A

(a) Decrease in lung function; (b) Aggravation of asthmatic symptoms; 

(c) Aggravation of cardio-pulmonary disease; (d) Vegetation damage; 

(e) Degradation of visibility; (f) Property damage

Lead (Pb) 1.5 μg/m3, 30-day 0.15 μg/m3, 3-month 

rolling

(a) Learning disabilities; (b) Impairment of blood formation and nerve 

conduction

VisibilityReducing

Particles

In sufficient amount such 

that the extinction 

coefficient is greater than 

0.23 inverse kilometers at 

relative humidity less than 

70 percent, 8-hour 

average (10am - 6pm)

N/A Visibility impairment on days when relative humidity is less than 70 

percent

ppm – parts per million by volume ppb – parts per billion by volume

State standards are “not-to-exceed” values; Federal standards follow the design value form of the NAAQS

# More detailed health effect information can be found in the 2012 AQMP Appendix I or the U.S. EPA NAAQS documentation at 

http://www.epa.gov/ttn/naaqs/
Final 2012 AQMP Appendix II: Current Air Quality

II-1-8

Design Values

Air quality statistics can be presented in terms of the maximum concentrations measured 

at monitoring stations or in air basins, as well as for the number of days exceeding state 

or federal standards. These are instructive in regard to trends and the effectiveness of 

control programs. However, it should be noted that an exceedance of the concentration 

level of a federal standard does not necessarily lead to a violation of the NAAQS or that 

lead to a nonattainment designation. The form of the standard as defined by the federal 

NAAQS regulations must also be considered. For 24-hour PM2.5, the form of the 

standard is the 98th percentile measurement of all the 24-hour PM2.5 samples at each 

station. For 8-hour O3, the 4th highest measured 8-hour average concentration is used 

for each station. For NAAQS attainment/nonattainment decisions, the most recent 3 

years of data are considered, along with the form of the standard, and are typically 

averaged to calculate a Design Value for each station. The overall design value for an 

air basin is the highest design value of all the stations in that basin. U.S. EPA also 

allows certain data to be flagged and not considered for NAAQS attainment status, when 

that data is influenced by exceptional events, such as high winds, wildfires, volcanoes, 

or some cultural events (Independence Day fireworks) that meet strict criteria. Table 1-3 

shows the design value requirements utilizing the form of the federal standards for the 

federal criteria pollutants.
Chapter 1: Introduction

II-1-9

TABLE 1-3

Primary National Ambient Air Quality Standards (NAAQS) and Design Value Requirements

Pollutant Averaging

Time

Standard

Level

Design Values and 

Form of Standards*

Ozone

(O3)

1-Hour**

(1979)

0.12 ppm Not to be exceeded more than once per year averaged over 3 

years

8-Hour

(1997)

0.08 ppm Annual fourth highest 8-hour average concentration, 

averaged over 3 years 

8-Hour

(2008)

0.075 ppm Annual fourth highest 8-hour average concentration, 

averaged over 3 years 

Carbon Monoxide

(CO)

1-Hour 35 ppm

Not to be exceeded more than once a year

8-Hour 9 ppm

Nitrogen Dioxide

(NO2)

1-Hour 100 ppb Three-year average of the annual 98th percentile of the daily 

maximum 1-hour average concentrations (rounded)

Annual 0.053 ppm Annual average concentration, averaged over 3 years

Sulfur Dioxide

(SO2)

1-Hour 75 ppb 99th percentile of 1-hour daily maximum concentrations, 

averaged over 3 years

24-Hour#0.14 ppm Not to be exceeded more than once per year

Annual#0.03 ppm Annual arithmetic average

Particulate Matter

(PM10)

24-Hour 150 μg/m3 Not to be exceeded more than once per year averaged over 3 

years

Annual** 50 μg/m3 Annual average concentration, averaged over 3 years

Particulate Matter

(PM2.5)

24-Hour 35 μg/m3 Three-year average of the annual 98th percentile of daily 24-

hour concentration

Annual 15.0 μg/m3 Annual average concentration, averaged over 3 years

Lead

(Pb)

3-Month

Rolling## 0.15 μg/m3 Highest rolling 3-month average of the three years

* Standard is attained when the design value (form of concentration listed) is equal to or less than the NAAQS; 

for pollutants with the design values based on “exceedances” (1-hour O3, 24-hour PM10, CO, and 24-hour 

SO2), the NAAQS is attained when the concentration associated with the design value is less than or equal to 

the standard:

 For 1-hour O3 and 24-hour PM10, the standard is attained when the 4th highest daily concentrations of the 

3-year period is less than or equal to the standard

 For CO and 24-hour SO2, the standard is attained when the 2nd highest daily concentration of the most 

recent year is equal to or less than the standard

** Standard has been revoked. For 1979 1-hour O3, nonattainment areas have some continuing obligations under 

the former 1979 standard. For 8-hour O3, the standard has been lowered from (0.08 ppm to 0.075 ppm), but the 

1997 O3 standard and most related implementation requirements remain in place until further action by U.S. 

EPA

# Annual and 24-hour SO2 NAAQS will be revoked one year from attainment designations for the new (2010) 1-

hour SO2 standard

## 3-month rolling Pb averages of the first year (of the three year period) include November and December 

monthly averages of the prior year. The 3-month average is based on the average of “monthly” averages
Final 2012 AQMP Appendix II: Current Air Quality

II-1-10

Summary of Criteria Pollutants and Air Quality Standards

Ambient air quality standards are periodically reviewed by U.S. EPA and state agencies 

to incorporate the findings from the most current research available on the effects of 

pollutants. Alert and advisory levels for advising the public about unhealthful air quality 

are also recommended. The section below summarizes the pollutant properties and 

health information, along with the air quality standards, including the recently revised or 

newly established standards and recently proposed revisions of the particulate NAAQS. 

Further discussion of the health effects of air pollutants is presented in Chapter 2 and 

more detailed health effects information is presented in Appendix I.

Particulate Matter Properties

Particulate matter (PM) air pollution is a complex mixture of small particles and liquid 

droplets, made up of a number of components, including acids and salts (such as nitrates 

and sulfates), organic chemicals, metals, and soil or dust particles. Particles originate 

from a variety of anthropogenic mobile and stationary sources and from natural sources. 

These particles can be emitted directly or formed in the atmosphere by transformations 

of gaseous emissions, such as sulfur oxides (SOx), nitrogen oxides (NOx), ammonia 

(NH3) and volatile organic compounds (VOC). Examples of secondary particle 

formation include: 1) conversion of SOx and NOx to acid droplets or vapor that further 

react with ammonia to form ammonium sulfate and ammonium nitrate; and 2) reactions 

involving gaseous VOC, yielding organic compounds that condense on existing particles 

to form secondary organic aerosol (SOA) particles.

The size of particles is directly linked to their potential for causing health problems. 

Particles that are 10 micrometers (μm) in diameter or smaller (PM10) are of more 

concern than larger particles because those are the particles that generally pass through 

the throat and nose and enter the lungs. (A μm is 1/1000th of a millimeter; there are 

25,400 micrometers in an inch.) Once inhaled, these particles can affect the heart and 

lungs and cause serious health effects. PM air pollution is typically grouped into two 

overlapping categories:

 Inhalable coarse particles (PM10), such as those found near roadways and dusty 

industries, are smaller than 10 μm in diameter. PM10 includes all PM2.5 

particles;
Chapter 1: Introduction

II-1-11

 Fine particles (PM2.5), such as those found in smoke and haze, are 2.5 μm in 

diameter and smaller. These particles can be directly emitted from combustion 

sources, such as from diesel exhaust (soot) or forest fire smoke, or they can form 

when gases emitted from power plants, industries and motor vehicles react in the 

air. PM2.5 is a subset of PM10 particles.

PM10 Properties

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.

PM10 particles are both directly emitted and formed chemically in the atmosphere from 

diverse emission sources. Major sources of PM10 include re-suspended road dust or soil 

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

These are mainly the coarser particles, in the PM10-PM2.5 coarse fraction range (often 

referred to as PM-Coarse, i.e., particles in the size range between 2.5 μm and 10 μm). 

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

precursor emissions. These are mostly the smaller particles, mainly in the PM2.5 size 

range.

PM2.5 Properties

PM2.5, also known as fine particles, are the finer sized particles less than 2.5 μm in 

diameter, small enough to penetrate the defenses of the human respiratory system and 

lodge in the deepest recesses of the lung, causing potential adverse health impacts. The 

health effects include increased risks of heart attacks and strokes, aggravated asthma, 

acute bronchitis and chronic respiratory problems such as shortness of breath and painful 

breathing (in children, the elderly and sensitive people), and premature deaths (mainly in 

the elderly due to weaker immune systems). Sources of PM2.5 include diesel-powered 

vehicles such as buses and trucks, fuel combustion from automobiles, power plants, 

industrial processes, and wood burning.

In the Basin, much of the PM10 fraction is actually PM2.5 and smaller in size than 2.5 

μm, a situation 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 visibility in this region.
Final 2012 AQMP Appendix II: Current Air Quality

II-1-12

Total Suspended Particulate (TSP) Properties

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

particles suspended in the atmosphere, with no strict differentiation for particle size. 

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 to be weighed for mass and chemically analyzed to determine the 

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

based on the analysis of TSP samples. In 2011, TSP samples were collected by the 

District at 14 sites. In addition, the District measured TSP lead at several source-specific 

sites in the vicinity of facilities known to emit lead, in order to comply with recent 

federal requirements to monitor those sources. The lead measurements throughout the 

Basin are detailed further at the end of this Chapter. Other than the specific health 

effects of lead, the fine fraction of TSP has greater effects on health and visibility than 

the coarse fraction. Of greatest concern to public health are the particles small enough to 

be inhaled into the lungs (PM10) and especially the smaller fine particles that are inhaled 

more deeply into the lungs (PM2.5). As a result the federal standard for TSP mass has 

been replaced with the PM10 and PM2.5 standards.

Particulate Matter (PM) Air Quality Standards

PM10 Air Quality Standards

In 1987, U.S. EPA adopted PM10 standards, replacing the earlier TSP standard. The 

District began PM10 monitoring in late 1984. U.S. EPA promulgated both a short-term 

24-hour average standard (150 μg/m3)

3

and an annual standard (50 μg/m3). Over the 

years, the forms and levels of the federal PM10 standards were reviewed by U.S. EPA. 

Changes to the federal standards for PM10 became effective on December 17, 2006. 

U.S. EPA first proposed to revise the 24-hour PM10 standard by establishing a new 

indicator for coarse particles (particles generally between 2.5 and 10 μm in diameter, 

PM10-2.5), to include PM10-2.5 that is mainly generated by resuspended dust from 

high-density traffic on paved roads, industrial sources, and construction sources; but 

specifically excluding PM10-2.5 that is generated by rural windblown dust and soils and 

by agricultural and mining sources. U.S. EPA proposed to set the PM10-2.5 standard at a 

level of 70 μg/m3. However, the coarse particle standard was not included as part of the 

final regulation which retained the 24-hour PM10 standard (150 μg/m3). U.S. EPA also

revoked the annual PM10 standard due to a cited lack of evidence of adverse health 

 

3

μg/m3= micrograms per cubic meter
Chapter 1: Introduction

II-1-13

effects linked to long-term exposure to coarse particles, beyond that already protected 

against by the PM2.5 annual standard. As part of the revision to the ambient air 

monitoring regulations in 2006, PM10-2.5 monitoring was required at National Core 

(NCore) multi-pollutant monitoring stations by January 1, 2011. Currently, the District 

measures PM10-2.5 at two NCore PM monitoring sites in the Basin (Central Los 

Angeles and Riverside-Rubidoux). In the most recent review of the PM standards 

completed in June of 2012, U.S. EPA did not propose changes to the PM10 standard.

PM2.5 Air Quality Standards

In 1997, U.S. EPA adopted new federal air quality standards for the subset of fine 

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

range of inhalable particulate matter. The District began monitoring PM2.5 

concentrations in 1999. Federal annual and 24-hour standards and a state annual 

standard for PM2.5 were established. In 2006, U.S. EPA significantly lowered the level 

of the 24-hour PM2.5 standard, from 65 μg/m3to 35 μg/m3, while retaining the level of 

the annual PM2.5 standard at 15 μg/m3.

In the 2006 PM NAAQS review, U.S. EPA determined that individuals with pre-existing 

heart and lung diseases, older adults, and children are at greater risk from the effects 

associated with fine PM exposures. Based on the results of the previous studies and an 

extensive new body of scientific evidence that links the negative health impacts of 

PM2.5 exposure on these and possibly additional sensitive subpopulations (e.g., fetuses

(unborn babies), newborns, and genetically susceptible populations) at lower levels than 

previously understood, U.S. EPA has proposed to strengthen the annual PM2.5 standard. 

On June 14, 2012 U.S. EPA proposed a lower annual standard with a concentration 

range between 12 and 13 μg/m3. The current 24-hour standard of 35 μg/m3is proposed 

to remain unchanged. In addition, U.S. EPA proposed a requirement for near-roadway 

PM2.5 monitoring in urban areas. They also proposed adjustments to the Air Quality 

Index (AQI), which is used to report current and forecasted pollutant levels, to be 

consistent with the current 24-hour and new proposed annual PM2.5 standards. Final 

action on the proposed PM2.5 standard is anticipated by December 14, 2012.

For the 3-year (2009-2011) PM2.5 annual design value (the 3-year average of the annual 

PM2.5 averages), the Basin exceeded the current federal annual PM2.5 standard at only 

one location, (in Northwestern Riverside County at Mira Loma). Lowering the annual 

standard concentration to 13 or 12 μg/m3 would have resulted in 6 to 10 additional 

stations exceeding the annual standard level in 2011. Figure 1-5 shows the effect of the 
Final 2012 AQMP Appendix II: Current Air Quality

II-1-14

proposed annual PM2.5 standard on the Basin’s attainment status, based on the 2009-

2011 annual PM2.5 design values.

Recently, ultrafine particles (UFP; diameter less than 0.1 μm) have received particular 

attention due to their ability to penetrate deep into the human respiratory tract, cross into 

the blood stream and other organs, and to cause adverse health effects in humans. 

However, UFPs are not currently regulated by the U.S. EPA (see Chapter 9 of the 2012 

AQMP for additional details). Table 1-4 summarizes the history of the PM NAAQS to 

date.

13.4 13.4 13.3 13.1

12.1

11.5 11.2 11.2

10.6 11.0

8.6

15.8

14.0

12.1

7.3

6.2

13.6

13.0

12.1

9.0

0

2

4

6

8

10

12

14

16

18

20 Annual PM2.5 Design Value (μg/m3

)

Los Angeles County Orange County Riverside County San Bernardino County

Current Federal Annual Standard (15 μg/m3)

Proposed Annual Standard (12-13 μg/m3)

FIGURE 1-5

Annual PM2.5 3-Year (2009-2011) Design Values by Station Compared to Current and Proposed 

Federal Standards
Chapter 1: Introduction

II-1-15

TABLE 1-4

Summary of National Ambient Air Quality Standards (NAAQS) for Particulate Matter, 1971-

Present (with Proposed)

Year of

Final Rule

Indicator Averaging

Time

Level

(μg/m3)

1971 TSP - Total Suspended 

Particles ( < 25-45 μm)

24-hour 260

Annual 75 

1987 PM10 24-hour 150

Annual 50

1997 PM2.5 24-hour 65

Annual 15

PM10 24-hour 150

Annual 50

2006 PM2.5 24-hour 35

Annual 15

PM10 24-hour* 150

Annual (revoked)

2012

(proposed)

PM2.5 24-hour 35

Annual 12-13**

PM10 24-hour 150

* In the 1997 revision of the 24-hour PM10 standard, the form of the standard was revised to 99th percentile, 

averaged over 3 years. When the 1997 standards were vacated, the form of 1987 standards remained in place (not 

to be exceeded more than once per year averaged over 3 years).

** A lower PM2.5 annual standard was proposed by U.S. EPA on June 14, 2012, with comments solicited on a 

concentration range from 12 to 13 μg/m3

Ozone Properties

The Basin's unique air pollution problem was first recognized in the 1940's. The Los 

Angeles urban area smog was worse than other areas. Early research showed that ozone

was being formed in the Basin's atmosphere from VOCs and NOx being emitted into the 

air in the presence of steady sunshine and trapped laterally by the mountainous terrain 

and vertically by strong low-altitude temperature inversions that act as a lid to vertical 
Final 2012 AQMP Appendix II: Current Air Quality

II-1-16

mixing of air. 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 0.60 ppm (600 ppb) were recorded at that time.

Ozone (O3), a colorless gas with a sharp odor at very high concentrations, is a highly 

reactive form of oxygen. High ozone concentrations exist naturally high above the earth 

in the stratosphere. Some mixing of stratospheric ozone downward to the earth's surface 

does occur; however, the extent of ozone transport from aloft is limited. At the earth's 

surface in sites remote from urban areas, ozone concentrations are normally very low 

(0.03-0.05 ppm).

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

reactions between VOCs, NOx, and the oxygen in the air. A decrease in ozone

precursors may or may not result in a linear decrease in ozone. Ozone concentrations are 

dependent not only on overall precursor levels, but also on the ratio of the concentrations

of VOCs to NOx , the reactivity of the specific VOCs present, the spatial and temporal 

distribution of emissions, the level of solar radiation, and other weather factors.

While ozone is beneficial in the stratosphere because it blocks skin-cancer-causing 

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 to react with organic materials causes it to be damaging to 

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

cause adverse 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 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 and damage to forests and other 

ecosystems.

Ozone Air Quality Standards

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

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

September 16, 1997, the U.S. Environmental Protection Agency (U.S. EPA) adopted an 
Chapter 1: Introduction

II-1-17

8-hour average federal ozone standard with a level of 0.08 ppm (not to exceed), 

intending to replace the 1-hour standard that was adopted in 1979 (0.12 ppm, not to 

exceed). This 8-hour ozone standard was more stringent than the 1-hour standard (0.12 

ppm) and provided greater protection to public health. The 8-hour standard is intended 

to 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. (Due to the 

monitoring and reporting requirements of the older ozone standards, a level of 0.085

ppm or 85 ppb is required to exceed the 1997 8-hour standard and 0.125 ppm or 125 ppb 

is required to exceed the 1979 1-hour standard.)

The U.S. EPA eventually revoked the 1979 federal 1-hour ozone standard, effective June 

15, 2005. However, the South Coast Air Basin and the former Southeast Desert 

Modified Air Quality Management Area (which included the Coachella Valley) had not 

attained the 1-hour federal ozone standard by the attainment date and have some 

continuing obligations under the former standard.

The 8-hour standard was subsequently lowered from 0.08 to 0.075 ppm (75 ppb, not to 

exceed, i.e., 76 ppb exceeds), effective May 27, 2008. However, nonattainment areas of 

the 1997 8-hour ozone standard still have some continuing obligations to demonstrate 

attainment of that standard by the applicable attainment date. In 2010, U.S. EPA 

proposed to lower the 8-hour ozone standard again and solicited comments on a 

proposed standard between 0.060 and 0.070 ppm. U.S. EPA did not take final action on 

a lower ozone standard and the NAAQS currently remains at the 0.075 ppm, as 

established in 2008. Potential new ozone standards are under review with proposed 

regulations expected by 2014. Statistics presented in this Appendix refer to both the 

current (2008) 8-hour standard and the former 1997 8-hour and 1979 1-hour standards

for purposes of historical comparison and assessment of progress towards attainment of 

those standards. 

The State of California Air Resources Board (CARB), established a new 8-hour average 

state ozone standard (0.070 ppm), effective May 17, 2006. The earlier state 1-hour 

ozone standard (0.09 ppm) also continues to remain in effect. Comparisons of the 

current (2008) and 1997 8-hour ozone standards, along with the former 1-hour ozone 

standard, for the Basin and the Coachella Valley can be found in Chapters 2 and 7.

While the 1-hour ozone episode levels and the related health warnings still exist, they are 

essentially replaced by the more protective health warnings associated with the current 

NAAQS. The 1-hour O3 episode warning levels include the state Health Advisory (0.15 

ppm), Stage 1 (0.20 ppm), Stage 2 (0.35 ppm) and Stage 3 (0.50 ppm). Only the lowest 
Final 2012 AQMP Appendix II: Current Air Quality

II-1-18

of these 1-hour episode thresholds, the state Health Advisory, was exceeded in 2011. 

The last 1-hour O3 Stage 1 episode occurred in 2003. The last Stage 2 episode occurred 

in 1988, and the last Stage 3 episode occurred in 1974.

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 2000, 98 percent 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. CO concentrations have continued to decrease due to reformulated fuels and 

more efficient combustion in newer vehicles.

As a primary pollutant, carbon monoxide is directly emitted into the air, and 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 and locations 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 at night during the coolest, most atmospherically 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 

adverse effect after exposure to CO and ozone.
Chapter 1: Introduction

II-1-19

CO Air Quality Standards

The state and federal CO standards have been reviewed recently, with no changes 

recommended. The CO standards are based on both short-term (1-hour; 35 ppm federal 

and 20 ppm state) and longer-term (8-hour; 9 ppm federal and 9.0 ppm state) exposures.

NO2 Properties 

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

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

conditions of high temperature and pressure which are generally present during 

combustion of fuels; NO reacts with the oxygen in air to give NO2. NO2 is largely 

responsible for the brownish tinge of polluted urban air. The two gases, NO and NO2, 

are referred to collectively as oxides of nitrogen (NOx). In the presence of sunlight, NO2

reacts to produce nitric oxide and an oxygen atom. The oxygen atom can react further to 

produce ozone, via a complex series of chemical reactions involving hydrocarbons 

(VOCs). NO2 may also react to produce nitric acid (HNO3) which reacts further to 

produce nitrates, which are a component of PM.

NO2 is a respiratory irritant and reduces resistance to respiratory infection. Children and 

people with respiratory disease are most susceptible to its effects.

Nitrogen Dioxide Standards

U.S. EPA has established a new primary NO2 1-hour standard to supplement the existing 

annual standard, at a level of 100 ppb (based on the 3-year average of the annual 98th

percentile of 1-hour daily maximum concentrations for each station). U.S. EPA has also 

established new requirements for the NO2 monitoring network in large metropolitan 

areas that will include monitors at locations within 50 meters of major roadways. This 

near-source monitoring requirement is in addition to the ambient monitoring 

requirements to measure the area-wide NO2 concentrations that occur more broadly 

across communities. This rule became effective on April 12, 2010. The 1971 annual 

NO2 federal standard (0.053 ppm) remains in effect. Effective March 20, 2008, the 

California Air Resources Board (CARB) revised the state NO2 1-hour state standard 

from 0.25 ppm to 0.18 ppm, and established a new annual state standard of 0.030 ppm.

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 deposition, and sulfates, which is a 
Final 2012 AQMP Appendix II: Current Air Quality

II-1-20

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 defenses of 

the lungs, and it 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.

Sulfur Dioxide Standards

U.S. EPA established a new 1-hour SO2 standard at a level of 75 ppb, based on the 3-

year average of the annual 99th percentile of 1-hour daily maximum concentrations and 

has revoked both the 24-hour and annual primary SO2 standards, effective June 2, 2010.

Sulfate Properties

Sulfates are chemical compounds which contain the sulfate ion (SO4

2-

) and are part of 

the mixture of solid materials which make up PM2.5, 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 produce sulfuric 

acid (H2SO4), which contributes to acid deposition. The reaction of sulfuric acid with 

basic substances such as ammonia yields sulfates, a component of PM.

Lead (Pb) Properties

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

gasoline and lead smelters had historically been the main Basin sources of lead emitted 

into the air. Due to the phasing out of leaded gasoline, there has been a dramatic 

reduction in atmospheric lead in the Basin over the past three decades.

Lead Standards

The national standard for Lead (Pb) was revised on October 15, 2008 from a quarterly 

average of 1.5 μg/m3to a rolling 3-month average of 0.15 μg/m3, with a maximum (notto-be-exceeded) form, evaluated over a 3-year period (36 months). The current indicator 

of Pb in total suspended particles (Pb-TSP) was retained. The revision became effective 

on January 12, 2009.
Chapter 1: Introduction

II-1-21

U.S. EPA has also enhanced the Pb monitoring requirements in its 2008 NAAQS 

revisions, requiring air monitoring near Pb sources with potential 3-month average Pb 

concentration exceeding the revised standard of 0.15 μg/m3. Pb monitoring is required 

in large urban areas with monitors located to measure Pb concentrations in areas 

impacted by resuspended dust from roadways, nearby industrial sources identified as 

significant Pb sources, hazardous waste sites, construction and demolition projects, or 

other fugitive dust sources of Pb. Following a petition in 2009, U.S. EPA revised the 

monitoring requirements, lowering the emission threshold at which monitoring is 

required for both source-oriented and large urban area-based non-source oriented 

monitoring. The monitoring revision became effective in January 2011. In 2011, the

District’s Pb monitoring network included 10 regular monitoring sites and an additional 

five source-specific sites, one of which exceeded the revised Pb standard (at a lead 

source in the City of Vernon, Los Angeles County). A separate Pb SIP addressing the 

2008 Pb standard was submitted to U.S. EPA in June 2012.

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

and the Riverside County (Coachella Valley) portion of the Salton Sea Air Basin 

(SSAB), respectively. For ozone, PM10, and PM2.5, the pollutants for which the Basin 

is still designated as nonattainment of the federal standards, maps are presented which 

show the geographical air quality variability. 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, for the years 1995 through 2011. Please refer to Appendix II 

from the 2003 AQMP for the 1976-1989 prior-year statistics and to Appendix II from the 

2007 AQMP for 1990-2005 data.
CHAPTER 2

AIR QUALITY IN THE SOUTH COAST AIR BASIN

Air Quality in the South Coast Air Basin

Violations of Standards

Design Values and NAAQS Attainment Status

Air Quality Compared to Other U.S. Metropolitan Areas

Air Quality Trends

Spatial and Temporal Variability

Pollutant-Specific Air Quality Discussion

Particulate Matter (PM)

Ozone (O3)

Nitrogen Dioxide (NO2)

Carbon Monoxide (CO)

Sulfur Dioxide (SO2)

Sulfate (SO4

2-

)

Lead (Pb)
Chapter 2: Air Quality in the South Coast Air Basin

II-2-1

AIR QUALITY IN THE SOUTH COAST AIR BASIN

Violations of Standards

In the South Coast Air Basin (Basin), the maximum pollutant concentrations measured at 

District monitoring stations in 2011 exceeded the levels of the federal and state standards 

for ozone (O3), PM2.5, nitrogen dioxide (NO2), and lead (Pb). In the year 2011, a total 

of 125 days exceeded the levels of the current short-term (24-hour average or less) 

federal standards for 8-hour O3, 1-hour NO2, or 24-hour PM2.5 at one or more Basin 

locations. As discussed below, the NO2 reading did not cause a “violation” of the 

standard. The more stringent state 8-hour O3 or 24-hour PM10 standards were exceeded 

on 137 days (based on the FRM filter data for PM10, which is not sampled every day). 

While the Basin exceeded the state annual and 24-hour PM10 standards, it did not 

exceed the 24-hour federal standard. The federal and state annual PM2.5 standards were 

exceeded in the Basin in 2011, with only one station exceeding the federal standard. 

While the state PM10 annual standard was exceeded, the revoked federal annual PM10 

standard was not. The other criteria pollutants, sulfur dioxide (SO2), carbon monoxide 

(CO), and sulfate (SO4

2-

) did not exceed federal or state standards. Figure 2-1 shows the 

Basin maximum pollutant concentrations for 2011, as a percentage of the federal and 

state standards.

* High lead concentrations recorded at monitoring sites adjacent to sources known to emit lead

FIGURE 2-1

2011 South Coast Air Basin Maximum Pollutant Concentrations

(as Percent of State and Federal Standards)

0

50

100

150

200

250

300

350

Ozone

(1-Hour)

Ozone

(8-Hour) 

(2008)

PM2.5

(24-Hour)

PM2.5

(Annual)

PM10

(24-Hour)

Nitrogen

Dioxide

(1-Hour)

Sulfur

Dioxide

(1-Hour)

Carbon Monoxide

(8-Hour)

Sulfate

(24-Hour)

Lead*

(rolling 3- Months) Percent of Standard

Standard

State Standard

Federal Standard

100%
Final 2012 AQMP Appendix II: Current Air Quality

II-2-2

Design Values and NAAQS Attainment Status

As shown above, the Basin exceeded the pollutant concentration levels defined by the 

National Ambient Air Quality Standards (NAAQS) for ozone, PM2.5, NO2, and Pb. 

However, attainment of the NAAQS is measured with the three-year design values that 

take into account the form of the federal standards and multi-year averages, as detailed 

previously in Table 1-3. The exceedances of the NO2 standard level on one day in 2011 

at two stations did not constitute a violation of the NAAQS or affect the Basin’s NO2

designation. The Basin did not exceed the federal standard for PM10 in 2011, or any 

year since 2008; the exceedances in 2007 and 2008 were flagged in the U.S. EPA AQS 

database to request exclusion from attainment consideration under the U.S. EPA 

Exceptional Events Rule. Figure 2-2 shows the federal ozone and PM design value 

status for the Basin, along with the Coachella Valley, for the 2009-2011 3-year period. 

The current U.S. EPA NAAQS attainment designations for the Basin are presented in 

Table 2-1.

FIGURE 2-2

South Coast Air Basin and Coachella Valley 3-Year (2009-2011) Design Values

(Percentage of Federal Standards, by Criteria Pollutant)

142%

126%

114%

110% 107%

65%

84%

123%

109%

91%

42%

48%

68%

56%

0%

20%

40%

60%

80%

100%

120%

140%

160%

2008

8-Hour

Ozone

1997

8-Hour

Ozone

1-Hour

Ozone

(Revoked)

24-Hour

PM2.5

Annual

PM2.5

24-Hour

PM10

Annual

PM10

(Revoked)

Basin Coachella Valley

Design Values as Percent of Standards

Federal Standard
Chapter 2: Air Quality in the South Coast Air Basin

II-2-3

TABLE 2-1

National Ambient Air Quality Standards (NAAQS) Attainment Status

South Coast Air Basin

Criteria

Pollutant Averaging Time Designationa) AttainmentDateb)

1979

1-Hour Ozonec)

1-Hour

(0.12 ppm) Nonattainment (Extreme) 11/15/2010(not attained)

1997

8-Hour Ozoned)

8-Hour

(0.08 ppm) Nonattainment (Extreme) 6/15/2024

2008

8-Hour Ozone

8-Hour

(0.075 ppm) Nonattainment (Extreme) 12/31/2032

CO 1-Hour (35 ppm)

8-Hour (9 ppm) Attainment (Maintenance) 6/11/2007(attained)

NO2

e) 1-Hour (100 ppb) Unclassifiable/Attainment N/A

Annual (0.053 ppm) Attainment (Maintenance) 9/22/1998

SO2

f)

1-Hour (75 ppb) Designations Pending N/A

24-Hour (0.14 ppm)

Annual (0.03 ppm) Unclassifiable/Attainment 3/19/1979(attained)

PM10 24-hour (150 μg/m3

) Nonattainment (Serious)g)

12/31/2006

(redesignation

request submitted)g)

PM2.5 24-Hour (35 μg/m3

) Nonattainment 12/14/2014h)

Annual (15.0 μg/m3) Nonattainment 4/5/2015

Lead (Pb) 3-Months Rolling

(0.15 μg/m3)

Nonattainment (Partial)i) 12/31/2015

a) U.S. EPA often only designates Nonattainment areas; everywhere else is listed as Unclassifiable/Attainment or 

Unclassifiable

b) A design value below the NAAQS for data through the full year or smog season prior to the attainment date is 

typically required for attainment demonstration

c) 1979 1-hour O3 standard (0.12 ppm) was revoked, effective June 15, 2005 ; however, the Basin did not attain this 

standard based on 2008-2010 data and has continuing obligations under the former standard

d) 1997 8-hour standard (0.08 ppm) was reduced (0.075 ppm), effective May 27, 2008; the 1997 O3 standard and 

most related implementation rules remain in place until the 1997 standard is revoked by U.S. EPA

e) New NO2 1-hour standard, effective August 2, 2010; attainment designations January 20, 2012; annual NO2

standard retained

f) The 1971 annual and 24-hour SO2 standards were revoked, effective August 23, 2010; however, these 1971 

standards will remain in effect until one year after U.S. EPA promulgates area designations for the 2010 SO2 1-

hour standard. Area designations are expected in 2013, with the Basin likely designated Unclassifiable 

/Attainment

g) Annual PM10 standard was revoked, effective December 18, 2006; redesignation request to attainment of the 24-

hour PM10 standard is pending with U.S. EPA

h) Attainment deadline for the 2006 24-Hour PM2.5 NAAQS is December 14, 2014

i) Pb partial nonattainment designation – Los Angeles County portion of the Basin only
Final 2012 AQMP Appendix II: Current Air Quality

II-2-4

Air Quality Compared to Other U.S. Metropolitan Areas

Despite significant improvement, the Basin still has some of the worst air quality in the 

nation in terms of the number of days per year exceeding the federal standards. In 2011, 

the U.S. location with the highest number of days over the federal 8-hour average ozone

standard was located in the Basin (Central San Bernardino Mountains-Crestline, 84 

days). The Basin exceeded the 24-hour average PM2.5 standard on multiple days, but 

the 98th percentile PM2.5 concentration (which is used to compare with the federal 

PM2.5 standard) exceeded the standard at one location only in Northwestern Riverside 

County (Mira Loma). The Basin did not exceed the federal 24-hour average and annual 

PM10 standards in 2011.

Figures 2-3 and 2-4 show maximum pollutant concentrations in 2011 for the Basin

compared to other urban areas in the U.S. and California, respectively. Maximum 

concentrations in all of these areas exceeded the 2008 federal 8-hour average O3

standard. The annual PM2.5 standard was exceeded in the South Coast Air Basin and in 

one other California air basin (San Joaquin Valley). The 24-hour PM2.5 standard, 

however, was exceeded in a few of the other large U.S. urban areas and in many 

California air basins. The 24-hour PM10 standard was exceeded in one of the U.S. 

urban areas shown (Phoenix), although potential flagging of exceptional events may 

affect the treatment of that data. It is important to note that maximum pollutant 

concentrations do not necessarily indicate potential NAAQS violations and subsequent 

nonattainment designations, as the design values that are used for attainment status are 

based on the form of the standard.
Chapter 2: Air Quality in the South Coast Air Basin

II-2-5

0%

50%

100%

150%

200%

South Coast Houston 

Metropolitan

Phoenix New York Washington D.C. Atlanta Chicago Maximum Concentration (Percent of Federal Standard)

Criteria Pollutants by Metropolitan Area

Ozone (8-hour, 2008) Ozone (1-hour, Revoked)* PM2.5 (Annual) PM2.5 (24-hour)++

PM10 (24-hour) NO2 (1-Hour)** SO2 (1-Hour)**

* Based on the former standard

** Based on the recently established standards

++ Based on the filter data, excluding exceptional events data

FIGURE 2-3

2011 South Coast Air Basin Air Quality Compared to Other U.S. Urban Areas

(Maximum Pollutant Concentrations as Percentages of the Corresponding Federal Standards)
Final 2012 AQMP Appendix II: Current Air Quality

II-2-6

0%

50%

100%

150%

200%

250%

South Coast San Joaquin 

Valley

San Francisco 

Bay Area

Sacramento 

Valley

South Central 

Coast

San Diego Maximum Concentration (Percent of Federal Standard)

Criteria Pollutants by Metropolitan Area

Ozone (8-hour, 2008) Ozone (1-hour, Revoked)* PM2.5 (Annual) PM2.5 (24-hour)++

PM10 (24-hour) NO2 (1-Hour)** SO2 (1-Hour)**

* Based on the former standard

** Based on the recently established standard

++ Based on the Filter data, excluding exceptional events data 

FIGURE 2-4

2011 South Coast Air Basin Air Quality Compared to Other California Air Basins

(Maximum Pollutant Concentrations as Percentages of the Corresponding Federal Standards)

NO2 concentrations exceeded the recently established 1-hour standard in the Basin and 

Phoenix (on one day each). Denver, Colorado (not shown in Figure 2-3), was the only 

other U.S. urban area exceeding the NO2 standard in 2011. SO2 concentrations were 

below the recently established 1-hour federal standard in the Basin and all of the urban 

areas shown in Figures 2-3 and 2-4. However, the SO2 standard was exceeded in other 

U.S. areas, with the highest concentrations recorded in Hawaii, due to volcanic

emissions. The CO standards were not exceeded in the U.S. in 2011.

In 2011, the Central San Bernardino Mountains area in the Basin recorded the highest 

maximum 1-hour and 8-hour average ozone concentrations in the nation (0.160 and 

0.136 ppm, respectively). The highest 8-hour average concentration was more than one 

and a half times the federal standard level. In 2011, seven out of ten stations with the 

highest maximum 8-hour average ozone concentrations in the nation were located in the 

Basin4. The South Coast Air Basin also exceeded the 8-hour ozone standard on more 

 

4 The 10 highest measured O3 concentrations in 2011 included 7 Basin stations: Central San Bernardino Mountains 

(Crestline), East San Bernardino Valley (Redlands), Central San Bernardino Valley (Fontana and San Bernardino), Santa 

Clarita Valley (Santa Clarita), Northwest San Bernardino Valley (Upland), and Metropolitan Riverside (Rubidoux).
Chapter 2: Air Quality in the South Coast Air Basin

II-2-7

days (106) than most other urban areas in the country in 2011, with only California’s San 

Joaquin Valley exceeding on more days (109).

Air Quality Trends

There have been significant improvements in the Basin’s air quality over the years since 

measurements began, with PM2.5 showing the most dramatic improvement in recent 

years. Figure 2-5 shows the trend (1990-2011) of basin-days5exceeding the federal 

standards for ozone and particulates, as a percentage of days with monitoring data. 

Figure 2-6 shows the trend of maximum pollutant concentrations in the Basin for the 

past two decades, as percentages of the corresponding federal standards. Note that this is 

based on maximum concentrations and that actual attainment of the standards is based 

on the design value. The pollutant-specific sections of this chapter contain additional 

trends by pollutant.

0%

25%

50%

75%

1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Percent of Basin-Days O3 (8-Hour)

2008

O3 (8-Hour)

1997

O3 (1-Hour)

Revoked

PM2.5 (24-Hour) PM10 (24-Hour)

FIGURE 2-5

Trend of Basin-Days Exceeding Federal Standards, 1990-2011

 

5 A "basin-day" is recorded if one or more locations in the air basin exceeded the level of the standard. Multiple 

locations exceeding on the same day count as a single basin-day.
Final 2012 AQMP Appendix II: Current Air Quality

II-2-8

0%

50%

100%

150%

200%

250%

300%

350%

400%

1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Maximum Concentration (Percent of Standard)

PM2.5 (Annual) O3 (8-Hour, 2008) NO2 (1-Hour)

PM10 (Annual, Revoked) O3 (1-Hour, Revoked)

Federal Standard

FIGURE 2-6

Trends of South Coast Air Basin Maximum Pollutant Concentrations 

(Percentages of Federal Standards)

Spatial and Temporal Variability

Air quality in the Basin varies widely by season and by area. The highest pollutant 

concentrations were all recorded in, or downwind of, the densely populated areas of the 

Basin. The number of days exceeding the current (2008) 8-hour federal ozone standard 

(0.075 ppm6, or 75 ppb7, not to exceed) varied widely by location, from zero to 84 days. 

Exceedances were fewest along the coast, increasing in the inland valleys to a maximum 

in the Basin's Central San Bernardino Mountains. The District station in the Central San 

Bernardino Mountains area (Crestline-Lake Gregory) exceeded the 2008 federal 8-hour 

average ozone standard most frequently (84 days).

Ozone concentrations tend to be higher on weekends than on weekdays, although this 

difference is less distinct in recent years. The time of day with highest average ozone

concentrations is in the early to middle afternoon, although the inland areas of the Basin 

will peak later in the afternoon on the higher days. Day-of-week and time-of-day PM2.5

concentrations vary considerably by location but, overall for 2009-2011, weekday 

 

6

ppm = parts per million, by volume

7

ppb = parts per billion, by volume; 1 ppm = 1000 ppb
Chapter 2: Air Quality in the South Coast Air Basin

II-2-9

PM2.5 concentrations were slightly higher on Fridays and daily peaks occur in the 

morning, after the period of heaviest traffic.

The Basin’s air quality concentrations and the occurrence of exceedances vary with 

season due to seasonal differences in the weather, sunlight for photochemical reactions, 

and to a lesser extent, seasonal variations in emissions. High ozone concentrations are 

generally recorded during the May to October “smog season” and exceedances of the 

federal and state standards are most frequent in July and August. Particulate matter 

(PM10 and PM2.5) levels do not have as clear of a pattern as ozone, and high 

concentrations may be recorded throughout the year. However, high PM10 and PM2.5 

concentrations are typically recorded during late fall and winter months. Figure 2-7 

shows the number of Basin-wide days per month when the most stringent of the state or 

federal standards were exceeded in the Basin in 2011. Additional spatial and temporal 

analyses are presented in the pollutant-specific sections that follow.

* The term Basin-days represents the number of days a standard was exceeded by at least one monitoring station in the Basin

FIGURE 2-7

Number of Basin-Days per Month Exceeding the Most Stringent State

or Federal Standards in 2011

0

5

10

15

20

25

30

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Basin-Days Exceeding*

2 or More Standards

PM10 (State)

PM2.5 (Federal)

Ozone (State 8-Hour)
Final 2012 AQMP Appendix II: Current Air Quality

II-2-10

POLLUTANT-SPECIFIC AIR QUALITY DISCUSSION

Particulate Matter (PM)

PM10 and PM2.5 concentrations are monitored throughout the District by samples 

collected on quartz or teflon filters in samplers with size selective inlets, known as 

Federal Reference Methods (FRM). Some stations also have continuous monitors, using 

either Beta Attenuation Monitor (BAM) or Tapered Element Oscillating Microbalance 

(TEOM) instrumentation. This data is available in real-time and is used for air quality 

forecasting and public reporting of current conditions. Where the continuous BAM or 

TEOM PM10 monitors have been certified by U.S. EPA to be Federal Equivalent 

Methods (FEM), the continuous PM10 data is averaged for the 24-hour period (midnight 

to midnight) and used for comparison to the standards on days when a valid FRM filter 

measurement was not collected. For PM2.5, there are significant differences between 

the FEM and FRM results that have been recognized by national assessments of the 

technologies. The District measures FRM PM2.5 on a daily basis at the critical stations 

in the Basin, and does not use the FEM PM2.5 data to compare to the NAAQS. This 

issue is being explicitly addressed in U.S. EPA’s new proposed PM2.5 NAAQS, and 

future use of FEM data will be consistent with the final federal requirements. In 2011, 

the District measured PM10 and PM2.5 concentrations at 26 and 20 locations, 

respectively, including two locations in the Coachella Valley for both. Figures 2-8 and 

2-9 show the PM2.5 and PM10 monitoring sites, respectively, in the District’s 

jurisdiction.
Chapter 2: Air Quality in the South Coast Air Basin

II-2-11

FIGURE 2-8

South Coast Air Quality Management District PM2.5 Air Monitoring

FIGURE 2-9

South Coast Air Quality Management District PM10 Monitoring
Final 2012 AQMP Appendix II: Current Air Quality

II-2-12

PM2.5 Air Quality

The District began routine monitoring of PM2.5 regularly in 1999 and the number of 

PM2.5 monitoring stations has increased in recent years. In 2011, the District monitored 

PM2.5 concentrations at 25 routine sampling locations (including 2 in the Coachella

Valley), 22 with Federal Reference Method (FRM) filter samplers and 3 with Federal 

Equivalent Method (FEM) continuous monitors (shown in Figure 2-8). The FRM PM2.5 

measurements, based on samplers with size-selective inlets using teflon filters, are 

collected for a 24-hour period every 3 days at most locations, except for seven stations 

that historically have higher concentrations where daily FRM samples are collected. 

One station in the Big Bear Lake area has a 24-hour sample collected every 6 days.

All PM2.5 data from sites in the District’s network using FRM samplers are suitable for 

comparison to PM2.5 NAAQS for attainment purposes. The PM2.5 network also 

includes continuous FEM and non-FEM Beta Attenuation Monitors (BAM) throughout

the District’s jurisdiction. At the sites where both 24 hour FRM PM2.5 samplers and 

FEM PM2.5 continuous analyzers are deployed together, the 24 hour FRM PM2.5 

sampler remains the primary analyzer used for attainment purposes. On many days, 

there is poor comparability of the FEM PM2.5 monitors and the FRM method. 

Therefore, the continuous hourly measurements that are available in real time are used 

primarily for forecasting and public notification of PM2.5 air pollution levels.

The highest 24-hour PM2.5 measurement recorded in 2011 in the Basin (94.6 μg/m3on 

July 5 at East San Gabriel Valley at Azusa) was flagged in the U.S. EPA Air Quality 

System (AQS) database for exclusion under the U.S. EPA Exceptional Event Rule, due 

to Independence Day fireworks displays. With this data included, the 2009-2011 24-

hour design value for Azusa would exceed the federal standard level in 2011 and the 3-

year design value. With that exceptional event flagged (pending further documentation 

and U.S. EPA concurrence), the only station with a 24-hour design value exceeding the 

24-hour federal standard is in Metropolitan Riverside County (Mira Loma). The daily 

FRM sampler at Mira Loma exceeded the 24-hour federal standard on 8 days in 2011. 

The annual and 24-hour design values for the former Basin maximum station in 

Metropolitan Riverside County (Riverside-Rubidoux) are currently below the federal 

standards, based on the 2009-2011 data.

The federal 24-hour PM2.5 standard concentration level was exceeded at 75 percent of 

the locations monitored in the District in 2011. With the one exceptional event day 

flagged, the Basin’s next-highest 24-hour average (65.0 μg/m3) occurred in the Central 

San Bernardino Valley (City of San Bernardino) and was 183 percent of the federal 24-
Chapter 2: Air Quality in the South Coast Air Basin

II-2-13

hour PM2.5 standard. However, that location did not exceed the 98th percentile design 

value form of the standard in 2011, nor the 2009-2011 3-year design value.

In 2011, the federal annual average PM2.5 standard was exceeded at one location 

(Metropolitan Riverside at Mira Loma). The maximum annual average recorded there

(15.3 μg/m3) was 101 percent of the federal standard and 126 percent of the state 

standard. The maximum 24-hour and annual average PM2.5 concentrations in 2011 are 

summarized by county in Tables 2-2 and 2-3, respectively, along with comparisons to 

the federal and state standards. Tables A-9 to A-12 in the Attachment to this appendix 

show the annual arithmetic mean, percentage of sampling days over the 24-hour federal 

standard, maximum 24-hour average concentrations, and 98th percentile 24-hour 

concentrations for the years 1999-2011 at all monitoring stations.

TABLE 2-2

2011 Maximum 24-hour Average PM2.5 Concentrations by Basin and County

Basin/County

Maximum

24-Hr

Average#

(g/m3)

Percent of

Federal

Standard*

(35 g/m3)

Area

South Coast Air Basin

Los Angeles** 49.5 139 East San Gabriel Valley

Orange 39.2 110 Central Orange County

Riverside 60.8 171 Metropolitan Riverside County

San Bernardino 65.0 183 Central San Bernardino Valley

Salton Sea Air Basin

Riverside*** 35.4 99.7 Coachella Valley

# Based on FRM data

* Although maximum 24-hour concentrations exceed the standard, the 98th percentile form of the 2009-2011 

design value only exceeded the standard at one station in Metropolitan Riverside County

** One higher concentration that was recorded due to “Independence Day” firework activities has been flagged 

for exclusion from NAAQS comparison in accordance with the U.S. EPA Exceptional Events Regulation;

with this data included, the 2009-2011 design value for East San Gabriel Valley would also exceed the 

federal standard

*** While this concentration of 35.4 μg/m3is near the level of the standard, it is technically not exceeding the 

standard (35.5 μg/m3exceeds); this concentration was associated with a high wind exceptional event
Final 2012 AQMP Appendix II: Current Air Quality

II-2-14

TABLE 2-3

2011 Maximum Annual Average PM2.5 Concentrations by Basin and County

Basin/County

Annual

Average*

(g/m3)

Percent of

Federal

Standard

(15 g/m3)

Percent of

State

Standard

(12 g/m3)

Area

South Coast Air Basin

Los Angeles 13.2 87 109 Central Los Angeles

Orange 11.0 73 90 Central Orange County

Riverside 15.3 101 126 Metropolitan Riverside County

San Bernardino 13.2 87 109 Southwest San Bernardino Valley

Salton Sea Air Basin

Riverside 7.2 48 60 Coachella Valley

* Based on FRM data

PM2.5 Spatial Variation

Figure 2-10 shows the 2011 annual average arithmetic mean PM2.5 concentrations 

mapped throughout the Basin. Like PM10, PM2.5 annual concentrations were higher in 

the inland valley areas of Metropolitan Riverside County. Figure 2-11 shows the 2011 

24-hour PM2.5 concentrations, using the 98th percentile form of the standard, mapped 

throughout the Basin. As is seen with the annual average, the 98th percentile 

concentration only exceeds the 24-hour federal standard in the Metropolitan Riverside 

County area (Mira Loma). A larger area is just below the NAAQS, with concentrations 

in the 30 to 35 μg/m3range, from the eastern San Fernando Valley and Central Los 

Angeles in the western Basin through the urban areas of Riverside and San Bernardino.

The higher PM2.5 concentrations in the Basin are mainly due to the secondary formation 

of smaller particulates resulting from mobile, stationary and area source emissions of 

gases (NOx, SOx, NH4, VOC) that are converted to particulate matter in the atmosphere. 

In contrast to PM10, PM2.5 concentrations were low in the Coachella Valley area of 

SSAB. While PM10 concentrations are normally higher in the desert areas due to 

windblown and fugitive dust emissions, PM2.5 is relatively low in the desert due to 

fewer combustion-related emissions sources.
Chapter 2: Air Quality in the South Coast Air Basin

II-2-15

FIGURE 2-10

Annual Average PM2.5 (μg/m3) in 2011

(Annual PM2.5 NAAQS = 15 μg/m3, annual arithmetic mean)

FIGURE 2-11

98th Percentile 24-Hour Average PM2.5 (μg/m3) in 2011

(24-hour PM2.5 NAAQS = 35 μg/m3)
Final 2012 AQMP Appendix II: Current Air Quality

II-2-16

PM2.5 Trends

Figure 2-12 shows the Basin 3-year design values (plotted by end year) for the current 

24-hour and annual PM2.5 standards, for the period from 2001 through 2011. This 

illustrates the significant progress toward attainment of the standards in the last ten 

years.

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 PM2.5 Design Value (μg/m3

)

24-Hour PM2.5 3-Year Design Value Annual PM2.5 3-Year Design Value

Annual Standard

2 4-Hour Standard

FIGURE 2-12

South Coast Air Basin PM2.5 Design Value Trends, 2001-2011

PM2.5 Temporal Variation

Seasonal and day-of-week variations in PM2.5 concentrations are complex and location 

dependant, and may vary from year to year depending on meteorological conditions, the 

presence of large wildfires, and other factors. Previous analyses showed that the highest 

PM2.5 concentrations tend to occur in the fall, of most years. That held true in 2011. 

Figure 2-13 shows the Basin-wide monthly averaged PM2.5 concentrations, by month 

for the year 2011. In that year, the monthly PM2.5 averages were highest in October, 

followed closely by December. The somewhat lower multi-station averages in 

November 2011 likely resulted from an above-normal number of offshore wind days in 

that month that generally provided good dispersion and brought cleaner air from the 

deserts into the Basin.
Chapter 2: Air Quality in the South Coast Air Basin

II-2-17

11.7

10.2

9.7 9.3 9.5

10.7

11.7

12.5

15.0

16.9

13.5

16.3

0

5

10

15

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

Average PM2.5 Concentration (μg/m3

)

South Coast Air Basin

FIGURE 2-13

2011 PM2.5 Variation of Basin-wide FRM Monthly Average Concentration

Figure 2-14 shows an analysis of day-of-week variation in Basin-wide PM2.5 daily 

concentrations averaged for the three most recent years (2009-2011). This shows that

Fridays have slightly higher average PM2.5, possibly due to increased traffic and/or 

build up of pollution over multiple week-days. Saturdays and Thursdays follow, but the 

average difference from the lowest day (Monday) to the highest (Friday) is only 3.2 

μg/m3.
Final 2012 AQMP Appendix II: Current Air Quality

II-2-18

16.1

16.9

16.6

17.9

19.3

18.2

16.7

14

15

16

17

18

19

20

MON TUE WED THU FRI SAT SUN Average PM2.5 Concentration (μg/m3

)

Day of Week

South Coast Air Basin

FIGURE 2-14

PM2.5 Basin-wide Day-of-Week Variation of 24-hour Average FRM PM2.5 Concentrations, 2009-

2011

Figure 2-15 shows average PM2.5 concentration by hour of the day for the period 2009-

2011, based on the hourly BAM sampler data. The diurnal plots are for the Basin 

maximum PM2.5 monitor (Metropolitan Riverside at Mira Loma), Central Los Angeles 

(Downtown), Central Orange County (Anaheim), and the average of several sites 

throughout the Basin. In general, PM2.5 concentrations peak around 8 a.m. (Pacific 

Standard Time), with the morning traffic. They decrease in the early afternoon, then 

peak in the evening due to secondary aerosol formation following evening traffic, and 

late at night when the lower nighttime temperature inversion traps the pollutants in a 

shallower layer near the surface.
Chapter 2: Air Quality in the South Coast Air Basin

II-2-19

0

5

10

15

20

25

30

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

Average Hourly PM2.5 Concentration (μg/m3

)

HOUR (PST)

Basin Average Central Los Angeles Central Orange County

Metro Riverside County South Coast LA County

South Coast Air Basin

FIGURE 2-15

Diurnal Variation of Hourly FEM PM2.5, Averaged by Time of Day (2009-2011)

PM2.5 Speciation

PM2.5 speciation sampling to determine the chemical components of PM2.5 is also a 

part of the District’s PM2.5 measurement program. Currently, PM2.5 speciation 

samplers are deployed at four representative locations in each of the Basin’s counties

(Anaheim, Fontana, Los Angeles and Rubidoux). Analysis of the filters from the 

ambient network Speciation Air Sampling System (SASS) samplers are conducted at the 

District’s laboratory. Figure 2-16 shows the trends of the annual concentration of six 

PM2.5 component species: Elemental Carbon (EC), Organic Carbon (Organics), Sulfate

(SO4), Nitrate (NO3), Ammonium (NH4), and Crustal Elements (soils). Most of the 

components show a downward trend in recent years. Figure 2-17 shows the composition 

from the speciation sampler at the Riverside-Rubidoux station, comparing the 2010 

annual average to the 2010 peak 24-hour average sampled at this location. This is the 

closest PM2.5 speciation station to the Basin maximum PM2.5 station (Riverside-Mira 

Loma) and it was the Basin maximum location before monitoring began at Mira Loma. 

On the high day, the nitrate becomes a larger fraction of the mass compared to the 

annual average, indicating the importance of secondary atmospheric processes to the 

PM2.5 composition in Riverside County.
Final 2012 AQMP Appendix II: Current Air Quality

II-2-20

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5 2004 2005 2006 2007 2008 2009 2010 EC (μg/m3

)

Anaheim Fontana Los Angeles Rubidoux

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0 2004 2005 2006 2007 2008 2009 2010 NO3 (μg/m3

)

Anaheim Fontana Los Angeles Rubidoux

0.0

1.0

2.0

3.0

4.0

5.0 2004 2005 2006 2007 2008 2009 2010 SO4 (μg/m3

)

Anaheim Fontana Los Angeles Rubidoux

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0 2004 2005 2006 2007 2008 2009 2010 Organics (μg/m3

)

Anaheim Fontana Los Angeles Rubidoux

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0 2004 2005 2006 2007 2008 2009 2010 Crustal (μg/m3

)

Anaheim Fontana Los Angeles Rubidoux

0.0

0.5

1.0

1.5

2.0

2.5

3.0 2004 2005 2006 2007 2008 2009 2010 NH4 (μg/m3

)

Anaheim Fontana Los Angeles Rubidoux

FIGURE 2-16

South Coast Air Basin PM2.5 SASS Speciation Network Annual Trends 2004-2010

Annual Averaged PM2.5 Elemental Carbon (EC), Organics, Sulfate (SO4), Nitrate (NO3), Ammonia 

(NH4), and Crustal Component Concentrations, for Anaheim, Fontana, Los Angeles, and Rubidoux 

Stations
Chapter 2: Air Quality in the South Coast Air Basin

II-2-21

FIGURE 2-17

2010 PM2.5 Speciation for Annual Average and Highest Day

(Riverside-Rubidoux SASS Speciation Sampler)

PM10 Air Quality

In 2011, the District measured PM10 concentrations at 23 locations throughout the Basin 

and two locations in the Salton Sea Air Basin (Coachella Valley), as shown in Figure 2-

9. Size-selective inlet (SSI) manual high volume FRM samplers are operated at 19 sites 

in the Basin and two sites in the Coachella Valley to meet the requirements for PM10 

Federal Reference Method (FRM) sampling. All of these FRM monitors operate on a 

one-in-six-day schedule, with the exception of two that operate on a one-in-three-day 

schedule (Riverside-Rubidoux in the Basin and Indio in the Coachella Valley).

PM10 continuous analyzers, including Beta Attenuation Monitor (BAM) and Tapered 

Element Oscillating Microbalance (TEOM), are operated at 13 sampling sites, including 

four that are not collocated with FRM samplers. Real-time monitors, for the most part, 

are clustered in the higher concentration areas. At locations where both FRM samplers 

and PM10 continuous analyzers are deployed together, the data is generally combined 

for attainment purposes, with the FRM data considered the primary data source.

The highest annual PM10 concentrations were recorded in and around the metropolitan 

Riverside County area and further inland in the San Bernardino Valley areas. The 
Final 2012 AQMP Appendix II: Current Air Quality

II-2-22

federal 24-hour standard (150 g/m3) was not exceeded at any of the locations monitored 

in 2011, although Riverside County came close with a 24-hour concentration of 152 

μg/m3(98 percent of the federal 24-hour standard; the concentration must reach 155 

μg/m3to exceed the NAAQS). The revoked annual average PM10 federal standard (50 

μg/m3) was also not exceeded in the Basin in 2011.

The more stringent state annual (20 μg/m3) and 24-hour (50 μg/m3) PM10 standards 

were exceeded in more than two-thirds of the areas monitored. The state 24-hour 

standard was also exceeded most frequently in the Basin’s inland valleys, centered on 

Metropolitan Riverside County. Maximum 24-hour and annual average PM10 

concentrations in 2011 are shown in Tables 2-4 and 2-5. For each routine District 

ambient air monitoring station, the annual arithmetic mean, percent of sampling days 

exceeding state and federal standards, and maximum 24-hour average concentrations are 

shown in Tables A-6 to A-8 in the Attachment for the years 1995-2011. Please refer to 

Appendix II from the 2003 AQMP for the 1976-1989 prior-year statistics and to 

Appendix II from the 2007 AQMP for 1990-2005 data.

TABLE 2-4

2011 Maximum 24-hour Average PM10 Concentrations by Basin and County

Basin/County

Maximum

24-Hr

Average*

(g/m3)

Percent of

Federal

Standard

(150 g/m3)

#

Percent of

State

Standard

(50 g/m3)

Area

South Coast Air Basin

Los Angeles 119 77 233 Central Los Angeles

Orange 79 51 155 Central Orange County

Riverside 152 98 298 Metropolitan Riverside County

San Bernardino 127 82 249 Central San Bernardino Valley

Salton Sea Air Basin**

Riverside 120 77 235 Coachella Valley

* Based on the FRM and FEM data

** Higher concentrations were recorded for high wind events in the Coachella Valley which have been flagged 

for exclusion from NAAQS comparison in accordance with the U.S. EPA Exceptional Events Rule

# A level of 155 g/m3

is needed to exceed the federal standard, thus percentages are based on 155 g/m3
Chapter 2: Air Quality in the South Coast Air Basin

II-2-23

TABLE 2-5

2011 Maximum Annual Average PM10 Concentrations by Basin and County

Basin/County

Annual

Average*

(g/m3)

Percent of

Federal

Standard**

(50 g/m3)

Percent of

State

Standard

(20 g/m3)

Area

South Coast Air Basin

Los Angeles 32.7 64 163 East San Gabriel Valley

Orange 24.9 49 124 Central Orange County

Riverside 41.4 81 206 Metropolitan Riverside County

San Bernardino 31.8 62 158 Central San Bernardino Valley

Salton Sea Air Basin

Riverside 32.6 64 162 Coachella Valley

* Based on the FRM and FEM data

** The federal annual PM10 standard was revoked in 2006

PM10 Spatial Variation

Figure 2-18 shows the contour map of the annual average (arithmetic mean) PM10 

concentrations distribution in the Basin in 2011. The areas with the highest annual 

average PM10 concentrations were located in the Metropolitan Riverside County area. 

The maximum annual average recorded (41.4 μg/m3) was 81 percent of the former 

federal annual PM10 standard.

FIGURE 2-18

Annual Arithmetic Mean PM10 Particulate Matter (μg/m3) in 2011
Final 2012 AQMP Appendix II: Current Air Quality

II-2-24

PM10 Trends

Figure 2-19 shows the trend for the period between 2000 and 2011 of the design value 

form of the 24-hour federal PM10 standards for the Basin (i.e., the fourth highest 24-

hour average PM10 concentration in three years). It also shows the trend for the design 

value form of the revoked annual federal PM10 standard, that is, the 3-year average of 

the annual arithmetic mean concentrations. Since 2005, the Basin has remained below 

the design value form of the federal PM10 standard (150 μg/m3). The District has 

petitioned U.S. EPA to consider redesignation of the Basin to attainment for the PM10 

standard. The most recent year, 2011, was also remained below the revoked federal 

annual PM10 standard (50 μg/m3).

FIGURE 2-19

PM10 Particulate Matter Design Value Trend

(2000 through 2011 data, 3-Year Average of Annual Arithmetic Mean and 4th Highest 24-Hour 

PM10 Concentration in 3 Years, μg/m3)

PM10 Temporal Variation

Exceedances of the 24-hour PM10 federal standard in the Basin have become rare in 

recent years. In fact, the only exceedances in the Basin for several years have been 

associated with exceptional events, such as high wind natural events or cultural events 

(Independence Day fireworks). As a consequence, variations in exceedances of the state 

0

50

100

150

200

250

300

0

10

20

30

40

50

60

70

80

90

100

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

PM10 Annual Average (AAM, μg/m3

)

4th Highest 24-Hour PM10 (μg/m3

)

3-Year Average Annual Arithmetic Mean (AAM) PM10

3-Year 24-Hour 4th High PM10

Standard
Chapter 2: Air Quality in the South Coast Air Basin

II-2-25

standard are considered here for the seasonal and day-of-week patterns in the Basin, 

using the FRM and FEM PM10 measurements combined.

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

concentrations 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

(Long Beach), monthly average PM10 concentrations and the average number of days 

exceeding the state standard were highest in the late fall and winter months.

Figure 2-20 shows the number of days in each month exceeding the state standard at one 

or more Basin locations over the period 2009-2011. Overall, the greatest number of 

exceedances of the state standard occurred in the summer months. Due to the higher 

number of exceedances in the inland valleys, the pattern for the Basin is more similar to 

those for individual sites in the inland valley areas. Figure 2-21 shows the monthly 

exceedances for stations in two areas, Metropolitan Riverside County (RiversideRubidoux) and South Coastal Los Angeles County (Long Beach). As was found in the 

previous analyses, the number of days exceeding state standards are more frequent in the 

summer and fall months in the inland valley areas, but higher in the late fall and winter 

months in the coastal areas. Most of the coastal high values occur at that time due to 

windblown dust from the strong, offshore Santa Ana winds that occur in the fall and 

winter.

FIGURE 2-20

Basin-Days Exceeding the State PM10 Standard (50 μg/m3) by Month, 2009-2011

0

10

20

30

40

50

60

70

80

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

Basin-Days > State PM10 Standard
Final 2012 AQMP Appendix II: Current Air Quality

II-2-26

FIGURE 2-21

Number of Station Days Exceeding State PM10 Standard (50 μg/m3) by Month, 2009-2011

Figure 2-22 shows the total number of days exceeding the state standard by day of week 

in the Basin and at selected sites in each county, for the period 2009-2011. The highest 

numbers of PM10 state standard exceedances occur on Thursday and Friday, possibly 

due to vehicle traffic, especially truck traffic, on those days and more construction 

activities than the weekend. Stations in the western Basin showed significant 

improvement on the weekends. On Sundays, the number of exceedances was lowest

across the Basin, on average.

0

10

20

30

40

50

60

70

80

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

Station Days > State PM10 Standard

Metropolitan Riverside County

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

II-2-27

0

10

20

30

40

50

60

70

80

90

Mon Tue Wed Thu Fri Sat Sun

Days > State PM10 Standard 

Basin Mira Loma Rubidoux Los Angeles San Bernardino Anaheim

FIGURE 2-22

PM10 Day-of-Week Variation, 2009-2011

(Number of Days Exceeding State the Standard (50 μg/m3) by Day of Week, for Basin and 

Individual Stations)
Final 2012 AQMP Appendix II: Current Air Quality

II-2-28

Figure 2-23 shows average PM10 concentrations for each hour of the day for the period 

2009-2011 for the entire Basin and for select monitoring stations in the Basin, based on 

the hourly BAM and TEOM data. On average, PM10 concentrations show a peak 

around near 0900 to 1100 PST in the morning, just after the heaviest morning traffic 

rush-hour traffic.

0

10

20

30

40

50

60

70

80

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

Hourly PM10 (μg/m3

)

HOUR (PST)

Central Los Angeles Central Orange County

Metropolitan Riverside County Northwest San Bernardino Valley

Basin Averages

FIGURE 2-23

PM10 Diurnal Variation, 2011

(Annual Averaged FEM Hourly PM10 Concentrations, by Hour of the Day)

Ozone 

Current Ozone Air Quality

In 2011, the District monitored ozone concentrations at 27 locations in the Basin and two 

in the Coachella Valley portion of the SSAB. All counties of the Basin and the 

Coachella Valley exceeded the current (2008) 8-hour ozone standard (0.075 ppm) in 

2011. That standard was exceeded on 106 days, Basin-wide. All counties in the Basin, 

except Orange County, exceeded the 1997 8-hour ozone standard (0.08 ppm). The 

highest 8-hour average (0.136 ppm) in 2011 occurred in the Central San Bernardino 
Chapter 2: Air Quality in the South Coast Air Basin

II-2-29

Mountains (Crestline) and was 180 percent of the 2008 8-hour ozone standard and 160 

percent of the 1997 standard.

The revoked 1979 federal 1-hour ozone standard was exceeded on 16 days in the Basin, 

with all counties exceeding, except Orange County. The maximum 1-hour concentration 

(0.160 ppm) also occurred in the Central San Bernardino Mountains (Crestline) and was 

128 percent of the 1979 1-hour standard.

The more stringent California state standards were exceeded almost everywhere in the 

Basin, except for a few coastal stations, with the greatest number of exceedances 

occurring in the Central San Bernardino Mountains (Crestline) and adjacent valleys. The 

California state 1-hour (0.09 ppm) and 8-hour (0.070 ppm) standards were exceeded on 

90 days and 125 days, respectively. The highest 1-hour average and 8-hour average 

ozone concentrations recorded in 2011 (0.160 ppm and 0.136 ppm) were 176 percent 

and 192 percent of the state standards, respectively.

In 2011, all stations measured 1-hour ozone well below the Stage 1 episode level (0.20 

ppm, 1-hour). Except for one day in 2003, the stage 1 episode level has not been 

exceeded in the Basin since 1998. There have been no exceedances of the Stage 2 

episode level (1-hour average ozone ≥ 0.35 ppm) since 1988 and the Stage 3 episode 

level (1-hour average ozone ≥ to 0.50 ppm) has not been exceeded since 1974. The 

maximum concentrations measured in the Basin in 2011 exceeded the California 1-hour 

ozone Health Advisory level (0.15 ppm) at two stations on one day (July 2), with 1-hour 

concentrations of 0.160 ppm (Central San Bernardino Mountains – Crestline) and 0.151 

ppm (East San Bernardino Valley - Redlands).

Tables 2-6 and 2-7 show the maximum 1-hour and 8-hour O3 concentrations by air basin 

and county, along with the percentages over the federal and state standards. Tables A-2 

through A-5 in the Attachment show the number of days exceeding the federal 8-hour 

and 1-hour ozone standards, as well as the 4

th high 8-hour average and maximum 1-hour 

concentrations, at all routine District air quality monitoring stations, for the period 1995-

2011. Please refer to Appendix II from the 2003 AQMP for the 1976-1989 prior-year 

statistics and to Appendix II from the 2007 AQMP for 1990-2005 data.
Final 2012 AQMP Appendix II: Current Air Quality

II-2-30

TABLE 2-6

2011 Maximum 1-Hour Average Ozone Concentrations by Basin and County

Basin/County

Maximum

1-Hr

Average

(ppm)

Percent of

Federal

Standard

(0.12 ppm)

Percent of

State

Standard

(0.09 ppm)

Area

South Coast Air Basin

Los Angeles 0.144 115 158 Santa Clarita Valley

Orange 0.095 76 104 North Orange County

Riverside 0.133 106 146 Lake Elsinore

San Bernardino 0.160 128 176 Central San Bernardino Mountains

Salton Sea Air Basin

Riverside 0.124 99 136 Coachella Valley

TABLE 2-7

2011 Maximum 8-Hour Average Ozone Concentrations by Basin and County

Basin/County

Maximum

8-Hr

Average

(ppm)

Percent of

Federal

Standard

(0.075 ppm)

Percent of

State

Standard

(0.07 ppm)

Area

South Coast Air Basin

Los Angeles 0.122 162 172 Santa Clarita Valley

Orange 0.083 110 117 Saddleback Valley

Riverside 0.115 152 162 Metropolitan Riverside County

San Bernardino 0.136 180 192 Central San Bernardino Mountains

Salton Sea Air Basin

Riverside 0.098 130 138 Coachella Valley

Ozone Spatial Variation

The number of days exceeding federal standards for ozone in the Basin varies widely by 

area. Figures 2-24 and 2-25 map the number of days in 2011 exceeding the current 8-

hour and former 1-hour ozone federal standards in different areas of the Basin in 2011. 

The former 1-hour federal standard was not exceeded in areas along or near the coast in 

the Counties of Los Angeles and Orange, due in large part to the prevailing sea breeze 

which transports emissions inland before high ozone concentrations can be reached. The 

standard was exceeded most frequently in the Central San Bernardino Mountains. 

Ozone exceedances also extended through San Bernardino and Riverside County valleys 

in the eastern Basin, as well as the northeast and northwest portions of Los Angeles 
Chapter 2: Air Quality in the South Coast Air Basin

II-2-31

County in the foothill and valley areas. The number of exceedances of the 8-hour 

federal ozone standard was also lowest at the coastal areas, increasing towards the 

Riverside and San Bernardino valleys and the adjacent mountain areas. The Central San 

Bernardino Mountains area recorded the greatest number of exceedances of the 1-hour 

and 8-hour federal standards (8 days and 84 days, respectively) and 8-hour state standard 

(103 days). While the Coachella Valley did not exceed the former 1-hour ozone 

standard in 2011, the current 8-hour federal standard was exceeded on 54 days.

FIGURE 2-24

Number of Days in 2011 Exceeding the 1979 1-Hour Ozone Federal Standard

(1-hour average Ozone standard > 0.12 ppm)
Final 2012 AQMP Appendix II: Current Air Quality

II-2-32

FIGURE 2-25

Number of Days in 2011 Exceeding the Current (2008) Federal 8-Hour Ozone Standard

(8-hour average Ozone standard > 0.075 ppm)

Ozone Trends

The rate of ozone air quality improvement has been dramatic since the concerted effort 

to manage air quality in the Basin began in the 1970s. Significant improvements were 

seen throughout the 1990s. While the rate of improvement in ozone has slowed 

somewhat in the past decade, the overall trend, as well as the expectation for the future, 

is continuing gradual improvement. Figure 2-26 shows the Basin-wide trend (1990-

2011) of number of days exceeding the 2008 and 1997 8-hour ozone standards and the

former (1979) 1-hour ozone standard, along with the trend of Basin maximum 8-hour 

averaged ozone concentrations. Figure 2-27 shows the trend (1990-2011) of the 8-hour 

and 1-hour ozone 3-year design values for the Basin.
Chapter 2: Air Quality in the South Coast Air Basin

II-2-33

0.000

0.050

0.100

0.150

0.200

0.250

0

50

100

150

200

250

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 Maximum Ozone Concentration (ppm) Basin-Days Exceeding

2008 8-Hour Ozone Standard (0.075 ppm)

Former (1997) 8-Hour Federal Ozone Standard (0.08 ppm)

Former 1-Hour Federal Ozone Standard (0.12 ppm)

Maximum 8-Hour Ozone Concentration (ppm)

FIGURE 2-26

Trend of Annual Basin Days Exceeding Federal 8-Hour and 1-hour Ozone Standards (left axis)

and Peak Concentrations (red line, right axis)

(South Coast Air Basin; by year, 1990-2011)

0

50

100

150

200

250

300

350

1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 Ozone Design Values (ppb)

1-Hour Design Value

8-Hour Design Value

2008 8-Hour Standard (75 ppb)

Former 1-Hour Standard (125 ppb)

FIGURE 2-27

South Coast Air Basin Ozone Design Value Trends, 1990-2011

(1 ppb = 0.001 ppm)
Final 2012 AQMP Appendix II: Current Air Quality

II-2-34

Ozone Temporal 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 in 

summer than in winter and summertime temperature inversions are stronger and more 

persistent. 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 September.

Figure 2-28 shows the number of days per month that one or more monitoring stations 

exceeded the most recent (2008) federal 8-hour ozone standard level for the years 2000, 

2005 and 2011. Most exceedances occur in July and August, with most days exceeding 

the federal standard in those months. 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. 

By the late 1990's there were no exceedances in the months of November through 

February. There have been relatively few exceedances in March or October in more 

recent years. The frequency of exceedances in the spring (April-June) has continued to 

decline in recent years.

0

5

10

15

20

25

30

35

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

2000

2005

2011

FIGURE 2-28

Monthly Distribution of Basin Days Exceeding the (2008) Federal 8-hour Ozone Standard

(South Coast Air Basin, for Years 2000, 2005 and 2011)
Chapter 2: Air Quality in the South Coast Air Basin

II-2-35

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 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. This “weekend effect” was quite pronounced in previous years in the 

Basin. CARB 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 these observations. Carryover of matured precursors from weekdays to weekends is 

also suggested as a contributing factor. It is generally expected that this difference will 

decrease as ozone precursor emissions continue to decline.

In 2005, more exceeding station-days8in the Basin occurred on either Saturdays or 

Sundays than any one weekday by more than a factor of two. The number of 

exceedances was slightly higher on Sundays than Saturdays. Figure 2-29 shows the 

number of station-days exceeding the federal 8-hour ozone standard for each day of the 

week in the Basin for the year 2011. In 2011, the weekends were still higher than the 

weekdays, with Sundays having the most exceedances, but by a much smaller margin 

than in earlier analyses. Averaged ozone concentrations by day-of-week also show a 

pattern similar to the average number of exceedances, with weekends somewhat higher 

than weekdays.

 

8 The term station-days represents the total number of days the standard was exceeded at individual monitoring stations 

summed for all stations in the Basin.
Final 2012 AQMP Appendix II: Current Air Quality

II-2-36

92

79

95

80 81

113

129

0

20

40

60

80

100

120

140

Mon Tue Wed Thu Fri Sat Sun Station-Days Exceeding

Day of Week

FIGURE 2-29

8-Hour Ozone Day-of-Week Variation, 2011

(Basin Station-Days Exceeding the 2008 Federal Ozone Standard)

Because time and sunlight are required for 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. 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.

Figure 2-30 illustrates the average of the smog season (May-October) 1-hour ozone 

concentrations for each hour of the day (shown in Pacific Standard Time), by station, for 

the year 2011. The average peak occurs near noon at the coastal stations (LAX) and 

most stations in the Basin reach their peak by the 2 p.m. The far inland stations at 

Central San Bernardino Valley (San Bernardino) and Central San Bernardino Mountains 

(Crestline, where the highest concentrations have been measured in recent years) peak 

near 3 or 4 p.m., but the ozone at Crestline decreases at a slower rate in the evening, 

leading to higher 8-hour ozone values. On the worst smog days, this station can remain 

relatively high through the night.
Chapter 2: Air Quality in the South Coast Air Basin

II-2-37

0

25

50

75

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

Hourly O3 Concentration (ppb)

HOUR (PST)

LAX Los Angeles Santa Clarita Anaheim

Rubidoux San Bernardino Crestline

FIGURE 2-30

Diurnal Variation of Basin May-October 2011 Averaged Hourly Ozone Concentrations

Carbon Monoxide (CO)

CO Air Quality

The District currently monitors carbon monoxide air quality at 25 of its 34 air 

monitoring stations, including one station in the Coachella Valley. The highest CO 

concentrations are found in coastal and central Los Angeles County. The highest 8-hour 

average CO concentration in 2011 (4.7 ppm) was recorded in South Central Los Angeles 

county and was 49 percent of the federal 8-hour standard (9 ppm) and 52 percent of the 

state 8-hour standard (9.0 ppm). In recent years, the Basin has measured the lowest 

concentrations since carbon monoxide monitoring began in this region, several decades 

ago. The highest 1-hour average concentration in 2011 (6 ppm) was 17 percent of the 

federal 1-hour standard (35 ppm) and 29 percent of the state 1-hour standard (20 ppm). 

Concentrations in the less urbanized areas of the Basin and in the SSAB were well below 

the standards.

Carbon monoxide has continued to remain below the federal standards at all locations 

monitored since 2003. U.S. EPA redesignated the Basin to attainment of the federal CO 
Final 2012 AQMP Appendix II: Current Air Quality

II-2-38

standards, effective June 11, 2007. The highest concentrations are typically recorded in 

Los Angeles County, in the area of South Central Los Angeles. There have also been no 

exceedances of the Stage 1 episode (federal alert) level (8-hour average CO greater than 

or equal to 15 ppm) since 1997. Table 2-8 shows the 2011 maximum 8-hour and 1-hour

average carbon monoxide concentrations by Basin and county. The annual maximum 8-

hour CO concentrations at all District air monitoring stations are shown in Table A-13 in 

the Attachment, for the period 1995-2011.

TABLE 2-8

2011 Maximum 8-Hour and 1-Hour CO Concentrations by Basin and County

Basin/County

Maximum

8-Hr

Average

(ppm)

Percent of

Federal

Standard

(9 ppm)

Maximum

1-Hr

Average

(ppm)

Percent of

Federal

Standard

(35 ppm)

Area

South Coast Air Basin

Los Angeles 4.7 49 6.0 17 South Central L.A. County

Orange 2.2 23 3.4 10 North Coastal Orange County

Riverside 1.9 20 2.7 8 Metropolitan Riverside County

San Bernardino 1.7 18 1.8 5 Central San Bernardino Valley

Salton Sea Air Basin

Riverside 0.6 6 3.0 8 Coachella Valley

Nitrogen Dioxide (NO2)

NO2 Air Quality

In 2011, the District monitored NO2 concentrations at 25 locations, including one in the 

Coachella Valley. For the newly-promulgated 1-hour NO2 standard, the Basin had not 

exceeded the federal annual standard for NO2 (0.053 ppm or 53 ppb) since 1991, when 

the Los Angeles County portion of the Basin recorded the last exceedance of the 

standard in any U.S. county. The level of the recently established 1-hour average NO2

federal standard (100 ppb), however, was exceeded on one day in 2011. The state NO2

standards were not exceeded in the Basin. 

The maximum 1-hour and annual average NO2 concentrations for 2011 are shown in 

Table 2-9, by basin and county. The Basin maximum annual average NO2 concentration 

(24.6 ppb, recorded in the Pomona/Walnut Valley area) was 46 percent of the federal 

annual NO2 standard and 82 percent of the state annual standard (0.030 ppm or 30 ppb). 

The maximum 1-hour average NO2 concentration in the Basin (109.6 ppb, in Central Los 

Angeles County) was 109 percent of the new federal standard (100 ppb) and 61 percent 
Chapter 2: Air Quality in the South Coast Air Basin

II-2-39

of the state standard (180 ppb). Concentrations in the downwind Coachella Valley areas 

were much lower than in the Basin.

The exceedances of the federal 1-hour NO2 standard in 2011 occurred on the same day at 

two stations in Los Angeles County (Central Los Angles and Long Beach). When 

considering the 98th percentile form of the federal standard or the 3-year design value, 

the Basin did not exceed the NAAQS and attainment status is not affected. Although the 

Basin is in attainment of the state and federal standards, NO2 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.

The annual averages and annual maximum 1-hour average concentrations for each 

monitoring station in the District for the years 1995-2011 are shown in Tables A-14 and 

A-15, respectively, in the Attachment.

TABLE 2-9

2011 Maximum 1-Hour and Annual Average NO2 Concentrations by Basin and County

Basin/County

Maximum

1-Hour

Average

(ppb)

Percent of

Federal

Standard

(100 ppb)

Maximum

Annual

Average

(ppb)

Percent of

Federal

Standard

(53 ppb)

Area

South Coast Air Basin

Los Angeles 109.6* 109 24.6 46 Central Los Angeles County;

Pomona/Walnut Valley

Orange 73.8 73 16.8 31 North Orange County

Riverside 63.3 63 16.9 32 Metropolitan Riverside County

San Bernardino 76.4 76 21.1 39 Central San Bernardino Valley

Salton Sea Air Basin

Riverside 44.7 44 8.0 15 Coachella Valley

* Although the maximum 1-hour concentrations exceeded the standard, the 98th percentile form of the design 

value did not exceed the NAAQS

Sulfur Dioxide (SO2)

SO2 Air Quality

In 2011, sulfur dioxide was measured at seven Basin locations. Based on the review of 

the SO2 standards, U.S. EPA has established the 1-hour SO2 standard to protect the 

public health against short-term exposure. The level of the standard is now set at 75 ppb 

1-hour average, revoking the existing annual (0.03 ppm) and 24-hour (0.14 ppm) federal 

standards, effective August 2, 2010. No violations have occurred of the current federal 
Final 2012 AQMP Appendix II: Current Air Quality

II-2-40

1-hour standards, the former federal annual or 24-hour standards, or the state standards 

(0.25 ppm, 1-hour or 0.04 ppm, 24-hour). The annual and 24-hour federal standards 

were last exceeded in the 1960’s and the state standards were last exceeded in 1990.

The maximum 1-hour average SO2 concentrations recorded in the District in 2011 are 

shown in Table 2-10. The highest 1-hour average SO2 concentration (51.2 ppb in 

Metropolitan Riverside County) was 68 percent of the federal 24-hour standard. While 

SO2 concentrations in the Basin no longer exceed standards, SO2 is a precursor of 

sulfate, which is a component of PM10 and PM2.5. The highest 24-hour average SO2, 

measured in the South Coastal Los Angeles County area, near the Ports of Los Angeles 

and Long Beach was 0.013 ppm, 32 percent of the state standard. Annual maximum 1-

hour average SO2 concentrations for each air monitoring station for the years 1995-2011 

are shown in Table A-16 in the Attachment.

TABLE 2-10

2011 Maximum 1-Hour Average SO2 Concentrations by Basin and County

Basin/County

Maximum

1-hr

Average

(ppb)

Percent of

Federal

Standard

(75 ppb)

Area

South Coast Air Basin

Los Angeles 19.8 26 Central Los Angeles

Orange 7.7 10 North Coastal Orange County

Riverside 51.2 68 Metropolitan Riverside County

San Bernardino 12.3 16 Central San Bernardino Valley

Salton Sea Air Basin

Riverside N.D. Coachella Valley

N.D. = No Data. Historical measurements and lack of emissions sources indicate concentrations are well below 

standards.

Sulfate (SO4

2-

)

Sulfate Air Quality

In 2011, sulfate concentrations were measured at 21 Basin locations and one in the 

Coachella Valley. The current form of the state standard (25 μg/m3) is based on sulfate 

from PM10 (24-hour average); there is no federal sulfate standard. In 2011, the state 

PM10-sulfate standard was not exceeded anywhere in the Basin and this standard has not 

been exceeded in the Basin or the Coachella Valley in many years. Maximum 

concentrations by air basin and county are shown in Table 2-11. The maximum sulfate 

concentration (12.6 μg/m3) recorded in the District was 50 percent of the state standard.
Chapter 2: Air Quality in the South Coast Air Basin

II-2-41

The maximum 24-hour average concentrations at each District air monitoring station for 

the years 1995-2011 are shown in Table A-17 in the Attachment.

TABLE 2-11

2011 Maximum 24-Hour Average Sulfate (PM10) Concentrations by Basin and County

Basin/County

Maximum

24-hr 

Average

(μg/m3)

Percent of

State

Standard

(25 μg/m3)

Area

South Coast Air Basin

Los Angeles 8.0 32 Central Los Angeles County

Orange 6.5 26 Central Orange County

Riverside 5.3 21 Metropolitan Riverside County

San Bernardino 6.0 24 Central San Bernardino Valley

Salton Sea Air Basin

Riverside 5.7 23 Coachella Valley

Lead (Pb)

Current Lead Air Quality

In 2011 lead concentrations were measured at ten Basin urban ambient air monitoring 

stations and five source-specific stations near major Pb emissions sources. Except for 

the source-specific monitoring that is now required under the new NAAQS, there have 

been no violations of the lead standards at the District’s regular ambient air monitoring 

stations since 1982, primarily as a direct result of the removal of Pb from gasoline. 

However, monitoring at two stations immediately adjacent to stationary sources of Pb 

have recorded exceedances of the standards in localized areas of the Basin in more 

recent years.

U.S. EPA designated the Los Angeles County portion of the Basin (excluding the high 

desert areas, and San Clemente and Santa Catalina Islands) as nonattainment for the 

recently revised (2008) federal Pb standard (0.15 μg/m3, rolling 3-month average), due 

to the source-specific monitoring under the new federal regulation. This designation was 

based on two source-specific monitors in the Los Angeles County Cities of Vernon and 

Industry exceeding the new standard in the 2007-2009 period of data used by U.S. EPA. 

For the most recent 2009-2011 design value data period, only one of these stations 

(Vernon) still exceeded the Pb standard, with a maximum 3-month rolling average of 

0.67 μg/m3that was measured in 2009 (432 percent of the federal standard). In 2011, 

the maximum rolling 3-month average at the Vernon site was 0.46 μg/m3(297 percent of 
Final 2012 AQMP Appendix II: Current Air Quality

II-2-42

the federal standard). A separate PB SIP addressing the 2008 lead standard in the Basin 

was submitted to U.S. EPA in June 2012.

The remainder of the Basin, other than the one source specific monitor in the Los 

Angeles County nonattainment area, is currently attaining the new Pb standard, 

including both ambient and source-specific monitoring. The old (1978) Pb standard (1.5 

μg/m3, as a quarterly average) remained in effect until one year after the area was 

designated for the 2008 standard, for areas in attainment of the 1978 standard. While the 

entire Basin has remained in attainment of the 1978 lead standard, U.S. EPA’s current 

Pb designations for the new standard became effective on December 31, 2010 so the old 

standard is now fully superseded by the 2008 revised NAAQS. Nonetheless, the 

revoked (1978) federal lead standard (1.5 μg/m3, as a quarterly average) and the state Pb 

standard (1.5 μg/m3, as a 30-day average) were not exceeded in the District’s ambient 

network in 2011. The highest 30-day average in 2011 at the source-specific monitor at 

Vernon was 0.45 μg/m3(30 percent of the state standard). The highest 30-day average 

for an ambient Pb monitor was 0.02 μg/m3(less than 2 percent of the state standard).

Table 2-12 shows the maximum 3-month rolling average Pb concentrations recorded in 

2011, for each county in the Basin. The state standard maximum monthly average and 

federal standards maximum quarterly and 3-month rolling average lead concentrations at 

each District air monitoring site for the years 1995-2011 are given in Tables A-18 to A20 in the Attachment.
Chapter 2: Air Quality in the South Coast Air Basin

II-2-43

TABLE 2-12

2011 Maximum 3-Month Rolling Pb Concentrations by Basin and County

Basin/County

Maximum

3-Month 

Rolling

Average

(g/m3

)

Percent of

Federal

Standard

(0.15 g/m3

)

Area

South Coast Air Basin

Los Angeles* 0.46 297 Central Los Angeles 

Orange N.D.

Riverside 0.01 6 Metropolitan Riverside County

San Bernardino 0.01 6 Northwest San Bernardino Valley,

Central San Bernardino Valley

Salton Sea Air Basin

Riverside N.D. Coachella Valley

* This high lead concentration was measured at a site immediately downwind of a lead source.

N.D. = No Data. Historical measurements indicate concentrations are well below standards.
CHAPTER 3

AIR QUALITY IN THE RIVERSIDE COUNTY PORTION 

OF THE SALTON SEA AIR BASIN (COACHELLA 

VALLEY)

Air Quality in the SSAB, Riverside County (Coachella Valley)

Fine Particulate Matter (PM2.5)

Particulate Matter (PM10)

Ozone (O3)

Carbon Monoxide (CO)

Nitrogen Dioxide (NO2)

Sulfur Dioxide (SO2)

Sulfate (SO4

2-

)

Lead (Pb)
Chapter 3: Air Quality in the Riverside County Portion of the Salton Sea Air Basin

II-3-1

AIR QUALITY IN THE SSAB, RIVERSIDE COUNTY

(COACHELLA VALLEY)

In 2011, the District monitored air quality at two routine locations in the Riverside 

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

Figure 3-1 shows a map of the area and topography. One monitoring station (Palm 

Springs) is located immediately downwind of the densely populated South Coast Air 

Basin (Basin). The second station (Indio) is located further downwind in the Coachella 

Valley.

FIGURE 3-1

Location and Topography of the Coachella Valley

(Dashed red box indicates the San Gorgonio Pass; District Coachella Valley air monitoring 

stations are located at Palm Springs and Indio)
Final 2012 AQMP Appendix II: Current Air Quality

II-3-2

Federal and state standards for PM2.5, carbon monoxide (CO), and nitrogen dioxide 

(NO2) were not exceeded in the Coachella Valley in 2011, nor was the state standard for 

Sulfate (SO4

2-

, from PM10). However, the Coachella Valley exceeded state and federal 

standards for ozone (O3) and PM10. The most current (2008) federal 8-hour O3 standard 

was exceeded on 54 days in this area in 2011. 

The two days in 2011 that exceeded the 24-hour PM10 National Ambient Air Quality 

Standards (NAAQS) were flagged by the District for consideration under the U.S. EPA 

Exceptional Events Rule9, due to high-wind natural events (windblown dust from 

thunderstorm outflows). With those days flagged, the Coachella Valley did not violate 

the 24-hour PM10 NAAQS.

The maximum concentrations measured at the District’s Coachella Valley air monitoring 

stations in 2011 are shown in Figure 3-2, as percentages of the state and federal 

standards. Figure 3-3 shows the Coachella Valley 3-year (2009-2011) design values, as 

percentages of the current and revoked federal standards. 

FIGURE 3-2

Coachella Valley 2011 Maximum Pollutant Concentrations 

as Percent of State and Federal Standards

 

9The U.S. EPA Exceptional Events Rule, Treatment of Data Influence by Exceptional Events, became effective May 21, 

2007. The previous U.S. EPA Natural Events Policy for Particulate Matter was issued on May 30, 1996. Under the 

Exceptional Events Rule, U.S. EPA allows certain data to be flagged in the U.S. EPA Air Quality System (AQS) 

database and not considered for NAAQS attainment status when that data is influenced by exceptional events, such as 

high winds, wildfires, volcanoes, or some cultural events (Independence Day fireworks) that meet strict requirements.

0

50

100

150

200

250

Ozone

(1-Hour)

Ozone

(8-Hour) 

(2008)

PM2.5

(24-Hour)

PM2.5

(Annual)

PM10

(24-Hour)

Nitrogen

Dioxide

(1-Hour)

Carbon Monoxide

(8-Hour)

Sulfate

(24-Hour) Percent of Standard

State Standard

Federal Standard

Level of Standard
Chapter 3: Air Quality in the Riverside County Portion of the Salton Sea Air Basin

II-3-3

123%

109%

91%

42%

48%

68%

56%

0%

20%

40%

60%

80%

100%

120%

140%

2008

8-Hour

Ozone

1997

8-Hour

Ozone

1-Hour

Ozone

(Revoked)

24-Hour

PM2.5

Annual

PM2.5

24-Hour

PM10

Annual

PM10

(Revoked)

Design Values as Percent of Standards

Federal Standard

FIGURE 3-3

Coachella Valley 3-Year (2009-2011) Design Values as Percent of Federal Standards

The current NAAQS, as attainment designations for the Coachella Valley are presented 

in Table 3-1. Coachella Valley station data is also included, along with the Basin 

stations, in the tables by pollutant for the years 1995-2011, in the Attachment to this 

Appendix.
Final 2012 AQMP Appendix II: Current Air Quality

II-3-4

TABLE 3-1

National Ambient Air Quality Standards (NAAQS) Attainment Status

Coachella Valley Portion of the Salton Sea Air Basin

Criteria

Pollutant Averaging Time Designationa) AttainmentDateb)

1979

1-Hour Ozonec)

1-Hour

(0.12 ppm) Nonattainment (Severe-17) 11/15/2007(not timely attainedc)

1997

8-Hour Ozoned)

8-Hour

(0.08 ppm) Nonattainment (Severe-15) 6/15/2019

2008

8-Hour Ozone

8-Hour

(0.075 ppm) Nonattainment (Severe-15) 12/31/2027

CO 1-Hour (35 ppm)

8-Hour (9 ppm) Unclassifiable/Attainment N/A

NO2

e)

1-Hour (100 ppb) Unclassifiable/Attainment N/A

Annual (0.053 ppm) Unclassifiable/Attainment N/A

SO2

f)

1-Hour (75 ppb) Designations Pending N/A

24-Hour (0.14 ppm)

Annual (0.03 ppm) Unclassifiable/Attainment N/A

PM10 24-hour (150 μg/m3

) Nonattainment (Serious)g)

12/31/2006

(redesignation

request submitted)

PM2.5 24-Hour (35 μg/m3

)

Annual (15.0 μg/m3)

Unclassifiable/Attainment N/A

Lead (Pb) 3-Months Rolling

(0.15 μg/m3)

Unclassifiable/Attainment N/A

a) U.S. EPA often only designates Nonattainment areas; everywhere else is listed as Unclassifiable/Attainment or 

Unclassifiable

b) A design value below the NAAQS for data through the full year or smog season prior to the attainment date is 

typically required for attainment demonstration

c) 1-hour O3 standard (0.13 ppm) was revoked, effective June 15, 2005; the Southeast Desert Modified Air Quality 

Management Area, including the Coachella Valley, did not attain this standard based on 2005-2007 data and has

some continuing obligations under the former standard (latest 2009-2011 data shows attainment)

d) 1997 8-hour O3 standard (0.08 ppm) was reduced (0.075 ppm), effective May 27, 2008; the 1997 O3 standard and 

most related implementation rules remain in place until the 1997 standard is revoked by U.S. EPA

e) New NO2 1-hour standard, effective August 2, 2010; attainment designations January 20, 2012; annual NO2

standard retained

f) The 1971 annual and 24-hour SO2 standards were revoked, effective August 23, 2010; however, these 1971 

standards will remain in effect until one year after U.S. EPA promulgates area designations for the 2010 SO2 1-hour 

standard. Area designations expected in 2012, with SSAB likely designated Unclassifiable /Attainment

g) Annual PM10 standard was revoked, effective December 18, 2006; redesignation request to Attainment of the 24-

hour PM10 standard is pending with U.S. EPA
Chapter 3: Air Quality in the Riverside County Portion of the Salton Sea Air Basin

II-3-5

Fine Particulate Matter (PM2.5)

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

PM2.5 monitoring, using filter-based Federal Reference Method (FRM) samplers on a 1-

in-3-day schedule. PM2.5 has remained relatively low compared to the South Coast Air 

Basin due to fewer combustion-related emissions sources and also the increased vertical 

mixing and horizontal dispersion in the desert area. In 2011, federal PM2.5 standards 

(35 μg/m3, 24-hour average; 15.0 μg/m3, annual average) were not exceeded at either of 

the two Riverside County SSAB air monitoring sites. The Coachella Valley maximum 

24-hour average and annual average concentrations recorded in 2011 (35.4 μg/m3and 

7.2 μg/m3) were, respectively, 99.7 percent and 48 percent of the federal 24-hour and 

annual standards.

While not exceeding the 24-hour federal standard, the relatively high 24-hour 

concentration of 35.4 μg/m3 was unusual for the Coachella Valley and occurred at Indio 

on one of the exceptional event days that had extremely high PM10 due to windblown 

dust from thunderstorm activity. The second high 24-hour PM2.5 average for the 

Coachella Valley was 26.3 μg/m3(74 percent of the federal standard), at Palm Springs. 

When looking at the 3-year design values (2009-2011) that considers the form of the 

federal standard, the Coachella Valley PM2.5 24-hour design value is 15.0 μg/m3(42 

percent of the short-term standard) and the PM2.5 annual design value is 7.3 μg/m3(48 

percent of the annual standard).

The annual PM2.5 state standard (12.0 μg/m3) was not exceeded in the Coachella 

Valley, with the maximum annual average of 7.2 μg/m3(at Palm Springs) at 60 percent 

of the standard. This suggests that the Coachella Valley will also be in attainment of the 

upcoming revision to the federal annual PM2.5 standard, which has been proposed 

within a range from 12.0 to 13.0 μg/m3. The Coachella Valley was between 55 and 60 

percent of the proposed new PM2.5 annual standard for the year 2011. Figure 3-4 shows 

the trend of the annual average PM2.5 and PM10 concentrations in the Coachella Valley 

for the station showing the highest PM10 measurements from 1990 through 2011. 

Tables A-9 to A-12 in the Attachment to this appendix show the annual arithmetic mean, 

percentage of sampling days over the 24-hour federal standard, maximum 24-hour 

average concentrations, and 98th percentile 24-hour concentrations for the years 1999-

2011 for all monitoring stations, including the two in the Coachella Valley. 
Final 2012 AQMP Appendix II: Current Air Quality

II-3-6

0

10

20

30

40

50

60

70

80

90

1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 PM Concentration (μg/m3

)

PM10 Annual PM2.5 Annual

Coachella Valley Particulate Air Quality Trends 1990-2011

FIGURE 3-4

Coachella Valley Trend of Annual Average PM2.5 and PM10, 1990-2011

Particulate Matter (PM10)

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

primarily 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.,

natural wind-blown sources, construction and agricultural activities, and re-entrained 

dust from paved road travel) and not as a result of secondary particulates generated from 

precursor gaseous emissions. PM10 is the only pollutant which has sometimes reached 

higher concentrations in the SSAB than in the Basin.

The Coachella Valley is subject to frequent high winds which generate wind-blown sand 

and dust, especially from disturbed soil and natural desert blowsand10. Air forced 

 

10 The blowsand process is a natural sand migration caused by the action of winds on the vast areas of sand in the 

Coachella Valley. The sand is supplied by weather erosion of the surrounding mountains and foothills. Although the 

sand migration is somewhat disrupted by urban growth in the Valley, the overall region of blowsand activity 

encompasses approximately 130 square miles, extending from near Cabazon in the San Gorgonio Pass to near Indio.
Chapter 3: Air Quality in the Riverside County Portion of the Salton Sea Air Basin

II-3-7

through the San Gorgonio Pass (also referred to as Banning Pass) creates strong 

northwesterly winds along the centerline of the Coachella Valley. This forcing is often

related to the marine air mass and westerly onshore (sea-breeze) flows in the South 

Coast Air Basin pushing through the Pass. At other times, storm systems with frontal 

passages create strong winds through the Pass and along the Valley. Hourly averaged 

winds measured near Cathedral City, in the Whitewater River Wash near the centerline 

of the Valley, exceeded 25 mph for at least one hour on approximately one third of the 

days between 2005 and 2009.

High PM10 concentrations in the Coachella Valley can also be caused by desert dust and 

sand entrained by downdraft outflows from the thunderstorms activity that is common in 

the southwestern U.S. deserts in the summer. On some of the high days, transport of 

wind-generated dust and sand occurs with relatively light winds in the Coachella Valley, 

when deeply entrained dust from desert thunderstorm outflows travels to the Coachella 

Valley from the desert areas of southeastern California, Arizona, Nevada, or northern 

Mexico. All days in recent years that exceeded the 24-hour federal PM10 standard at 

Indio or Palm Springs would not have exceeded except for the contribution of 

windblown dust and sand due to strong winds in the upwind source area (high-wind 

natural events).

PM10 is measured daily at both Indio and Palm Springs by supplementing the primary 1-

in-3-day Federal Reference Method (FRM) filter sampling at Indio and the 1-in-6-day 

FRM at Palm Springs with secondary continuous hourly Federal Equivalent Method 

(FEM) measurements at both stations.

In 2011, two high-wind exceptional events occurred in the Coachella Valley that caused 

high 24-hour PM10 concentrations (397 and 344 μg/m3, at Palm Springs and Indio, 

respectively on July 3; 375; and 265 μg/m3at Indio and Palm Springs, respectively on 

August 28). The high PM10 concentrations measured on these days were due to strong 

outflows from thunderstorms over Arizona and northern Mexico that deeply entrained 

dust and sand and transported it to the Coachella Valley. These natural events have been 

flagged in the U.S. EPA Air Quality System (AQS) database to be excluded for 

comparison to the NAAQS, as allowed by the U.S. EPA Exceptional Events Rule. 

Further documentation and U.S. EPA concurrence is pending.

After application of the U.S. EPA Exceptional Event Rule (and its predecessor, the 

Natural Events Policy) to high wind natural events in the Coachella Valley, no days 

since the mid-1990s have exceeded the federal 24-hour PM10 standard at Indio or Palm 

Springs. As a result, AQMD requested that U.S. EPA redesignate the Coachella Valley 
Final 2012 AQMP Appendix II: Current Air Quality

II-3-8

from nonattainment to attainment of the PM10 NAAQS. Further action on this request 

by U.S. EPA is pending11.

After flagging the high-wind natural events that exceeded the 24-hour PM10 federal 

standard, the federal PM10 standard was not exceeded in the Riverside County part of 

SSAB in 2011. The next highest PM10 24-hour concentration in the Coachella Valley 

was 120 μg/m3, 77 percent of the 24-hour NAAQS. The former annual average PM10 

federal standard (50 μg/m3) was not exceeded, even with the exceptional events 

included. The highest annual average PM10 concentration in the Coachella Valley in 

2011 was 32.6 μg/m3(65 percent of the revoked annual federal standard), with the 

exceptional events excluded. When considering the form of the federal PM10 standards,

after consideration for the exceptional events, the 3-year (2009-2011) 24-hour PM10 

design value for the Coachella Valley was 105 μg/m3(68 percent of the NAAQS) and 

the annual design value was 31 μg/m3(56 percent of the revoked annual PM10 

NAAQS).

In 2011, the state 24-hour PM10 standard (50 μg/m3) was exceeded on 19 days (21 days 

if the high-wind events are included) in the Coachella Valley, which is 5.2 percent of the 

sampling days (using FRM and FEM data combined). The peak value of 120 μg/m3, not 

including the exceptional events, was 238 percent of the state 24-hour standard. The 

state annual standard (20 μg/m3) was also exceeded. The annual average PM10 

concentration of 32.6 μg/m3 was 151 percent of the state standard.

For each routine District ambient air monitoring station, the annual arithmetic mean, 

percent of sampling days exceeding state and federal standards, and maximum 24-hour 

average concentrations are shown in Tables A-6 to A-8 in the Attachment for the years 

1995-2011. Please refer to Appendix II from the 2003 AQMP for the 1976-1989 prioryear statistics and to Appendix II from the 2007 AQMP for 1990-2005 data.

Ozone (O3)

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

transported from the Basin and formed photochemically 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 

 

11 U.S. EPA has requested additional temporary PM10 monitoring in the southeastern Coachella Valley to further assess 

windblown dust in that area; this project is currently ongoing.
Chapter 3: Air Quality in the Riverside County Portion of the Salton Sea Air Basin

II-3-9

Bernardino area and the adjacent mountains. As the air is transported still further inland 

into the desert areas, ozone concentrations typically decrease somewhat due to dilution, 

although ozone standards can still be exceeded. 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.

In 2011, the 1979 1-hour federal ozone standard level was not exceeded in the Coachella 

Valley, with 2011 being the fourth consecutive year with no exceedances of the former 

short-term standard. The maximum 1-hour concentration measured was 0.124 ppm, just 

below (99 percent of) the former 1-hour federal standard (0.125 ppm exceeds). The 

former (1997) 8-hour federal ozone standard was exceeded on 18 days. The current, 

more stringent, 2008 8-hour federal standard (0.075 ppm) was exceeded on 54 days. 

The maximum 8-hour ozone concentration was 0.098 ppm (130 percent of the 2008 

standard and 115 percent of the 1997 standard).

The state 1-hour and 8-hour ozone standards were exceeded on 25 days and 78 days, 

respectively, in the Coachella Valley in 2011. The maximum 1-hour average O3

concentration (0.124 ppm) was 136 percent of the state 1-hour standard (0.09 ppm). The 

maximum 8-hour average O3 concentration (0.098 ppm) was 138 percent of the state 8-

hour standard (0.070 ppm). The 1-hour ozone health advisory level (0.15 ppm) has not 

been exceeded in the Coachella Valley area since 1999. No stage 1 ozone episode levels 

(0.20 ppm) have been recorded in the Coachella Valley area since 1989.

Tables A-2 through A-5 in the Attachment show the number of days exceeding the 

federal 8-hour and 1-hour ozone standards, as well as the 4th highest 8-hour average and 

maximum 1-hour concentrations, at all routine District air quality monitoring stations 

including the two Coachella Valley sites, for the period 1995-2011. Please refer to 

Appendix II from the 2003 AQMP for the 1976-1989 prior-year statistics and to 

Appendix II from the 2007 AQMP for 1990-2005 data. Figure 3-5 shows the trend of 

the total number of days exceeding federal (2008 8-hour and former 1979 1-hour) and 

state (8-hour and 1-hour) ozone standards at Coachella Valley monitoring sites for the 

years 1990-2011. Figure 3-6 shows the trend of the maximum 1-hour and 8-hour ozone 

concentrations in the Coachella Valley from 1990 through 2011.
Final 2012 AQMP Appendix II: Current Air Quality

II-3-10

0

20

40

60

80

100

120 Days Exceeding

8-Hour Federal (2008) 1-Hour Federal 8-Hour State 1-Hour State

Coachella Valley Ozone Air Quality Trends 1990-2011

FIGURE 3-5

Coachella Valley Federal and State Ozone Trends, 1990-2011

(Number of Days Exceeding Standards)
Chapter 3: Air Quality in the Riverside County Portion of the Salton Sea Air Basin

II-3-11

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

Ozone Concentration (ppm)

8-Hour Ozone 1-Hour Ozone

FIGURE 3-6

Trends of Coachella Valley Maximum 1-hour and 8-hour Ozone Concentrations, 1990-2011

Carbon Monoxide (CO)

Carbon monoxide was measured at one Coachella Valley air monitoring station in 2011. 

Neither the federal nor state standards were exceeded. The maximum 8-hour average 

CO concentration recorded in 2011 (0.6 ppm) was less than 7 percent of both the federal

(9 ppm) and state (9.0 ppm) standards. The maximum 1-hour CO concentration (3.0 

ppm) was 8 percent of the federal (35 ppm) and 15 percent of the state (20 ppm) 1-hour 

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

SSAB area shows that the area has not exceeded the federal CO standards in nearly three 

decades.

The annual maximum 8-hour CO concentrations at all District air monitoring stations, 

including the Coachella Valley, are shown in Table A-13 in the Attachment, for the 

period 1995-2011.
Final 2012 AQMP Appendix II: Current Air Quality

II-3-12

Nitrogen Dioxide (NO2)

Nitrogen dioxide was measured at one station in the Coachella Valley in 2011. The 

maximum 1-hour average NO2 concentration (44.7 ppb) was 44 percent of the new 

(2010) federal 1-hour standard (100 ppb) and 25 percent of the state 1-hour standard

(180 ppb). The maximum annual average NO2 concentration (8.0 ppb) was 15 percent 

of the federal annual standard (53 ppb) and 27 percent of the state annual standard (30 

ppb).

The annual averages and annual maximum 1-hour average concentrations for each 

monitoring station in the District (including the Coachella Valley) for the years 1995-

2011 are shown in Tables A-14 and A-15, in the Attachment.

Sulfur Dioxide (SO2)

Sulfur dioxide concentrations were not measured in the Riverside County SSAB in 2011. 

Historical measurements have shown SO2 concentrations to be well below the state and 

federal standards and there are no significant emissions sources of SO2 in the Coachella 

Valley.

Sulfate (SO4

2-

)

Sulfate from PM10 was measured at one station in the Coachella Valley in 2011. The 

maximum 24-hour average sulfate concentration was 5.7 μg/m3(23 percent of the 25 

μg/m3state sulfate standard). There is no federal sulfate standard. The maximum 24-

hour average concentrations at each District air monitoring station, including the 

Coachella Valley, for the years 1995-2011 are shown in Table A-17 in the Attachment.

Lead (Pb)

Lead concentrations were not measured at either of the two Coachella Valley air 

monitoring stations in 2011. Measurements in past years have shown concentrations to 

be less than the state and federal standards and no major sources of lead emissions are

located in the Coachella Valley.
ATTACHMENT TO APPENDIX II
Final 2012 AQMP Appendix II: Current Air Quality

II-A-2

TABLE A-1

Air Monitoring Stations and Source/Receptor Areas

SOURCE/RECEPTOR

AREA # AREA* LOCATION STN #

LOS ANGELES COUNTY

1 Central LA Los Angeles 087

2 Northwest Coastal LA County West Los Angeles 091

3 Southwest Coastal LA County 1 Hawthorne (moved) 094

3 Southwest Coastal LA County 2 LAX-Hastings 820

4 South Coastal LA County 1 North Long Beach 072

4 South Coastal LA County 2 South Long Beach 077

6 West San Fernando Valley Reseda 074

7 East San Fernando Valley Burbank 069

8 West San Gabriel Valley Pasadena 088

9 East San Gabriel Valley 1 Azusa 060

9 East San Gabriel Valley 2 Glendora 591

10 Pomona/Walnut Valley Pomona 075

11 South San Gabriel Valley Pico Rivera 085

12 South Central LA County 1 Lynwood (moved) 084

12 South Central LA County 2 Compton 112

13 Santa Clarita Valley Santa Clarita 090

ORANGE COUNTY

16 North Orange County La Hebra 3177

17 Central Orange County Anaheim 3176

18 North Coastal Orange County Costa Mesa 3195

19 Saddleback Valley 1 El Toro (moved) 3186

19 Saddleback Valley 2 Mission Viejo 3812

RIVERSIDE COUNTY

22 Norco/Corona Norco 4155

23 Metropolitan Riverside County 1 Riverside – Rubidoux 4144

23 Metropolitan Riverside County 2 Riverside – Downtown 4146

23 Mira Loma Mira Loma 4165

24 Perris Valley Perris 4149

25 Lake Elsinore Area Lake Elsinore 4158

26 Temecula Valley Temecula – Lake Skinner 4163

29 Banning Airport Banning Airport 4164

30 Coachella Valley 1** Palm Springs 4137

30 Coachella Valley 2** Indio 4157

SAN BERNARDINO COUNTY

32 Northwest San Bernardino Valley Upland 5175

33 Southwest San Bernardino Valley Ontario 5817

34 Central San Bernardino Valley 1 Fontana 5197

34 Central San Bernardino Valley 2 San Bernardino 5203

35 East San Bernardino Valley Redlands 5204

37 Central San Bernardino Mountains Crestline – Lake Gregory 5181

38 East San Bernardino Mountains Big Bear Lake 5818

 * Source/receptor areas and area numbers are mapped in Figure A-1

** Salton Sea Air Basin
Appendix II – Attachment A

II-A-3

FIGURE A-1

South Coast Air Basin and Adjoining Areas of Salton Sea Air Basin

(with Source/Receptor Areas)
Final 2012 AQMP Appendix II: Current Air Quality

II-A-4

TABLE A-2

Ozone – Number of Days Exceeding the 2008 Federal Standard

(0.075 ppm, 8-Hour Average)

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

060 East San Gabriel Valley 1 88 53 26 33 19 27 25 17 35 21 14 17 20 28 17 4 12

069 East San Fernando Valley 49 25 15 24 15 23 7 14 38 36 10 23 13 17 14 5 6

072 South Coastal Los Angeles County 2 2 0 0 1 1 0 0 0 0 0 0 0 0 0 1 0

074 West San Fernando Valley 39 49 11 23 7 10 21 44 73 62 26 33 28 26 19 22 26

075 Pomona/Walnut Valley 1 73 36 16 28 14 10 5 24 38 22 17 27 18 35 23 7 16

084 South Central Los Angeles County 1 0 0 0 0 0 0 0 0 0 0 1 0 1 0 -- -- --

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1 0 0

085 South San Gabriel Valley 46 24 15 22 4 9 5 3 14 6 0* 4 5 5 3 1 0

087 Central Los Angeles 21 17 8 11 5 8 4 6 8 5 2 3 3 3 2 1 0

088 West San Gabriel Valley 70 45 21 26 10 25 23 19 40 25 12 23 11 16 12 3 5

090 Santa Clarita Valley 66 68 42 39 25 36 41 90 89 74 68 62 44 62 64 28 31

091 Northwest Coastal Los Angeles County 10 10 6 2 1 1 1 1 12 5 4 0 2 2 3 1 0

094 Southwest Coastal Los Angeles County 1 5 9 8 0 1 0 6 0 1 -- -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- 12 1 0 0 0 0 0 0

591 East San Gabriel Valley 2 105 69 45 49 19 30 49 33 58 33 26 29 26 45 42 24 30

ORANGE COUNTY:

3176 Central Orange County 1 8 7 1 7 1 3 0* 1 11 29 2 3 1 4 1 1 0

3177 North Orange County 18 13 8 6 4 7 2 2 7 3 0 7 8 5 3 1 0

3186 Saddleback Valley 1 8 11 5 14 -- -- -- -- -- -- -- -- -- -- -- -- --

3195 North Coastal Orange County 3 2 1 2 0 2 0 0 7 5 0 0 0 3 0 1 1

3812 Saddleback Valley 2 -- -- -- -- -- 4 8 6 15 16 6 13 5 15 10 2 2

RIVERSIDE COUNTY:

4137 Coachella Valley 1** 52 73 54 47 38 61 77 82 70 55 61 61 58 51 53 55 49

4144 Metropolitan Riverside County 104 99 79 69 46 50 50 64 86 70 55 57 46 64 35 50 68

4149 Perris Valley 101 93 67 41 17 71 85 72 72 44 16 83 73 77 67 53 54

4157 Coachella Valley 2** 44 46 3 22 30 18 40 45 40 50 34 28 29 27 24 22 19

4158 Lake Elsinore 82 18 1 63 64 65 77 67 57 43 41 54 35 69 37 23 28

4163 Temecula Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1

4164 Banning Airport -- -- 127 63 63 64 72 86 84 64 64 74 43 74 70 62 41

4165 Mira Loma -- -- -- -- -- -- -- -- -- -- -- 44 23 47 22 40 36

SAN BERNARDINO COUNTY:

5175 Northwest San Bernardino Valley 97 52 52 47 24 32 52 32 46 28 30 51 35 50 49 42 36

5181 Central San Bernardino Mountains 113 120 89 111 104 94 103 112 107 92 98 96 93 97 92 75 84

5197 Central San Bernardino Valley 1 88 75 47 56 30 26 43 34 69 48 45 46 43 58 48 38 39

5203 Central San Bernardino Valley 2 109 105 89 60 54 50 62 42 62 55 56 56 51 63 62 47 39

5204 East San Bernardino Valley 118 111 105 72 68 76 73 74 101 74 44 62 58 75 73 61 80

District Maximum 118 120 127 111 104 94 103 112 107 92 98 96 93 97 92 75 84

 * Less than 12 full months of data ** Salton Sea Air Basin Refer to 2003 AQMP for 1976 to 1994 data
Appendix II – Attachment A

II-A-5

TABLE A-3

Ozone – Number of Days Exceeding the Former (1979) 1-Hour Federal Standard

(0.12 ppm, 1-Hour Average)

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

060 East San Gabriel Valley 1 63 26 11 19 2* 11 9 5 11 2 4 7 3 7 4 0 0

069 East San Fernando Valley 20 6 2 7 0 3 2 1 4 2 2 6 0 1 1 0 0

072 South Coastal Los Angeles County 0 0 0* 0 1 0 0 0 0 0 0 0 0 0 0 0 0

074 West San Fernando Valley 8 11 0 7 0 0 2 9 14 2 2 6 1 0 1 0 3

075 Pomona/Walnut Valley 1 47 16 7 18 2 3 1 5 13 4 3 9 2 5 1 0 0

084 South Central Los Angeles County 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0* -- -- --

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0 0 0

085 South San Gabriel Valley 20 32 6 10 0 2 1 0 1 0 -- 1* 2 0 1 0 0

087 Central Los Angeles 5 24 0 5 1 1 0 0 1 0 0 0 0 0 1 0 0

088 West San Gabriel Valley 44 54 5 14 0 7 1 3 7 1 2 5 3 0 3 0 0

090 Santa Clarita Valley 26 68 13 16 0 1 9 32 35 13 11 20 2 8 5 1 3

091 Northwest Coastal Los Angeles County 1 13 0 1 0 0 0 0 1 0 0 0 0 0 1 0 0

094 Southwest Coastal Los Angeles County 1 0 1 0 0 1 0 0 0 0 0* -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- 0* 0 0 0 0 0 0 0

591 East San Gabriel Valley 2 73 49 18 28 3 11 13 12 22 5 8 10 3 12 7 0 4

ORANGE COUNTY:

3176 Central Orange County 1 2 1 0 2 0* 1 0* 0 2 0 0 0 1 0 0 0 0

3177 North Orange County 4 5 1 5 0 1 0 0 1 0 0 3 1 0 0 0 0

3186 Saddleback Valley 1 1 2 2 2 0 1* -- -- -- -- -- -- -- -- -- -- --

3195 North Coastal Orange County 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

3812 Saddleback Valley 2 -- -- -- -- -- 2* 1 2 4 0 1 0 0 0 0 0 0

RIVERSIDE COUNTY:

4137 Coachella Valley 1** 9 12 4* 8 1 0 6 2 4 1 4 2 1 0 0 0 0

4144 Metropolitan Riverside County 52 36 13* 32 3 3 7 12 18 8 3 8 2 8 0 1 4

4149 Perris Valley 36 31 6 8 0 15 19 4 7 2 1 12 4 4 1 0 2

4157 Coachella Valley 2** 3 0 0 2 1 0 0 0 0 0 0 0 0 0 0 0 0

4158 Lake Elsinore 23 17 4 22 5 1 12 6 7 2 3 3 3 6 1 0 1

4163 Temecula Valley 0 0* 0* -- -- -- -- -- -- -- -- -- -- -- -- -- 0

4164 Banning Airport -- -- -- 25 5 4 16 13 27 7 10 8 1 10 1 0 3

4165 Mira Loma -- -- -- -- -- -- -- -- -- -- -- 4 0 4 0 0 1

SAN BERNARDINO COUNTY:

5175 Northwest San Bernardino Valley 67 35 12 30 4 10 14 5 15 3 8 14 7 9 3 1 5

5181 Central San Bernardino Mountains 65 62 29 57 30 17 26 22 34 9 18 9 13 16 7 6 8

5197 Central San Bernardino Valley 1 57 38 10 32 4 7 13 8 26 7 9 12 9 8 3 2 5

5203 Central San Bernardino Valley 2 61 63 32 39 14 7 18 6 19 6 9 10 8 11 2 1 2

5204 East San Bernardino Valley 69 65 35 43 12 11 21* 23 38 12 6 11 7 12 1 1 7

District Maximum 73 68 35 57 30 17 26 32 38 13 18 20 13 16 7 6 8

* Less than 12 full months of data ** Salton Sea Air Basin Refer to 2003 AQMP for 1976 to 1994 data
Final 2012 AQMP Appendix II: Current Air Quality

II-A-6

TABLE A-4

Ozone – Annual Maximum 4th Highest 8-Hour Average (ppb)

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

060 East San Gabriel Valley 1 138 127 113 126 95 108 102 97 104 92 87 90 96 101 91 76 82

069 East San Fernando Valley 106 98 95 101 84 97 87 91 96 89 81 97 88 92 86 77 81

072 South Coastal Los Angeles County 71 73 67 65 68 66 60 59 63 70 59 56 56 64 64 57 60

074 West San Fernando Valley 101 110 83 100 81 80 89 111 119 101 98 103 92 95 93 87 91

075 Pomona/Walnut Valley 1 136 113 95 120 89 88 82 99 109 95 96 108 102 100 95 81 86

084 South Central Los Angeles County 1 51 57 53 51 41 50 54 49 57 65 63 64 56 55+ -- -- --

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 64 50 61

085 South San Gabriel Valley 105 93 97 102 80 86 81 74 82 78 51 78 79 77 72 59 63

087 Central Los Angeles 91 93 81 96 79 85 76 77 82 77 70 75 72 73 73 64 60

088 West San Gabriel Valley 130 117 100 117 86 104 90 95 101 93 85 96 89 91 95 75 77

090 Santa Clarita Valley 130 123 116 127 95 97 112+ 131 137 107 118 112 101 108 103 88 101

091 Northwest Coastal Los Angeles County 81 88 78 70 69 71 64 73 83 76 76 67 67 73 75 70 62

094 Southwest Coastal Los Angeles County 1 78 86 83 63 66 65 79 64 70 56* -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- 86* 68 62 66 65 61 59 62

591 East San Gabriel Valley 2 148 140 121 142 96 112 110 110 123 95 97 106 104 112 108 91 95

ORANGE COUNTY:

3176 Central Orange County 1 82 81 68 87 61 74 66 69 80 88 75 70 73 76 68 64 67

3177 North Orange County 96 90 82 93 78 83 73 71 80 75 65 89 82 78 75 71 69

3186 Saddleback Valley 1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

3195 North Coastal Orange County 75 70 70 76 70 67 69 66 79 75 66 60 65 75 66 60 67

3812 Saddleback Valley 2 -- -- -- -- -- 87 72 81 95 84 78 90 80 92 84 69 74

RIVERSIDE COUNTY:

4137 Coachella Valley 1** 106 116 101 108 98 96 111 109 105 99 108 98 97 96 96 93 92

4144 Metropolitan Riverside County 142 130 118 136 104 106 109 109 120 111 105 111 99 111 89 94 107

4149 Perris Valley 132 122 105 115 91 111 124 107 116 95 82 113 103 106 101 100 94

4157 Coachella Valley 2** 96 98 82 97 89 87 93 97 100 94 92 85 87 88 85 84 85

4158 Lake Elsinore 126 108 111 128 106 98 111 104 112 102 97 101 97 108 96 88 92

4163 Temecula Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

4164 Banning Airport 101 107 93 81 114+ 102 116 113 127 112 119 104 95 108 100 99 100

4165 Mira Loma -- -- -- -- -- -- -- -- -- -- 105 103 100 109 86 92 96

SAN BERNARDINO COUNTY:

5175 Northwest San Bernardino Valley 145 138 112 137 103 117 120 105 114 102 101 112 112 108 102 91 98

5181 Central San Bernardino Mountains 167 155 125 183 133 122 133 131 130 122 130 111 126 120 108 109 106

5197 Central San Bernardino Valley 1 143 137 115 132 98 100 123 114 132 111 113 114 112 110 100 94 105

5203 Central San Bernardino Valley 2 152 145 127 145 115 111 128 105 123 112 113 118 117 112 101 96 101

5204 East San Bernardino Valley 162 138 126 148 115 112 131 117 137 119 113 124 112 112 100 97 113

District Maximum 167 155 127 183 133 122 133 131 137 122 130 124 126 120 108 109 113

+ Site relocated * Less than 12 full months of data ** Salton Sea Air Basin
Appendix II – Attachment A

II-A-7

TABLE A-5

Ozone – Annual Maximum 1-Hour Average (ppm)

LOCATION 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987

087 Central Los Angeles .34 .21 .30 .31/ .29 .32 .40 .26 .29 .30 .22 .22

060 East San Gabriel Valley 1 .38 .32 .40 .45 .41 .35 .36 .39 .31 .36 .31 .30

069 East San Fernando Valley .35 .31 .30 .39 .35 .27 .25 .31 .26 .30 .28 .23

091 Northwest Coastal Los Angeles County .28 .18/ .24/ .26 .21 .23 .28 .23 .27/ .27 .20 .28

072 South Coastal Los Angeles County .16 .15 .19 .21 .20 .23 .22 .30 .27 .23 .18 .17

074 West San Fernando Valley .27 .34 .27 .33 .38 .25 .22 .26 .26 .25 .22 .22

075 Pomona/Walnut Valley 1 .36 .32 .41 .35 .37 .33 .31 .34 .31 .33 .27 .29

094 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- .19 .20

820 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- -- --

088 West San Gabriel Valley .34 .32 .42 .44 .41 .33 .37/ .34 .30 .37 .26 .28

090 Santa Clarita Valley .33 .33 .32 .32 .36 .29 .26/ .29 .27 .24 .24 .21

084 South Central Los Angeles County 1 .24 .24 .18 .29 .18 .21 .26 .23 .27 .21 .20 .24

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- --

085 South San Gabriel Valley .35 .32 .43 .39 .39 .35 .39 .33 .27 .31 .24 .28

591 East San Gabriel Valley 2 -- -- -- -- .49 .39 .36 .38 .34 .39 .35 .33

3176 Central Orange County 1 .30 .19 .29 .33 .28 .26 .26 .30 .25 .25 .20 .22

3177 North Orange County 1 .30 .25 .35 .38 .31 .27 .32 .27 .32 .34 .25 .24

3195 North Coastal Orange County .16 .18 .22 .21/ .16 .20 .18 .25 .25 .21 .17 .16

3186 Saddleback Valley 1 .23 .20 .34 .32 .34 .33 .27 .29 .30 .28 .23 .20

3812 Saddleback Valley 2 -- -- -- -- -- -- -- -- -- -- -- --

4137 Coachella Valley 1** .22 .21 .20 .24 .21 .19 .19 .19 .20 .24 .18 .17

4157 Coachella Valley 2** .16 .19 .17 .21 .11 .18 .17 .18 .19 .20 -- .16

4155 Norco/Corona .33 .36 .40 .33/ .34 .37 .35 .35 .30 .35 .27 .24

4141 Hemet/San Jacinto Valley .19 .25 .27 -- -- -- -- -- .18* .23 .18 .18

4144 Metropolitan Riverside County 1 .36 .35 .39 .34 .37 .30 .31 .36 .32 .35 .25 .29

4149 Perris Valley .22 .28 .32 .25 .29 .24 .28 .26 .22 .29 .22 .20

4150 San Gorgonio Pass .28 .27 .30 .27 .26 .23 .24 .26 .25 .29 .22 .21

4164 BanningAirport -- -- -- -- -- -- -- -- -- -- -- --

4163 Temecula Valley .21 .17 .23 -- -- -- -- -- -- -- -- --

4158 Lake Elsinore .20 .23 .30 -- -- -- -- -- -- -- -- --

5203 Central San Bernardino Valley 2 .32 .37 .36 .34 .36 .36/ .30 .32 .30 .27/ .30 .25

5204 East San Bernardino Valley .35 .33 .39 .34/ .32 .24 .29 .30 .29 .33/ .29 .24

5175 Northwest San Bernardino Valley -- -- -- -- -- -- -- .36 .32 .33 .29 .28

5197 Central San Bernardino Valley 1 .38 .39 .42 .42 .42 .35/ .31 .32 .32 .34 .31 .29

5181 Central San Bernardino Mountains 1 .23 .32 .33 .40 .31 .35 .32 .28 .34 .30 .26 .29

District Maximum .38 .39 .43 .45 .49 .39 .40 .39 .34 .39 .35 .33

 * Less than 12 full months of data. / Station location change

** Salton Sea Air Basin

Refer to 2003 AQMP for 1955 to 1975 data
Final 2012 AQMP Appendix II: Current Air Quality

II-A-8

TABLE A-5 (continued)

Ozone – Annual Maximum 1-Hour Average (ppm)

LOCATION 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

087 Central Los Angeles .21 .25 .20 .19 .20 .16 .19 .17 .14 .12 .15 .13

060 East San Gabriel Valley 1 .30 .33 .23 .28 .27 .24 .25 .21 .20 .16 .20 .14

069 East San Fernando Valley .24 .20 .20 .22 .22 .18 .17 .17 .14 .13 .18 .12

091 Northwest Coastal Los Angeles County .24 .25 .16 .18 .17 .18 .16 .14 .14 .11 .13 .12

072 South Coastal Los Angeles County .16 .16 .12 .11 .15 .14 .16 .11 .11 .10 .12 .13

074 West San Fernando Valley .25 .23 .19 .22 .17 .19 .14 .15 .21 .12 .16 .10

075 Pomona/Walnut Valley 1 .29 .25 .24 .24 .26 .21 .24 .22 .19 .16 .18 .14

094 Southwest Coastal Los Angeles County .22 .19 .10 .11 .15 .13 .11 .12 .13 .11 .09 .15

820 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- -- --

088 West San Gabriel Valley .29 .27 .26 .23 .27 .22 .26 .21 .17 .14 .17 .12

090 Santa Clarita Valley .30 .25 .23 .24 .22 .22 .26 .21 .17 .16 .18 .12

084 South Central Los Angeles County 1 .21 .14 .15 .16 .17 .12 .12 .09 .10 .08 .09 .12

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- --

085 South San Gabriel Valley .30 .26 .19 .26 .26 .19 .22 .18 .14 .13 .18 .12

591 East San Gabriel Valley 2 .34 .34 .29 .32 .30 .28 .30 .22 .21 .17 .22 .14

3176 Central Orange County 1 .27 .24 .18 .25 .22 .17 .21 .13 .13 .10 .11 .10*

3177 North Orange County 1 .29 .26 .21 .21 .21 .19 .25 .16 .15 .13 .18 .12

3195 North Coastal Orange County .13 -- .15 .17 .15 .13 .12 .11 .10 .10 .12 .10

3186 Saddleback Valley 1 .21 .23 .19 .24 .16 .16 .18 .15 .14 .13 .16 .10

3812 Saddleback Valley 2 -- -- -- -- -- -- -- -- -- -- -- --

4137 Coachella Valley 1** .20 .19 .17 .18 .15* .17 .17 .16 .16 .16 .17 .13

4157 Coachella Valley 2 ** -- .16 .16 .18 .14 .16 .12 .14 .12 .11 .13 .13

4155 Norco/Corona .25 .23 .17 .22 .23 .16 .17 .19 .16 -- -- --

4141 Hemet/San Jacinto Valley .18 .19 .22 .19 .15 .18 .16 .15 .12 -- -- --

4144 Metropolitan Riverside County .28 .27 .29 .24 .26 .26 .25 .21 .20 .19 .20 .14

4149 Perris Valley .23 .21 .19 .20 .21 .20 .18 .20 .18 .14 .15 .11

4150 San Gorgonio Pass .26 .23 .22 .20 .16 .16 .20 .18 .19 .13 .12/ --

4164 Banning Airport -- -- -- -- -- -- -- -- -- -- .17 .14

4163 Temecula Valley -- -- -- .17* .13 .13 .10* .11 .10 .10* -- --

4158 Lake Elsinore -- .24 .19 .20 .17 .19 .19 .19 .15 .16 .17 .14

5203 Central San Bernardino Valley 2 .28 .30 .29 .25 .28 .21 .25 .20 .24 .20 .21 .16

5204 East San Bernardino Valley .29 .27 .30 .25 .27 .27 .23 .24 .22 .20 .22 .15

5175 Northwest San Bernardino Valley .35 .32 .29 .27 .28 .24 .25 .24 .22 .19 .21 .15

5197 Central San Bernardino Valley 1 .29 .32 .27 .29 .28 .24 .25 .22 .22 .17 .20 .14

5181 Central San Bernardino Mountains 1 .29 .27 .33 .27 .28 .24 .27 .26 .20 .21 .24 .17

District Maximum .35 .34 .33 .32 .30 .28 .30 .26 .24 .21 .24 .17

* Less than 12 full months of data. / Station location change 

** Salton Sea Air Basin

Refer to 2003 AQMP for 1955 to 1975 data
Appendix II – Attachment A

II-A-9

TABLE A-5 (concluded)

Ozone – Annual Maximum 1-Hour Average (ppm)

LOCATION 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

087 Central Los Angeles .136 .116 0.122 0.152 0.110 0.121 0.108 0.115 0.109 0.139 0.098 0.087

060 East San Gabriel Valley 1 .174 .189 0.136 0.150 0.134 0.145 0.165 0.158 0.135 0.15 0.104 0.111

069 East San Fernando Valley .152 .129 0.128 0.134 0.137 0.142 0.166 0.116 0.133 0.145 0.111 0.12

091 Northwest Coastal Los Angeles County .104 .099 0.118 0.134 0.107 0.114 0.099 0.117 0.11 0.131 0.099 0.098

072 South Coastal Los Angeles County .118 .091 0.084 0.099 0.090 0.091 0.081 0.099 0.093 0.089 0.101 0.073

074 West San Fernando Valley .109 .140 0.152 0.179 0.131 0.138 0.158 0.129 0.123 0.135 0.122 0.13

075 Pomona/Walnut Valley 1 .152 .144 0.150 0.161 0.131 0.140 0.151 0.153 0.141 0.138 0.115 0.119

094 Southwest Coastal Los Angeles County .095 .098 0.088 0.110 0.069* -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County -- -- -- -- 0.120* 0.086 0.084 0.087 0.086 0.077 0.089 0.078

088 West San Gabriel Valley .157 .160 0.137 0.152 0.130 0.145 0.151 0.149 0.122 0.176 0.101 0.107

090 Santa Clarita Valley .131/ .184 0.169 0.194 0.158 0.173 0.156 0.135 0.16 0.14 0.126 0.144

084 South Central Los Angeles County 1 .089 .077 0.072 0.081 0.083 0.111 0.088 0.102 0.078* -- -- --

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- 0.104 0.081 0.082

085 South San Gabriel Valley .139 .132 0.111 0.128 0.104 0.077 -- 0.135 0.107 0.131 0.112 0.096

591 East San Gabriel Valley 2 .172 .190 0.152 0.162 0.134 0.160 0.175 0.147 0.156 0.15 0.124 0.134

3176 Central Orange County 1 .132 .114 0.103 0.136 0.120 0.095 0.113 0.127 0.105 0.093 0.104 0.088

3177 North Orange County 1 .137 .107 0.121 0.165 0.099 0.094 0.146 0.152 0.104 0.115 0.118 0.095

3195 North Coastal Orange County .102 .098 0.087 0.107 0.104 0.085 0.074 0.082 0.094 0.087 0.097 0.093

3186 Saddleback Valley 1 .129 -- -- -- -- -- -- -- -- -- -- --

3812 Saddleback Valley 2 .119 .125 0.136 0.153 0.116 0.125 0.123 0.108 0.118 0.121 0.117 0.094

4137 Coachella Valley 1** .124 .137 0.136 0.141 0.125 0.139 0.126 0.126 0.11 0.12 0.114 0.124

4157 Coachella Valley 2 ** .112 .114 0.114 0.123 0.111 0.114 0.103 0.106 0.12 0.097 0.1 0.099

4155 Norco/Corona -- -- -- -- -- -- -- -- -- -- -- --

4141 Hemet/San Jacinto Valley -- -- -- -- -- -- -- -- -- -- -- --

4144 Metropolitan Riverside County .140 .143 0.155 0.169 0.141 0.144 0.151 0.131 0.146 0.116 0.128 0.128

4149 Perris Valley .164 .152 0.147 0.155 0.128 0.088 0.169 0.139 0.142 0.125 0.122 0.125

4150 San Gorgonio Pass -- -- -- -- -- -- -- -- -- -- -- --

4164 Banning Airport .138 .149 0.160 0.166 0.156 0.144 0.139 0.129 0.149 0.133 0.124 0.127

4163 Temecula Valley -- -- -- -- -- -- -- -- -- -- -- --

4158 Lake Elsinore .128 .151 0.139 0.154 0.130 0.149 0.142 0.13 0.139 0.128 0.107 0.133

5203 Central San Bernardino Valley 2 .149 .184 0.147 0.160 0.157 0.163 0.154 0.153 0.157 0.15 0.129 0.135

5204 East San Bernardino Valley .152 .167* 0.158 0.174 0.160 0.146 0.165 0.149 0.154 0.145 0.128 0.151

5175 Northwest San Bernardino Valley .184 .171 0.139 0.155 0.138 0.149 0.166 0.145 0.155 0.146 0.131 0.145

5197 Central San Bernardino Valley 1 .169 .165 0.159 0.176 0.149 0.150 0.159 0.144 0.162 0.142 0.143 0.144

5181 Central San Bernardino Mountains 1 .176 .171 0.161 0.163 0.163 0.182 0.164 0.171 0.176 0.149 0.142 0.16

District Maximum .176 .190 0.169 0.194 0.163 0.182 0.175 0.171 0.176 0.176 0.143 0.160

 * Less than 12 full months of data. / Station location change 

** Salton Sea Air Basin

Refer to 2003 AQMP for 1955 to 1975 data
Final 2012 AQMP Appendix II: Current Air Quality

II-A-10

TABLE A-6

Particulate Matter (PM10)

#

– Annual Arithmetic Mean (μg/m3)

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

060 East San Gabriel Valley 1 49 45 46 41 56 46 45 46 44 35 35 32 36+ 35 32 30 33

069 East San Fernando Valley 42 42 45 36 44 39 41 38 38* 38 34 36 40 36 39 30 29

072 South Coast Los Angeles County 1 39 35 41 32 39 38 37 36 33 33 30 31 30+ 29 31 22 24

077 South Coast Los Angeles County 2 -- -- -- -- -- -- -- -- -- 38 43 45 41+ 36 33 27 29

087 Central Los Angeles 43 41 43 37 45 40 44 39 35 33 30 30 33 31* 33 27 29

090 Santa Clarita Valley 37 33 33 30 38 33 32 33 32 28 26 30+ 26 23 21 21

094 Southwest Coastal Los Angeles County 1 36 33 36 33 36 36 37 37 30 31* -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- 25 23 27 29 26 25 21 22

ORANGE COUNTY:

3176 Central Orange County 1 44 35 39 36 49 40 36 34 33 34 28 33 31+ 29+ 31 22 25

3186 Saddleback Valley 1 38 30 35 31 37 29 -- -- -- -- -- -- -- -- -- -- --

3812 Saddleback Valley 2 -- -- -- -- 29 28 26 31 27 24 19 23 23 23 24 18 19

RIVERSIDE COUNTY:

4137 Coachella Valley 1** 27 29 26 26 29 24 27+ 27 27 26 26 25+ 31 23+* 23 19 19+

4144 Metropolitan Riverside County 1 69 61 65 56 72 60 63 59 57 56 52 54 55+ 47 43 33 34

4149 Perris Valley 47 40 45 38 50 41 41 45 44 41 39 45 55+ 38* 35 28 29

4150 San Gorgonio Pass 30 34 38 28 -- -- -- -- -- -- -- -- -- -- -- -- --

4155 Norco/Corona 54 44 50 47 55 49 -- 45 41 38 32 37 40+ 34 36 27 28

4157 Coachella Valley 2** 52+ 51+ 49+ 48+ 53 52+ 50+ 51+ 50+ 39+ 46 53+ 54+ 40+ 33+ 29 33+

4163 Temecula Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

4164 Banning Airport -- -- -- 27 35 29 35 28 29 29 27 31 33 26 26 22 20

4165 Mira Loma -- -- -- -- -- -- -- -- -- -- -- 64 69 57 53 42 41

SAN BERNARDINO COUNTY:

5171 Southwest San Bernardino Valley 1 54 51 51 47 55 -- -- -- -- -- -- -- -- -- -- -- --

5181 Central San Bernardino Mountains 20 24 24 25 27 24 -- 37* 26* 26 26 26 26 24* 25 19 19

5197 Central San Bernardino Valley 1 61 55 54 50 60 53 51 50 47* 48 50 54 55+ 40 40 34 32

5203 Central San Bernardino Valley 2 57 53 51 46 57 50 52 50 45 49 42 46 51+ 43 42 32 32

5204 East San Bernardino Valley 48 46 43 41 47 46 47 41 37 39 33 36 40 29 30 26 26

5817 Southwest San Bernardino Valley 2 -- -- -- -- 66 50 52 45 43 43 41 42 43+ 39 36 32 31

District Maximum 69 61 65 56 72 60 63 59 57 56 52 64 69+ 57 53 42 41

 * Less than 12 full months of data.

** Salton Sea Air Basin

 + Excludes data flagged for exceptional events Refer to 2003 AQMP for 1985-1994 data

 # Federal Reference Method (FRM) filter data only
Appendix II – Attachment A

II-A-11

TABLE A-7

Particulate Matter (PM10)#– Percent of Sampling Days Exceeding State (50 μg/m3)

and Federal (150 μg/m3) 24-Hour Standards

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

060 East San Gabriel Valley 1 40/2 41/0 40/0 28/0 58/0 42/0 38/0 40/0 35/0 15/0 22/0 12/0 20/0+ 27/0 14/0 9/0 15/0

069 East San Fernando Valley 25/0 25/0 30/0 15/0 35/0 23/0 23/0 12/0 14/0* 12/0 8/0 19/0 19/0 13/0 18/0 2/0 4/0

072 South Coast Los Angeles County 1 19/0 15/0 18/0 10/0 22/0 21/0 17/0 9/0 7/0 7/0 9/0 10/0 9/0+ 2/0 5/0 0/0 0/0

077 South Coast Los Angeles County 2 -- -- -- -- -- -- -- -- -- 20/0 31/0 33/0 38/0+ 16/0 9/0 3/0 0/0

087 Central Los Angeles 23/0 18/0 25/0 17/0 33/0 25/0 33/0 15/0 10/0 8/0 7/0 5/0 9/0 4/0 7/0 0/0 2/0

090 Santa Clarita Valley 14/0 9/0 9/0 6/0 21/0 7/0 7/0 12/0 16/0 3/0 2/0 2/0 9/0+ 4/0 2/0 0/0 0/0

094 Southwest Coastal Los Angeles County 1 21/0 8/0 7/0 12/0 10/0 16/0 14/0 20/0 5/0 13/0* -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- 0/0* 0/0 0/0 5/0 0/0 2/0 0/0 0/0

ORANGE COUNTY:

3176 Central Orange County 1 23/2 10/0 18/0 20/0 39/0 13/0 20/0 8/0 10/0 12/0 5/0 13/0 9/0+ 5/0 2/0 0/0 3/0

3186 Saddleback Valley 1 18/0 7/0 7/0 10/0 10/0 3/0 -- -- -- -- -- -- -- -- -- -- --

3812 Saddleback Valley 2 -- -- -- -- 3/0 3/0 5/0 8/0 4/0 0/0 0/0 2/0 5/0 0/0 2/0 0/0 0/0

RIVERSIDE COUNTY:

4137 Coachella Valley 1** 4/0 3/0 2/0 5/0 5/0 0/0 2/0+ 5/0 7/0 3/0 3/0 4/0+ 11/0 9/0+* 2/0 0/0 0/0+

4144 Metropolitan Riverside County 1 62/7 68/2 70/2 54/0 72/2 70/0 67/0 69/0 57/2 61/0 56/0 60/0 57/0+ 41/0 29/0 6/0 13/0

4149 Perris Valley 38/0 33/0 32/0 26/0 50/0 22/0 27/0 39/0 33/0 25/0 32/0 35/0 56/0+ 27/0* 16/0 2/0 5/0

4150 San Gorgonio Pass 12/0 19/0 25/0 9/0 -- -- -- -- -- -- -- -- -- -- -- -- --

4155 Norco/Corona 47/3 33/0 42/2 40/0 55/0 48/0 33/0 34/0 26/0 19/0 9/0 18/0 17/0+ 15/0 12/0 0/0 3/0

4157 Coachella Valley 2** 44/2 50/0+ 43/0+ 40/0+ 54/0 50/0+ 45/0+ 45/0+* 42/0+ 20/0+* 34/0 50/0+ 61/0+ 22/0+ 8/0+ 5/0 2/0+

4163 Temecula Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

4164 Banning Airport -- -- -- 4/0 12/0 8/0 13/2 11/0 15/0 12/0 3/0 15/0 15/0 2/0 2/0 2/0 2/0

4165 Mira Loma -- -- -- -- -- -- -- -- -- -- -- 70/0 75/0+ 57/0 56/0 42/0 42/0

SAN BERNARDINO COUNTY:

5171 Southwest San Bernardino Valley 1 51/5 53/0 36/2 34/0 56/0 -- -- -- -- -- -- -- -- -- -- -- --

5181 Central San Bernardino Mountains 2/0 0/0 0/0 0/0 0/0 0/0 -- 19/0 0/0* 2/0 0/0 2/0 4/0 0/0* 2/0 0/0 0/0

5197 Central San Bernardino Valley 1 57/3 57/0 48/0 47/0 61/0 52/0 57/0 53/0 54/0* 48/0 48/0 52/0 59/0+ 23/0 22/0 17/0 7/0

5203 Central San Bernardino Valley 2 53/0 58/0 45/0 38/0 56/0 53/0 52/0 56/0 39/0 48/0 38/0 42/0 49/0+ 32/0 21/0 5/0 5/0

5204 East San Bernardino Valley 41/2 42/0 38/0 32/0 40/0 44/0 45/0 32/0 26/0 33/0 21/0 20/0 32/0 7/0 3/0 2/0 3/0

5817 Southwest San Bernardino Valley 2 -- -- -- -- 67/2 45/0 42/2 41/0 29/0 29/0 32/0 27/0 24/0+ 24/0 15/0 5/0 5/0

 * Less than 12 full months of data

** Salton Sea Air Basin # Federal Reference Method (FRM) filter data only

 + Excludes data flagged for exceptional events Refer to 2003 AQMP for 1985-1994 data
Final 2012 AQMP Appendix II: Current Air Quality

II-A-12

TABLE A-8

Particulate Matter (PM10)#– Annual Maximum 24-Hour Average (μg/m3)

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

060 East San Gabriel Valley 1 157 100 116 87 103 94 106 91 119 83 76 81 83+ 98 74 70 65

069 East San Fernando Valley 135 110 92 75 82 74 86 71 81* 74 92 71 109 66 80 51 61

072 South Coast Los Angeles County 1 146 113 87 69 79 105 91 74 63 72 66 78 75+ 62 62 44 43

077 South Coast Los Angeles County 2 -- -- -- -- -- -- -- -- -- 83 131 117 123+ 81 83 76 50

087 Central Los Angeles 141 138 102 80 88 80 97 65 81 72 70 59 78 66* 72 42 53

090 Santa Clarita Valley 87 91 67 60 75 64 62 61 72 54 55 53 131+ 91 56 40 45

094 Southwest Coastal Los Angeles County 1 136 107 79 66 69 74 75 121 58 52* -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- 47* 44 45 128 50 52 37 41

ORANGE COUNTY:

3176 Central Orange County 1 172 101 91 81 122 126 93 69 96 74 65 104 75+ 61+ 63 43 53

3186 Saddleback Valley 1 122 79 86 70 111 60 -- -- -- -- -- -- -- -- -- -- --

3812 Saddleback Valley 2 -- -- -- -- 56 98 60 80 64 47 41 57 74 42 56 34 48

RIVERSIDE COUNTY:

4137 Coachella Valley 1** 68 130 63 72 104 44 53+ 75 108 79 66 73+ 83 75+* 140 37 42+

4144 Metropolitan Riverside County 1 219 162 163 116 153 139 136 130 164 137 123 109 118+ 115 77 75 82

4149 Perris Valley 145 87 139 98 112 87 86 100 142 83 80 125 120+ 85* 80 51 65

4150 San Gorgonio Pass 138 122 227 76 -- -- -- -- -- -- -- -- -- -- -- -- --

4155 Norco/Corona 177 94 158 93 136 129 109+ 78 116 76 79 74 93+ 86 79 50 60

4157 Coachella Valley 2** 199 117+ 144+ 114+ 119 114+ 149+ 139+ 124+ 83+ 106 122+ 146+ 128+ 132+ 107 106+

4163 Temecula Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

4164 Banning Airport -- -- -- 62 86 69 219 70 79 82 76 75 78 51 99 55 51

4165 Mira Loma -- -- -- -- -- -- -- -- -- -- -- 124 142 135 108 89 79

SAN BERNARDINO COUNTY:

5171 Southwest San Bernardino Valley 1 167 129 208 92 112 -- -- -- -- -- -- -- -- -- -- -- --

5181 Central San Bernardino Mountains 53 45 47 45 47 49 -- 52* 47* 52 49 63 89 41* 57 39 43

5197 Central San Bernardino Valley 1 178 130 122 101 116 108 106 102 101* 106 108 142 111+ 75 75 62 84

5203 Central San Bernardino Valley 2 148 136 108 114 134 108 106 94 98 118 72 92 136+ 76 66 63 56

5204 East San Bernardino Valley 172 128 103 97 92 109 102 83 92 88 61 103 97 58 52 57 71

5817 Southwest San Bernardino Valley 2 -- -- -- -- -- 124 166 91 149 93 74 78 115+ 90 70 87 70

District Maximum 219 162 227 116 153 139 219 139 164 137 131 142+ 146+ 135 140 107 106

 * Less than 12 full months of data.

** Salton Sea Air Basin # Federal Reference Method (FRM) filter data only

 + Excludes data flagged for exceptional events Refer to 2003 AQMP for 1985-1994 data
Appendix II – Attachment A

II-A-13

TABLE A-9

Fine Particulate Matter (PM2.5)

#

– Annual Arithmetic Mean (μg/m3)

STN# LOCATION 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

060 East San Gabriel Valley 23.9 20.2 21.7 21.0 19.3 18.3 17.0 15.5 15.9 14.1 13.2 10.9 12.1

069 East San Fernando Valley 22.9 21.4 24.8 24.0 22.1 19.1 17.9 16.6 16.8 14.1 14.4 12.6 13.2

072 South Coastal Los Angeles County 1 20.7 19.6 21.2 19.5 18.0 17.9 16.0 14.2 14.6 14.2 13.0 10.6 11.0

074 West San Fernando Valley 17.3 18.0 18.4 18.9 16.5 15.6 13.9 12.9 13.1 11.9 11.4 10.3 10.2

077 South Coastal Los Angeles County 2 -- -- -- -- 20.5 16.5 14.7 14.5 13.7 13.7 12.5 10.4 10.7

084 South Central Los Angeles County1 24.3 23.0 24.5 23.3 20.3 18.5 17.5 16.7 15.9 15.5 -- -- --

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- 14.7 12.6 13.0

085 South San Gabriel Valley 25.7 24.0 25.4 24.0 20.6 20.0 17.0 16.7 16.7 15.1 14.8 12.6 12.5

087 Central Los Angeles 23.0 21.9 22.9 22.1 21.4 19.7 18.1 15.6 16.8 15.7 14.3 11.9 13.0

088 West San Gabriel Valley 19.9 19.4 20.9 20.3 18.6 16.6 15.1 13.4 14.3 12.9 12.3 10.4 10.9

ORANGE COUNTY:

3176 Central Orange County 26.0 20.3 22.0 18.6 17.3 17.0 14.7 14.1 14.5 13.6 11.7 10.2 11.0

3812 Saddleback Valley 16.6 14.7 15.8 15.5 13.1 12.0 10.7 11.0 11.3 10.3 9.4 8.0 8.5

RIVERSIDE COUNTY:

4137 Coachella Valley 1** -- 9.7 10.7 10.0 9.0 8.9 8.4 7.7 8.7 7.2 6.6 6.0 6.0

4144 Metropolitan Riverside County 1 30.2 28.3 31.0 27.4 24.8 22.1 21.0 19.0 19.1 16.5 15.3 13.2 13.6

4146 Metropolitan Riverside County 2 26.7 25.3 28.2 27.1 22.6 20.8 18.0 17.0 18.1 13.4 13.5 11.1 11.8

4157 Coachella Valley 2** 12.8 11.2 12.2 12.0 11.4 10.7 10.5 9.5 9.8 8.4 8.0 6.9 7.2

4165 Mira Loma -- -- -- -- -- -- -- 20.6 21 18.2 16.8 15.2 15.3

SAN BERNARDINO COUNTY:

5197 Central San Bernardino Valley 1 25.7 24.5 24.9 24.3 22.1 19.9 18.9 17.6 19 15.4 14.2 12.1 12.6

5203 Central San Bernardino Valley 2 25.6 25.9 26.1 25.8 22.2 21.9 17.4 17.8 18.3 13.5 12.9 11.3 12.2

5817 Southwest San Bernardino Valley 25.4 24.1 26.5 25.4 23.8 20.9 18.8 18.5 17.9 15.6 14.8 12.9 13.2

5818 East San Bernardino Mountains 10.3 10.2 11.2 11.5 10.6 9.7 12.1 11.2 10.4 9.2 9.9 8.5 8.4

District Maximum 30.2 28.3 31.0 27.4 24.8 22.1 21.0 20.6 21.0 18.2 16.8 15.2 15.3

* Less than 12 full months of data.

** Salton Sea Air Basin

 # Federal Reference Method (FRM) filter data only
Final 2012 AQMP Appendix II: Current Air Quality

II-A-14

TABLE A-10

Fine Particulate Matter (PM2.5)

#

– Percent of Sampling Days Exceeding the Federal Standard (35 μg/m3)

##

STN# LOCATION 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

060 East San Gabriel Valley 17 9 14 12 9 8 6* 3* 7 2 4 1 2

069 East San Fernando Valley 18 14* 16 19 14 10 8 6 9 2 2 1 2

072 South Coastal Los Angeles County 1 9 11* 14 9 7 7 4 2* 4 2 2 0 0

074 West San Fernando Valley 8* 8 7 10 7 4 4 1 1 2 1 1 1

077 South Coastal Los Angeles County 2 -- -- -- -- 10 5 2 2 2 2 1 0 1

084 South Central Los Angeles County 1 18 14 16 18 9 7 7 4 4 3 -- -- --

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- 3 1 0

085 South San Gabriel Valley 20 13 22 19 9 9 9* 6 5 4 2 0 1

087 Central Los Angeles 15 13 15 13 14 7 7 3 6 3 2 1 1

088 West San Gabriel Valley 9* 6 8 11 10 6 4 1 3 2 3 0 1

ORANGE COUNTY:

3176 Central Orange County 17 14* 16* 9 7 6 4 2 4 4 1 0 1

3812 Saddleback Valley 4* 4 5 3 3 3 0 1 2 0 1 0 0

RIVERSIDE COUNTY:

4137 Coachella Valley 1** -- 0 1 1 0 0 0* 0 0 0 0 0 0

4144 Metropolitan Riverside County 1 30 26* 33 25 21 15 11 11 11 4 4 1 1

4146 Metropolitan Riverside County 2 25 22 23 24 19 13 5 9 8 3 2 2 2

4157 Coachella Valley 2** 0* 0 0 0 0 0 2 0 0 0 0 0 0

4165 Mira Loma -- -- -- -- -- -- -- 12 12 9 6 2 3

SAN BERNARDINO COUNTY:

5197 Central San Bernardino Valley 1 17 19 15 19 14 14 6 6 9 5 2 2 2

5203 Central San Bernardino Valley 2 21 21* 23 24 15 15 3 8 11 3 2 2 2

5817 Southwest San Bernardino Valley 22 14 21 18 17 13 7 7 6 5 3 1 2

5818 East San Bernardino Mountains -- 0 0 0 0 0 4 2* 2 2 2 0 0

District Maximum 30 22 33 25 21 15 11 12 12 9 6 2 3

 * Less than 12 full months of data.

** Salton Sea Air Basin

 # Federal Reference Method (FRM) filter data only

## Effective December 17, 2006, U.S. EPA has strengthen the standard level from 65 μg/m3to 35 μg/m3
Appendix II – Attachment A

II-A-15

TABLE A-11

Fine Particulate Matter (PM2.5)

#

– Annual Maximum 24-Hour Average (μg/m3)

STN# LOCATION 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

060 East San Gabriel Valley 81.3 92.5 79.7 72.4 121.2 75.6 132.7* 52.8* 63.8 53.1 72.1 44.4 49.5

069 East San Fernando Valley 79.5 84.4* 94.7 63.0 120.6 60.1 63.2 50.7 56.5 57.5 67.5 43.7 47.8

072 South Coastal Los Angeles County 1 66.9 81.5* 72.9 62.7 115.2 66.6 53.9 58.5* 82.9 57.2 63 35 39.7

074 West San Fernando Valley 79.0* 67.5 71.1 48.8 47.5 56.2 39.6 44.1 43.3 50.5 39.9 40.7 39.8

077 South Coastal Los Angeles County 2 -- -- -- -- -- 59.7 50.8 53.6 68 60.9 55.8 33.7 42.0

084 South Central Los Angeles County 1 67.8 82.1 73.1 64.0 54.8 55.8 54.6 55 49 44.2 -- -- --

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- 69.2 38.2 35.3

085 South San Gabriel Valley 85.6 89.5 77.3 61.0 90.3 60.7 58.2* 72.2 63.6 47.3 71.1 34.9 41.2

087 Central Los Angeles 69.3 87.8 73.4 66.3 83.7 75.0 73.7 56.2 64.2 78.3 61.7 39.2 49.3

088 West San Gabriel Valley 73.0* 66.3 78.1 57.8 89.0 59.4 62.9 45.9 68.9 66 52 35.2 43.8

ORANGE COUNTY:

3176 Central Orange County 68.7 113.9* 70.8* 68.6 115.5 58.9 54.7 56.2 79.4 67.9 64.6 31.7 39.2

3812 Saddleback Valley 56.6* 94.7 53.4 58.5 50.6 49.4 35.4 47 46.9 32.6 39.2 19.9 33.4

RIVERSIDE COUNTY:

4137 Coachella Valley 1** -- 28.5 44.7 42.3 21.2 27.1 26.2* 24.8 32.5 18.1 21.8 12.8 26.3

4144 Metropolitan Riverside County 1 111.2 119.6* 98.0 77.6 104.3 91.7 98.7 68.5 75.7 57.7 54.5 46.5 60.8

4146 Metropolitan Riverside County 2 90.0 79.3 74.9 75.5 73.3 93.8 95.0 55.3 68.6 43 42.2 43.7 51.6

4157 Coachella Valley 2** 29.6* 28.6 33.5 26.8 26.8 28.5 44.4 24.3 26.8 21.6 27.5 16.0 35.4

4165 Mira Loma -- -- -- -- -- -- -- 63.0 69.7 50.9 49.2 54.2 56.3

SAN BERNARDINO COUNTY:

5197 Central San Bernardino Valley 1 98.0 72.9 74.8 66.6 98.1 71.4 96.8 52.6 77.5 49 46.4 42.6 60.1

5203 Central San Bernardino Valley 2 121.5 89.8* 78.5 82.1 73.9 93.4 106.3 55 72.1 43.5 37.8 39.3 65.0

5817 Southwest San Bernardino Valley 85.8 73.4 71.2 64.8 88.9 86.1 87.8 53.7 72.8 54.2 46.9 46.1 52.9

5818 East San Bernardino Mountains 32.1 29.0 34.6 34.1 35.0 28.6 38.8 40.1* 45.4 36.8 40.8 35.4 30.6

District Maximum 121.5 119.6 98.0 82.1 121.2 93.8 132.7 72.2 82.9 78.3 72.1 54.2 60.8

 * Less than 12 full months of data.

** Salton Sea Air Basin

 # Federal Reference Method (FRM) filter data only
Final 2012 AQMP Appendix II: Current Air Quality

II-A-16

TABLE A-12

Fine Particulate Matter (PM2.5)

#

– Annual 24-Hour Average 98th Percentile Concentration (μg/m3)

STN# LOCATION 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

060 East San Gabriel Valley 64 62 61 51 56 54 53 39 49 35 43 35 31

069 East San Fernando Valley 50 83 69 55 60 49 51 43 48 35 34 33 34

072 South Coastal Los Angeles County 1 51 64 49 47 47 46 41 35 41 36 34 28 28

074 West San Fernando Valley 40 50 57 45 45 53 36 32 33 26 27 30 24

077 South Coastal Los Angeles County 2 -- -- -- -- 53 42 38 35 34 35 30 27 27

084 South Central Los Angeles County1 53 63 66 53 52 53 48 45 46 37 -- -- --

112 South Cenral Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- 38 32 32

085 South San Gabriel Valley 60 71 67 58 50 52 54 43 50 38 35 32 32

087 Central Los Angeles 52 73 58 55 61 50 53 39 51 40 34 27 32

088 West San Gabriel Valley 60 54 55 49 48 47 43 32 45 32 36 25 26

ORANGE COUNTY:

3176 Central Orange County 66 66 59 48 52 48 42 41 47 39 32 25 28

3812 Saddleback Valley 45 37 46 46 38 39 31 26 35 27 24 17 29

RIVERSIDE COUNTY:

4137 Coachella Valley 1** 23 33 23 20 23 25 16 21 17 15 13 13

4144 Metropolitan Riverside County 1 79 77 74 66 77 60 58 54 54 41 40 32 31

4146 Metropolitan Riverside County 2 62 67 66 64 56 54 41 48 57 39 34 27 28

4157 Coachella Valley 2** 30 26 30 22 25 27 25 19 27 19 17 12 16

4165 Mira Loma -- -- -- -- -- -- -- 53 60 47 41 36 37

SAN BERNARDINO COUNTY:

5197 Central San Bernardino Valley 1 66 65 70 57 54 63 48 44 65 47 33 31 28

5203 Central San Bernardino Valley 2 72 70 68 66 58 72 43 48 68 41 35 30 33

5817 Southwest San Bernardino Valley 86 65 65 57 67 60 50 42 53 45 36 31 35

5818 East San Bernardino Mountains 31 27 30 32 29 23 37 40 34 33 29 28 31

District Maximum 86 83 74 66 77 72 58 54 68 47 43 36 37

 * Less than 12 full months of data.

** Salton Sea Air Basin

 # Federal Reference Method (FRM) filter data only
Appendix II – Attachment A

II-A-17

TABLE A-13

Carbon Monoxide – Annual Maximum 8-Hour Average (ppm)

(To Be Compared to Federal Standard (9 ppm) and State Standard (9.0 ppm), 8-Hour Average)

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

060 East San Gabriel Valley 1 6.3 4.0 4.3 3.9 3.9 4.9 2.9 2.4 2.6 2 1.7 1.7 1.8 1.6 1.7 1.3 1.4

069 East San Fernando Valley 12.0 9.3 7.4 7.5 9.0 6.1 4.9 4.6 4.7* 3.7 3.4 3.5 2.8 2.6 2.9 2.4 2.4

072 South Coastal Los Angeles County 6.6 6.9 6.7 6.6 5.4 5.8 4.7 4.6 4.7 3.4 3.5 3.4 2.6 2.6 2.2 2.1 2.6

074 West San Fernando Valley 10.3 8.5 9.8 9.3 7.6 9.8 6.0 4.8 4.1 3.5 3.5 3.4 2.8 2.9 2.8 2.6 2.8

075 Pomona/Walnut Valley 6.1 5.0 5.0 7.3 6.7 4.9 3.4 3.3 4.4 3.1 2.5 2.1 2 2 1.8 1.8 1.6

084 South Central Los Angeles County 1 13.86 17.3 17.0 13.4 11.0 10.0 7.7 10.1 7.3 6.7 5.9 6.4 5.1 4.3* -- -- --

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4.6 3.6 4.7

085 South San Gabriel Valley 7.86 8.1 6.2 6.1 5.6 5.3 4.0 4 4 3.6 2.4* 2.7* 2.9 2.1 2.1 1.9 2.4

087 Central Los Angeles 8.37 8.4 7.9 6.1 6.3 6.0 4.6 4 4.6 3.2 3.1 2.6 2.2 2.1 2.2 2.3 2.4

088 West San Gabriel Valley 9.12 7.1 6.0 6.3 6.6 7.4 5.0 4 3.8 3.4 2.8 2.8 2.3 2.1 2.1 2 2.2

090 Santa Clarita Valley 4.12 3.9 6.8 3.4 3.6 4.9 3.1 1.9 1.7 3.7 1.3 1.3 1.2 1.1 1.4 1.1 0.8

091 Northwest Coastal Los Angeles County 5.62 4.5 4.4 4.5 3.8 4.3 3.0 2.7 2.7 2.3 2.1 2 2 2 1.5 1.4 1.6

094 Southwest Coastal Los Angeles County 1 8.86 11.6 10.3 9.4 8.4 7.0 5.1 6.1 5 4.4* -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- 3.0* 2.1 2.3 2.4 2.5 1.9 2.2 1.8

591 East San Gabriel Valley 2 -- -- -- -- -- 3.1 2.5-- 2.3 2.1 2 1.9 2 2 3 2.1 1.3 1.1

ORANGE COUNTY:

3176 Central Orange County 8.00 7.5 5.8 5.3 5.3 6.8 4.7 5.4 3.9 4.1 3.3 3 2.9 3.6 2.7 2 2.1

3177 North Orange County 6.62 6.9 6.0 6.1 5.3 6.1 4.7 4.4 4.1 4 3.1 3 2.9 2.9 2.3 1.8 2.1

3186 Saddleback Valley 1 4.00 4.0 3.6 3.1 2.5 2.3 -- -- -- -- -- -- -- -- -- -- --

3195 North Coastal Orange County 6.57 7.3 5.8 7.0 6.4 6.3 4.6 4.3 5.8 4.1 3.2 3 3.1 2 2.2 2.1 2.2

3812 Saddleback Valley 2 -- -- -- -- -- 3.3 2.4 3.6 1.8 1.6 1.6 1.8 2.2 1.1 1 0.9 1

RIVERSIDE COUNTY:

4137 Coachella Valley 1** 1.50 1.6 1.4 1.6 1.8 1.6 1.5 1.2 1.3* 1 0.8 1 0.8 0.6 0.7 0.5 0.6

4144 Metropolitan Riverside County 1 5.71 5.0 5.8 4.6 4.4 4.3 3.4 3 3.7 3 2.5 2.1 2.9 2 1.9 1.8 1.4

4146 Metropolitan Riverside County 2 6.50 5.4 5.0 4.6 4.1 4.3 4.5 3.9 3.4 2.1 2.4 2.3 2.1 2 1.8 1.7 1.5

4157 Coachella Valley 2** -- -- -- -- -- 2.1 -- -- -- -- -- -- -- -- -- -- --

4158 Lake Elsinore -- -- -- -- -- 2.0 2.0 2 1.3* 0.9 1 1 1.4 1 0.7 0.6 0.7

4165 Mira Loma -- -- -- -- -- -- -- -- -- -- -- 2.7 2.1 1.9 2.4 1.9 1.9

SAN BERNARDINO COUNTY:

5175 Northwest San Bernardino Valley -- -- -- -- -- 2.6 1.8 1.6 2.9 2.1 1.8 1.8 1.7 1.6 1.5 1.8 1.3

5197 Central San Bernardino Valley 1 -- -- -- -- -- -- -- -- -- 2.1* 2.1 2 1.8 1.9 1.5 1.4 1.1

5203 Central San Bernardino Valley 2 6.3 4.6 6.0 4.6 4.0 4.3 3.3 3.3 4.6 3.3 2.4 2.3 2.3 1.8 1.9 1.7 1.7

District Maximum 13.9 17.3 17.0 13.5 11.7 10.0 7.7 10.1 7.3 6.7 5.9 6.4 5.1 4.3 4.6 3.6 4.7

 * Less than 12 full months of data.

** Salton Sea Air Basin

Refer to 2003 AQMP for 1976-1994 data
Final 2012 AQMP Appendix II: Current Air Quality

II-A-18

TABLE A-14

Nitrogen Dioxide – Annual Average (pphm)

(To Be Compared to Federal Standard (5.34 pphm) and State Standard (3.0 pphm), Annual Average of All Hours)

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

060 East San Gabriel Valley 1 4.64 4.15 3.38 3.64 3.90 3.66 3.31 3.36 2.96 2.04 2.51 2.58 2.53 2.3 1.94 1.85 1.9

069 East San Fernando Valley 4.54 4.61 4.24 4.16 4.56 4.15 4.19 4.02 3.56* 3.32 2.94 2.74 2.89 2.85 2.74 2.41 2.21

072 South Coastal Los Angeles County 3.67 3.42 3.33 3.39 3.42 3.13 3.08 2.98 2.88* 2.80 2.41 2.15 2.07 2.08 2.12 1.98 1.77

074 West San Fernando Valley 3.17 3.07 2.60 2.66 2.87 2.85 2.66 2.48 2.6* 2.14 2.02 1.74 1.86 1.8 1.71 1.67 1.49

075 Pomona/Walnut Valley 1 4.56 4.26 4.33 4.33 5.03 4.35 3.71 3.65 3.52 3.14 3.12 3.07 3.18 3.02 2.74 2.62 2.46

084 South Central Los Angeles County 1 4.63 4.12 4.28 3.93 4.28 3.86 3.69 3.57 3.12 3.01 -- 3.06 2.91 3.01* -- -- --

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 2.14 1.79 1.86

085 South San Gabriel Valley 4.56 3.93 3.63 3.69 3.91 3.66 3.52 3.44 3.53 3.05 3.12 2.83* 2.49 2.63 2.59 2.29 2.37

087 Central Los Angeles 4.50 4.36 4.30 3.98 3.91 4.04 3.78 3.27 3.38 3.28 3.08* 2.88 2.99 2.75 2.81 2.5 2.31

088 West San Gabriel Valley 3.75 3.78 3.41 3.51 3.79 2.96 3.45 3.35 3.22 2.70 2.78 2.45 2.46 2.35 2.21 1.96 2.03

090 Santa Clarita Valley 3.05 -- -- -- 2.84 2.46 2.39 2.00 2.21 2.04 2.41 1.84 1.96 1.65 1.51 1.43 1.33

091 Northwest Coastal Los Angeles County 2.78 2.89 2.85 2.71 2.91 2.73 2.51 2.49 2.31 1.98 1.90 1.73 2 1.84 1.7 1.56 1.39

094 Southwest Coastal Los Angeles County 1 3.05 2.85 2.80 2.95 2.95 2.75 2.50 2.44* 2.38 3.10* 1.78 -- -- -- -- -- --

820 Southwest Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- 1.36* 1.34 1.55 1.4 1.43 1.59 1.21 1.34

591 East San Gabriel Valley 2 3.80 3.28 3.00 2.76 3.28 2.90 2.74 2.72 2.71 2.40 2.24 2.06 2.27 1.82 1.7 1.54 1.29

ORANGE COUNTY:

3176 Central Orange County 3.71 3.19 3.32 3.36 3.27 3.00 2.93* 2.44 2.40 1.99 2.11 1.97 2.08 2.03 1.79 1.75 1.68

3177 North Orange County 3.91 3.54 3.29 3.44 3.51 3.04 2.75 2.56 2.84 2.52 2.49 2.24 2.19 2.06 2.06 2.01 1.681.

77

3195 North Coastal Orange County 2.39 2.06 1.99 2.00 2.09 2.05 1.82 1.87 1.99 1.51 1.31 1.45 1.32 1.32 1.3 1.13 1.00

RIVERSIDE COUNTY:

4137 Coachella Valley 1** 2.23 2.10 1.58 1.70 1.95 1.78 1.75 1.72 1.73* 1.30 1.20 1.03 1.03 0.93 0.81 0.85 0.8

4144 Metropolitan Riverside County 1 3.06 2.94 2.62 2.25 2.25 2.36 2.47 2.37 2.17 1.72 2.22 1.99 2.06 1.92 1.71 1.68 1.66

4146 Metropolitan Riverside County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- 2.58* 2 1.72 1.69

4157 Coachella Valley 2** -- -- -- -- -- 0.99 -- -- -- -- -- -- -- -- -- -- --

4158 Lake Elsinore 2.08 1.82 1.65 1.74 2.00 1.75 1.85 1.73 1.82* 1.51 1.42 1.51 1.74 1.29 1.29 1.01 0.96

4164 Banning Airport -- -- -- 2.15 2.43 2.37 2.11 1.99 1.93* 1.65 1.48 1.61 1.47 1.28 1.09 1.16 0.95

4165 Mira LOma -- -- -- -- -- -- -- -- -- -- -- 1.94 1.81 1.74 1.58 1.51 1.53

SAN BERNARDINO COUNTY:

5175 Northwest San Bernardino Valley 4.64 3.87 3.41 3.59 3.98 3.80 3.84 3.69 3.49 3.05 3.13 3.1 2.76 2.35 2.39 2.04 1.96

5197 Central San Bernardino Valley 1 4.24 3.86 3.65 3.62 3.88 3.64 3.58 3.34* 3.07 2.73 3.10 2.7 2.39 2.07 2.35 2.31 2.11

5203 Central San Bernardino Valley 2 4.04 3.84 3.53 3.39 3.58 3.25 3.03 2.96 2.70 2.61 2.59 2.52 2.45 2.17 1.96 1.88 1.69

District Maximum 4.64 4.61 4.33 4.33 5.03 4.35 4.19 4.02 3.56 3.32 3.13 3.10 3.18 3.02 2.81 2.62 2.46

* Less than 12 full months of data. ** Salton Sea Air Basin Refer to 2003 AQMP for 1976-1994 data
Appendix II – Attachment A

II-A-19

TABLE A-15

Nitrogen Dioxide – Annual Maximum 1-Hour Average (ppm)

(To Be Compared to Federal Standard (0.100 ppm) and State Standard (0.18 ppm), 1-Hour Average)

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

060 East San Gabriel Valley 1 0.22 0.15 0.16 0.14 0.16 0.15 0.12 0.12 0.12 0.10 0.09 0.11 0.12 0.10 0.10 0.077 0.080

069 East San Fernando Valley 0.18 0.20 0.20 0.14 0.18 0.17 0.25 0.26 0.14 0.12 0.09 0.10 0.09 0.11 0.09 0.082 0.068

072 South Coastal Los Angeles County 0.21 0.17 0.20 0.16 0.15 0.14 0.13 0.13 0.14 0.12 0.14 0.10 0.11 0.13 0.11 0.093 0.106

074 West San Fernando Valley 0.14 0.16 0.20 0.14 0.12 0.11 0.09 0.09 0.13 0.08 0.09 0.07 0.08 0.09 0.07 0.075 0.056

075 Pomona/Walnut Valley 1 0.18 0.18 0.15 0.15 0.16 0.14 0.13 0.11 0.12 0.11 0.08 0.10 0.10 0.11 0.10 0.097 0.087

084 South Central Los Angeles County 1 0.21 0.25 0.20 0.16 0.18 0.14 0.15 0.14 0.13 0.10 0.11 0.14 0.10 0.12* -- -- --

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0.09 0.077 0.075

085 South San Gabriel Valley 0.23 0.17 0.15 0.14 0.16 0.14 0.14 0.12 0.14 0.12 0.09 0.10* 0.11 0.10 0.10 0.079 0.091

087 Central Los Angeles 0.24 0.25 0.20 0.17 0.21 0.16 0.14 0.14 0.16 0.16 0.13 0.11 0.10 0.12 0.12 0.089 0.110

088 West San Gabriel Valley 0.22 0.19 0.17 0.16 0.16 0.17 0.15 0.15 0.14 0.12 0.10 0.12 0.09 0.11 0.08 0.071 0.087

090 Santa Clarita Valley 0.16 -- -- -- 0.10 0.10 0.10 0.10 0.12 0.09 0.09 0.08 0.08 0.07 0.06 0.059 0.060

091 Northwest Coastal Los Angeles County 0.20 0.18 0.14 0.13 0.13 0.16 0.11 0.11 0.12 0.09 0.08 0.08 0.08 0.09 0.08 0.071 0.081

094 Southwest Coastal Los Angeles County 1 0.18 0.15 0.17 0.15 0.13 0.13 0.11 0.10 0.12 0.08 -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- 0.09* 0.09 0.10 0.08 0.09 0.08 0.076 0.098

591 East San Gabriel Valley 2 0.20 0.14 0.13 0.13 0.14 0.13 0.12 0.10 0.12 0.12 0.09 0.10 0.11 0.10 0.09 0.079 0.078

ORANGE COUNTY:

3176 Central Orange County 0.18 0.15 0.10 0.13 0.12 0.13 0.12 0.10 0.13 0.12 0.09 0.11 0.10 0.09 0.07 0.073 0.074

3177 North Orange County 0.20 0.16 0.15 0.13 0.16 0.12 0.13 0.12 0.16 0.12 0.09 0.09 0.08 0.08 0.10 0.083 0.070

3195 North Coastal Orange County 0.18 0.14 0.12 0.12 0.12 0.11 0.08 0.11 0.11 0.10 0.09 0.10 0.07 0.08 0.07 0.070 0.061

RIVERSIDE COUNTY:

4137 Coachella Valley 1** 0.09 0.08 0.07 0.07 0.07 0.07 0.08 0.10 0.06 0.07 0.10 0.09 0.06 0.05 0.05 0.046 0.045

4144 Metropolitan Riverside County 1 0.15 0.11 0.12 0.10 0.13 0.10 0.15 0.10 0.09 0.09 0.08 0.08 0.07 0.09 0.08 0.065 0.063

4146 Metropolitan Riverside County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- 0.09* 0.08 0.061 0.057

4157 Coachella Valley 2** -- -- -- -- -- 0.06 -- -- -- -- -- -- -- -- -- -- --

4158 Lake Elsinore 0.21 0.10 0.11 0.09 0.11 0.08 0.09 0.07 0.08 0.06 0.07 0.07 0.06 0.06 0.06 0.051 0.050

4164 Banning Airport -- -- -- 0.26 0.31 0.21 0.24 0.15 0.09 0.08 0.07 0.11 0.08 0.08 0.06 0.066 0.061

4165 Mira Loma -- -- -- -- -- -- -- -- -- -- -- 0.08 0.07 0.10 0.08 0.062 0.059

SAN BERNARDINO COUNTY:

5175 Northwest San Bernardino Valley 0.20 0.15 0.15 0.14 0.13 0.15 0.13 0.12 0.11 0.11 0.10 0.10 0.10 0.09 0.11 0.079 0.069

5197 Central San Bernardino Valley 1 0.17 0.17 0.14 0.15 0.15 0.12 0.13 0.12* 0.12 0.06 0.10 0.09 0.09 0.10 0.11 0.072 0.076

5203 Central San Bernardino Valley 2 0.16 0.15 0.14 0.11 0.14 0.10 0.11 0.11 0.10 0.12 0.0.08 0.09 0.08 0.09 0.08 0.069 0.062

District Maximum 0.24 0.25 0.2 0.26 0.31 0.21 0.25 0.26 0.16 0.16 0.14 0.14 0.12 0.13 0.12 0.097 0.110

* Less than 12 full months of data. ** Salton Sea Air Basin Refer to 2003 AQMP for 1976-1994 data
Final 2012 AQMP Appendix II: Current Air Quality

II-A-20

TABLE A-16

Sulfur Dioxide – Annual Maximum 1-Hour Average (ppm)

(To Be Compared to Federal Standard (0.075 ppm) and State Standard (0.25 ppm), 1-Hour Average)

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

 60 East San Gabriel Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

 69 East San Fernando Valley 0.01 0.01 0.04 0.01 0.01 0.01 0.01 0.01 0.01* 0.02 0.01 0.01 0.01 0.01 0.01 0.015 0.009

 72 South Coastal Los Angeles County 0.14 0.04 0.04 0.08 0.05 0.05 0.05 0.03 0.03 0.04 0.04 0.03 0.11 0.09 0.02 0.040 0.015

 74 West San Fernando Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

 84 South Central Los Angeles County 0.03 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

 85 South San Gabriel Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

 87 Central Los Angeles 0.01 0.01 0.02 0.14 0.05 0.08 0.03 0.02 0.05* 0.08 0.07

0.03 0.01 0.01 0.01 0.010

0.0200

.012

 88 West San Gabriel Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

 90 Santa Clarita Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

 91 Northwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

 94 Southwest Coastal Los Angeles County 1 0.06 0.06 0.1 0.03 0.09 0.17 0.04 0.07 0.03 0.03* -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- 0.02* 0.04 0.02 0.02 0.02 0.02 0.026 0.012

ORANGE COUNTY:

3176 Central Orange County 1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

3177 North Orange County 0.02 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

3190 Central Orange County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

3195 North Coastal Orange County 0.02 0.01 0.03 0.02 0.02 0.02 0.01 0.03 0.02 0.03 0.01 0.01 0.01 0.01 0.01 0.010 0.008

RIVERSIDE COUNTY:

4144 Metropolitan Riverside County 0.01 0.01 0.04 0.03 0.03 0.11 0.02 0.02 0.02 0.02 0.02 0.01 0.02 0.01 0.01 0.018 0.051

SAN BERNARDINO COUNTY:

5175 Northwest San Bernardino Valley -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

5197 Central San Bernardino Valley 1 0.02 0.01 0.01 0.02 0.01 0.02 0.01 0.03* 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.007 0.012

5203 Central San Bernardino Valley 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

District Maximum 0.14 0.06 0.1 0.14 0.09 0.17 0.05 0.07 0.05 0.08 0.07 0.03 0.11 0.09 0.02 0.04 0.051

 * Less than 12 full months of data.

** Salton Sea Air Basin

Refer to 2003 AQMP for 1976-1994 data
Appendix II – Attachment A

II-A-21

TABLE A-17

Sulfate (PM10) – Annual Maximum 24-Hour Average (μg/m3)

(To Be Compared to State Standard of 25 μg/m3, 24-Hour Average)

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

 60 East San Gabriel Valley 12.7 11.9 12.9 10.5 16.9 14.3 12.7 12.3 13.1 10.8 10.8 17.0 34.2 17.3 7.3 7.3 6.6

 69 East San Fernando Valley 14.9 12.0 14.7 9.8 11.4 15.7 14.6 12.2 15.3 11.0 11.8 13.3 10.2 10.8 8.8 8.0 7.4

 72 South Coastal Los Angeles County 1 18.2 14.9 11.3 12.8 13.1 11.9 15.0 14.4 15.6 14.7 10.8 16.5 10.3 9.7 9.5 10.0 6.1

 77 South Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- 15.0 15.9 13.5 17.9 8.4 11.0 7.3 12.6 5.9

 87 Central Los Angeles 16.2 14.7 16.2 10.3 16.7 14.6 16.2 13.5 14.5 10.5 11.7 13.1 9.4 12.7 9.5 7.5 8.0

 89 Santa Clarita Valley 1 11.2 8.4 10.4 7.2 17.3 -- -- -- -- -- -- -- -- -- -- -- --

 90 Santa Clarita Valley 2 -- -- -- -- -- -- 9.2 9.2 11.2 8.9 9.3 8.8 9.2 6.7 6.0 6.9 6.1

 94 Southwest Coastal Los Angeles County1 18.1 16.1 15.3 11.6 17.6 -- -- -- -- -- -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- 12.6 11.0 12.4 10.7 13.4 8.4 8.5 5.9

ORANGE COUNTY:

3176 Central Orange County 1 14.5 17.3 14.7 12.9 9.6 -- 9.9 11.8 11.3 12.2 9.0 12.8 12.1 8.7 7.6 6.6 6.5

3186 Saddleback Valley 1 12.3 15.1 14.2 9.1 8.8 -- -- -- -- -- -- -- -- -- -- -- --

3812 Saddleback Valley 2 -- -- -- -- 8.6 12.3 10.1 10.9 10.5 9.2 9.2 9.4 8.8 6.8 6.1 7.4 4.8

RIVERSIDE COUNTY:

4137 Coachella Valley 1** 6.8 5.7 5.9 5.5 5.4 6.2 6.0 5.3 6.5 5.2 5.5 4.9 5.8 5.2 4.8 5.1 4.4

4144 Metropolitan Riverside County 1 22.3 14.9 14.8 10.0 11.1 10.7 11.3 10.5 12.4 24.8 10.5 10.9 13.7 7.3 8.3 7.2 5.3

4149 Perris Valley 13.5 8.0 9.1 7.9 8.7 7.4 8.3 7.9 6.9 7.8 7.7 9.0 10.1 6.5 6.3 5.8 4.4

4150 San Gorgonio Pass 7.3 8.5 8.7 6.5 2.7 -- -- -- -- -- -- -- -- -- -- -- --

4155 Norco/Corona 13.6 11.3 13.1 9.8 10.1 11.0 10.2 10.5 9.9 10.1 7.1 10.7 18.9 13.4 10.7 7.0 5.1

4157 Coachella Valley 2** 10.4 6.7 5.8 5.4 4.9 6.9 7.5 7.2 6.2 6.7 6.1 5.4 5.2 5.6 5.1 4.8 5.7

4164 Banning Airport 6.1 4.6 6.9 6.4 8.0 5.8 6.7 7.1 7.5 6.2 6.3 5.4 5.5 4.4

4165 Mira Loma Van Buren -- -- -- -- -- -- -- -- -- -- -- 10.1 19.6 8.6 5.9 5.3 5.4

SAN BERNARDINO COUNTY:

5181 Central San Bernardino Mountains 4.8 5.2 4.7 4.5 3.0 5.1 5.2 4.0 3.7 4.7 5.9 4.2 3.9 4.4 3.9 4.7 4.0

5197 Central San Bernardino Valley 1 14.2 11.0 11.2 9.8 11.6 11.6 11.3 11.6 12.4 10.2 9.0 11.7 22.2 8.9 6.1 6.2 6.0

5203 Central San Bernardino Valley 2 11.9 11.6 9.2 13.1 10.8 10.6 10.3 10.8 11.4 10.4 9.3 10.0 9.7 8.3 5.6 6.6 5.5

5204 East San Bernardino Valley 11.3 9.9 8.8 9.6 9.8 10.2 9.0 9.7 9.0 10.5 8.6 11.7 11.3 7.4 5.4 6.6 4.9

5817 Southwest San Bernardino Valley -- -- -- 4.6 10.1 10.2 11.4 10.7 11.0 11.1 9.3 11.2 22.8 12.4 7.0 7.3 5.5

District Maximum 22.3 17.3 16.2 13.1 17.6 15.7 16.2 14.4 15.6 24.8 13.5 17.9 34.2 17.3 10.7 12.6 8.0

 * Less than 12 full months of data.

** Salton Sea Air Basin

Refer to 2003 AQMP for 1976-1994 data
Final 2012 AQMP Appendix II: Current Air Quality

II-A-22

TABLE A-18

Lead (TSP) – Annual Maximum Calendar Quarter Mean (μg/m3)

(To Be Compared to Former Federal Standard of 1.5 μg/m3, Calendar Quarter Average)

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

 69 East San Fernando Valley 0.04 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

 72 South Coastal Los Angeles County 1 0.04 0.08 0.03 0.04 0.05 0.04 0.04 0.02 0.05 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

 77 South Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- 0.01 0.01 0.01 0.01 0.01 0.01

 84 South Central Los Angeles County 1 0.06 0.05 0.07 0.04 0.09 0.06 0.10 0.04 0.04 0.03 0.02 0.02 0.03 0.02* -- -- --

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- 0.01* 0.02 0.01 0.01

 85 South San Gabriel Valley 0.06 0.06 0.06 0.05 0.09 0.06 0.05 0.05 0.04 0.02 0.03 0.02 0.02 0.02 0.02 0.01 0.01

 87 Central Los Angeles 0.06 0.06 0.07 0.04 0.07 0.05 0.05 0.03 0.03 0.03 0.02 0.01 0.03 0.02 0.01 0.01 0.01

 94 Southwest Coastal Los Angeles County 0.04 0.03 0.05 0.04 0.04 0.05 0.04 0.02 0.03 0.01 -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- -- -- 0.01 0.01 0.01 0.01 0.01 0.01

LOS ANGELES COUNTY (Source-Specific):

 Van Nuys Airport, Van Nuys -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0.03 0.04

 Trojan Battery, Santa Fe Springs -- -- -- -- -- -- -- -- -- -- -- -- -- 0.08 0.10 0.07 0.08

 Quemetco, City of Industry -- -- -- -- -- -- -- -- -- -- -- -- -- 0.06* 0.10 0.10 0.06

 Exide (Rehrig), Vernon -- -- -- -- -- -- -- -- -- -- -- -- -- 2.41 0.48 0.39 0.45

 Exide (ATSF), Vernon -- -- -- -- -- -- -- -- -- -- -- 0.21 0.52 0.22 0.08 0.05 0.06

 Exide (Ayers St.), Vernon -- -- -- -- -- -- -- -- -- -- -- -- -- 0.03 0.02 0.02

ORANGE COUNTY:

3176 Central Orange County 0.04 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

RIVERSIDE COUNTY:

4144 Metropolitan Riverside County 1 0.04 0.04 0.04 0.04 0.05 0.05 0.03 0.02 0.02 0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01

4146 Metropolitan Riverside County 2 0.03 0.03 0.04 0.05 0.04 0.03 0.03 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

SAN BERNARDINO COUNTY:

5175 Northwest San Bernardino Valley 0.04 0.04 0.04 0.04 0.05 0.05 0.04 0.02 0.02 0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01

5203 Central San Bernardino Valley 0.04 0.04 0.04 0.03 0.05 0.05 0.04 0.02 0.08 0.01 0.01 0.01 0.02 0.02 0.01 0.01 0.01

District Maximum 0.06 0.08 0.07 0.05 0.09 0.06 0.10 0.05 0.08 0.03 0.03 0.21 0.52 2.41 0.48 0.39 0.45

 * Less than 12 full months of data.

Refer to 2003 AQMP for 1976-1994 data
Appendix II – Attachment A

II-A-23

TABLE A-19

Lead (TSP) – Annual Maximum Monthly Average (μg/m3)

(To Be Compared to State Standard of 1.5 μg/m3, Monthly Average)

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

 69 East San Fernando Valley 0.05 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

 72 South Coastal Los Angeles County 1 0.05 0.09 0.05 0.07 0.06 0.05 0.05 0.03 0.10 0.02 0.01 0.01 0.02 0.02 0.01 0.01 0.01

 77 South Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- 0.02 0.02 0.01 0.02 0.01 0.02 0.01 0.01

 84 South Central Los Angeles County 1 0.06 0.09 0.07 0.04 0.17 0.09 0.23 0.04 0.04 0.03 0.03 0.02 0.03 0.03 -- -- --

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0.03 0.01 0.01

 85 South San Gabriel Valley 0.07 0.09 0.08 0.07 0.21 0.09 0.07 0.06 0.05 0.03 0.03* 0.03 0.04 0.02 0.04 0.02 0.01

 87 Central Los Angeles 0.07 0.08 0.07 0.06 0.13 0.06 0.06 0.05 0.15 0.03 0.03 0.02 0.04 0.02 0.02 0.01 0.01

 94 Southwest Coastal Los Angeles County 0.04 0.04 0.06 0.06 0.05 0.08 0.04 0.02 0.17 0.01 -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- 0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01

LOS ANGELES COUNTY (Source-Specific):

 Van Nuys Airport, Van Nuys -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0.04 0.06

 Trojan Battery, Santa Fe Springs -- -- -- -- -- -- -- -- -- -- -- -- -- 0.10 0.15 0.08 0.12

 Quemetco, City of Industry -- -- -- -- 0.28 0.44 0.46 0.15 0.18 0.13 0.38 0.10 -- 0.06* 0.11 0.12 0.07

 Exide (Rehrig), Vernon -- -- -- -- -- -- -- -- -- -- -- -- 1.97* 2.88 0.80 0.48 0.54

 Exide (ATSF), Vernon -- -- -- -- -- -- -- -- -- -- -- 0.23 1.01 0.25 0.09 0.08 0.07

 Exide (Ayers St.), Vernon -- -- -- -- -- -- -- -- -- -- -- -- -- 0.04* 0.03 0.02

ORANGE COUNTY:

3176 Central Orange County 0.04 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

RIVERSIDE COUNTY:

4144 Metropolitan Riverside County 1 0.04 0.08 0.07 0.08 0.06 0.06 0.04 0.03 0.02 0.02 0.02 0.01 0.02 0.01 0.01 0.01 0.01

4146 Metropolitan Riverside County 2 0.05 0.05 0.07 0.10 0.05 0.04 0.03 0.02 0.02 0.01 0.01 0.01 0.02 0.01 0.01 0.01 0.01

SAN BERNARDINO COUNTY: 0.05 0.04 0.04 0.05 0.07 0.07 0.05 0.02 0.08 0.02 0.02 0.01 0.02 0.01 0.01 0.01 0.01

5175 Northwest San Bernardino Valley 0.05 0.06 0.04 0.05 0.07 0.06 0.05 0.03 0.14 0.02 0.02 0.03 0.04 0.02 0.01 0.01 0.01

5203 Central San Bernardino Valley 0.07 0.09 0.08 0.10 0.28 0.44 0.46 0.15 0.18 0.13 0.38 0.23 1.01 2.88 0.80 0.48 0.54

District Maximum 0.07 0.09 0.08 0.10 0.21 0.09 0.23 0.06 0.17 0.03 0.03 0.28 0.23 1.97 2.88 0.80 0.45

 * Less than 12 full months of data.

Refer to 2003 AQMP for 1976-1994 data
Final 2012 AQMP Appendix II: Current Air Quality

II-A-24

TABLE A-20

Lead (TSP) – Annual Maximum 3-Month Rolling Average (μg/m3)

(To Be Used for Comparison to Federal Standard of 0.15 μg/m3, 3-Month Rolling Average)

STN# LOCATION 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

LOS ANGELES COUNTY:

 69 East San Fernando Valley 0.05 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

 72 South Coastal Los Angeles County 1 0.04 0.04 0.04 0.04 0.05 0.05 0.04 0.03 0.04 0.04 0.01 0.01 0.01 0.01 0.01 0.01 0.01

 77 South Coastal Los Angeles County 2 -- -- -- -- -- -- -- -- -- 0.06 0.01 0.01 0.01 0.01 0.01 0.01 0.01

 84 South Central Los Angeles County 1 0.05 0.07 0.07 0.05 0.09 0.07 0.11 0.04 0.04 0.03 0.03 0.02 0.03 0.03 -- -- --

112 South Central Los Angeles County 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0.02 0.01 0.01

 85 South San Gabriel Valley 0.06 0.06 0.07 0.06 0.10 0.08 0.05 0.05 0.03 0.03 0.02 0.02 0.03 0.02 0.02 0.01 0.01

 87 Central Los Angeles 0.06 0.06 0.07 0.05 0.07 0.05 0.05 0.04 0.06 0.06 0.02 0.01 0.03 0.02 0.02 0.01 0.01

 94 Southwest Coastal Los Angeles County 0.04 0.04 0.05 0.05 0.04 0.05 0.04 0.03 0.07 0.07 -- -- -- -- -- -- --

820 Southwest Coastal Los Angeles County -- -- -- -- -- -- -- -- -- 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

LOS ANGELES COUNTY (Source-Specific):

 Van Nuys Airport, Van Nuys -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 0.04 0.04

 Trojan Battery, Santa Fe Springs -- -- -- -- -- -- -- -- -- -- -- -- -- 0.08 0.12 0.07 0.11

 Quemetco, City of Industry -- -- -- -- 0.22 0.37 0.33 0.12 0.15 0.11 0.22 0.09 -- -- 0.10 0.10 0.06

 Exide (Rehrig), Vernon -- -- -- -- -- -- -- -- -- -- -- -- -- 2.49 0.66 0.39 0.4650

 Exide (ATSF), Vernon -- -- -- -- -- -- -- -- -- -- -- 0.21 0.55 0.22 0.08 0.05 0.06

 Exide (Ayers St.), Vernon -- -- -- -- -- -- -- -- -- -- -- -- -- 0.03 0.02 0.02

ORANGE COUNTY:

3176 Central Orange County 0.04 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

RIVERSIDE COUNTY:

4144 Metropolitan Riverside County 1 0.04 0.05 0.04 0.05 0.05 0.05 0.05 0.02 0.02 0.02 0.02 0.02 0.01 0.01 0.03 0.01 0.01

4146 Metropolitan Riverside County 2 0.03 0.03 0.05 0.06 0.04 0.03 0.03 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

SAN BERNARDINO COUNTY:

5175 Northwest San Bernardino Valley 0.04 0.04 0.04 0.04 0.05 0.05 0.04 0.02 0.04 0.03 0.02 0.01 0.02 0.01 0.01 0.01 0.01

5203 Central San Bernardino Valley 0.04 0.05 0.03 0.04 0.05 0.05 0.05 0.03 0.08 0.07 0.01 0.02 0.02 0.02 0.01 0.01 0.01

District Maximum 0.06 0.07 0.07 0.06 0.22 0.37 0.33 0.12 0.15 0.11 0.22 0.21 0.55 2.49 0.66 0.39 0.4650

 * Less than 12 full months of data.

Refer to 2003 AQMP for 1976-1994 data