Staff Report 

Proposed 2007 State Implementation Plan 

for the South Coast Air Basin – 

PM2.5 Annual Average and 8-Hour Ozone 

National Ambient Air Quality Standards 

Release Date: September 21, 2007 

This document has been prepared by the staff of the California Air Resources Board. 

Publication does not signify that the contents reflect the views and policies of the Air 

Resources Board. The Air Resources Board will consider this document as a 

revision to the California State Implementation Plan at a noticed public meeting 

tentatively scheduled for September 27, 2007. 

Air Resources Board 

California Environmental Protection Agency
Electronic copies of this document can be found on ARB’s website at 

http://www.arb.ca.gov/planning/sip/sip.htm. Alternatively, paper copies may be 

obtained from the Public Information Office, Air Resources Board, 1001 I Street, 

Visitors and Environmental Services Center, 1st Floor, Sacramento, California 

95814, (916) 322-2990. 

For individuals with sensory disabilities, this document is available in Braille, 

large print, audiocassette, or computer disk. Please contact ARB’s Disability 

Coordinator at (916) 323-4916 by voice or through the California Relay Services 

at 711, to place your request for disability services. If you are a person with 

limited English and would like to request interpreter services, please contact 

ARB’s Bilingual Manager at (916) 323-7053. 

This document has been prepared by the staff of the California Air Resources 

Board. Publication does not signify that the contents reflect the views and 

policies of the Air Resources Board, nor does a reference to trade names or 

commercial products constitute endorsement or recommendation for use.

For questions, please contact:

Ms. Sylvia Oey, Manager 

Southern California Liaison Section 

California Air Resources Board 

P.O. Box 2815 

Sacramento, California 95812 

Phone: (916) 322-8279 

Email: soey@arb.ca.gov
 Report 

Proposed 2007 State Implementation Plan 

for the South Coast Air Basin – 

PM2.5 Annual Average and 8-Hour Ozone 

National Ambient Air Quality Standards 

Table of Contents 

EXECUTIVE SUMMARY ................................................................................ES-1 

I. BACKGROUND .........................................................................................1 

A. Profile of the South Coast Air Basin 

1. PM2.5 

2. 8-Hour Ozone 

B. AIR QUALITY PLANNING 

1. Federal Air Quality Planning Requirements 

2. Emission Reduction Responsibilities 

II. PLAN EVALUATION ..................................................................................6 

A. Emissions Inventories 

B. Baseline Emission Trends 

1. Summary of Emission Sources 

C. Air Quality Modeling 

1. Overview 

2. Grid-based Modeling 

3. Supplemental Analyses 

D. Ozone Attainment Demonstration 

1. Request for Reclassification to Extreme Nonattainment for the 

8-Hour Ozone Standard 

2. Attainment Demonstration 

3. Supplemental Analyses 

E. PM2.5 SIP Attainment Demonstration 

1. Request for Extension of the PM2.5 Attainment Date 

2. PM2.5 Modeling 

3. Supplemental Analysis 

F. South Coast District Control Strategy 

1. District Measures 

a. Proposed Backstop Measures for Indirect Sources of Emissions 

from Ports and Port-Related Facilities [NOx, SOx, PM] 

b. Structure of District Commitment 

c. Reductions from Adopted Rules 

d. Reductions from the District’s Proposed Stationary Source 

Control Measures 

2. Transportation and Land Use Planning 

G. Proposed State Strategy 
1. Proposed Control Measures 

H. Local Government Measures 

I. Federal Measures 

J. Reasonable Further Progress 

K. Contingency Measures 

L. Reasonably Available Control Measures (RACM) Analysis 

III. COACHELLA VALLEY OZONE ATTAINMENT DEMONSTRATION .......33 

A. Profile of Coachella Valley 

B. Nature of the Problem 

C. Emissions Inventory 

D. Attainment Demonstration 

E. Photochemical Modeling 

F. Supplemental Analysis 

IV. ON-ROAD MOTOR VEHICLE EMISSIONS BUDGETS...........................38 

A. Budget Approach 

V. REVIEW OF PUBLIC PROCESS.............................................................40 

VI. POTENTIAL IMPACTS..................................................................................40 

GLOSSARY OF ACRONYMS 

APPENDIX A – SUPPLEMENTAL ANALYSIS: 8-HOUR OZONE ATTAINMENT 

APPENDIX B – SUPPLEMENTAL ANALYSIS: PM2.5 ATTAINMENT 

APPENDIX C – PM2.5 REASONABLE FURTHER PROGRESS 

 CALCULATIONS 
ES-1 

EXECUTIVE SUMMARY 

Air Resources Board (ARB) staff is proposing Board approval of the South Coast 

Air Quality Management District (District) 2007 State Implementation Plan (SIP) 

for the federal 8-hour ozone and PM2.5 standards. The local SIP elements, 

combined with the ARB’s 2007 Statewide SIP Strategy, demonstrate attainment 

of the standards by applicable deadlines. The local SIP elements were approved 

by the District on June 15, 2007, when it adopted its comprehensive 2007 Air 

Quality Management Plan (AQMP). Under State law the District adopts an 

AQMP to address to state and federal air quality requirements. Only the portions 

of the AQMP intended to address federal standards are being submitted to the 

U.S. Environmental Protection Agency as a SIP revision. The ARB is 

considering approval of the 2007 Statewide Strategy concurrent with the District’s 

SIP elements. 

Some of the nation’s highest concentrations of PM2.5 and ozone occur in the 

South Coast Air Basin despite stringent State and local controls and substantial 

air quality progress. The South Coast Air Basin is one of two PM2.5 

nonattainment areas in the State, and the most serious in the nation. It is also 

the nation’s worst area for ozone, with 8-hour ozone levels that are currently 50 

percent above the federal standard. The ozone standard is exceeded 

somewhere in the basin on an average of 85 days per year. 

This staff report summarizes a consensus agreement reached by staff of the 

ARB, the District, and SCAG for attaining the new national PM2.5 and 8-hour 

ozone standards in the South Coast Air Basin. This agreement provides for 

achievement of the District’s 2014 emission reduction target through additional 

actions by ARB and the District, the federal government, and local cities and 

counties. The agreement will require new regulations as well as new sources of 

public and private funding dedicated to air pollution control. A process for 

encouraging the development of the new technologies that will be needed to 

meet the 8-hour ozone standard in the South Coast by 2023 is also included. 

ARB staff recommends that the Board approve the 2007 SIP for the South Coast 

Air Basin as modified by the consensus agreement. The new reductions from the 

agreement will come from accelerating the replacement or retrofit of older diesel 

trucks, reducing emissions from Metrolink commute trains, and targeting existing 

clean air incentive funds to projects that provide the greatest emission 

reductions. The agreement also incorporates the District’s proposal to reduce 

emissions from fireplaces and commercial charbroiling operations, and sets a 

federal funding target to mitigate a portion of the 2014 emissions from sources 

under federal jurisdiction. 
ES-2 

Much of California’s past air pollution success came from requiring new vehicles 

and industrial equipment to be as clean as possible. The short timeframe for 

reaching the PM2.5 standard requires strategy that relies heavily on the early 

replacement or retrofit of the existing sources. In many cases the required level 

of reductions will be feasible only if the owners of the older equipment and 

vehicles are provided with financial assistance or incentives. Some money is 

available now through bonds and Carl Moyer program; more will be needed. The 

success of this strategy depends on the ARB, District, SCAG, and local 

governments working together to secure needed funding and ensure that all 

available funding is used in a way that maximizes cost-effective emission 

reductions. 

The 2007 AQMP also addresses 8-hour ozone planning requirements for 

Riverside County’s Coachella Valley, a portion of the District that lies in the 

Salton Sea Air Basin. Staff recommends approval of the Coachella Valley ozone 

attainment demonstration. 

PM2.5 Strategy

California must meet the new annual PM2.5 standard by 2014. The District has 

determined that emissions of nitrogen oxides (NOx) and sulfur oxides (SOx) – 

pollutants generated largely from mobile sources ranging from passenger cars to 

container ships – must be reduced by 55% and almost 70% respectively from 

2006 levels to meet the 2014 deadline for attaining the PM2.5 standard. The 

District’s plan also calls for a 30% reduction in emissions of reactive organic 

gasses (ROG) and a 15% reduction in directly emitted PM2.5. The District used 

photochemical air quality modeling to identify emission levels that that would 

allow the basin to attain the PM2.5 annual average standard – the carrying 

capacity – and the corresponding emission reduction targets. The District has 

since modeled the impact of the proposed strategy to verify that it will result in 

attainment by 2014. 

The following table summarizes the PM2.5 attainment demonstration for the 

South Coast Air Basin. 
ES-3 

South Coast Air Basin PM2.5 

Carrying Capacity vs. Projected 2014 Emissions 

Annual Average Emissions, Tons per Day (tpd) 

NOx SOx PM2.5* ROG 

2014 2014 2014 2014 

Baseline Emissions 654 43 102 528

Carrying Capacity 460 20 86 474

Reductions Needed (tons) 194 23 16 54

New AQMD Reductions 28 3 4 10

New ARB Reduction 152 20 12 43

Additional Federal Reductions 10 

Additional Local Reductions 4 

Total Reductions 194 23 16 53

The District’s AQMP and State Strategy now achieve the reductions necessary to 

meet the modeled carrying capacity. ARB staff’s assessment of PM2.5 precursor 

emissions, combined with ambient levels of PM2.5 and precursor emissions 

measured in the South Coast Air Basin is also provided in this staff report. This 

supplemental analysis indicates that a somewhat lower level of reductions than 

those shown above could result in attainment. Because of the uncertainties 

inherent in photochemical modeling, U.S. EPA’s Guidance provides for the use of 

supplemental analyses to demonstrate attainment with a higher level of 

emissions than the modeled carrying capacity. Meeting the District’s emission 

reduction target provides additional certainty to the attainment demonstration. 

Ozone 

The South Coast Air Basin is currently required to reach the national 8-hour 

ozone standard by 2020, but the Act allows states to request an extension to 

2023. The District has determined that NOx emissions in the South Coast must 

be reduced by 76% to reach the standard. It has requested the extension to 

2023, which also allows the SIP to rely in part on future technologies, not yet fully 

identified, in its attainment demonstration. 

The measures currently identified in the proposed State Strategy, together with 

proposed District measures and existing controls, will provide three-quarters of 

the reductions needed to attain the federal 8-hour ozone standard in the South 

Coast Air Basin by 2023 – less than one-fourth of the reductions needed in the 

plan’s 17-year timeframe rely on the new technology provision. The AQMP 

includes 22 local control options that the District has identified for further 

investigation that may also reduce this shortfall. 
ES-4 

South Coast Air Basin 8-hour Ozone SIP 

Summer Planning Inventory, Tons per Day (tpd) 

NOx ROG 

2023 2023 

Baseline Emissions 506 536

Carrying Capacity 114 420

Reductions Needed from 2023 Baseline 383 116

New AQMD Measures 19 9

New ARB Measures 164 56

Total Short-and Mid-term Reductions 183 65

Long-Term Reductions 200 51

It is clear, however, that it will be a challenge to reduce emissions to 25% of 

current levels in the face of projected population and vehicle use increases. 

Because of this, ARB, the District, and SCAG have agreed to initiate a 

coordinated government, private, and public effort to establish emission goals for 

critical source categories and identify technology advancement opportunities. 

The Nature of the Commitments

The AQMP commitment adopted by the District specifies an emission reduction 

schedule and identifies control options that the District will pursue to reduce 

emissions by the amounts and in the timeframes identified in the AQMP. It does 

not bind the District to adopt specific measures identified in the plan or to achieve 

the reductions the District staff has estimated for each measure. This approach 

allows the District to revise its strategy as it develops and learns more about 

specific regulations, while ensuring that the District meets its overall emission 

reduction schedule and commitment. ARB staff is proposing a comparable 

approach for the State Strategy. 

ARB staff is proposing that the Board include in its Board Resolution a 

commitment to deliver all the 2014 emissions reduction commitments from State 

or District proposed measures for mobile sources, with the following exceptions: 

o SIP Credit for Reductions from Local City and County DMV Registration Fees 

Revenues: Aside from providing needed emission reductions, this measure is 

intended in part to encourage cities and counties within the South Coast Air 

Basin to use a substantial portion of their DMV surcharge revenues to 

maximize emission reductions. A State commitment to achieve these 

reductions should local governments fail to do so would undermine that goal. 

o Federal Funding to Mitigate Locomotive Emissions: The State’s ability to 

reduce emissions from locomotives is impacted by jurisdictional issues, the 

cost of controls, and the availability of clean engines to meet the lowest 

emission standards. U.S. EPA, by virtue of its ability to establish engine 
ES-5 

emission standards, holds the key to the introduction of the cleanest engines 

needed to meet federal air quality standards in California. ARB and the 

District cannot make up the reductions where California is preempted by 

federal law. Existing agreements with the rail industry are reducing emissions 

in the South Coast Air Basin beyond federal requirements. However, the 

severity of the region’s PM2.5 problem and the attainment deadline make it 

necessary to further mitigate locomotive emissions in 2014. 

Coachella Valley Ozone SIP

The Coachella Valley is an area under District jurisdiction that lies outside the 

South Coast Air Basin. It is the portion of Riverside County that lies in the 

Salton Sea Air Basin, east of the South Coast Air Basin. Most of the Coachella 

Valley’s residents live in communities along Highway 111 from Palm Springs to 

the town of Coachella. 

The Coachella Valley has been classified as a “serious” ozone nonattainment 

area with an attainment date of June 15, 2013. In 2006, the Valley exceeded the 

standard on 26 days with an ozone design value of 0.102 parts per million (ppm), 

which is approximately 21 percent over the 0.085 ppm standard. Existing and 

proposed control programs in the South Coast Air Basin are expected to reduce 

the transport of ozone and ozone precursors ROG and NOx by about 29 and 46 

percent, respectively, by the 2013 deadline. The District has adopted a twopronged air quality improvement program for the Coachella Valley that consists 

of an aggressive control program in the upwind South Coast Air Basin, and 

additional control of locally generated mobile source emissions via the State 

Strategy. The District’s analysis indicates that the anticipated reductions from 

these programs will not be sufficient to attain the 8-hour ozone NAAQS in 2013. 

The AQMP requests a reclassification to “Severe-17”, which would extend the 

attainment date to 2021. Subsequent modeling that reflects the consensus 

agreement for PM2.5 indicates that the new reductions in the South Coast Air 

Basin will also accelerate air quality improvement in the Coachella Valley, and 

may result in attainment as early as 2018. 

Staff Recommendation: 

Staff recommends that the Board approve the South Coast 8-hour ozone and 

PM2.5 SIPs as modified by the consensus agreement reached by the ARB, 

District, and SCAG staff and reflected in the ARB’s 2007 Statewide SIP Strategy 

being considered concurrently on September 27, 2007. Staff also recommends 

approval of the Coachella Valley ozone SIP. 
ES-6 
1 

I. Background 

A. Profile of the South Coast Air Basin 

The South Coast Air Basin is the nation’s second largest urban area and 

California’s largest metropolitan region. It includes the southern two-thirds of Los 

Angeles County, all of Orange County, and the western, urbanized portions of 

Riverside and San Bernardino counties. The South Coast Air Basin is home to 

16 million people, about 40 percent of the State’s population. The basin is also 

home to over 10 million vehicles. Fifty thousand heavy duty diesel trucks travel 

nearly 10 million miles through the region annually, and well over 50,000 diesel 

engines are used to move goods and power construction and mining equipment. 

The Air Basin’s complex terrain combines with its temperate climate to provide 

the perfect conditions for creating “smog”. Ozone levels in much of the coastal 

area now meet federal standards, thanks to the combined impacts of local, State, 

and federal emission controls. However, inland portions of the air basin continue 

to face a challenging ozone problem. Regional PM2.5 levels are also well above 

the federal annual standard. 

Residual pollution from the South Coast Air Basin is transported to several 

downwind air basins – the Mojave Desert, the Salton Sea, the South Central 

Coast, and San Diego. The transport impact on the downwind areas will decline 

as emissions in the South Coast Air Basin decrease with the implementation of 

the AQMP. 

Some of the nation’s highest concentrations of inhalable particles under 2.5 

microns (PM2.5) and ozone occur in the South Coast Air Basin despite decades 

of increasingly stringent air pollution controls. The South Coast Air Basin is one 

of two PM2.5 nonattainment areas in the State, and the most serious in the 

nation. Its ozone levels are currently 50 percent above the federal standard, 

making it the nation’s worst ozone area. 

1. PM2.5 

Unlike most air pollutants, PM2.5 is identified its size rather than its chemical 

composition. PM2.5 can be formed in the air through the reaction of precursor 

gasses, primarily NOx, SOx, ROG, and ammonia. The resulting particles are 

referred to as secondary PM2.5. The two main components of secondary PM2.5 

in the South Coast are ammonium nitrate and ammonium sulfate, which are 

formed when NOx and SOx interact with ammonia. The smallest particles of 

smoke, dust, and soot can also be in the PM2.5 size range. These directly 

emitted particles, made up of organic and elemental carbon, come from sources 

like residential fireplaces, gasoline and diesel engines, and airborne soil (dust). 

PM2.5 concentrations are much lower today than they were when we started 

measuring this pollutant in 1990. Between 1990 and 1998, PM2.5 annual 
2 

average concentrations dropped by 30 to 40 percent throughout the basin. In 

addition, the South Coast now attains the federal 24-hour standard of 65 ug/m3. 

Although PM2.5 concentrations remain the highest in the eastern portion of the 

air basin, the rate of decrease in PM2.5 and the response to ongoing control 

programs has also been the greatest in this region. 

Analysis of the trends in different components of PM2.5 has shown that over the 

last six years, decreases in ammonium nitrate have had the greatest impact on 

declining PM2.5 levels, with ammonium nitrate concentrations at RiversideRubidoux dropping by 39 percent. During this same period, NOx emissions and 

NOx levels measured in the air also decreased. Similarly, measured ammonium 

nitrate and ammonium sulfate levels declined significantly, concurrent with 

decreases in the amounts of NOx and SOx emitted. These significant trends – 

reductions in ambient PM2.5 concentrations corresponding to reductions in NOx 

and SOx emissions – suggest even greater air quality improvement resulting 

from this plan, which will reduce both NOx and SOx emissions at a much faster 

rate than we have seen in the past. 

The 2006 monitoring data show the positive PM2.5 trends continuing. Average 

PM2.5 concentrations in 2006 decreased at most sites compared to 2005, and 

are all lower than 2004 and earlier years at all sites. The figure below illustrates 

that PM2.5 concentrations are declining throughout the air basin. 

PM2.5 Average Concentrations

0

5

10

15

20

25

30

35

2000 2001 2002 2003 2004 2005 2006

Concentrations (ug/m3)

LA-North Main

Rubidoux

Fontana

Ontario

San Bernardino

2. 8-Hour Ozone 

Thirty years ago, high ozone days were the norm throughout the South Coast Air 

Basin and throughout the year. During the mid- to late-1970s, maximum 8-hour 

ozone concentrations were nearly four times the level of the current national 
3 

standard. Had the current 8-hour standard existed at that time, it would have 

been exceeded on more than 200 days each year. Since then, an emissions 

control strategy based on reducing both NOx and ROG has reduced both 

maximum concentrations and the number of exceedance days by almost 

60 percent. 

The South Coast Air Basin still faces one of the biggest ozone air quality 

challenges in the nation. While air quality has improved over the years, the 

8-hour ozone standard was exceeded somewhere in the Basin on 85 days in 

2006, with 53 exceedance days occurring at Crestline. The highest recorded 

value, 0.142 ppm, is almost 50 percent over the standard. 

Despite the magnitude of the problem, basinwide measures of maximum 

concentration, exceedance days, and design value are all down by about 

30 percent over the last decade, and more than half of the basin’s residents live 

in areas that are now clean. The following maps show the substantial progress 

made in the past ten years. 

Crestline in San Bernardino County and Santa Clarita in northern Los Angeles 

County continue to stand out as the monitoring sites that record the highest 

8-hour ozone concentrations. Residents of Crestline and Santa Clarita 

experienced an average of 64 and 46 days per year over the standard, 

respectively, from 2004 through 2006. 
4 

South Coast Air Basin 

Federal 8-Hour Ozone Exceedance Days 

1995 to 2005
5 

B. Air Quality Planning 

 1. Federal Air Quality Planning Requirements 

The federal Clean Air Act Amendments of 1990 (CAA or Act) establish the 

planning requirements for those areas that routinely exceed the health-based 

National Ambient Air Quality Standards (NAAQS), and hold each state 

responsible for implementing the provisions of the Act. California law identifies 

air quality planning responsibilities within the State. In the South Coast, those 

responsibilities are shared among the South Coast District, SCAG, and ARB. 

In April 2004, U.S. EPA finalized Phase 1 of its implementation rule for 8-hour 

ozone SIPs. This rule established the classification scheme for nonattainment 

areas and continuing obligations with respect to the existing 1-hour ozone 

requirements. The South Coast Air Basin is classified as Severe-17 with an 

attainment date of June 2021. On November 9, 2005, U.S. EPA supplemented 

its Phase 1 implementation rule with a Phase 2 rule for SIP development. On 

March 29, 2007, U.S. EPA released an implementation rule for PM2.5. 

These federal rules outline the emission controls and planning elements that the 

PM2.5 and 8-hour ozone SIPs must address. These include: 

• base year and future year emission inventories for manmade sources of air 

pollution in the nonattainment area between 2006 and the respective 

attainment years. 

• air quality modeling that demonstrates attainment of the federal standard. 

• adopted control strategies capable of meeting attainment, and contingency 

measures in the event the controls fall short of achieving needed reductions. 

• reasonable further progress plans. 

• a demonstration that all reasonably available control technology (RACT) and 

reasonably available control measures (RACMs) have been applied to 

existing sources. 

• transportation conformity emission budgets to ensure transportation plans 

and projects are consistent with the SIP, and will not hinder attainment. 

• supplemental analysis of air quality and emission data and trends supporting 

the modeled attainment demonstration. 

As part of its AQMP, the South Coast District has developed a comprehensive 

SIP that provides the technical foundation and control strategy for both federal 

standards. The draft AQMP requests an attainment extension for both PM2.5 

and ozone; it is designed to demonstrate attainment of the federal PM2.5 

ambient air quality standard by 2014 and the federal 8-hour ozone standard by 

2023. 
6 

 2. Emission Reduction Responsibilities 

ARB has primary regulatory authority over most mobile sources operated in 

California, and consumer products. The U.S. EPA has primary regulatory 

authority over large new farm and construction equipment, locomotives, oceangoing vessels, and aircraft. Air Districts such as the South Coast District primary 

authority over stationary emission sources, including industrial and commercial 

equipment. The regional association of governments or planning organization, in 

this case SCAG, is responsible for developing the regional transportation plans 

that are used to estimate mobile source emissions. These transportation plans 

can also impact land use patterns, and the availability and attractiveness of 

transit alternatives. 

Unlike most other districts, the South Coast District also has a significant 

research and testing program for innovative motor vehicle control technologies. 

The District has also used Moyer funds and emission fees to provide funding 

assistance for replacement and retrofits for a wide variety of mobile sources. 

II. Plan Evaluation 

 A. Emissions Inventories 

Emission inventories estimate the air pollutant emissions that are released into 

the environment, both as a result of human activities (“anthropogenic” sources) 

and by natural sources such as vegetation in open areas, and wildfires 

(“non-anthropogenic” sources). Air quality plans focus on anthropogenic 

sources, although emissions from non-anthropogenic sources are also estimated 

and these estimates are used in air quality modeling. The inventories used in the 

2007 AQMP were developed using the most recent planning assumptions and 

the best available technical information. 

The baseline inventories used in the South Coast AQMP and the proposed State 

Strategy reflect the emissions impact of District regulations adopted through June 

30, 2006, and ARB regulations adopted through December 2006. The baseline 

emissions also reflect the approximately 20 increase in population growth and 

11 percent increase in the miles traveled by cars and trucks, from 2006 to 2023. 

The inventories take into account seasonal changes in activity, temperature, and 

humidity. The inventories used in the air quality models reflect day-specific 

activity levels and climatic factors such as temperature and humidity. 

The following tables summarize the largest sources of precursor emissions in the 

South Coast Air Basin. The future year estimates reflect the emission reduction 

benefits of existing rules and the impacts of projected population growth and 

economic activity in the region. These tables do not include potential reductions 

from the new District measures identified in the South Coast AQMP or ARB 
7 

staff’s proposed State Strategy. Chapter 3 of the South Coast AQMP provides 

detailed emission inventories for ROG, NOx, SOx, and PM2.5. ARB’s website 

also provides more information about these inventories, at 

http://www.arb.ca.gov/ei/ei.htm. 

 1. Baseline Emission Trends 

The following tables show trends in PM2.5 and ozone precursor emissions from 

all source categories in the South Coast Air basin, from 2006 to the 2014 and 

2023 attainment years. These inventories also reflect emissions from ships and 

harbor craft to 100 miles from the shoreline, as these emissions impact on-shore 

air quality. Note that in ARB’s California Emission Forecasting System (CEFS) 

data base, the District inventory includes emissions to 100 miles offshore but 

includes the Coachella Valley which is in the Salton Sea Air Basin, while the Air 

Basin inventory reflects emissions to only three miles offshore. The inventory 

used in this plan was created by supplementing the CEFS South Coast Air Basin 

inventory with the difference between the CEFS Air Basin and District inventories 

for the category of Ships and Commercial Boats. 

2007 AQMP for PM2.5 

Baseline Precursor Emissions 2006-2014* 

(Summer Season Inventory in tons per day)** 

2007 AQMP for PM2.5 

Baseline Precursor Emissions 2006-2014* 

(Summer Season Inventory in tons per day)** 

ROG NOx

Source Category 2006 2014 Change 2006 2014 Change 

Stationary/Areawide 259 260 0% 87 71 -19% 

On-Road 264 149 -44% 526 287 -46% 

Off-Road 208 157 -24% 360 293 -19% 

TOTAL 731 566 -23% 972 650 -33% 

SOx PM

Source Category 2006 2014 Change 2006 2014 Change 

Stationary/Areawide 22 17 -21% 58 63 8% 

On-Road 4 2 -47% 20 17 -16% 

Off-Road 37 25 -32% 22 18 -19% 

TOTAL 63 45 -29% 101 98 -3% 
8 

2007 AQMP for Ozone 

ROG and NOx Baseline Emission Trends 2006-2023* 

(Summer Season Inventory in tons per day)** 

ROG NOx Source Category 2006 2023 Change 2006 2023 Change 

Stationary/Areawide 259 281 +8% 87 68 -22% 

On-Road 264 105 -60% 526 161 -69% 

Off-Road 208 149 -28% 360 276 -25% 

Inventory Adjustment*** (.2) (9) 

TOTAL 731 536 -27% 972 497 -49% 

*Reference: ARB

**Numbers may not add due to rounding.

***Inventory decreases to reflect the aggregate of emission benefits and shortfalls from rules adopted after the 2006 

inventory was “frozen”. 

 2. Summary of Emission Sources 

Mobile sources (including commercial trucks, passenger vehicles, construction 

equipment, ships, and locomotives) currently account for nearly 85 percent of the 

NOx emissions in the South Coast Air Basin, decreasing to 72 percent by 2023 

as a result of existing controls. On-road sources show the greatest projected 

decrease in NOx emissions – approximately 70 percent between 2006 and 2023. 

Emissions from ships and commercial boats are projected to increase by over 

50 percent during this time period. 
9 

NOx Emissions 

South Coast Air Basin 

2007 SIP Summer Season Emissions Inventory1

(Prioritized by 2006 emissions) 

 

 

Source Category 2006 2014 2023 

HEAVY DUTY DIESEL TRUCKS 259 140 73 

PASSENGER VEHICLES 205 101 53 

Passenger Cars 83 36 18 

Light Trucks, Minivans and SUVs 83 43 24 

Medium Duty Trucks 38 21 12 

OFF-ROAD EQUIPMENT (CONSTRUCTION AND MINING) 120 81 41 

OFF-ROAD EQUIPMENT (OTHER) 87 53 35 

Industrial Equipment 39 19 11 

Commercial 16 12 7 

Cargo Handling Equipment 12 5 3 

Transport Refrigeration Units 8 9 10 

Airport Ground Support Equipment 5 4 2 

Oil Drilling and Workover 5 3 2 

Other 1 1 0 

SHIPS AND COMMERCIAL BOATS (to 100 miles offshore) 74 87 116 

Ocean Going Vessels 48 71 102 

Commercial Harbor Craft 25 16 14 

GASOLINE FUELED COMMERCIAL TRUCKS 36 24 17 

LOCOMOTIVES 31 23 28 

RESIDENTIAL FUEL COMBUSTION 18 16 14 

Water Heating 7 5 3 

Space Heating 5 5 5 

Cooking 3 4 4 

Other (Clothes Dryers, BBQs, Pool Heaters and Fireplaces) 2 2 2 

MANUFACTURING AND INDUSTRIAL (BOILERS- IC ENGINES) 17 15 15 

SERVICE AND COMMERCIAL (BOILERS- IC ENGINES) 16 12 11 

TOTAL OF TOP 10 863 552 403 

TOTAL OF SCAB 972 650 505 

TOP 10 PERCENT OF TOTAL EMISSIONS 89% 85% 80% 

Sources that tend to increase with population growth dominate the South Coast 

Air Basin’s ROG emissions inventory. Population-driven sources such as cars, 

recreational boats, consumer products, lawn and garden equipment, architectural 

coatings, and gas cans make up approximately 65 percent of the current 2023 

ROG inventory. 

 

1 Derived from ARB’s CEFS ROG inventory for the SCAB, v1.06 RF#980 (November 2006). 
10 

ROG Emissions 

South Coast Air Basin 

2007 SIP Summer Season Emissions Inventory2

(Prioritized by 2006 emissions) 

 

Source Category 2006 2014 2023 

PASSENGER VEHICLES 207 112 76 

Passenger Cars 114 52 31 

Light Trucks, Minivans and SUVs 68 42 32 

Medium Duty Trucks 24 17 13 

CONSUMER PRODUCTS 101 103 110 

RECREATIONAL BOATS 64 53 51 

Pleasure Boats 50 42 38 

Personal Water Craft 14 11 12 

OFF-ROAD EQUIPMENT (LAWN AND GARDEN) 52 40 38 

Lawn & Garden Residential 29 20 16 

Lawn & Garden Commercial 23 20 22 

ARCHITECTURAL COATINGS (PAINTS AND THINNERS) 31 29 31 

OFF-ROAD EQUIPMENT (OTHER) 28 15 12 

Commercial 14 8 6 

Industrial Equipment 7 4 3 

Transport Refrigeration Units 4 1 2 

Airport Ground Support Equipment 1 1 1 

Cargo Handling Equipment 1 1 1 

Oil Drilling and Workover 1 0 0 

Other <1 0 0 

PETROLEUM MARKETING (GASOLINE EVAPORATIVE 

LOSSES) 27 28 31 

COATINGS (PAINTS AND THINNERS - NON ARCHITECTURAL) 27 25 28 

GASOLINE FUELED COMMERCIAL TRUCKS 24 13 8 

GAS CANS 21 10 7 

TOTAL OF TOP 10 581 428 392 

TOTAL OF SCAB 731 566 534 

TOP 10 PERCENT OF TOTAL EMISSIONS 79% 76% 73% 

B. Air Quality Modeling 

 1. Overview 

Air quality modeling is used to establish a "carrying capacity" – a combination of 

precursor emissions that the air basin can accommodate without exceeding the 

health-based standard3 – and to assess whether the proposed control strategy 

 

2

 Derived from ARB’s CEFS ROG inventory for the SCAB, v1.06 RF#980 (November 2006). 3

 An emissions carrying capacity is defined as the maximum level of emissions that enable the attainment and 

maintenance of an ambient air quality standard for a pollutant. Under State law, the South Coast District, with 

participation from SCAG, must establish an emissions carrying capacity with each formal plan review; it must also 

update the carrying capacity to reflect new data and modeling results. 
11 

will result in attainment of federal standards. The CAA requires that 

nonattainment areas designated as serious and above use a photochemical grid 

model to demonstrate attainment. 

 2. Grid-based Modeling 

The 2007 AQMP attainment demonstrations for both PM2.5 and 8-hour ozone 

were conducted using photochemical dispersion and meteorological modeling 

tools developed in response to U.S EPA modeling guidelines, and 

recommendations from air quality modeling experts. The air quality modeling 

performed for the AQMP has undergone scientific peer review and was made 

available for public review. ARB and South Coast District staffs worked together 

on the modeling for this plan, including development of a gridded modeling 

inventory and meteorological and geological data inputs, model performance 

analysis, and validation of the attainment demonstrations. 

The modeling platforms, chemical mechanisms, and inventories used in the 

photochemical modeling are summarized below and described in more detail in 

the AQMP’s Appendix V: Modeling and Attainment Demonstrations. 

Draft 2007 AQMP Dispersion Modeling Methodology 

(PM2.5 and 8-Hour Ozone) 

Mechanism Model 

Dispersion Platform CAMx 

Chemistry SAPRC99 (PMCAMx for PM2.5) 

Meteorology MM5/FDDA 

Mobile Emissions EMFAC2007 

Boundary WRAP-CAMx-GEOCHEM 

The District’s attainment analysis uses a combination of observed pollutant 

concentrations and modeled relative response factors (RRF) to reconcile the 

model outputs with the observed concentrations at air quality monitors through 

the air basin; a procedure recommended in U.S. EPA modeling guidance. Each 

of the episodes used in the RRF calculation satisfies the U.S. EPA’s model 

performance and threshold criteria. For the annual PM2.5 attainment 

demonstration, the model was run for the base and future years in their entirety. 

The model runs utilized speciated data collected during the District’s Multiple Air 

Toxics Exposure Study (MATESI) monitoring program to reflect the numerous 

chemical species that constitute PM2.5. The modeling procedures and analyses 

used by the District are also described in AQMP Appendix V. 

 
12 

 3. Supplemental Analyses 

Air quality modeling has inherent uncertainties since we cannot precisely 

measure, and models cannot precisely replicate, all of the spatial and temporal 

nuances in emissions, atmospheric conditions, and chemical reactions that 

influence air quality. U.S. EPA modeling guidance recommends the use of 

supplemental data analyses to help mitigate the uncertainty in air quality 

modeling. Such analyses include additional modeling, analyses of trends in 

ambient air quality and emissions, and observational models and diagnostic 

analyses. When a modeled design value is within 2-3 parts per billion (ppb) of 

the 8-hour ozone standard, or within 5 micrograms per cubic meter (ug/m3) of 

the PM2.5 annual average standard, U.S. EPA guidance has provisions for using 

supplemental analyses. 

C. Ozone Attainment Demonstration 

 1. Request for Reclassification to Extreme Nonattainment 

 for the 8-Hour Ozone Standard 

The South Coast Air Basin is currently classified as a severe nonattainment area 

with a 2021 attainment deadline. The Act allows states to request a voluntary 

reclassification to a higher classification.4

 The District requests and ARB staff 

recommends Board approval of a “bump up” to the extreme classification. If a 

state requests a reclassification to extreme, U.S. EPA must grant it. The extreme 

classification requires attainment no later than 2023, and allows the attainment 

demonstration to include reductions based on the anticipated development of 

new control technologies or improvement of existing technologies for attainment.5 

ARB staff agrees with the District’s assessment that we cannot demonstrate 

attainment without relying in part on technologies that do not exist and cannot be 

identified today. 

With out a reclassification to extreme, the Plan would not be able to demonstrate 

attainment by the applicable ozone deadline and the air basin would be subject 

to federal sanctions on permitted industrial sources, a prohibition on federally 

funded road projects, and federally imposed controls on mobile and stationary 

sources in the region. 

Staff of ARB, the District, and SCAG, have agreed to the development of a 

discussion paper, to be prepared within four months of the adoption of the SIP, 

on potential strategies for achieving the additional emission reductions needed to 

meet the 8-hour ozone standard. The paper will explore new or transformative 

strategies, such as state-of-technology zero and near-zero transportation 

systems, mechanisms such as fee-based incentives, and the availability of public 

funding assistance programs. 

 

4

 Section 181(b)(3)

5

 Section 182(e)(5) 
13 

Because the Basin was classified as extreme under the prior one-hour ozone 

standard, it has already adopted the permit and project review rules required for 

extreme areas and reclassification would not impose additional stationary source 

requirements. 

 2. Attainment Demonstration 

The District’s ozone photochemical modeling used five episodes from the years 

2004 and 2005 that were chosen to reflect recent ozone design values, along 

with a 1997 episode that was used to maintain continuity with the District’s 2003 

AQMP. The modeling results indicate that all sites in the South Coast will reach 

attainment by the 2024 deadline with a 76 percent reduction in NOx emissions 

and a 22 percent reduction in ROG emissions. The modeling projects that this 

level of reductions will give Crestline, the current high site for ozone, a design 

value of 0.083 ppm. 

For ozone, the South Coast district selected a carrying capacity of 420 tons per 

day ROG and 114 tons per day NOx emissions in their draft plan. ARB’s 

proposed strategies, along with the existing control program and proposed 

stationary source emission controls, will provide about 80 percent of the 

combined ROG and NOx emission reductions needed to demonstrate attainment 

of the ozone air quality standard. 

South Coast Air Basin 

Ozone Attainment Demonstration Summary 

(summer season, tons per day) 

 NOx ROG 

2006 Emissions Inventory 972 732 

Carrying Capacity 114 420 

Emission Reduction Target 858 312 

- Emission Reductions from Adopted SIP Measures 467 199 

- Emission Reductions from New Local Measures 9 19 

- Emission Reductions from New State Measures 141 54 

- Long-Term Measures 241 40 

Total Reductions 858 312 

Emission Reductions from Adopted SIP Measures = Emissions reduced from measures adopted through 2006. 

Emission Reductions from New Measures = Emissions reduced from measures in the State Strategy or new local 

measures adopted after 2006. 

Long-Term Measures = Emissions to be reduced from new or evolving technology, as allowed in section 182(e)(5) of 

the Clean Air Act. 
14 

 3. Supplemental Analyses 

ARB staff independently conducted supplemental analyses, and reviewed the 

District’s modeling and supplemental analyses, using U.S. EPA modeling 

guidelines. ARB staff concurs with the 2023 attainment projection based on the 

following factors: 

• Basinwide, the maximum ozone concentration, design value, and number of 

exceedance days declined by about 30 percent in the last ten years. The 

basinwide numbers reflect the “worst case” sites; the year-to-year 

improvement in sub-regions is even greater. More than half of the Basin 

population now lives in areas with design values that meet the federal 8-hour 

ozone standard. 

• Comparisons of emissions trends and changes in ambient precursor levels to 

ozone trends support the premise that both ROG and NOx reductions are 

important for ozone improvement. 

• Analyses suggest that improvements in regional ozone concentrations are 

primarily attributable to substantial emission reductions. The decline in the 

number of exceedance days between 1990 and 2000 was not a result of 

favorable weather, because the number of days with adverse weather 

conditions actually increased or remained level during this time period while 

the number of exceedance days decreased. Furthermore, even though 

ozone levels have been relatively flat during the last five to six years, 

analyses suggest that more adverse weather conditions are now required to 

produce an exceedance of the federal standard. 

• Photochemical modeling shows a design value of 0.083 ppm at Crestline by 

the end of 2023. The design values at other sites in the Basin are predicted 

at or below 0.081 ppm. These values are below the level of a federal 8-hour 

ozone standard of 0.085 ppm. 

Considered in tandem with the modeling results, these analyses indicate that the 

ozone carrying capacity identified in the AQMP will allow all sites in the South 

Coast to attain the federal 8-hour ozone standard in 2023 as is required to meet 

U.S. EPA’s June 15, 2024, attainment date for extreme ozone nonattainment 

areas. ARB staff’s supplemental ozone analysis is provided in Appendix A. 

Because emissions from the South Coast can be transported to areas outside 

the Basin, emissions reductions in the South Coast area should result in ozone 

downwind areas such as Ventura County, Coachella Valley, and the Mojave 

Desert Air Basin. 

ARB Staff Recommendation

Staff finds the air quality modeling analysis and ozone attainment demonstration 

satisfy U.S. EPA requirements and recommends approval for submittal as a SIP 
15 

revision. ARB staff has also conducted supplemental analyses for the ozone 

attainment demonstrations in the AQMP. The ozone evaluation, provided in 

Appendix A of this staff report, supports the District’s ozone attainment 

demonstration. 

 D. PM2.5 SIP Attainment Demonstration 

 1. Request for Extension of the PM2.5 Attainment Date 

Under the Clean Air Act6

 PM2.5 areas can apply for up to a five-year extension of 

the serious area attainment deadline of April 15, 2010. In order to obtain the 

extension, there must be a showing that: (1) the plan for the area includes the 

most stringent measures that are included in the SIP of any state or are achieved 

in practice in any state, and can feasibly be implemented in the area, (2) the 

state complied with all requirements and commitments pertaining to the area in 

the implementation plan for the area, and (3) attainment by 2010 would be 

impracticable. 

The District is formally requesting U.S. EPA to grant the five-year extension 

based upon the severity of the problem the significant reductions in NOx and 

SOx emission levels required for attainment. 

ARB staff believes that a five-year extension is justified given the severity of the 

PM2.5 problem in the South Coast Air Basin. The AQMD modeling indicates 

required levels of reductions from 2006 emissions of NOx (55 percent beyond 

current controls), SOx (68 percent), PM2.5 (15 percent), and ROG (30 percent) 

that cannot be achieved by 2010. 

 2. PM2.5 Modeling

The District’s PM2.5 model uses the same platforms as the model used for 

ozone planning. The District used the model to simulate PM2.5 concentrations 

throughout a year, and then averaged the results to develop a projected PM2.5 

annual average design value. The District supplemented monitored data used 

from the 1997 California Ozone Study with speciated PM2.5 data collected 

during its Multiple Air Toxics Exposure Study (MATES) field studies. The PM2.5 

modeling uses a 2005 base year. 

The model was initially used to establish emission reduction targets to be used in 

developing the control strategy. Once the strategy was agreed to, the District 

used the photochemical model to verify that the projected emission reductions 

would result in attainment of the PM2.5 NAAQS throughout the basin by 2014. 

 

6

 Section 188(e) 
16 

The precursor reductions modeled by the District, which the District’s modeling 

indicated would result in attainment throughout the South Coast Air Basin in 

2024, are summarized in the following table. 

South Coast AQMP 

PM2.5 Attainment Demonstration Summary 

(annual average emissions, tpd) 

NOx ROG SOx Direct 

PM2.5 

2014 Baseline Emissions 654 528 43 102 

Carrying Capacity 452 469 20 87 

Emission Reduction Target 202 59 23 15 

Reductions from New Measures 129 59 23 15 

 3. Supplemental Analyses 

ARB staff evaluated emissions and air quality trends, and conducted enhanced 

rollback modeling analysis to estimate the impacts of future emission reductions 

on resulting air quality. Data from three Basin monitoring sites that are part of 

the Speciation and Trends Network (SPN) provide speciation measurements 

used in this analysis: Riverside County-Rubidoux, and Los Angeles CountyNorth Main. The rollback technique estimated that the substantial additional 

emission reductions identified in the Proposed State Strategy as released on 

April 26, 2007, together with the District’s approved AQMP, are likely to be 

sufficient to provide for attainment at Riverside-Rubidoux as well Los AngelesNorth Main. By contrast, the District’s grid-based modeling indicates that this 

combination of controls would result in a 2014 value of 15.7 ug/m3. The future 

year concentrations predicted with the rollback modeling are consistent with 

observed air quality trends and the response to past emission reductions, though 

more optimistic than the grid-based modeling results. 

Both approaches indicate that substantial reductions of all PM2.5 precursors, 

particularly NOx and SOx, will be needed for attainment. ARB staff’s PM2.5 

supplemental analysis is provided in Appendix B. 

Staff’s detailed review of South Coast air quality and emissions trends concludes 

that the carrying capacity established by the District will result in attainment of the 

PM 2.5 standard by 2014. Staff recommends that the Board direct staff to submit 

both the South Coast District’s modeled PM2.5 carrying capacity, and the ARB 

staff supplemental analyses to U.S. EPA as part of the PM2.5 attainment 

demonstration for the South Coast Air Basin. 
17 

 E. South Coast District Control Strategy 

The South Coast District is primarily responsible for controlling emissions from 

stationary and area-wide sources (with the exception of consumer products). 

The District’s 2007 AQMP control measures are based on the application of 

available technologies and management practices as well as development and 

implementation of advanced technologies and control methods. Some 

measures, such as MCS-07 (All Feasible Measures for All Pollutants) and BCM 

01 (PM Control Devices for stationary sources) are designed to bring older, more 

polluting equipment up-to-date. The District’s control strategy is discussed in 

detail in Appendix IV of the 2007 AQMP. Since the adoption of the AQMP, 

District staff has also proposed new local actions to provide additional emission 

reductions by 2014 as shown below. 

Additional Actions to Meet the District’s 

PM2.5 Emission Reduction Target 

(NOx Emission Reductions – 2014 tpd) 

Action / Measure Responsible 

Agency NOx

Enhanced Heavy-Duty Truck Measure ARB 27 

Co-Benefits from Greenhouse Gas Reduction Measures ARB 3 

SOON Program Opt-in for Construction Equipment District 12 

Residential Wood Burning and Commercial Cooking Rule District 11 

Additional Incentive Funds for Port-Related and Other Sources District/ARB* 3 

Funding for Selective Catalytic Reduction on Metrolink Trains District/ARB* 3 

DMV Registration Fees Used for SIP-Creditable Projects Local Gov 4 

Federal Funding to Mitigate Locomotive Emissions in 2014 Pending 

Implementation of Proposed New Locomotive Standards Federal Gov 10 

SIP Credit for Moyer Program Projects Already Funded District 3 

Additional Reductions 76 

* Joint funding commitment with ARB backstop of emission reduction commitment.

 1. District Measures 

The following table shows the new measures included in the District AQMP as 

approved on June 15, 2007 – additional measures agreed to after District 

adoption of the AQMP were discussed above. The District commitment is to 
18 

 

South Coast Air Quality Management District 

Short- and Mid-Term Stationary Control Measures 

with Quantified Emission Reduction Estimates7

Reduction 

Target8

(tons/day) 

Control 

Measure # 

Title 

2014 2023 

Remaining 2003 AQMP Revision Control Measures

FUG-02 Emission Reductions from Gasoline Transfer and Dispensing Facilities [VOC] 3.7 4.0 

BCM-03 Emission Reductions from Wood-Burning Fireplaces and Wood Stoves [PM2.5] 1.0 1.6 

BCM-05 Emission Reductions from Under-Fired Charbroilers [PM2.5] 1.1 1.2 

New Control Measures

CTS-01 Emission Reductions from Lubricants [VOC] 1.9 2.0 

CTS-03 Consumer Products Certification and Emission Reductions from Use of Consumer 

Products at Institutional and Commercial Facilities [VOC] 2.1 2.29

CTS-04 Emission Reductions from the Reduction of VOC Content of Consumer Products Not 

Regulated by the State Board [VOC] 5.8 6.010

CMB-01 NOx Reduction from Non-RECLAIM Ovens, Dryers and Furnaces [NOx] 3.5 4.1 

CMB-02 Further SOx Reductions for RECLAIM [SOx] 3.0 3.0 

CMB-03 Further NOx Reductions from Space Heaters [NOx] 0.8 1.1 

2.0 9.2

MCS-01 1.6 2.2

Facility Modernization [VOC] 

 [NOx] 

 [PM2.5] 0.4 1.7

MCS-05 Emission Reductions from Livestock Waste [VOC] 0.8 0.6 

0.7 1.6 FLX-02 Petroleum Refinery Pilot Program [VOC] 

 [PM2.5] 0.4 0.4

0.0 0.8

EGM-01 0.0 0.6

Emission Reductions from New and Redevelopment Projects [NOx] 

 [VOC] 

 [PM2.5] 0.0 0.5

7.5 12.9 MOB-04 Emission Reductions from Carl Moyer Program3

 [NOx] 

 [PM2.5] 0.2 0.4

0.4 0.4 MOB-05 AB923 Light-Duty Vehicle High-Emitter Identification Program [NOx] 

[VOC] 0.8 0.7

0.5 0.6 MOB-06 AB923 Medium-Duty Vehicle High-Emitter Identification Program [NOx] 

 [VOC] 0.5 0.6

TOTAL VOC 10.4 19.3 

NOx 6.8 9.2 

SOx 3.0 3.0

PM2.5 2.9 5.4

 

7 The District also identifies carbon monoxide (CO) emission reductions that will be achieved through implementation of the State’s motor vehicle 

control program because CO emissions are to a limited extend an ozone precursor. For purposes of this staff report, ARB considers these benefits 

to be part of the baseline and are not included in this discussion. 8

 The emission reduction estimates are based on the 2014 annual average inventory and 2023 planning inventory in the proposed modifications to 

the Draft 2007 AQMP. The actual reductions are subject to change during rulemaking based on the latest available emission inventory data. 9 Emission reductions resulting from the implementation of this control measure will be credited towards AQMD’s SIP obligation provided ARB does 

not develop a similar regulation. Any remaining excess reductions will then contribute to fulfilling ARB’s SIP commitment. Reductions for this 

measure are not included in total reductions in this table. 10 Emission reductions from the past and future projects under the Carl Moyer Program presented under this measure are not included in total 

reductions in this table. 
19 

achieve the total tonnages shown; specific control measures may provide more 

or less reductions than the AQMP estimates. ARB staff will review and comment 

on proposed District rules to help ensure that each rule provides the greatest 

feasible reductions. The District and SCAG have also committed to use incentive 

funding mechanisms to enhance ARB’s mobile source controls prior to the 2014 

PM2.5 attainment date. 

The South Coast AQMP also identifies 22 measures for further review. The 

District has not estimated potential emission reductions for these measures, 

which are shown below. 

Staff recommends that the local measures identified in the SIP be submitted as 

part of the attainment demonstration, with the exception of the District’s 

Proposed Rule Control Strategy MOB-03, Backstop Measures for Indirect 

Sources of Emissions from Ports and Port-Related Facilities, which is discussed 

later.

South Coast 2007 AQMP 

 Non-Quantified Control Approaches and Measures* 

Number Title 

Energy Efficiency/Conservation

MCS-02 Urban Heat Island [All Pollutants] 

MCS-03 Energy Efficiency and Conservation [All Pollutants] 

Good Management Practices 

FUG-01 Improved Leak Detection and Repair [VOC] 

FUG-04 Emission Reductions from Pipeline and Storage Tank Degassing [VOC] 

BCM-01 PM Control Devices (Baghouses, Wet Scrubbers, and Other Devices) [PM2.5] 

MCS-04 Emissions Reduction from Green Waste Composting [VOC, PM2.5] 

MCS-06 Improved Start-up, Shut-down & Turnaround Procedures [All Pollutants] 

Market Incentives/Compliance Flexibility 

CTS-02 Clean Coatings Certification Program [VOC] 

FLX-01 Economic Incentive Programs [All Pollutants] 

Area Source Programs 

FUG-03 Emission Reductions from Cutback Asphalt [VOC] 

CMB-04 Natural Gas Fuel Specifications [All Pollutants] 

BCM-02 PM Emission Hot Spots – Localized Control Program [PM2.5] 

BCM-03 Emission Reductions from Wood Burning Fireplaces and Wood Stoves [PM2.5] 

BCM-04 Additional PM Emission Reductions from Rule 444 – Open Burning [PM2.5] 

MCS-07 Application of All Feasible Measures [All Pollutants] 

MCS-08 Emission Charges of $5,000 Per Ton for Stationary Sources with Potential to Emit 

Over 10 Tons per Year [VOC, NOx] 

Table continued on following page.
20 

South Coast 2007 AQMP 

 Non-Quantified Control Approaches and Measures* 

continued 

Emission Growth Management 

EGM-02 Emission Budget and Mitigation for General Conformity Projects [All Pollutants] 

EGM-03 Emissions Mitigation at Federally-Permitted Projects [All Pollutants] 

Mobile Source Programs 

MOB-01 Mitigation Fee for Federal Sources [All Pollutants] 

MOB-02 Expanded Exchange Program [All Pollutants] 

MOB-03 Backstop Measures for Indirect Sources Emissions from Ports and Port-Related 

Facilities [All Pollutants] 

MOB-07 Concurrent Reductions from Global Warming Strategies [All Pollutants] 

*Draft 2007 AQMP, Chapter 4 

 a. Proposed Backstop Measures for 

 Indirect Sources of Emissions from Ports and 

 Port-Related Facilities [NOx, SOx, PM] 

ARB staff’s understanding is that AQMP measure MOB-03 is intended to ensure 

that the port-related emission reductions identified in the AQMP, and in the Clean 

Ports Plan being developed by the Ports of Los Angeles and Long Beach, are 

achieved in a timely manner. The measure would allow the District to impose 

additional controls and permit requirements on port-related sources if annual 

emission and risk reduction goals are not met. 

In reality, ARB’s emission reduction commitment covers most of the reductions 

that will be achieved from sources at the port and other mobile sources. The 

proposed State Strategy would establish a commitment to reduce emissions from 

a large group of source categories that is sufficient to meet the SIP carrying 

capacities identified by the District. ARB staff has associated emission reduction 

estimates with specific source categories to (1) identify the types of sources for 

which staff expects to develop controls; (2) ensure the Board and the public that 

the overall commitment is reasonable and achievable, and (3) establish goals 

that can be used as staff develops the specific programs. However, because the 

proposed commitment establishes basin-wide emission reduction goals, and is 

structured to allow the Board flexibility as it considers control options, it cannot be 

used to establish enforceable emission targets or backstop measures for a 

specific source such as the port complex. The remaining goals identified as 

targets in this measure should not be included in the SIP as they are not related 

to attaining to the Ozone or PM2.5 NAAQS. 

Staff recommends that these targets be excluded from the SIP submittal. Such 

an action would not impact any authority the District may have to adopt and 

implement this measure as part of its AQMP. 
21 

 b. Structure of District Commitment 

The District's SIP commitment for the 2007 AQMP is structured into two 

components: reductions from adopted rules and reductions from proposed new 

control measures. Along with the proposed ARB State Strategy, the District 

relies on these reductions to demonstrate expeditious progress and attainment of 

the federal PM2.5 and 8-hour ozone standards. 

Chapter 4 of the AQMP discusses specific methodologies the District will use to 

track emission reductions against its SIP commitments: 

• The District will continue its existing outreach efforts for rule development 

and improved emission calculation methodologies. Should additional 

technical analysis (including source testing) indicate that actual emissions 

are less than previously estimated, the District will credit the surplus 

reductions toward the SIP commitments. 

• If the inventory for a source category changes as rules are developed, the 

District will use the updated inventory information for assessing the rule’s 

impact, but will calculate progress against the inventory used in the SIP to 

ensure that the reductions can be compared against commitments made in 

the attainment demonstration. 

• The District may have to adopt regulations to reflect reductions accounted for 

in the SIP even though the regulations may not provide reductions beyond 

what has actually occurred in practice. The AQMP provides for exceptions to 

this procedure where new reductions are determined to be real, quantifiable, 

and surplus to the 2007 AQMP baseline inventories, and enforceable through 

other State and/or federal regulations. 

• Inventory revisions that have gone through a peer review and public review 

process can be counted as credit towards the District’s SIP commitment. 

• Credit for an additional 3 tpd of NOx reductions can also be taken for Carl 

Moyer Program projects already funded by the District but not previously 

included in ARB’s or the District’s SIP credit accounting. 

 c. Reductions from Adopted Rules 

Current and projected emission reductions from rules that have already been 

adopted or implemented become assumptions in developing the SIP’s future 

year inventories. Continued implementation of these rules is essential to 

maintaining the attainment demonstration. The 2007 AQMP lists the rules 

adopted by the District since the adoption of the 2003 AQMP and their expected 

emission reductions. 
22 

 d. Reductions from the District’s Proposed 

 Stationary Source Control Measures 

The District’s commitment is to adopt and implement control measures that will 

achieve, in aggregate, the emission reductions specified in the AQMP for shortand mid-term measures, as well as reductions from long-term measures. The 

AQMP includes an annualized commitment in terms of rule adoption and 

implementation dates. The District proposes to apply emission reductions in 

excess of a given year's emission reduction commitment to emission reduction 

commitments of subsequent years. 

If the District determines that a substitute measure is needed and viable, the 

AQMP specifies that the District will complete rule development for the substitute 

measure no later than 12 months from the scheduled adoption date of the 

original control measure with implementation of the new measure to occur no 

later than two years from the final implementation date of the measure 

substituted. The District will annually notify the public of proposed revisions 

through its Rule Forecast Report, and will provide annual quantitative reports on 

the AQMP’s implementation progress at governing board meetings. 

In response to concerns raised by the regulated community that costly controls 

may be required to meet SIP obligations, the District has established a costeffectiveness threshold of $16,500 per ton of ROG reductions for tiered levels of 

analysis. Rules anticipated to be more costly than this would trigger a more 

rigorous average cost-effectiveness, incremental cost-effectiveness, and 

socioeconomic impact analysis, and a more extensive public review and 

decision-making process. This process does not change the District’s SIP 

emission reduction commitments. 

 2. Transportation and Land Use Planning 

The transportation sector, including goods movement sources, is the largest 

contributor to air pollution in Southern California. SCAG is responsible for 

designing the region’s transportation system, in coordination with local agencies. 

SCAG, along with the South Coast District and the Mobile Source Air Pollution 

Reduction Review Committee, also controls extensive public funding to mitigate 

the air quality impact of vehicle emissions. 

Federal law and regulations require transportation plans within the Basin to 

conform to the approved air quality plans11 and demonstrate that the region’s 

 

11 1990 Federal Clean Air Act and the Intermodal Surface Transportation and Efficiency Act (ISTEA), 

Transportation Equity Act for the 21st-Century (TEA-21) and the Safe, Accountable, Flexible, Efficient 

Transportation Equity Act: A Legacy for Users (SAFETEA-LU). The regulations governing the 

implementation of transportation projects within air basins are stipulated in U.S. EPA’s Transportation 

Conformity Rule (40 CFR Parts 51 and 93) and also the Joint Federal Highway Administration 

(FHWA)/Federal Transit Administration (FTA) regulations, "Planning Assistance and Standards," 23 

CFR Part 450 and 49 CFR Part 613.
23 

transportation plans and programs conform to federal clean air mandates in a 

timely manner.12 

SCAG’s Regional Transportation Plan (RTP) is developed every four years with a 

20-year planning horizon and satisfies the long term planning requirements for 

the basin. The magnitude of long-term emission reductions needed for 

attainment requires not only a commitment to cleaner vehicles, but also to 

strategies that discourage unnecessary vehicle travel. The 2004 RTP (modified) 

includes draft policies, actions, and growth scenarios that control 

transportation-related emissions increases through strategies designed to reduce 

vehicle trips and trip lengths. 

Short-term transportation requirements in the Basin are addressed in SCAG’s 

biennial Regional Transportation Improvement Program (RTIP). The first two 

years of the RTIP are fiscally constrained and demonstrate timely implementation 

of air quality-related transportation projects called Transportation Control 

Measures (TCMs). 

Pursuant to the Clean Air Act, U.S. EPA requires the SIP to identify the TCMs in 

the RTIP13. U.S. EPA also requires the measures to be tracked for timely 

implementation, and that the measures selected satisfy federal RACM 

requirements. The transportation strategy and related elements approved by 

SCAG and incorporated in the 2007 AQMP fall in the following categories: 

• High Occupancy Vehicle (HOV) Measures: Construction and dedication of 

new high occupancy vehicle (HOV) lanes, and differential tolls for HOVs. 

• Transit and Systems Management Measures: Bus, rail, and shuttle transit 

expansion and improvements; park and ride lots and inter-modal transfer 

facilities; bicycle and pedestrian facilities; railroad consolidation programs, 

such as grade separation projects; intersection improvements; and traffic 

signal synchronization. 

• Information-based Transportation Strategies: Programs that promote 

alternatives to single occupancy vehicle commutes, and improve congestion 

management strategies. 

The emission benefits associated with the regional transportation strategy are 

estimated at 1.8 tpd ROG and 0.24 tpd PM2.5 reductions in 2014, and 1.7 tpd 

ROG and 0.2 tpd NOx reductions in 2023. Because SCAG’s 2004 RTP was 

used to develop motor vehicle emission inventories for the Basin, these 

reductions are reflected in the baseline inventories.14

 

12 For the discussion on transportation conformity requirements, refer to Chapter V of this report. 13 Section 108 (f)(1)(A) and also by U.S. EPA’s Transportation Conformity Rule (40 CFR Part 93). 

14 For a detailed discussion of the emission reductions associated with the regional transportation 

strategy, refer to Appendix IV-C (Regional Transportation Strategy and Control Measures).
24 

 F. Proposed State Strategy 

The proposed State Strategy and accompanying staff report are contained in a 

separate document.15 The following table summarizes the emission reductions 

expected from the State Strategy in the South Coast Air Basin in 2014, 2020, and 

2023. The consensus agreement for PM2.5 calls on ARB, the District, local 

agencies, and the federal government to provide 76 tpd NOx reductions by, by 

2014, beyond the reductions shown in the table. ARB is responsible for 30 tpd of 

the new reductions in the agreement. ARB commitments for 2020 are included 

to ensure reductions in the South Coast Air Basin that are needed to provide for 

attainment by 2021 in the Coachella Valley. 

Summary of Emission Reduction Commitments – South Coast 

Year NOx ROG Direct 

PM2.5 SOx 

2014 122 46 9 20 

2020 1 144 52 -- -- 

2023 141 54 -- -- 

2023 CAA 182(e)(5) 

measures 

241 2 40 2 -- -- 

1 The 2020 commitment in the South Coast is necessary to provide for attainment in downwind 

nonattainment areas. 2 The reductions of NOx and ROG from 182(e)(5) measures will be reassessed as new SIPs 

are developed and revised. 

 1. Proposed Control Measures 

The following tables describe ARB staff's emission proposed emission reduction 

commitment for the South Coast portion of the State Strategy. The commitment 

includes reductions from sources traditionally under State control, such a 

consumer products and passenger vehicles, and reductions from sources such 

as ships and trains, which have traditionally been considered to be subject to 

federal or international control. In a separate Board item, ARB staff proposes a 

commitment to achieve the emission reductions set forth in these tables, by the 

dates indicated. The reductions may be achieved through a combination of 

actions, including regulations, incentives, and other enforceable mechanisms. 

 

15 The reader can review or download the proposed State Strategy and staff report at 

http://www.arb.ca.gov/planning/sip/2007sip/2007sip.htm
25 

The 2007 AQMP identifies the relative impact of NOx, ROG, PM2.5, and SOx 

emissions on ambient PM2.5 levels, as indicated by the District’s air quality 

modeling. ARB’s emission reduction commitment for the PM2.5 SIP is 

predicated on the State’s ability to substitute emission reductions of one pollutant 

for another, using ratios derived from the District’s modeling. Table V-2-14 of the 

AQMP, replicated below, identifies the relative contribution of PM2.5 precursor 

emissions to ambient PM2.5 concentrations. Using these factors, for example, a 

1-tpd SOx reduction would be equivalent to 10 tpd of ROG or 3.33 tpd of NOx. 

Relative Contributions of Precursor Emissions Reductions to Simulated 

Controlled Future-Year PM2.5 Concentrations 

Precursor (TPD) PM2.5 Component Standardized 

Contribution to Mass 

VOC Organic Carbon Factor of 1 

NOx Nitrate Factor of 3 

PM2.5 Elemental Carbon & Others Factor of 5 

SOx Sulfate Factor of 10 
26 

Expected Emission Reductions from Proposed State Strategy 

South Coast PM2.5 Attainment Demonstration 

(2014 planning inventory, tpd) 

Proposed New Measures NOx ROG Direct 

PM2.5 SOx 

ON-ROAD SOURCES 

Passenger Vehicles 14.4 17.7 0.2 --

 Smog Check Improvements (BAR) 12.0 10.5 0.2 -- 

 Expanded Vehicle Retirement 2.4 2.8 0.05 -- 

 Modifications to Reformulated Gasoline Program -- 4.4 -- -- 

Heavy-Duty Trucks 76 5.1 3.0 --

 Cleaner In-Use Heavy-Duty Trucks 76 5.1 3.0 -- 

GOODS MOVEMENT SOURCES 49.4 0.7 3.6 20.1 

 Ship Auxiliary Engine Cold Ironing and Clean Technology 18.5 -- 0.3 0.4 

 Cleaner Main Ship Engines and Fuel 20.0 -- 2.4 19.7 

 Port Truck Modernization 2.0 -- 0.5 -- 

 Accelerated Introduction of Cleaner Line-Haul Locomotives* 4.3 0.7 0.2 -- 

 Clean Up Existing Harbor Craft 4.6 -- 0.2 -- 

OFF-ROAD EQUIPMENT 10.5 2.7 2.6 

 Cleaner In-Use Off-Road Equipment (over 25hp) 10.5 2.7 2.6 -- 

 Cleaner In-Use Agricultural Equipment NYQ NYQ -- -- 

OTHER OFF-ROAD SOURCES 0.4 8.9 

 New Emission Standards for Recreational Boats 0.4 4.2 -- -- 

 Expanded Off-Road Recreational Vehicle Emission Standards -- 2.4 -- -- 

 Additional Evaporative Emissions Standards -- NYQ -- NYQ 

 Vapor Recovery for Above Ground Storage Tanks -- NYQ -- NYQ 

AREAWIDE SOURCES 

 Consumer Products Program -- 12.9 -- -- 

 Pesticides: DPR 2008 Pesticide Plan -- NYQ -- --

Total Emission Reductions from Proposed New Measures 122 46 9 20 

NYQ = Not Yet Quantified. BAR = Bureau of Automotive Repair. DPR = Department of Pesticide Regulation 

* Ship and Commercial Boats to 100 miles 

** Locomotive measure relies on U.S. EPA rulemaking and industry agreement to accelerate fleet turnover. 

Note: Emission reductions reflect the combination impact of regulations and supportive incentive programs. 
27 

Expected Emission Reductions from Proposed New Measures 

South Coast Air Basin – 2020 and 2023 

(planning inventories, tpd) 

2020 2023 

Proposed New Measures 

NOx ROG NOx ROG 

ON-ROAD SOURCES 

Passenger Vehicles 9.6 12.9 7.1 10.5 

 Smog Check Improvements (BAR) 8.3 8.7 6.9 7.5 

 Expanded Vehicle Retirement 1.3 1.2 0.2 0.5 

 Modifications to Reformulated Gasoline Program -- 3.0 -- 2.5 

Heavy-Duty Trucks 26.9 2.6 18.3 1.7 

 Cleaner In-Use Heavy-Duty Trucks 26.9 2.6 18.3 1.7 

GOODS MOVEMENT SOURCES 87.1 1.8 99.2 1.9 

 Ship Auxiliary Engine Cold Ironing and Clean Technology 28.3 -- 30.8 -- 

 Cleaner Main Ship Engines and Fuel 32.3 -- 39.9 -- 

 Port Truck Modernization 8.0 -- 7.0 -- 

 Accelerated Introduction of Cleaner Line-Haul Locomotives** 13.4 1.8 15.6 1.9 

 Clean Up Existing Harbor Craft 5.1 NYQ 5.9 NYQ 

OFF-ROAD EQUIPMENT 18.7 2.9 13.9 1.9 

 Cleaner In-Use Off-Road Equipment (over 25hp) 18.7 2.9 13.9 1.9 

 Cleaner In-Use Agricultural Equipment NYQ NYQ NYQ NYQ 

OTHER OFF-ROAD SOURCES 1.6 21.1 2.4 27.7 

 New Emission Standards for Recreational Boats 1.6 12.8 -- 17.6 

 Expanded Off-Road Recreational Vehicle Emission 

Standards -- 5.1 -- 6.4 

 Additional Evaporative Emission Standards -- NYQ -- NYQ 

 Vapor Recovery for Above Ground Storage Tanks -- NYQ -- NYQ 

AREAWIDE SOURCES -- 13.7 

 Consumer Products Program -- 13.5 -- 13.7 

 Pesticides: DPR 2008 Pesticide Plan -- NYQ -- NYQ 

Total Emission Reductions from Proposed New Measures 144 52 141 54 

NYQ = Not Yet Quantified. BAR = Bureau of Automotive Repair. DPR = Department of Pesticide Regulation 

* Ship and Commercial Boats to 100 miles 

** Locomotive measure relies on U.S. EPA rulemaking and industry agreement to accelerate fleet turnover. 

Note: Emission reductions reflect the combination impact of regulations and supportive incentive programs. 
28 

G. Local Government Measures 

ARB staff proposes that air quality-related motor vehicle registration fees 

collected in the air basin be used to achieve an additional 4 tpd of NOx 

reductions through the funding of SIP-creditable projects. (SIP credit is not 

currently taken for projects funded with these fees.) South Coast cities and 

counties should target their air quality funds to get the most cost-effective 

emission reductions. This target represents about 40 percent of the funds under 

city and county control used for projects achieving cost-effectiveness similar to 

the Carl Moyer Program. ARB would amend its guidance on the use of the fees 

to include new cost-effectiveness guidelines and a suggested list of SIPcreditable projects. SIP credit could also be taken for South Coast Mobile 

Source Air Pollution Reduction Review Committee projects that achieve surplus 

emission reductions. 

H. Federal Measures 

Apart from California mobile source authority that is explicitly authorized under 

the Act, U.S. EPA has the authority to control emissions from mobile sources that 

are all or partly under exclusive federal jurisdiction (e.g., interstate trucks, some 

farm and construction equipment, aircraft, locomotives, and marine vessels that 

are US-flagged ships). International organizations develop standards for marine 

vessels and aircraft that operate outside U.S. territorial waters and airspace. 

Federal agencies have the lead role in representing the U.S. in the development 

of international standards. Measures in the proposed State Strategy to reduce 

emissions from interstate and international sources rely on the federal 

government to develop more stringent emissions standards and to ensure these 

standards go into effect as soon as possible. 

ARB is proposing to reduce ship emissions through a combination of regulations, 

incentives, and actions by ports and the private sector. However, national and 

international action to clean up shipping fleets is also needed to fully realize our 

clean air goals. And aircraft emissions, which will become one of the South 

Coast’s top five NOx sources by 2020, are unaddressed in the State Strategy 

due to the lack of effective international standards. 

The consensus reached among the staff of the ARB, the District, and SCAG 

proposes that the federal government provide funding to mitigate the impacts of 

federal sources that are less well controlled than California regulated sources in 

order to meet the PM2.5 attainment deadline. Line-haul and switcher 

locomotives operating in the South Coast would produce 10 tpd of excess NOx 

emissions in 2014 because the U.S. EPA’s proposed new engine standards for 

NOx are not expected to be fully implemented until 2017. This 10 tpd target is 

equivalent to the emission reductions that would have been achieved had U.S. 

EPA adopted its proposed Tier 4 NOx locomotives standard in time for the State 

to work to convert all locomotives operating in the basin to Tier 4 by 2014. 
29 

To the extent that SCAG, through its RTP process, identifies transportation 

infrastructure measures (e.g., rail electrification) that will achieve quantifiable 

reductions, these reductions can be used to substitute for the SIP commitments. 

 I. Reasonable Further Progress 

The CAA requires SIPs to provide for steady progress in reducing emissions 

during the years leading to the attainment date16. This requirement provides a 

way to measure compliance prior to the attainment date. U.S. EPA requires that 

the RFP plan show linear progress according to emission reduction milestones 

the region establishes for 2009 and every three years thereafter until the 

attainment year. 

PM2.5. For PM2.5, the Plan must show RFP for directly emitted PM2.5 and the 

precursor pollutants identified in the attainment demonstration, in this case, NOx, 

SOx, and ROG. Emission reductions and program milestone years used in the 

RFP plan must be based on the prior years’ emissions. Since the District is 

requesting an extension for attainment of the PM2.5 standard out to 2015, the 

years 2009, 2012, and 2014 are used to determine RFP. U.S. EPA guidance 

provides two alternatives for assessing RFP for PM2.5 strategies. The first 

assesses progress for each precursor against the required rate of progress 

without considering how much each precursor contributes to ambient PM2.5 

concentrations. The second uses information gained from the attainment 

demonstration modeling to consider how much reductions of each pollutant 

contribute to attainment. In essence, this equivalency approach tries to 

approximate the progress that will be made in improving air quality. 

The 1-year window between the completion of this plan and 2009 does not much 

allow time to new implement programs that will provide the steep reductions 

needed to meet a 2009 target. Nonetheless, the proposed strategy described in 

this report meets the 2009 RFP goal using the more robust equivalency 

approach. 

Ozone. Since U.S. EPA has already approved the District’s RFP plan for the 

1-hour ozone standard, the District is only required to provide for VOC and/or 

NOx reductions of three percent per year from the 2002 baseline year averaged 

over each consecutive three-year period beginning in 2008 until the Basin’s 

attainment date (i.e., June 2023). 

The AQMP meets the required rate of ozone progress for each milestone year on 

the basis of reductions from the existing regulatory program using a combination 

of ROG and NOx reductions. No new reductions from the proposed control 

measures in the Plan are needed for progress purposes. Up until the year 2017, 

projected ROG baseline emissions are sufficient to meet the CAA requirements. 

 

16 Section 172(c)(2)
30 

For the milestone years 2017, 2020, and 2023 the baseline ROG emission levels 

will be supplemented by projected NOx reductions to show compliance with the 

targeted thresholds. 

The following tables summarize the calculations needed to demonstrate RFP for 

8-hour ozone. These tables are also contained in Appendix D of the proposed 

State Strategy. 

Summary of Ozone RFP - ROG 

CALCULATION STEP a 2008 2011 2014 2017 2020 2023 

2002 Base Year Emissions b 896.7 896.7 896.7 896.7 896.7 896.7

Required Reduction (%) c 18% 27% 36% 45% 54% 63%

Emission Reductions Needed d 161.4 242.1 322.8 403.5 484.2 564.9

Target Level e 735.3 654.6 573.9 493.2 412.5 331.8

Projected Baseline f, g 654.9 603.1 569.1 549.5 538.4 536.0

Percent Reduction Achieved (%) g 

h 27% 33% 37% 39% 40% 40%

Summary of Ozone RFP Calculations – NOx 

CALCULATION STEP a 2008 2011 2014 2017 2020 2023 

2002 Base Year Emissions b 1078.5 1078.5 1078.5 1078.5 1078.5 1078.5

Required Reduction (%) c 0% 0% 0% 6% 14% 23%

Emission Reductions Needed d 0.0 0.0 0.0 64.7 151.0 248.1

Target Level e 0.0 0.0 0.0 1013.8 927.5 830.4

Projected Baseline f, g 848.2 738.5 650.3 578.4 523.9 505.6

Percent Reduction Achieved (%) g 

h 21% 32% 40% 46% 51% 53%

a

 Units are in tons per day (summer) unless otherwise noted; 

b

 Contains only anthropogenic emissions; 

c

 3% per year (total VOC reductions from 2002 baseline year); 

d

 [(Row 1) x (Row 2)]/100; 

e

 (Row 1) – (Row 3); 

f

 Projected baseline emissions shown in Appendix III taking into account existing rules and 

projected growth.; 

g

 The projected baseline includes the motor vehicle emissions depicted in the emission budgets 

showing that the motor vehicle emissions are below the RFP targets; 

 g h [(1-(Row 5)/(Row 1))] x 100
31 

 J. Contingency Measures 

The Act requires that the SIP provide for contingency measures in the event of a 

failure to meet RFP milestones and/or failure to attain the PM2.5 or the 8-hour 

ozone standard by the attainment date.17 These contingency measures are to 

take effect without further ARB or air district action, and thus must already be 

adopted when the SIP is submitted to U.S. EPA. Nonattainment areas classified 

as extreme for the 8-hour ozone standard must also adopt contingency 

measures to be implemented if the anticipated advanced technologies do not 

achieve the planned reductions. 

ARB’s existing mobile source program and the proposed State Strategy will 

achieve the bulk of emissions reductions needed to attain the federal standards. 

ARB has a well established history of adopting and implementing mobile source 

control regulations on-time or early. As a result, we expect to achieve and even 

exceed RFP goals without the need for contingency measures. However, the 

CAA requirements necessitate that we provide contingency measures regardless 

of our expected progress in reducing emissions toward the attainment goals. 

The emission reductions from adopted measures that go beyond the RFP 

requirements in each target year will constitute California’s contingency measure 

commitment implemented in the unlikely event that the State does not meet the 

reasonable further progress goals. 

ARB's contingency measure commitment is included in Appendix D of the 

Proposed State Strategy. 

The District has supplemented ARB’s proposal with four additional contingency 

measures. These measures include: revising stationary source NOx 

requirements to offset higher emission increases resulting from the use of natural 

gas with higher heating values, emission charges for major sources, episodic 

curtailments for older off-road equipment (operational requirements), and asking 

ARB to accelerated the development or implementation of mobile source 

measures if a reasonable further progress milestone is missed. 

 K. Reasonably Available Control Measures (RACM) Analysis 

Section 172(c)(1) and (c)(2) of the CAA requires each nonattainment area to 

demonstrate that it has adopted all reasonably available control measures 

(RACM) necessary to show that it will attain the applicable standard as 

expeditiously as practicable and to meet RFP requirements. RACM are those 

measures that are technologically and economically feasible within the 

nonattainment area. 

 

17 Section 172(c)(9) 
32 

District RACM. As part of the RACM demonstration, the District must show that 

there are no additional, existing reasonable measures available to the District 

that would advance the attainment date by at least one year or contribute to RFP 

for the area. The District must also consider, and include where applicable, 

cost-effective clean-air technologies that are contained in regulatory programs for 

other air districts in and outside of California. Where available, the District must 

also provide cost-effectiveness analyses of control measures evaluated. 

The District has included a RACM demonstration for the ozone precursor 

pollutants (i.e., ROG and NOx). This RACM demonstration identifies and 

evaluates all stationary source measures the District has implemented or plans to 

implement in the future and compares them with measures implemented by other 

agencies within and outside of the State. More detailed information on this 

analysis can be found in Appendix VI of the 2007 AQMP. 

Pursuant to California Health and Safety Code Section 39614 (SB 656, 2003), 

the District also evaluated a statewide list of feasible and cost-effective control 

measures to reduce directly emitted particulate matter (PM10 and PM2.5) and 

PM precursor emissions (i.e., ROG, NOx, and SOx). 

Based on these analyses, the District concluded that for the majority of stationary 

and area source categories, the District had the most stringent rules in California. 

However, the District identified one measure from the statewide RACM list – 

Wood Burning Fireplaces/Heaters – for adoption by the District and it is included 

in the 2007 AQMP for near-term adoption. 

The ARB submitted the District's ozone Reasonably Available Control 

Technology (RACT) SIP to U.S. EPA on January 31, 2007, with a finding that the 

revision meets federal requirements by demonstrating the application of RACT 

on all affected stationary sources of ozone precursor emissions. RACT 

measures are a subset of RACM. This submittal satisfies the RACM 

requirements for the 8-hour ozone standard. 

SCAG RACM. U.S. EPA’s RACM guidelines also call for an analysis of 

transportation control measures proposed in the plan. Consequently, SCAG has 

completed a RACM determination for transportation control measures that can 

be found in Appendix IV-C of the AQMP. 

ARB RACM. U.S. EPA has already determined that the California (i.e., ARB) 

control programs for mobile sources and fuels constitute BACM.18 Moreover, 

whereas U.S. EPA deems its federal mobile source program to establish best 

available control measures for the nation, the California program generally goes 

beyond federal mobile source requirements (where not otherwise prescribed by 

 

18See page 5419 of the February 4, 2004 proposed rulemaking for the San Joaquin Valley PM10 plan,

and page 30035 of the May 26, 2004 final rule. 
33 

federal law). Therefore, ARB believes that the State mobile source program 

exceeds federal RACM requirements. 

III. COACHELLA VALLEY OZONE ATTAINMENT DEMONSTRATION 

A. Profile of Coachella Valley 

The Coachella Valley federal nonattainment area lies in the Salton Sea Air Basin 

portion of Riverside County and is aligned in a northwest-southeast orientation 

stretching from San Gorgonio Pass to the Salton Sea. Geographically, the Valley 

is bounded by the San Jacinto Mountains to the west, the Little San Bernardino 

Mountains on the east, San Bernardino County to the north, and Imperial County 

on the south. Elevations range from approximately 500 feet above sea level in 

the northern part of the Valley to about 150 feet below seal level near the Salton 

Sea. The Valley was historically an agricultural area irrigated by water from the 

Colorado River, but is now experiencing significant population growth as a one of 

the fastest growing areas in the state. Winters are mild and summers are hot in 

this desert environment. Prevailing winds flow from west to east, carrying 

pollutants emitted in the South Coast Air Basin to the Valley. 

The Valley covers about 2,500 square miles and is home to about 410,000 

people. The region’s population is distributed throughout the Valley floor in 

modest-sized communities and is expected to grow by 32% over the next ten 

years. 

Air quality in the Coachella Valley is heavily impacted by ozone and ozone 

precursor emissions transported from the South Coast Air Basin. Levels of 

ozone precursor gasses emitted with in the Ozone Coachella Valley in 2006 – 

56 tpd of NOx and 22 tpd of ROG – were less than five percent of ROG and NOx 

emissions generated in the South Coast Air Basin. The San Gorgonio Pass is 

one of the major outlets for air pollution from the South Coast to the Coachella 

Valley. 

B. Nature of the Problem 

Air quality in the Coachella Valley has improved over the last decade as 

measured by the decline in measured ozone concentrations, and in the number 

of days over the 8-hour standard of 0.08 parts per million (ppm). 

Ozone “design values” are used to characterize a region’s air quality for SIP 

planning purposes. The design value is a three-year average of the annual 

fourth highest daily maximum 8-hour average ozone concentration. The use of 

the 3-year average helps minimize the year-to-year influence of meteorology. 

The U.S. Environmental Protection Agency (U.S. EPA) designated Coachella 

Valley as “nonattainment” based on its 2001-2003 design value. As the following 
34 

figure shows, the Valley’s design value has declined by 8 percent in the past ten 

years. 

Figure XX. Coachella Valley 

Federal 8-hr Ozone Design Value (1990-2006)

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Design Value (ppm)

The air quality monitor in Palm Springs has recorded the Valley’s highest ozone 

levels in all of the last 10 years. The monitoring site is located near the center of 

the city, in the northern portion of the Valley, and is at an elevation of 585 feet 

above sea level. Due to prevailing winds from northwest to southeast, the site is 

impacted primarily by emissions from the South Coast Air Basin through the 

nearby San Gorgonio Pass. Coachella Valley’s 2006 design value is 0.102 ppm. 
35 

The number of days over the standard (exceedance days) is an indication of how 

frequently the population is exposed to unhealthful air quality. The next figure 

illustrates the decline in number of days over the standard in Coachella Valley. 

In the past ten years, the number of days annually in which ozone concentrations 

in the Valley exceeded the national 8-hour standard has declined by 50 percent. 

Figure XX. Coachella Valley 

Federal 8-hr Ozone Exceedance Days (1990-2006)

0

10

20

30

40

50

60

70

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Exceedance Days

C. Emissions Inventory 

The main sources of South Coast Air Basin’s and Coachella Valley’s ozone 

precursor emissions are reasonably similar. As a result, emission reduction 

strategies designed to move the South Coast Air Basin toward attainment will 

significantly reduce locally-generated emissions in the Coachella Valley. For 

NOx, the major sources are on-road vehicles and off-road equipment. For ROG, 

the inventory is dominated by on-road vehicles, off-road equipment, and 

consumer products. The following tables show the top ten NOx and ROG 

emission sources in the Coachella Valley. 
36 

Coachella Valley 

Top Ten NOx Emissions Sources 

2006 SIP Summer Season Emissions Inventory 

Coachella Valley 

Source Category 

Emissions 

(tpd) Ranking 

OFF-ROAD EQUIPMENT 4 2 

HEAVY HEAVY DUTY DIESEL TRUCKS 36 1 

PASSENGER VEHICLES 2 4 

MEDIUM HEAVY DUTY DIESEL TRUCKS 2 5 

LIGHT DUTY TRUCKS – LDT2 2 6 

SHIPS AND COMMERCIAL BOATS - NA 

MEDIUM DUTY TRUCKS 1 8 

TRAINS 3 3 

LIGHT HEAVY DUTY GAS TRUCKS 0.5 11 

LIGHT DUTY TRUCK – LDT1 0.6 10 

AIRCRAFT 1 7 

FARM EQUIPMENT 1 9 

 SUBTOTAL OF TOP CATEGORIES 53 

 TOTAL OF ALL CATEGORIES 56 

Coachella Valley 

Top Ten ROG Emissions Sources 

2006 SIP Summer Season Emissions Inventory 

Coachella Valley 

 Source Category 

Emissions 

(tpd) Ranking 

PASSENGER VEHICLES 3 1 

CONSUMER PRODUCTS 3 3 

OFF-ROAD EQUIPMENT 2 4 

RECREATIONAL BOATS 1 5 

LIGHT DUTY TRUCKS – LDT2 1 6 

ARCHITECTURAL COATINGS 0.8 8 

PETROLEUM MARKETING 0.5 13 

COATINGS AND RELATED PROCESSES 0.8 9 

MEDIUM DUTY TRUCKS 0.7 10 

LIGHT DUTY TRUCK – LDT1 0.7 11 

HEAVY HEAVY DUTY DIESEL TRUCKS 3 2 

PESTICIDES/FERTILIZERS 0.8 7 

 SUBTOTAL OF TOP CATEGORIES 17 

 TOTAL OF ALL CATEGORIES 22 

Because the ozone attainment deadline falls in the middle of the 2013 ozone 

season and design values are calculated for calendar years, the SIP must 

provide for sufficient emission reductions in 2012 in order to demonstrate 

attainment in 2013. The following table summarizes projected emission 

reductions from 2006, the base year for this plan, to 2012, the ozone season that 

must be modeled to demonstrate attainment by June 2013. The baseline 
37 

inventories reflected in this table reflect projected growth in the Coachella Valley, 

and State and local controls adopted through December, 2006. 

Coachella Valley 

Baseline Emission Trends with Measures Adopted as of 2006 

(summer planning inventory, tpd) 

ROG NOx

Source 

Category 2006 2012 % 

Change 2006 2012 % 

Change 

Stationary & 

Area-wide 6.6 7.3 +11% 1.4 1.3 -7% 

On-Road 

Motor 

Vehicles 

9.4 6.4 -32% 43.6 25.5 -41% 

Off-Road 

Vehicles and 

Equipment 

5.5 4.8 -13% 9.1 8.3 -9% 

TOTAL 21.6 18.6 -14% 54.1 35.1 -35% 

 Note: Totals may not add due to rounding. 

D. Attainment Demonstration 

Coachella Valley’s “serious” nonattainment area classification requires 

attainment of the 8-hour ozone NAAQS by June 15, 2013. The Valley needs to 

demonstrate a design value of 0.084 ppm (at most) in 2012 to attain the NAAQS. 

In 2006, the Valley exceeded the standard on 26 days with an ozone design 

value of 0.102 ppm, which is approximately 21 percent over the standard. 

Existing and proposed control programs in the South Coast Air Basin are 

expected to reduce the transport of ozone and ozone precursors ROG and NOx 

by about 29 and 46 percent, respectively, by the 2013 deadline. The District’s 

analysis indicates that these reductions will not be sufficient to attain the 8-hour 

ozone NAAQS in 2013. Instead, the District’s modeling analysis shows that the 

Coachella Valley will not attain the 8-hour ozone NAAQS until 2017. 

E. Photochemical Modeling 

The photochemical modeling used to determine the attainment date in the 

Coachella Valley was conducted by the District using the EPA-accepted 

“Comprehensive Air Quality Model with Extensions” (CAMx) modeling system to 

estimate the emissions reductions needed to achieve the ozone standards. A 

meteorological model, Mesoscale Model version 5 (MM5), was used to drive the 

transport and dispersion in the CAMx model. 

The District’s air quality modeling concluded that attainment of the 8-hour ozone 

NAAQS by 2013 was not possible, but that a design value of 0.084 ppm would 
38 

be achieved by 2017. U.S. EPA’s ozone modeling guidance indicates that when 

photochemical modeling projects attainment year concentrations of 0.082-0.087 

ppm, the State may conduct further analyses of the model outcomes and 

consider other evidence such as emissions and air quality trends data. If the 

weight of this evidence supports a finding that the proposed control program will 

result in attainment by the statutory deadline, the State may consider this 

evidence in determining whether the proposed control program will result in 

attainment. ARB staff conducted a weight of evidence (WOE) attainment 

demonstration to evaluate the likelihood of attainment by 2017. 

F. Supplemental Analysis 

The supplemental analysis conducted for the Coachella Valley concludes, on the 

basis of air quality and emission trends, that the Valley will attain the 8-hour 

ozone NAAQS by 2015. This result is due primarily to the overwhelming 

influence of transport from the South Coast Air Basin on Coachella Valley ozone 

levels, and the massive reductions in precursor pollutant emissions planned for 

the South Coast Air Basin over the next eight years. Statistical analysis of ozone 

air quality trends in the two areas shows a very high correlation between the 

South Coast Air Basin and the Coachella Valley levels during the period of 1997 

and 2005, and an analysis of diurnal variations shows that hourly ozone peaks 

occur progressively later in the day at monitoring sites at increasing distances 

east of the eastern boundary of the South Coast Air Basin. The ARB staff 

supplemental analysis concurs with the District’s conclusion of attainment by 

2018 or earlier. 

IV. ON-ROAD MOTOR VEHICLE EMISSIONS BUDGETS 

Under section 176(c) of the Act, transportation activities that receive federal 

funding or approval must be found to be fully consistent with the SIP. 

U.S. EPA's transportation conformity rule, found in 40 CFR parts 51 and 93, 

details the requirements for establishing motor vehicle emissions budgets in SIPs 

for the purpose of ensuring the conformity of transportation plans and programs 

with the SIP attainment demonstration. The on-road motor vehicle emissions 

budgets act as a "ceiling" for future on-road mobile source emissions. 

 

Exceedances of the budget indicate an inconsistency with the SIP, and could 

jeopardize the flow of federal funds for transportation improvements in the region. 

Projected regional on-road mobile source emissions are compared to these 

budgets during the periodic updates of regional transportation plans and 

programs. 
39 

The federal transportation conformity regulation19 requires SIPs to specify the 

levels of on-road motor vehicle emissions that are consistent with attainment and 

maintenance of air quality standards. To receive federal approval and funding, 

transportation agencies must demonstrate that emissions from transportation 

plans, programs, and projects conform to these “emission budgets.” 

Conformity budgets previously published in the 2007 AQMP and approved by the 

District board reflect the mobile source measures the District had proposed for 

ARB adoption. Budgets that reflect the approved SIP revision, including the 

approved State Strategy, will be made available for public review and comment 

as required by federal regulations, and for review by SCAG’s Conformity Working 

Group, before the budgets are adopted as separate action and submitted to 

U.S. EPA as a SIP revision. 

A. Budget Approach 

The ozone emission budgets for ROG and NOx are derived from the summer 

planning inventory and the reductions from defined new measures in the AQMP 

that reduce on-road mobile source emissions. The PM2.5 emission budgets for 

PM2.5, and the PM2.5 precursors ROG and NOx, are derived from the annual 

average inventory. These budgets reflect existing control programs and new 

commitments for technology and transportation control measures. 

For conformity budget calculation purposes, on-road emissions will be adjusted 

by the projected emission reductions from the proposed control measures 

specific to on-road sources. In the proposed Statewide Strategy, this includes 

the following ARB proposed control measures: 

• Smog Check Improvements 

• Expanded Vehicle Retirement 

• Modifications to the Reformulated Gasoline Program 

• Cleaner In-Use Heavy-Duty Trucks 

• Truck Modernization 

• Enhanced Heavy-Duty Truck Measures 

Proposed measures that may address but are not limited to on-road vehicles, 

such as the proposals to secure additional reductions from port-related sources 

or to use DMV registration fees for SIP-creditable projects, will not be will not be 

reflected in the conformity budgets. 

The approach is consistent with U.S. EPA's transportation conformity rule, which 

provides that if emission budgets rely on new control measures, these measures 

should be specified in the SIP and the emission reductions from each control 

 

19 U.S. EPA maintains online information on its transportation conformity program, including access to 

relevant rulemakings, policy guidance, and reports at: http://www.epa.gov/otaq/transp/traqconf.htm. 
40 

measure should be quantified and supported by agency commitments for 

adoption and implementation schedules. Moreover, to comply with U.S. EPA’s 

rule, the conformity analyses by transportation agencies cannot take credit for 

measures which have not been implemented unless the measures are "projects, 

programs, or activities" in the SIP supported by written implementation 

commitments by the responsible agencies.20

The emission budgets for ozone and PM2.5 are provided up to the respective 

attainment year (i.e., 2014 and 2023). However, since transportation analyses 

are needed beyond the attainment dates, the carrying capacities for the ozone 

attainment demonstration also serve as the budgets for future years (e.g., 2030 

for PM2.5 and ozone). Ozone precursor emissions from motor vehicles are 

projected to continue declining through these extended periods. 

V. REVIEW OF PUBLIC PROCESS 

The District held numerous public meetings, workshops, advisory group 

meetings, and regional hearings throughout the two year process leading up to 

its public hearing to consider approval of the AQMP. The District governing 

board also convened a hearing on the Draft AQMP in each county within the air 

basin as required by State law21. The District's 2007 AQMP document the public 

process and demonstrates compliance with State and federal public process 

requirements. 

The sequence of public meetings held to discuss the elements of the proposed 

State Strategy is described in the staff report developed for the Board’s 

consideration of the Strategy. In addition to the general workshops, ARB staff 

worked extensively with South Coast District staff to refine the technical 

components of the plan, and to develop control options and associated 

emissions reduction estimates for discussion in public workshops and inclusion in 

the draft AQMP and State Strategies. 

VI. POTENTIAL IMPACTS 

Potential environmental and economic impacts are addressed in the South Coast 

AQMP, which is available at 

http://www.aqmd.gov/aqmp/07aqmp/07AQMP_socio.html, 

and in the ARB staff Proposed State Strategy, available at 

http://www.arb.ca.gov/planning/sip/2007sip/2007sip.htm. 

 

20 62 FR 43780 and 40 CFR 93, subpart A. 21 California Health and Safety Code (HSC) section 40466.
41 

The environmental, economic, environmental justice, and global warming 

impacts associated with specific control measures will also be addressed as 

those programs are adopted. 
42 
GLOSSARY OF ACRONYMS 

2007 AQMP Proposed 2007 Air Quality Management Plan for the 

South Coast Air Basin 

South Coast District South Coast Air Quality Management District 

ARB California Air Resources Board 

PM2.5 Federal ambient air quality standard for particulate 

matter concentrations under 2.5 microns in size 

8-Hour Ozone Federal ambient air quality standard for ozone 

concentrations averaged over 8 hours 

SCAG Southern California Association of Governments 

VOC Volatile organic compounds 

ROG Reactive organic gases 

NOx Nitrogen oxides 

SOx Sulfur oxides 

TPD Tons per day 

RACMs Reasonably Available Control Measures 

RACT Reasonable Available Control Technology 

BARCT Best Available Retrofit Control Technology 

SCAB South Coast Air Basin 

CAA, or Act Federal Clean Air Act 

State Strategy Proposed ARB control measures for the 2007 AQMP 

ug/m3 Micrograms per cubic meter 

ppm Parts per million