EXECUTIVE SUMMARY

Introduction

Why Is This Plan Being Prepared?

What Is New in This Plan Revision?

How Was This Plan Revision Prepared?

Is Air Quality Improving?

What Are the Applicable Key Federal and State Requirements that 

This Plan Revision Addresses?

How Has the Emissions Inventory Changed?

Has the Overall Control Strategy Changed Significantly?

What Other Requirements Are Addressed in This Plan?

What Considerations Have Been Made for the New Federal 

Standards for Particulate Matter and Ozone?

What are the Challenges of Attainment?

Has the Attainment Projection Changed for Federal or

State Standards?
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INTRODUCTION

The air we Southern Californians breathe continues to get cleaner, with recent years 

registering as the cleanest in decades. The remarkable improvement in air quality is the 

direct result of Southern California’s comprehensive, multiyear strategy of reducing air 

pollution from all sources as outlined in its Air Quality Management Plan (AQMP). Yet 

the air in Southern California is far from meeting all federal and state air quality standards 

and, in fact, is among the worst in the nation. To reach the clean air goal in the few years 

remaining until Clean Air Act deadlines, Southern California must not only continue its 

diligence but intensify its pollution reduction efforts.

Continuing the progress toward clean air is a challenging task, not only to recognize and 

understand complex interactions between emissions and resulting air quality, but also to 

pursue the most effective possible set of strategies to improve air quality while

maintaining a healthy economy. To ensure continued progress toward clean air and comply 

with state and federal requirements, the South Coast Air Quality Management District 

(AQMD or District) in conjunction with the California Air Resources Board (CARB), the 

Southern California Association of Governments (SCAG) and the U.S. Environmental 

Protection Agency (U.S. EPA) is preparing the 2003 revision to its AQMP (2003 AQMP 

or 2003 Plan). The 2003 AQMP employs up-to-date science and analytical tools and 

incorporates a comprehensive strategy aimed at controlling pollution from all sources, 

including stationary sources, on-road and off-road mobile sources and area sources.

The 2003 AQMP updates the demonstration of attainment with the federal standards for 

ozone and PM10; replaces the 1997 attainment demonstration for the federal carbon

monoxide (CO) standard and provides a basis for a maintenance plan for CO for the future; 

and updates the maintenance plan for the federal nitrogen dioxide (NO2) standard that the 

South Coast Air Basin (Basin) has met since 1992.

The 2003 AQMP proposes policies and measures to achieve federal and state standards for 

healthful air quality in the Basin and those portions of the Salton Sea Air Basin (formerly 

named the Southeast Desert Air Basin) that are under District jurisdiction (namely,

Coachella Valley). The Coachella Valley PM10 Plan was recently revised in June 2002 

and forwarded to CARB and U.S. EPA for approval.

This revision to the Plan also addresses several state and federal planning requirements and 

incorporates significant new scientific data, primarily in the form of updated emissions 

inventories, ambient measurements, new meteorological episodes and new air quality

modeling tools. This Plan is consistent with and builds upon the approaches taken in the 

1997 AQMP and the 1999 Amendments to the Ozone SIP for the South Coast Air Basin 

for the attainment of the federal ozone air quality standard. However, this revision points 

to the urgent need for additional emission reductions (beyond those incorporated in the 

1997/99 Plan) to offset increased emission estimates from mobile sources and meet all 
Final 2003 AQMP

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federal criteria pollutant standards within the time frames allowed under the federal Clean 

Air Act.

This Plan as well as other key supporting information is available electronically and can be 

downloaded from the District’s home page on the Internet (http://www.aqmd.gov and click 

on “Clean Air Plans”).

WHY IS THIS PLAN BEING PREPARED?

The California Clean Air Act requires a non-attainment area to update its AQMP triennially 

to incorporate the most recent available technical information. In addition, U.S. EPA

requires that transportation conformity budgets be established based on the most recent 

planning assumptions (i.e., within the last 5 years). Both the 1997 SIP and the 1999 

amendments were based on demographic forecasts of the mid-1990’s using 1993 as the 

base year. Since then, updated demographic data has become available, new air quality 

episodes have been identified, and the science for estimating motor vehicle emissions and 

air quality modeling techniques for ozone and PM10 have improved. Therefore, a plan 

update is necessary to ensure continued progress toward attainment and to avoid a

transportation conformity lapse and associated federal funding losses.

On June 2, 2003, EPA published in the Federal Register its “Proposed Rule to Implement 

the 8-Hour Ozone National Ambient Air Quality Standard,” 68 Fed.Reg. 32801-32870. As 

part of that proposal, EPA solicits comment on a proposal to revoke the present 1-hour 

ozone standard either in whole or in part one year after EPA designates the 8-hour ozone 

nonattainment areas. (68 Fed.Reg. 32019.) It is expected that EPA will designate the 8-

hour ozone nonattainment areas by April 15, 2004. (68 Fed.Reg. 32808.) EPA is 

extremely unlikely to finalize this rule before the 2003 AQMP is adopted and submitted to 

EPA. At present, it is uncertain whether, when, or to what extent EPA will revoke the 

existing 1-hour ozone standard. Therefore, the 2003 AQMP assumes the 1-hour ozone 

standard will remain in effect for the foreseeable future.

WHAT IS NEW IN THIS PLAN REVISION?

Each revision of the AQMP represents a snapshot in time, based on the best available 

information. The 2003 AQMP generally is very similar to the structure of the 1997 Plan 

and the 1999 amendments to the ozone SIP but like all new editions includes significant 

enhancements. The key improvements incorporated in the 2003 AQMP are summarized as 

follows: 

1) Revised emissions inventory projections using 1997 as the base year, the CARB onroad motor vehicle emissions model EMFAC2002, and SCAG 2001 Regional

Transportation Plan (RTP) forecast assumptions;
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2) Revised control strategy that updates remaining control measures from the 1997/1999 

SIP and incorporation of new control measures based on current technology

assessments;

3) Reliance on 1997 ozone episodes and updated modeling tools for attainment

demonstration relative to ozone and PM10; and

4) An initial assessment of progress toward the new federal 8-hour ozone and PM2.5 

standards.

HOW WAS THIS PLAN REVISION PREPARED?

This AQMP Revision was developed based on input and participation of numerous

individuals and groups since the adoption of the 1997 AQMP and the 1999 amendments. 

In particular, the District Governing Board formed the AQMP Advisory Group and the 

Scientific, Technical & Modeling Peer Review (STMPR) Advisory Group to review the 

overall aspects of a draft AQMP and to make recommendations to staff concerning

emission inventories, modeling, control measures, and socioeconomic impacts. The 

AQMP Advisory Group consists of approximately 50 members representing a crosssection of the community, including major businesses, small businesses, academia, local 

government, ethnic interests, environmental interests, and appropriate governmental

agencies. The STMPR Advisory Group consists of approximately 22 members who are 

experts in the fields of socio-economic modeling, air quality modeling, air quality and 

meteorological monitoring, atmospheric science and medicine. In addition to the input 

from the AQMP and STMPR Advisory Groups in selecting the air quality model for the 

Plan, staff has also solicited and incorporated feedback from additional air quality

modeling experts in the field.

To help provide important technical and scientific data to support the update to the PM10 

Plan and provide the foundation for future PM2.5 plans, the Governing Board in December 

1997 established the PM10 Technical Enhancement Program (TEP), a multi-year 

cooperative study designed to provide new ambient data for particulates, improved

emissions inventories, and improved models to predict future levels of particulates and 

ozone. This program, which was designed to build upon the findings of its predecessor, 

PTEP, was jointly funded by the District, U.S. EPA, City of Los Angeles, County Sanitation 

Districts of Los Angeles, Western States Petroleum Association, Southern California Gas 

Company, CalMat, and Southern California Rock Products Association, and successfully 

delivered critical new analytical tools and information which was directly input to this 

Plan.

In preparing this Plan, the District coordinated closely with SCAG and the CARB, as well 

as the U.S. EPA. SCAG has the primary responsibility for providing future growth

projections and the development of transportation control measures; ARB has the primary 

responsibility for the development of mobile source emissions inventories as well as 

mobile source and consumer product control measures. Their inputs are included in this 
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Plan. Also, the U.S. EPA participated throughout the plan development process to provide 

guidance as to federal CAA requirements.

IS AIR QUALITY IMPROVING?

Yes. Over the years, the air quality in the Basin has improved significantly, thanks to the 

comprehensive control strategies implemented to reduce pollution from mobile and

stationary sources. For instance, the total number of days the Basin exceeds the federal 1-

hour standard has decreased dramatically over the last two decades from more than 200 

days to fewer than 50. However, the Basin still exceeds the federal 1-hour standard more 

frequently than any other location in the U.S. The Basin is designated as an "extreme" 

nonattainment area for ozone. Figure ES-1 shows the long-term trend in ambient ozone 

counts over the last two decades. The figure depicts the number of Basin-days above the 

federal 1-hour ozone standard, which represents the number of days the standard was 

exceeded anywhere in the Basin. 

In 2001, the Basin exceeded the federal and state standards for PM10, although

improvements have been registered on that front as well. Exceedances of the federal 

annual and 24-hour PM10 standards were confined to Riverside and San Bernardino 

counties. The more stringent state PM10 standards were exceeded over much larger areas. 

In 2001, the Basin did not exceed the standards for carbon monoxide, nitrogen dioxide, 

sulfur dioxide, sulfates or lead. Although the 2002 air quality data has not yet been quality 

assured/quality controlled, the preliminary data confirms the trend of continued progress. 

Figure ES-2 shows the annual average PM10 concentrations in the Basin in 2001.
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FIGURE ES-1

Total Basin-Days Above the Federal 1-Hour Ozone Standard from 1976-2001

Basin-Days Exceeding

0

50

100

150

200

250

76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01

YEAR
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FIGURE ES-2

Annual Average PM10 Concentration in 2001

WHAT ARE THE APPLICABLE KEY STATE AND FEDERAL 

REQUIREMENTS THAT THIS PLAN REVISION ADDRESSES?

The 1988 California Clean Air Act includes the following key requirements that must be 

addressed in any AQMP revision: apply Best Available Retrofit Control Technology; 

reduce nonattainment pollutants and their precursors at a rate of five percent per year, or, if 

this cannot be done, include all feasible measures and an expeditious implementation 

schedule; reduce population exposure to nonattainment pollutants (i.e. ozone, carbon

monoxide, and nitrogen dioxide for the Basin) according to a prescribed schedule; and, 

rank control measures by cost-effectiveness and implementation priority. Finally, state 

law requires the plan to provide for attainment of the federal and state ambient air quality 

standards at the earliest practicable date. 

The 1990 federal Clean Air Act Amendments overhauled the federal planning provisions 

for areas not meeting federal clean air standards. The amendments identified specific 

emission reduction goals, required both a demonstration of reasonable further progress 

and attainment by specified dates, and incorporated more stringent sanctions for failure to 

attain or to meet interim milestones. The 1997, 1999, and 2003 AQMPs were designed to 

meet applicable state and federal requirements. 

HOW HAS THE EMISSIONS INVENTORY CHANGED?

For this Plan revision, the 1997 emissions inventory is relied upon to establish baseline 

and future year projections. The inventories were developed according to procedures 

stemming from the federal Clean Air Act. To meet state and federal law requirements, 

updated emission inventories for two pre-1997 years (1990 and 1995) as well as nine 

future years (1998, 2000, 2002, 2005, 2006, 2007, 2008, 2010 and 2020) are also 

provided. 

The 1997 emissions inventory now represents the most comprehensive emissions

inventory ever established for the South Coast Air Basin and reflects all regulations that 

have been adopted and implemented as of 1997. The 1997 emissions inventory serves as 

the basis for the development of emission forecasts for future years. These forecasts 

reflect emission reductions from already adopted rules with post-1997 compliance dates 

and demographic and economic growth forecasts by SCAG.

In developing the revised inventories for this Plan revision, the most up-to-date inventory 

methodologies and emission factors were used. In addition, special studies were

conducted to better quantify ammonia emissions as well as emissions from aircraft and 
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marine vessels. The most notable inventory change, however, originated from the category 

of mobile sources. In 2002, CARB released its first off-road emissions inventory model 

and revised its on-road emissions inventory model, EMFAC2002, which revealed

significantly higher past, present and future emissions from mobile sources than previous

inventories.

HAS THE OVERALL CONTROL STRATEGY CHANGED

SIGNIFICANTLY?

The basic PM10 control strategy contained in the 1997 Plan, augmented by a few

additional PM10 control measures included in this Plan revision, appears to be adequate to 

demonstrate attainment of the federal PM10 standard. With respect to ozone, however, the 

basic strategy of the 1997 Plan and the 1999 amendments must be significantly overhauled 

to address the new realities of higher mobile source emissions and lower carrying

capacities for ozone as indicated by new modeling and meteorological episodes. 

Additional reductions, above and beyond those committed to in the 1997 Plan and 1999 

amendments, will be necessary to demonstrate attainment with the federal ozone standard

and present a significant challenge.

WHAT OTHER REQUIREMENTS ARE ADDRESSED IN THIS PLAN?

Under federal conformity regulations, all federal or federally funded transportation

projects must conform to the SIP, and must not be a cause of impeding progress toward 

attainment of the federal standards. To establish conformity, emissions from future 

projects must be accounted for in the future baseline emissions inventories, such that the 

attainment demonstrations include these future emissions. For transportation projects, 

planning is now underway out to the year 2030. The Plan establishes conformity budgets 

for the future years based on the 2006 PM10 and 2010 ozone attainment demonstrations. 

While ozone precursor emissions are expected to continue to decline in future years, 

primary PM10 emissions are expected to increase due to the expected growth in mobile 

vehicle population and vehicle miles traveled. To address this increase in primary PM10 

emissions from travel while continuing to provide for attainment after 2006, this plan 

establishes a mechanism for conformity demonstration purposes based on the

implementation of the new control measure, "Transportation Conformity Budget Backstop 

Control Measure" in which commitments are made to achieve additional primary PM10 

reductions from transportation-related PM10 source categories in 2020 and 2030 to 

offset the increased emissions. This measure will be revised in future SIP revisions to 

reflect updated PM10 emission inventories and attainment demonstrations.
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WHAT CONSIDERATIONS HAVE BEEN MADE FOR THE NEW 

FEDERAL STANDARDS FOR PARTICULATE MATTER AND OZONE?

In 1997, U.S. EPA promulgated new federal standards for ozone and particulate matter. 

Specifically, U.S. EPA established an 8-hour ozone standard, and a 24-hour and an annual 

average standard for fine particulates or PM2.5. Although the implementation guidelines 

for the new standards have not been finalized yet, preliminary feedback for U.S. EPA

indicates that the likely attainment dates for the PM2.5 and ozone standards will be 2014 

and 2021, respectively. The State Implementation Plans to demonstrate attainment with 

the new standards are expected to be due in 2007. 

Although, the new standards are not technically required to be addressed in the 2003 Plan 

revision, the District, cognizant of their importance and ramifications, is providing 

comparative information regarding the current attainment strategies relative to the

potential new standards. Generally, this assessment shows that the new standards are more 

restrictive than the current standards.

WHAT ARE THE CHALLENGES OF ATTAINMENT?

The improved mobile source inventories significantly increased emission estimates for the 

past, current, and future, causing more reductions needed to attain the standards. 

Furthermore, the new episode selected for the 2003 AQMP attainment demonstration is 

more conducive for ozone formation, resulting in a lower carrying capacity than the last 

plan. The Basin is required to demonstrate attainment of the federal PM10 standards by 

2006 and the federal 1-hour ozone standard by 2010. Significant improvements in air 

quality will be necessary to bring the Basin into attainment by federal deadlines,

particularly for the federal 1-hour ozone standard. Therefore, the attainment strategy 

incorporated in the 2003 AQMP ought to reflect the region’s utmost effort in reducing 

emissions from all sources contributing to Basin’s air pollution. To that end, the 2003 

AQMP builds upon improvements accomplished from the previous plans, and aims to 

incorporate all feasible control measures while balancing costs and socioeconomic 

impacts. The few years remaining to meet attainment deadlines afford little margin for 

error in implementing such a comprehensive control strategy. Further, one has to make 

sure that the control strategy selected to attain the current federal PM10 and 1-hour ozone 

standards will also complement and not significantly conflict with the Basin’s future 

efforts to attain the new federal 8-hour ozone and fine particulate (PM2.5) standards. The 

improved planning tools incorporated in the 2003 AQMP are vital in designing such a 

control strategy, and allow for its critical and objective evaluation and its realignment, if 

necessary. 
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HAS THE ATTAINMENT PROJECTION CHANGED FOR FEDERAL OR 

STATE STANDARDS?

No. The 2003 AQMP proposes to attain the state and federal standards in the same time 

frame as proposed in the 1997 AQMP. However, the portion of necessary emission 

reductions categorized as long-term measures has grown significantly and highlights the 

need for early rule adoption of available controls and the continuing need to foster new 

clean air technology and strategies. (See Figure ES-3.)

FIGURE ES-3

Attainment Target Dates

NO 

CO

PM10

Ozon

Federa

Met

Met

200

201

Met

Met

post-2010

post-2010

State