April 26, 2007 1 

Executive Summary 

Introduction

The Air Resources Board’s proposed State Strategy for California’s 2007 State 

Implementation Plan (SIP) is a comprehensive strategy designed to attain federal 

air quality standards through a combination of technologically feasible, costeffective, and far reaching measures. It describes the scope of the State’s ozone 

and fine particulate matter (PM2.5) nonattainment problems and presents ARB 

staff’s recommendations on how California can comply with federal standards. 

The proposed strategy will be considered for adoption by ARB’s Governing 

Board on June 21-22, 2007. 

Under State law, ARB has the responsibility to develop SIP strategies for mobile 

sources and consumer products, to coordinate SIP strategies with the Bureau of 

Automotive Repair (BAR) and Department of Pesticide Regulation (DPR), and to 

oversee local district programs for stationary sources. 

The 2007 SIP is the first plan designed to show how California will meet the 

federal 8-hour ozone standard – it represents a transition from the less stringent 

1-hour standard that was the benchmark for previous SIPs. Since the new 

standard is more stringent, the U.S. Environmental Protection Agency (U.S. EPA) 

set presumptive deadlines that allow more time for attainment. Nonetheless, the 

measures California has adopted to meet the 1-hour standard remain in place 

and will deliver substantial new reductions over the next few years. These 

measures have enabled San Diego, Ventura, Santa Barbara, and the San 

Francisco Bay Area to meet the 1-hour ozone standard. 

The benefits of California’s mobile source control program are evident and serve 

as the foundation for this new State Strategy. For example, the mobile source 

regulations already in place will reduce today’s emissions from passenger 

vehicles and heavy-duty trucks another 50 percent by 2015. The ARB staff’s 

proposed State Strategy would further accelerate the reductions. Staff’s 

proposed State Strategy addresses three key mobile source issues: the need to 

clean up the legacy diesel fleets, the national and international nature of many 

diesel fleets, and limitations on SIP credit for unsecured funding. 

The proposed State Strategy, in combination with local actions, would provide 

emission reductions necessary to the meet 8-hour ozone standard in the two 

most challenging regions -- the South Coast Air Basin and the San Joaquin 

Valley. The State Strategy is also necessary, in whole or part, for the 

Sacramento region, Ventura, and several locations downwind of urban areas. 

Ozone SIPs are due to U.S. EPA in June 2007. 

The State Strategy provides reductions needed for PM2.5 attainment in the 

South Coast and expected to be necessary for the San Joaquin Valley. PM2.5 

SIPs for these two regions are due in 2008. 
April 26, 2007 2 

Adoption of the State Strategy by the Board would create an enforceable 

commitment for new emission reductions by the attainment deadline for each 

region. These commitments reflect the proposed attainment deadlines of 2024 

for ozone for the South Coast and San Joaquin Valley and a deadline of 2015 for 

PM2.5. As in past SIPs, staff has estimated the expected emission reductions 

from various measures and a schedule for Board consideration. The Board 

retains the ability to modify staff proposals and achieve the necessary reductions 

through other measures or mechanisms. 

This proposal includes aggregate emission reduction commitments for 2014 for 

South Coast and San Joaquin Valley PM2.5, and for 2020 and 2023 for South 

Coast and San Joaquin Valley ozone. The commitments precede the attainment 

deadline by one year in order to comply with federal SIP requirements. Staff may 

propose additional commitments for Board consideration in the future to the 

extent necessary. A PM2.5 SIP is under development by the San Joaquin Valley 

District and on track for adoption in 2008. The South Coast has proposed early 

adoption of a PM2.5 SIP in parallel with the ozone SIP due this year. 

The 2023 commitment for ozone includes the long-term emission reductions 

needed for ozone attainment in the South Coast and San Joaquin Valley under 

the “new technology” provisions of the Clean Air Act (section 182(e)(5)). Staff 

proposes that ARB take on the full legal commitment for these reductions with 

the understanding that advances in technology for sources under local air 

districts’ jurisdiction should contribute to future reductions. Until new mobile and 

stationary technologies become available, we propose to defer the issue of how 

to apportion long-term emission reduction obligations among responsible 

agencies. This issue will be revisited in future SIP updates. In the meantime, 

ARB would be responsible for all the long-term reductions upon SIP approval. 

Proposed Mobile Source Strategy 

The mobile source strategy has two distinct components – more stringent 

standards for new engines and cleanup of existing fleets. For passenger 

vehicles, ARB’s Low Emission Vehicle Program ensures that new vehicles 

entering the fleet are exceptionally clean. The challenge is maintaining low 

emission levels over time and getting the oldest, dirtiest remaining vehicles off 

the road as soon as possible. The State Strategy proposes improvements to 

Smog Check and expansion of vehicle scrap programs to achieve these goals. 

The biggest mobile source challenge is cleaning up legacy fleets of diesel 

engines – including trucks, construction and farm equipment, ships and 

locomotives. Emissions of NOx (nitrogen oxides) from diesel engines contribute 

to both ozone and PM2.5 levels. Emissions of SOx (sulfur oxides) from ships are 

a significant contributor to PM2.5 levels. Directly emitted particulate matter from 

diesel engines contributes to PM2.5 levels. ARB has adopted a number of 

measures to reduce emissions from diesel fleets under ARB’s 2000 Diesel Risk 

Reduction Plan and 2006 Goods Movement Emission Reduction Plan. 
April 26, 2007 3 

The proposed State Strategy would incorporate measures from these plans into 

the California SIP. This includes new measures for port trucks, statewide truck 

fleets, ships traveling and in port, locomotives, and harbor craft. These 

measures would accelerate introduction of newer, cleaner engines and, where 

available, require retrofit controls. The cost of these measures will be in the 

billions of dollars but these reductions are necessary to meet air quality 

standards and reduce the health and economic impacts of air pollution in 

California. 

The mobile source reductions rely primarily on regulatory actions by ARB, BAR, 

and U.S. EPA. International actions to require cleaner new ship engines and 

retrofits are also part of the longer-term strategy. Actions by the ports and 

private sector and public funding would complement the regulatory strategies. 

However, the enforceable SIP obligation to achieve the specified emission 

reductions would rest with the Board. 

The Board’s authority to regulate mobile sources varies by category and 

circumstance. Under California law, the Board can set new engine standards for 

mobile sources, but federal preemptions and practical limitations apply to many 

diesel engines categories. For example, under the federal Clean Air Act, only 

U.S. EPA can set new engine standards for locomotives and construction and 

farm equipment equipped with off-road engines less than 175 horsepower. In the 

case of new heavy-duty diesel trucks and other new and in-use off-road engines, 

ARB may establish emission standards, but must obtain a waiver/authorization 

from U.S. EPA before it can enforce such regulations. The interstate nature of 

trucking makes national standards for new trucks a practical necessity. While not 

admitting preemption, we recognize that U.S. EPA has the responsibility to 

represent California’s interests in the international standard setting process for 

ocean-going ships. In short, ARB must rely on the federal action to set the new 

technology standards that form much of the basis for ARB staff’s proposed 

measures to accelerate cleanup of legacy diesel fleets. 

The timing of federal standards is an important part of the picture. California can 

only accelerate the introduction of cleaner technology once cleaner engines are 

available. The cleanest NOx standards phase in for trucks in 2010 and between 

2013-2017 for various types of construction and other off-road equipment. 

U.S. EPA has proposed more stringent NOx standards for new locomotives that 

would begin in 2017. ARB staff continues to make the case that these standards 

need to be implemented prior to 2014. While the interim standards now in place 

are contributing to current progress, the magnitude of the reductions needed in 

the South Coast and San Joaquin Valley will ultimately require the cleanest 

technology in every diesel engine application. 
April 26, 2007 4 

The proposed mobile source strategy and SIP commitments are described in 

Chapter 3. Individual measures are described in more detail in Chapter 5. The 

figure below shows the decrease in emissions for passenger vehicles, heavyduty trucks, and construction equipment between now and 2014 with the 

proposed State Strategy. Due to increasingly more stringent mobile source 

controls, emissions from these categories are all on a downward trend, despite 

growth in population, travel, and the economy. The new measures in the 

proposed State Strategy would accelerate these emissions reductions. ARB staff 

is proposing an aggressive new emission reduction commitment of 122 tons per 

day of NOx reductions in the South Coast by 2014 in order to meet the region’s 

PM2.5 attainment needs. This would bring the total mobile source NOx 

reductions achieved between 2006 and 2014 to about 450 tons per day. 

Impact of State Strategy by 2014

South Coast - NOx

0

50

100

150

200

250

2006 2014

Trucks

2006 2014

Passenger 

Vehicles

2006 2014

Construction 

Equipment

In contrast to passenger vehicles, trucks, and construction equipment that show 

substantial emission decreases with natural fleet turnover, locomotive and ships 

show an increase in emissions without the proposed State Strategy. Locomotive 

emissions have been decreasing in the South Coast due to the accelerated 

introduction of the cleanest current technology (Tier 2). However, as shown 

below, growth overtakes this benefit by 2014. The proposed State Strategy 

includes a measure to accelerate introduction of the next generation of clean 

technology once U.S. EPA adopts its proposed new Tier 4 standards. The 2014 

benefits assume Tier 4 engines becoming available in 2012. The 70 percent 

reduction projected for 2020 is based on the proposed measure to accelerate the 

introduction of Tier 4 locomotives to California. 
April 26, 2007 5 

Locomotives

South Coast-NOx

0

5

10

15

20

25

tons/per day

2014 2020

Without State Strategy

Without State Strategy

With 

State Strategy

With 

State Strategy

Ocean-going ships show an even greater increase in emissions without the State 

Strategy. Ship engines are largely uncontrolled, and growth in goods movement 

through California ports will exacerbate this problem. The figure below shows 

the benefits of the proposed State Strategy in the South Coast. 

Ships

South Coast - NOx

0

10

20

30

40

50

60

70

80

90

100

tons per day

2014 2020

Without State Strategy

Without State Strategy

With State 

Strategy

With State 

Strategy

Proposed Consumer Products Strategy

Consumer products are expected to become the largest source of reactive 

organic gas (ROG) emissions in the South Coast and the third largest source in 

the San Joaquin Valley by 2020. The magnitude of the emissions indicates that 

additional controls for this sector remain important, even though the average 

photochemical reactivity of the ROG emissions from consumer products is about 

one-third that of motor vehicle exhaust. The proposed State Strategy would 

continue ARB’s commitment to reduce ROG emissions from consumer products. 
April 26, 2007 6 

Two new phases of control are proposed. One is under development for Board 

consideration by 2008 and the other between 2010 and 2012. As part of ARB’s 

longer-term strategy, staff also proposes to explore additional market-based 

mechanisms to encourage the development, distribution, and purchase of 

cleaner, very low, or zero emitting products. 

The table below shows the expected reductions from the proposed State 

Strategy in 2014 for South Coast and San Joaquin Valley. The benefits of the 

State Strategy will increase over time. The expected reductions in 2020 and 

2023, along with the proposed timeframes for staff development, Board 

consideration, and implementation of the these measures is found in Chapter 3. 

Expected Emission Reductions from Proposed New SIP Measures 

(tons per day) 

South Coast and San Joaquin Valley -- 2014 

South Coast San Joaquin 

Valley 

Proposed New SIP Measures NOx ROG NOx ROG

Passenger Vehicles 14.4 17.7 3.8 6.5 

 Smog Check Improvements (BAR) 12.0 10.5 3.3 2.9 

 Expanded Vehicle Retirement 2.4 2.8 0.5 0.7 

 Modifications to Reformulated Gasoline Program -- 4.4 -- 2.9 

Heavy-Duty Trucks 47.3 5.1 61.4 6.4 

 Cleaner In-Use Heavy-Duty Trucks 47.3 5.1 61.4 6.4 

Goods Movement Sources 49.4 0.7 7.2 0.5 

 Ship Auxiliary Engine Cold Ironing & Clean Technology 18.5 -- -- -- 

 Cleaner Main Ship Engines and Fuel 20.0 -- -- -- 

 Port Truck Modernization 2.0 -- -- -- 

 Accelerated Intro. of Cleaner Line-Haul Locomotives 4.3 0.7 7.2 0.5 

 Clean Up Existing Harbor Craft 4.6 -- -- NYQ 

Off-Road Equipment 10.5 2.7 3.7 0.9 

 Cleaner In-Use Off-Road Equipment (e.g.,Construction) 10.5 2.7 3.7 0.9 

 Cleaner In-Use Agricultural Equipment NYQ NYQ NYQ NYQ 

Other Off-Road Sources 0.4 6.6 0.1 3.5 

 New Emission Standards for Recreational Boats 0.4 4.2 0.1 1.3 

 Expanded Off-Road Rec. Vehicle Emission Standards -- 2.4 -- 2.2 

 Additional Evaporative Emission Standards -- NYQ -- NYQ 

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

Areawide Sources -- 12.9 -- 5.7 

 Consumer Products Program -- 12.9 -- 3.2 

 Pesticides: DPR 2008 Regulation -- NYQ -- 2.5 

Emission Reductions from Proposed New Measures 122 46 76 23 

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

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

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

Emission reduction estimates for each proposed measure are shown for informational purposes only. Actual 

emission reductions from any particular measure may be greater than or less than the amounts shown. 
April 26, 2007 7 

Major Issues

 Bump Up to “Extreme” for Ozone 

There is concern that the proposed State Strategy does not provide sufficient 

emission reductions to show attainment of the ozone standard earlier than the 

deadlines proposed in the South Coast and San Joaquin Valley SIPs. Both 

ozone SIPs propose an “extreme” classification for the 8-hour ozone standard 

which sets an attainment deadline of 2024. Under the federal Clean Air Act, the 

extreme classification carries with it an ability to rely on as yet undefined new 

technologies where necessary (section 182(e)(5)). 

Both regions were previously classified as “extreme” for the 1-hour ozone 

standard based on the severity of their ozone problem. With the transition to the 

more stringent 8-hour standard, these districts were classified as severe-17, with 

an attainment deadline of 2021 (South Coast), and serious, with an attainment 

deadline of 2013 (San Joaquin Valley), based solely on their ambient 

concentrations of ozone. In reality, both districts need more time to accomplish 

the substantial emission reductions required for attainment. 

Air districts have the ability to request a reclassification, and in the case of a 

request to reclassify to “extreme,” U.S. EPA must grant the request. Since such 

a request frames a district’s attainment demonstration, ARB must also accept the 

reclassification request unless the Board rejects a district SIP as inconsistent 

with federal requirements. 

The proposed reclassifications raise the issue of how the 2024 attainment 

deadline will affect air quality progress and the health impacts of air pollution in 

these regions. This is a very real concern. Accordingly, in the SIP development 

process considerable effort was devoted to assessing whether these bump-ups 

could be avoided. 

ARB staff considered whether existing technologies, if applied across the board 

to all mobile and stationary sources, could achieve the necessary emission 

reductions to attain sooner. Unlike rulemaking processes, this analysis was 

performed for SIP development purposes without considering cost as a 

constraint. 

The analysis showed that all diesel fleets would need to turn over to the newest 

engine standards that phase in between 2010 and 2017, all passenger vehicles 

would need to be no older than 10 years, and substantial additional reductions 

would be needed from new technologies for both mobile and stationary sources. 

The only other potential option for fully achieving the remaining reductions would 

be to constrain growth, business operations, and personal travel. Absent policy 

decisions to impose such restrictions, ARB staff believes it is necessary to make 

use of the new technology provision of the Clean Air Act. For the San Joaquin 
April 26, 2007 8 

Valley, about 10 percent of the necessary reductions would fall in this category. 

For the South Coast, it would be about 25 percent of the necessary reductions. 

To address concerns about delays in attainment, ARB staff proposes to continue 

to identify and pursue additional actions that would further accelerate air quality 

progress. While it is unlikely that the entire ozone attainment gap will be filled 

without new technology, staff believes additional progress could be made if, for 

example, more incentive funds became available. Also, as regions move closer 

to attainment, episodic “spare the air” type programs may be able to provide the 

final increment of reductions needed a few days per year. Public education and 

outreach to encourage voluntary actions have historically been key elements of 

these programs. 

South Coast PM2.5 SIP 

How the SIP should address the PM2.5 attainment challenge in the South Coast 

continues to be controversial. The proposed State Strategy along with district 

measures leaves an emission reduction gap in the South Coast’s proposed 

attainment demonstration of about 70 tons per day of NOx in 2014. The South 

Coast air district staff has identified a set of measures -- mobile source NOx 

measures -- for ARB to adopt to close the gap. This would be above and beyond 

the 451 tons per day of NOx reductions in the proposed State Strategy. ARB 

staff believes the District’s suggested mobile source measures are not feasible 

without billions of dollars of unidentified subsidies to expedite the introduction of 

the newer, cleaner diesel vehicles and equipment. 

ARB technical staff has reviewed South Coast’s proposed PM2.5 attainment 

demonstration and identified additional local measures to reduce directly emitted 

particulate matter. ARB staff believes these measures can bridge the gap and 

achieve the standard by 2014. These measures would reduce emissions from 

residential wood smoke, restaurant cooking, and dust-generating activities. 

The ARB staff’s analysis and the peer review of the staff methodology are 

discussed in Chapter 4. 

It is important to recognize that the projected gap in reductions is based on a 

modeling assessment that is more pessimistic than the measured air quality 

trend. Between 2001 and 2006, the measured PM2.5 annual average dropped 

from 30 to just over 20 ug/m3 consistent with the downward emissions trend. If 

that trend continues, the emission reductions in the proposed State Strategy will 

be sufficient for attainment. The South Coast predicts that with ARB staff’s 

proposed State Strategy, the highest remaining concentration in 2014 would 15.7 

ug/m3 -- less than one microgram above the 15 ug/m3 standard. Even if that 

modeling is correct, ARB’s alternative attainment strategy would close that gap. 
April 26, 2007 9 

South Coast PM2.5 

Air Quality and Modeling

(Rubidoux)

0

5

10

15

20

25

30

35

2001 2006 2014

Concentrations (ug/m3)

Measured

Measured

Modeled

In light of the measured PM2.5 progress over the past 15 years, and the 

magnitude of the new emission reductions that will occur, ARB staff believes that 

the South Coast will attain the PM2.5 standard by 2015 with the mobile source 

measures in the proposed State Strategy. Nonetheless, to be health protective 

and meet U.S. EPA SIP modeling requirements, staff believes that additional 

feasible measures should be pursued. Using the South Coast model, ARB staff 

found that the proposed local measures for residential wood smoke, restaurant 

cooking, and fugitive dust would close the apparent gap. 

Proposed Action 

Staff is recommending that the Board adopt the proposed State Strategy to meet 

both ozone and PM2.5 attainment needs in the South Coast Air Quality 

Management District and the San Joaquin Valley Air Pollution Control District at 

ARB’s June 21-22, 2007 public meeting. The State Strategy, in combination with 

near-term local air district measures, must meet the emission reduction target in 

each region’s attainment demonstration. 

The sequence of public meetings to consider the various SIP elements is: 

• April 30, 2007 – San Joaquin Valley Air Pollution Control District 

Governing Board consideration of the San Joaquin Valley Ozone Plan. 

• June 1, 2007 (tentative) – South Coast Air Quality Management District 

Governing Board consideration of the South Coast Air Quality 

Management Plan. 

• June 14, 2007 – ARB consideration of San Joaquin Valley Ozone Plan. 

• June 21-22, 2007 – ARB consideration of the proposed State Strategy and 

South Coast District Air Quality Management Plan for ozone and PM2.5. 

• April 2008 – Completion of San Joaquin Valley PM2.5 SIP. 
April 26, 2007 10 

Next Steps

Once local plans and the State Strategy are approved by the local and State 

governing boards, they are submitted to U.S. EPA for approval. 

SIPs are generally updated on a triennial basis for regions with the most 

persistent air quality problems. When U.S. EPA revises national ambient air 

quality standards, new SIP planning processes are triggered. U.S. EPA recently 

tightened its 24-hour PM2.5 standard and is currently reviewing the 8-hour ozone 

standard. Final U.S. EPA action on the 8-hour ozone standard review is 

expected by March 2008. 

Technical Supporting Documents

By May 7, 2007 – 45 days before the June 21-22, 2007 Board hearing — ARB 

staff will release these additional elements as an appendix to this document. 

• Economic analysis; 

• Environmental impacts analysis; 

• Detailed emissions data; 

• Reasonable Further Progress demonstrations; 

• Contingency reductions for progress milestone years; and 

• Legal authority and other federally required submittals.