CALIFORNIA ENVIRONMENTAL PROTECTION AGENCY 

AIR RESOURCES BOARD 

STAFF REPORT: INITIAL STATEMENT OF REASONS 

PROPOSED DIESEL PARTICULATE MATTER CONTROL MEASURE FOR 

ON-ROAD HEAVY-DUTY DIESEL-FUELED VEHICLES OWNED OR 

OPERATED BY PUBLIC AGENCIES AND UTILITIES 

Date of Release: October 21, 2005 

Scheduled for Consideration: December 8-9, 2005 

This report has been reviewed by the staff of the California Air Resources Board and 

approved for publication. Approval does not signify that the contents necessarily reflect the 

views and policies of the Air Resources Board, nor does mention of trade names or 

commercial products constitute endorsement or recommendation for use. 
State of California 

California Environmental Protection Agency 

AIR RESOURCES BOARD 

PROPOSED DIESEL PARTICULATE MATTER CONTROL MEASURE FOR ON-ROAD 

HEAVY-DUTY DIESEL-FUELED VEHICLES OWNED OR OPERATED BY PUBLIC 

AGENCIES AND UTILITIES 

Staff Report 

October 2005 
i

TABLE OF CONTENTS 

EXECUTIVE SUMMARY .........................................................................................................1

I. INTRODUCTION...........................................................................................................2

A. Heavy-Duty Diesel Vehicles Operated by Public Agencies and Utilities........................2

B. Regulatory Authority......................................................................................................5

II. PUBLIC OUTREACH....................................................................................................8

A. Environmental Justice ...................................................................................................9

B. Outreach Efforts ............................................................................................................9

III. NEED FOR REDUCTION OF EMISSION REDUCTIONS...........................................11

A. Particulate Matter ........................................................................................................11

B. Ozone..........................................................................................................................11

IV. ENGINE AND EMISSION INVENTORY......................................................................12

A. Engine Inventory..........................................................................................................12

B. Emission Inventory ......................................................................................................13

V. SUMMARY OF PROPOSED CONTROL MEASURE .................................................14

A. Scope and Applicability ...............................................................................................14

B. Best Available Control Technology (BACT).................................................................15

C. Implementation Schedule ............................................................................................17

D. Calculating Fleet Size for Implementation ...................................................................22

E. Compliance Extensions ...............................................................................................23

F. Diesel Emission Control Strategy Special Circumstances...........................................26

G. Record Keeping Requirement .....................................................................................28

H. Contractor Compliance Requirement ..........................................................................29

I. Non-Compliance and Enforcement..............................................................................30

VI. TECHNOLOGICAL FEASIBILITY OF CONTROL MEASURE...................................30

A. Availability of Ultra-low Sulfur Diesel Fuel ...................................................................30

B. Verification of Diesel Emission Control Strategies.......................................................31

C. Diesel Emission Control Strategies for In-use Public and Utility Fleet Vehicles ..........33

D. Engine Technology for Public and Utility Fleet Vehicles..............................................39

E. ARB Exhaust Temperature Study................................................................................42

F. Implementation Assistance..........................................................................................42

VII. REGULATORY ALTERNATIVES...............................................................................42

A. Do Not Adopt This Regulation .....................................................................................43

B. Rely on Voluntary Programs........................................................................................43

C. Require Repowered Engines or New Vehicle Purchases............................................43

D. Require Alternative Fuel ..............................................................................................44

VIII. ECONOMIC IMPACT ..................................................................................................44

A. Legal Requirement ......................................................................................................45

B. Affected Manufacturers ...............................................................................................45

C. Estimated Costs to Investor-Owned Private Utilities....................................................45

D. Potential Impact on Utilities .........................................................................................49

E. Potential Impact on Businesses...................................................................................51

F. Potential Impact on Business Competitiveness...........................................................51

G. Potential Impact on Employment.................................................................................51

H. Potential Impact on Business Creation, Elimination or Expansion...............................51
ii

I. Potential Costs to Local Agencies ...............................................................................52

J. Potential Costs to State Agencies ...............................................................................53

K. Cost to Federal Agencies ............................................................................................54

L. Cost to Municipalities and Utilities Located in Low Population Counties .....................54

M. Cost to the Average Household for Utilities .................................................................54

IX. ENVIRONMENTAL IMPACT AND COST-EFFECTIVENESS ....................................55

A. Statewide Emission Benefits .......................................................................................55

B. Impacts on the State Implementation Plan for PM10 ....................................................57

C. Health Benefits of Reductions of Diesel PM Emissions...............................................58

D. Cost-Effectiveness of Proposed Regulation ................................................................60

E. Potential Negative Impacts..........................................................................................60

X. ISSUES .......................................................................................................................62

A. Low Population Definition ............................................................................................62

B. Biodiesel......................................................................................................................63

C. Alternative Compliance Plan or Alternative Early Compliance Plan ............................64

D. Cost to Local Government Agencies ...........................................................................64

E. Applicability of Proposed Rule to Federal Agencies ....................................................64

XI. SUMMARY AND STAFF RECOMMENDATION.........................................................65

XII. REFERENCES............................................................................................................66
iii

TABLE OF TABLES 

Table 1. Public Agency Fleet Distribution.....................................................................3

Table 2. Public Agencies' Diesel-Fueled Heavy-Duty Trucks By Application............3

Table 3. Private Utilities' Top Ten Vehicles by Application Type................................4

Table 4. Public and Utility Heavy-Duty Vehicles by Model Year Group in 2004........4

Table 5. Public Agencies' Engine Manufacturers.........................................................5

Table 6. Workshop Locations and Times....................................................................10

Table 7. Baseline Public Agency and Private Utility Inventory (Tons Per Year)......14

Table 8. Potential Reductions from the Use of DECSs. .............................................16

Table 9. Implementation Schedule for 1960 to 2006 MY Engines .............................17

Table 10. Low Population Counties: Populations Under 125,000...............................19

Table 11. Optional Impementation Schedule................................................................21

Table 12. Verified Level 3 DECS.....................................................................................31

Table 13. Verified Level 2 DECS.....................................................................................32

Table 14. Verified Level 1 DECS.....................................................................................32

Table 15. Emission Standards for New Heavy-Duty Engines......................................39

Table 16. Diesel PM Reductions by Alternative Compared to the Proposal. .............44

Table 17. Most-Likely Verification Retrofit Scenario....................................................47

Table 18. Average Capital Costs for Diesel Emission Control Strategies..................48

Table 19. Incremental Annual Operation and Maintenance Costs..............................48

Table 20. Average Total Statewide Costs .....................................................................49

Table 21. Initial and Annual Costs Average Small Utility with 5 Vehicles..................50

Table 22. Average Local Government Costs ................................................................53

Table 23. Average Costs to the State ............................................................................53

Table 24. Statewide Diesel PM Emission Reduction Benefits.....................................55

Table 25. Other Pollutant Reductions ...........................................................................56

Table 26. Statewide Diesel CO Emission Reduction Benefits.....................................56

Table 27. Statewide Diesel HC Emission Reduction Benefits.....................................56

Table 28. Statewide Diesel NOx Emission Reduction Benefits...................................57

Table 29. Counties with Populations Between 125,000 to 300,000.............................63
iv

APPENDICES 

APPENDIX A: PROPOSED DIESEL PARTICULATE MATTER CONTROL MEASURE 

FOR ON-ROAD HEAVY DUTY DIESEL-FUELED VEHICLES OWNED 

OR OPERATED BY PUBLIC AGENCIES AND UTILITIES 

APPENDIX B: PUBLIC AND UTILITY VEHICLE EMISSIONS INVENTORY 

APPENDIX C: COST EFFECTIVENESS METHODOLOGY 

APPENDIX D: ARB’S TEMPERATURE EXHAUST STUDY 

APPENDIX E: TOTAL FLEET CALCULATION EXAMPLES 

 
v

LIST OF ACRONYMS 

$/lb Dollars per pound 

AB Assembly bill 

ARB, or the Board Air Resources Board 

ATCM Air toxic control measure 

BACT Best available control technology 

CCR California Code of Regulations 

CO Carbon monoxide 

DECS Diesel Emission Control System or Strategy 

DOC Diesel Oxidation Catalyst 

DRRP, or Diesel Risk 

Reduction Plan 

Risk Reduction Plan to Reduce Particulate Matter Emissions from 

Diesel-Fueled Engines and Vehicles Risk Reduction Plan 

DTSC Department of Toxic Substances Control 

g/bhp-hr Grams per brake horsepower-hour 

GVWR Gross vehicle weight rating 

HC Hydrocarbon 

H&SC Health and Safety Code 

μg/m3 Microgram per cubic meter 

MY Model year 

Moyer Program Carl Moyer Memorial Air Quality Standards Attainment Program 

NO Nitrogen oxide 

NO2 Nitrogen dioxide 

NOx Oxides of nitrogen 

NOV Notice of violation 

OEHHA Office of Environmental Health Hazard Assessment 

O & M Operation and maintenance 

PM Particulate matter 

Ppmw Parts per million by weight 

SCAQMD South Coast Air Quality Management District 

SJVAPCD San Joaquin Valley Air Pollution Control District 

TAC Toxic air contaminant 

Tpd Tons per day 

Ultra low sulfur diesel 

fuel 

Diesel fuel with less than 15 ppmw sulfur content 

U. S. EPA United States Environmental Protection Agency 

VIN Vehicle identification number 

VOC Volatile organic compound 

 
1

EXECUTIVE SUMMARY 

The Air Resources Board’s (ARB or Board) mission is to provide healthful air to all 

Californians. In 1998, the Board identified diesel particulate matter (PM) as a toxic air 

contaminant and established a goal of reducing emissions of diesel PM to the lowest 

practicable levels. Diesel PM is by far the largest contributor to adverse health impacts 

from all toxic air contaminants identified, comprising 70% of statewide risk. 

In 2000, the Board adopted a comprehensive plan to reduce PM emissions from dieselfueled engines and vehicles (ARB 2000b). The ARB has already adopted several 

control measures recommended in that plan, including rules for transit buses, solid 

waste collection vehicles, stationary engines, diesel portable equipment, transportation 

refrigeration units, idling controls, new cleaner exhaust standards for heavy-duty trucks 

and off-road equipment, and ultra-low sulfur diesel fuel in mid-2006. 

The Diesel Risk Reduction Plan included control measures for on-road public fleets and 

other public and private fleets. This proposed regulation will meet that commitment. It 

will reduce ambient PM levels and exposure to primary and secondary diesel PM, in 

turn, reducing the prevalence of the diseases attributed to PM and diesel PM including 

hospitalizations for cardio-respiratory disease, and premature deaths. ARB staff 

estimates that approximately 37 deaths would be avoided by the year 2020 as a result 

of cumulative emission reductions obtained through this regulation. 

 

The ARB staff recommends that the Board adopt new sections 2022 and 2022.1 in Title 

13, California Code of Regulations (CCR), as set forth in the proposed Regulation Order 

in Appendix A. 
2

I. INTRODUCTION 

The Air Resources Board’s (ARB or Board) mission is to provide clean healthful air to all 

Californians. In 1998, the Board identified diesel particulate matter (PM) as a toxic air 

contaminant and established a goal of reducing emissions of diesel PM to the lowest 

practicable levels. Diesel PM is the largest contributor to adverse health impacts from 

all toxic air contaminants identified thus far, comprising 70% of statewide risk. 

In 2000, the Board adopted the “Risk Reduction Plan to Reduce Particulate Matter 

Emissions from Diesel-Fueled Engines and Vehicles” (Diesel Risk Reduction Plan) at a 

public meeting. Among other objectives, the Plan directs staff to develop “new retrofit 

requirements for existing on-road, off-road, and stationary diesel-fueled engines and 

vehicles where determined technically feasible and cost-effective.” 

The ARB has already adopted several of the recommended control measures, including 

rules for transit buses, solid waste collection vehicles, stationary engines, diesel 

portable equipment, transportation refrigeration units, idling controls, 2007 model year 

(MY) emission standards for heavy-duty trucks and off-road equipment, and ultra-low 

sulfur diesel fuel in mid-2006. 

The Diesel Risk Reduction Plan included a specific commitment to develop control 

measures for on-road public fleets and other public and private fleets. The proposed 

regulations are part of ARB’s continuing efforts to implement the Plan and reduce the 

public’s exposure to harmful diesel PM exhaust. 

A. Heavy-Duty Diesel Vehicles Operated by Public Agencies and Utilities 

California municipal or public fleets include all federal, state, county and city 

government fleets plus universities and special districts such as water, utility and 

irrigation districts. Airports, school districts and ports also are considered to be public 

fleets. In 2002, ARB contracted for a survey of public agencies to be used to develop 

an inventory of heavy-duty public fleet vehicles (TIAX LLC 2003). ARB staff followed up 

on the contractor's work and surveyed additional fleets not captured by the contractor. 

These include vehicles owned or operated by shareholder-owned utilities that provide 

natural gas, water or electricity services. 

Most public agencies have fleets of fewer than 15 vehicles (80.7%); 16.7 percent have 

15 to 99 vehicles, and 2.6 percent have 100 or more vehicles (Table 1). Although the 

majority of fleets have fewer than five vehicles, they account for less than 7% of the 

23,2271

 diesel fueled vehicles with over 14,000 gross vehicle weight rating (GVWR) 

owned by state and local agencies. On the other hand, only 2.6% of the fleets surveyed 

owned over 100 vehicles, but these fleets account for 46% of the vehicles owned by 

state and local agencies (Table 1). 

 

1

 Vehicle Numbers estimated by 2003 Department of Motor Vehicles (DMV) registered exempt license 

plates. 
3

Table 1. Public Agency Fleet Distribution 

Fleet Size Number of Fleets Percent (%) of 

Fleets 

Total # of 

Vehicles (%) 

0-4 324 56.5 6.9 

5-14 139 24.2 12.7 

15-49 81 14.1 23.6 

50-99 15 2.6 10.7 

100-999 15 2.6 46.0 

Total 574 100 100 

The picture for private utilities includes many small investor-owned water companies 

with one or two heavy-duty diesel-fueled vehicles each (90% of the utilities), about 15 to 

20 medium-sized utilities with 40 to 50 vehicles each (8% of the utilities) and a small 

number of large private utilities with 500 to 1,500 vehicles each (2% of the utilities). 

The TIAX report provided additional details on the types of vehicle types used by public 

agencies. Staff analyzed only the diesel-fueled trucks over 14,000 lbs gross vehicle 

weight rating (GVWR) reported by public agencies in the TIAX report. Based on this, 

there are ten vehicle types that comprise 71 percent of the total number of diesel trucks 

over 14,000 GVWR (Table 2). 

Table 2. Public Agencies' Diesel-Fueled Heavy-Duty Trucks By Application 

Application Percent of Fleet 

Dump Truck 22 

Plow & Spreader Truck 15 

Sweeper 7 

Cargo Truck 7 

Tractor Truck 5 

Sewer Truck 4 

Service Truck 3 

Flatbed Truck 3 

Aerial Lift Truck 3 

Crane Truck 2 

Total: 71 

Private utilities have more highly specialized vehicles when compared to public 

agencies. The three most common applications are specifically designed for working on 

and stringing power lines (Table 3) and comprise nearly half the total number of 

vehicles. For utilities, the top ten vehicle types account for 81 percent of the dieselfueled vehicle types. 
4

Table 3. Private Utilities' Diesel-Fueled Heavy-Duty Trucks Top Ten Vehicles by 

Application Type 

Application Percent of Fleet 

Aerial Lift Truck 23 

Bucket Truck 14 

Line Truck 11 

Material Handling Truck 9 

Dump Truck 6 

Flatbed Truck 5 

Mechanic Truck 5 

Pickup Truck 3 

Welding Truck 3 

Flatbed with Crane 2 

Total: 81 

Engine model year is particularly important for developing the emission inventory and 

analyzing the applicability of different technologies for reducing emissions. Staff also 

analyzed the diesel-fueled vehicles by engine type and model year. For the combined 

public agency and private utility fleet, half of the engines, as of 2004, were in the 1994 

to 2006 MY engine group (Table 4). These engines were certified at 0.1 gram per 

brakehorsepower-hour (g/bhp-hr) PM. Staff estimates that an additional 4% of new 

vehicles will be added when the regulation begins. 

Table 4. Public and Utility Heavy-Duty Diesel-Fueled Vehicles 

by Model Year Group in 2004 

Engine Model 

Year 

PM Certification 

(g/bhp-hr) No. of Vehicles Percent 

1960-1987 -- 6,165 21 

1988-1990 0.60 3,225 11 

1991-1993 0.25 3,988 13 

1994-2006 0.10 16,491 55 

Total 29,869 100 

The predominant engines by manufacturer are International, Cummins, and Caterpillar 

for these medium and heavy heavy-duty diesel vehicles (Table 5). 
5

Table 5. Public Agencies' Engine Manufacturers 

Engine Manufacturer Distribution 

International 36.8% 

Cummins 16.9% 

Caterpillar 16.5% 

Not Listed 10.9% 

Ford 5.9% 

Detroit Diesel 5.5% 

GMC 3.8% 

Navistar 1.7% 

Other 2.0% 

Total 99.9%

B. Regulatory Authority 

The Federal Clean Air Act (CCA) grants California the authority to control emissions 

from mobile sources. The California Clean Air Act (Health & Safety Code (H&SC) 

sections 39002, 43013, and 43018) establishes the ARB as the state agency that sets 

standards for mobile sources. Most important to this regulation, the California 

Legislature also granted ARB the authority to identify toxic air contaminants and 

establish airborne toxic control measures to reduce risk. 

1. Control of Toxic Air Contaminants 

In 1983, the California Legislature adopted Assembly Bill (AB) 1807 to enact a program 

to identify the health effects of toxic air contaminants and reduce exposure to these 

contaminants in order to protect public health (H&SC sections 39650 - 39674). The 

Legislature established a two-step process to address the potential health effects once 

a toxic air contaminant is identified: the first step is the risk assessment or identification 

phase while the second is the risk management or emission reduction phase. 

The Board is directed to address specific issues pursuant to the need for regulation 

(H&SC section 39665). These requirements were addressed in detail in the Diesel Risk 

Reduction Plan (DRRP), including the extent of present and anticipated future 

emissions, the estimated levels of human exposure, and the risks associated with those 

levels. The DRRP (ARB 2000b) describes the physical and chemical characteristics of 

diesel PM and the contribution to emissions by present sources, as well as the costs, 

availability, technological feasibility of control measures, and the potential adverse 

health or environmental impacts. Each of these issues is considered in the 

development of diesel PM regulations and will be discussed in this report specifically as 

each relates to this control measure. 
6

2. Other Authority that Provides for Exemptions 

Although they are owned and operated by public agencies, emergency vehicles and 

military tactical support vehicles are exempt from this rulemaking under other statutes 

and rules. 

The smoke inspection program which operates pursuant to H&SC section 43701 does 

not make a specific reference to “motor vehicle pollution control devices.” That section 

authorizes the adoption of standards, but does not mandate that those standards must 

be achieved by use of a “device.” Thus emergency vehicles are subject to the 

requirements designed to reduce visible smoke emissions. 

With regards to military tactical support equipment, the federal exemption for military 

tactical vehicles is stated in 40 Code of Federal Regulations (CFR) part 85, section 

1703, which refines the definition of “motor vehicle” stated in section 216(2) (42 USCA 

7550(2))of the CAA. California recognizes the federal military tactical vehicle exemption 

in section 1905 of title 13 CCR. 

3. Related California Statewide Regulations 

California has adopted regulations to ensure compliance with smoke emissions 

standards. California’s Heavy Duty Vehicle Inspection and Periodic Smoke Inspection 

Programs require that owners eliminate excessive smoke emissions and prohibit 

exhaust system tampering on diesel-fueled vehicles over 6,000 lbs GVWR; the rules 

apply to all trucks traveling within California. These regulations impose limits on the 

opacity of smoke from diesel engines when measured in accordance with a snapacceleration test procedure and have been in effect since 1991, with amendments 

adopted in 1997. 

In February 2000, the Board adopted a new fleet rule for transit agencies and more 

stringent emission standards for new urban bus engines and vehicles (ARB 1999, ARB 

2000c). The transit bus rule was designed to reduce NOx and PM by setting fleet 

emission reduction requirements, requirements for zero-emission bus (ZEB) 

demonstrations and acquisition and new more stringent mid- and long-term new bus 

purchasing standards. 

In September 2003, the Board adopted regulations for in-use solid waste collection 

vehicles. This rule requires best available control technology (BACT) on all diesel 

collection vehicles over 14,000 lbs GVWR. From 2004 through 2020, staff estimates 

that this rule will result in the elimination of over 2.26 million lbs of diesel PM from the 

air. Similar rules have been adopted for stationary engines, transportation refrigeration 

units, and portable equipment. 

The Board has also adopted limits on idling of diesel engines. In general, buses and 

commercial vehicles may idle no longer than 5 minutes. More stringent restrictions 

apply to vehicles idling near a school. 
7

4. Related Local Regulations 

The South Coast Air Quality Management District (SCAQMD) has adopted several fleet 

rules that apply to diesel vehicles. These rules generally require the affected public or 

private operator of fleets with more than fifteen vehicles to procure only alternative-fuel 

engines when purchasing new vehicles. In the case of school buses, the requirement is 

tied to the availability of grants. 

• Rule 1186.1 – Less Pollution Street Sweepers 

• Rule 1192 – Clean On-Road Transit Buses 

• Rule 1193 – Clean On-Road Residential and Commercial Refuse Collection 

Vehicles 

• Rule 1195 – Clean On-road School Buses 

• Rule 1196 – Clean On-Road Heavy-Duty Public Fleet Vehicles 

Some local air districts have enacted ordinances to encourage use of low-emission 

vehicles and retrofitting of existing vehicles. The Sacramento AQMD established the 

“Model Green Contracting Ordinance” and the “Model Low-Emission Vehicle and Fleet 

Ordinance” in October 2002, aimed at reducing ozone precursors in the Sacramento 

region. These ordinances encourage contractors to operate low-emission vehicles and 

amended local codes that regulate procuring and retrofitting of vehicles for public 

agency fleets. 

The Sacramento Area Council of Government's (SACOG) Board of Directors approved 

a strategic plan to implement a $70 million incentive program to help clean up the 

region's air. This program is known as the Sacramento Emergency Clean Air and 

Transportation (SECAT). SECAT will provide funds to vehicle owners to replace old 

engines with newer engines, use clean diesel formulations such as emulsified diesel, 

and retrofit in-use diesel engines with after-treatment. 

The San Joaquin Valley Air Pollution Control District has established a heavy-duty 

engine program, which provides incentive funds for the differential cost, associated with 

reduced emission technology as compared with the cost of conventional technology. 

Eligible funding categories include various heavy-duty on- and off-road vehicles and 

engines. 

5. California Voluntary and Incentive Programs 

Voluntary efforts play a key role in helping to achieve air quality goals. Incentives or 

early implementation credits can induce vehicle owners to reduce vehicle emissions 

prior to compliance deadlines or in excess of regulatory requirements. Several 

incentive programs exist in California which have reduced diesel PM emissions over the 

last several years. 

The California Legislature established the Carl Moyer Memorial Air Quality Standards 

Attainment Program (Moyer Program) in 1998 to reduce NOx emissions from existing 
8

vehicles. The Moyer Program funds the incremental cost of repower, retrofit, or 

purchase of new, cleaner engines that meet a specified cost-effectiveness level for NOx 

reduction. Recently, the Moyer Program has been expanded to include agricultural 

sources of air pollution as well as cars and light-duty trucks. Programs that may also be 

funded reduce hydrocarbon (HC) and PM pollution. The total Moyer Program is funded 

at approximately $140 million per year for the next 10 years. 

In 2000, the Legislature approved new funds to reduce emissions from school buses. 

The goal of this incentive program is to reduce the exposure of school children to both 

cancer-causing and smog-forming compounds. This program utilizes two strategies to 

attain these goals: pre-1987 model year school bus replacement and in-use controls for 

later model year diesel-fueled school buses. Funding for fiscal year 2005 to 2006 is $25 

million. 

6. Federal Programs 

The U.S. EPA established a Voluntary Diesel Retrofit Program in 2000 to address 

pollution from diesel construction equipment and heavy-duty on-highway vehicles. This 

program verifies technology that reduces emissions and allows fleet operators to 

choose appropriate, U.S. EPA-verified technologies that will reduce the emissions of the 

vehicles and engines in their fleets. U.S. EPA has also identified potential funding 

sources to assist air quality planners and fleet operators as they create and implement 

retrofit programs. The program assists air quality planners in determining the number of 

State Implementation Plan credits produced by their retrofit projects. The U.S. EPA has 

also established a program to fund school bus retrofits and replacements from penalty 

revenues. 

The Energy Bill authorizes up to $8.5 billion for federal Congestion Mitigation and Air 

Quality (CMAQ) programs and expresses a strong preference for funding diesel retrofit 

projects. In June 2005, the U.S. Senate passed an amendment to the Energy Bill called 

the Diesel Emissions Reduction Act (DERA) of 2005 that provides funding to cut 

emissions from high-polluting diesel engines. DERA would create a national program to 

fund the cleanup of all types of diesel-powered vehicles, including trucks, buses, 

tractors, ships, and trains. The legislation authorizes $200 million per year over five 

years in grants and loans for states and organizations to clean up existing diesel fleets. 

II. PUBLIC OUTREACH 

The ARB is committed to ensuring that all California communities have clean, healthful 

air by addressing not only the regional smog that hangs over our cities but also the 

nearby toxic pollution that is generated within our communities. The ARB works to 

ensure that all individuals in California, especially the children and elderly, can live, work 

and play in a healthful environment that is free from harmful exposure to air pollution. 
9

A. Environmental Justice 

The ARB is committed to integrating environmental justice in all its activities. On 

December 13, 2001 (ARB 2001), the Board approved Environmental Justice Policies 

and Actions,2

 which formally established a framework for incorporating environmental 

justice into the ARB's programs, consistent with the directives of State law. 

Environmental justice is defined as the fair treatment of people of all races, cultures, 

and incomes with respect to the development, adoption, implementation, and 

enforcement of environmental laws, regulations, and policies. These policies apply to 

all communities in California, but recognize that environmental justice issues have been 

raised more in the context of low-income and minority communities. 

To achieve this ambitious goal, the ARB has established a Community Health Program 

and placed new emphasis on community health issues in our existing programs. The 

Neighborhood Assessment Program is a key component in the Community Health 

Program. The Neighborhood Assessment Program Work Plan presents a plan that the 

ARB staff proposes to use to develop guidelines for evaluating and reducing air 

pollution impacts at the neighborhood-scale (ARB 2000a). 

The Environmental Justice Policies intends to promote the fair treatment of all 

Californians and cover the full spectrum of ARB activities. Underlying these Policies is 

a recognition that we need to engage community members in a meaningful way as we 

carry out our activities. People should have the best possible information about the air 

they breathe and what is being done to reduce unhealthful air pollution in their 

communities. The ARB recognizes its obligation to work closely with all stakeholders; 

communities, environmental and public health organizations, industry, business owners, 

other agencies, and all other interested parties to successfully implement these Policies. 

This control measure is in direct response to the environmental justice policy to reduce 

health risks from toxic air pollutants in all communities, especially low-income and 

minority communities. This control measure, when adopted, will provide immediate airquality benefits by reducing diesel PM emissions from public and utility vehicles which 

operate in neighborhoods. The actions we have taken in applying these policies in our 

rulemaking reflect the Board’s commitment to the fair treatment of all people throughout 

California. 

B. Outreach Efforts 

As part of the environmental justice policy to strengthen our outreach and education 

efforts in all communities, staff held seven public workshops, and many focused 

meetings in the development of this rule from April 2003 to August 2005. The 

workshops were held at times and locations that encouraged public participation. 

Attendees included representatives from local, state, and federal public agencies, 

utilities, environmental organizations, engine manufacturers, diesel emission control 

 

2

 Complete information for these programs can be found at http://www.arb.ca.gov/ch/ej.htm. 
10

manufacturers, and other interested parties. These individuals participated both by 

providing data, reviewing draft regulations and by participating in open forum 

workshops, in which staff directly addressed their concerns. In addition to this, ARB 

staff participated in a Diesel Emission Reduction for Public Agency and Utility Fleets 

Technical Conference sponsored by the California Air Pollution Control Officers 

Association (CAPCOA) in Sacramento on August 15-16, 2005. This conference was 

attended by over 500 individuals representing municipal and utility fleet managers, 

aftreatment device manufacturers, installers, engine manufacturers, fuel producers and 

environmental groups. 

Staff met with a number of stakeholders’ groups throughout the rulemaking process. 

Representatives from various public agencies and private utilities assisted ARB in 

gathering data about their fleets and provided input in developing our data survey forms. 

Alternatives were suggested to the proposed regulation and explored by staff. Staff met 

several times with representatives of the Regional Council of Rural Counties (RCRC) 

and presented at a RCRC board meeting on August 11, 2004, to specifically discuss 

compliance issues unique to small population counties and what special provisions 

could be provided in the rule. 

Workshops were in held in Sacramento and El Monte. The Sacramento workshops 

were broadcast over the internet (webcast), to provide opportunity for stakeholders 

throughout California to participate (Table 6). Over 3,000 individuals and companies 

were notified through a series of mailings. In addition, notices were posted to the web 

site and e-mailed to subscribers of ARB’s electronic list server. 

Table 6. Workshop Locations and Times 

Date Location Time 

April 3, 2003 El Monte 2:30 – 4:30 PM 

December 2, 2003 El Monte 10:00 – 12:00 PM 

December 3, 2003* Sacramento 10:00 – 12:00 PM 

May 17, 2004* Sacramento 10:00 – 12:00 PM 

May 18, 2004 El Monte 10:00 – 12:00 PM 

October 7, 2004 El Monte 10:00 – 12:00 PM 

October 8, 2004* Sacramento 10:00 – 12:00 PM 

*Webcasted workshops 

To generate additional public participation and to enhance the information flow between 

ARB and interested persons, staff made all documents, including workshop 

presentations, available via the ARB’s web site.3

 The web site provides background 

information on diesel PM, including fact sheets, workshop dates and locations, and 

other diesel related information and serves as a portal to other web sites with related 

information. 

 

3

 Located at http://www.arb.ca.gov/msprog/publicfleets/publicfleets.htm. 
11

III. NEED FOR REDUCTION OF EMISSION REDUCTIONS 

A. Particulate Matter 

PM emissions result primarily from incomplete combustion of fuel in the cylinder and 

lubrication oil that has entered the cylinder incidentally. Secondarily produced diesel 

PM is formed as a result of atmospheric reactions with diesel NOx emissions. The 

majority of diesel PM, approximately 98 percent, is smaller than ten microns in 

diameter. Diesel PM is a mixture of materials containing over 450 different 

components, including vapors and fine particles coated with organic substances. More 

than 40 chemicals in diesel exhaust are considered TACs by the State of California. 

Diesel PM has been linked to a wide range of serious health problems. Particles that 

are deposited deep in the lungs can result in lung cancer, increased hospital 

admissions; increased respiratory symptoms and disease; decreased lung function, 

particularly in children and individuals with asthma; alterations in lung tissue and 

respiratory tract defense mechanisms; and premature death. Increased PM exposure 

causes increased cardiopulmonary mortality risk as demonstrated in a validity and 

causality analysis of 57 epidemiological studies. (Dab, et al. 2001). Significant positive 

associations exist between lung cancer incidence and the number of days per year that 

respirable particulates (PM10) exceeded several thresholds (Beeson, et al. 1998). Longterm ambient concentrations of PM10 are associated with increased risks of all naturalcause mortality in males, mortality with any mention of nonmalignant respiratory causes 

in both sexes, and lung cancer mortality in males (Abbey, et al., 1999; McDonnell, et al., 

2000). 

B. Ozone 

Ground-level ozone is created by the photochemical reaction between NOx and reactive 

organic gases (ROG). Breathing ozone can trigger a variety of health problems 

including chest pain, coughing, throat irritation, shortness of breath, and congestion. It 

can worsen bronchitis, emphysema, and asthma. Ozone can also reduce lung function 

and inflame the linings of the lungs. Repeated exposure may permanently scar lung 

tissue. The elderly, children, and people with compromised respiratory systems are 

among those persons who may be most affected by exposure to ozone. 

Ground-level ozone also damages vegetation and ecosystems. It leads to reduced 

agricultural crop and commercial forest yields, reduced growth and survivability of tree 

seedlings, and increased susceptibility to diseases, pests, and other stresses such as 

harsh weather. Ground-level ozone also damages the foliage of trees and other plants, 

affecting the landscape of cities, parks and forests, and recreational areas. 

NOx is considered an important outdoor pollutant not only because it is an essential 

precursor in the formation of ground-level ozone, but also because it contributes to the 

formation of atmospheric acids and secondary particles. In addition, nitrogen dioxide is 
12

a reactive gas capable of damaging the cells lining the respiratory tract. The ARB staff 

is currently reviewing the NO2 standard for possible revision. 

IV. ENGINE AND EMISSION INVENTORY 

An improved engine and emission inventory was developed for this rule’s proposal, 

including a survey of vehicles used in California’s public fleets. The ARB contracted 

with TIAX LLC (formerly Arthur D. Little) to survey California public fleets to allow staff to 

develop a comprehensive understanding of vehicles and equipment used by various 

public agencies (TIAX LLC 2003). The survey started in February 2002 and was 

completed in February 2003. The final database contained data for 178 fleets 

representing 57 percent of the DMV estimated heavy-duty vehicles over 8,500 GVWR 

and equipment owned and operated by public agencies. The report also conveyed data 

on engine make, model, model year, vehicle types, as well as activity characteristics of 

vehicles (i.e., mileage and fuel consumption) used in public fleets in California. 

Federal agencies, some large public agencies and all private, shareholder-owned 

utilities were not included in the TIAX study, so staff continued the survey in 2004. In 

addition to the public agencies, staff contacted the three largest investor-owned private 

utilities4

 to request vehicle information. All responded with some information about their 

fleets. Two of the utilities provided detailed information on their vehicles such as engine 

make, model, model year, vehicle type and current odometer. In addition, staff 

surveyed smaller utilities and contacted them by telephone for information on their 

vehicles. 

A. Engine Inventory 

Staff estimates the population of diesel vehicles over 14,000 GVWR owned by state and 

local agencies is 23,227 based on analysis of the 2003 Department of Motor Vehicles 

(DMV) database for exempt vehicle license plates5

. We gathered engine and fleet data 

for approximately 57 percent of the vehicles used by these public fleets and 79 percent 

of the vehicles used by utilities. Staff extrapolated these data to obtain a picture of the 

entire fleet of California’s public and utility owned on-road diesel vehicles. The 

population is expected to remain relatively stable or increase slowly during the 

implementation of this regulation because of budgetary constraints. Public agencies 

tend to keep a vehicle in service for over ten years on average and thus fleet turnover 

(the time a vehicle is retired from service) is expected to remain relatively slow. 

Staff estimates there are 3,979 heavy-duty vehicles (as of 2004) owned or operated by 

private utilities subject to this rule. Approximately 3,130 of these are owned or operated 

by the three largest investor-owned utilities: Southern California Edison, PG&E, and 

Sempra Energy (Southern California Gas Company and San Diego Gas & Electric). In 

 

4

 Pacific Gas and Electric, Sempra Energy (Southern California Gas, San Diego Gas and Electric), 

Southern California Edison 

5

 This number excludes emergency vehicles, school buses, solid waste collection vehicles and transit 

buses. 
13

addition, staff identified about twenty additional utilities with 664 heavy-duty vehicles 

that are listed in the ARB’s Periodic Smoke Inspection Program (PSIP) database. Staff 

identified about 185 small water companies from the California Public Utilities 

Commission (CPUC) lists. Telephone contact with these small water companies 

determined that, on average, each has about one vehicle per company that may be 

impacted by this regulation. For federal fleets, the United States Postal Service 

(USPS), several military bases, and the federal General Service Administration (GSA) 

also submitted survey information on their heavy duty diesel vehicles accounting for 

approximately 2,663 vehicles subject to the rule. 

Combining these data, staff estimated the 2004 population of public agency and private 

utility vehicles covered by this proposal to be 29,869. 

B. Emission Inventory 

The California on-road vehicle emission inventory data consists of two elements: engine 

emissions and vehicle activity. The emissions-related data reflect new vehicle testing 

information and the latest vehicle registration data from the DMV. The activity-related 

data are updated by the regional transportation agencies that estimate the daily vehicle 

miles of travel, the distribution of travel by speed, and the number of starts per vehicle 

per day by year. In addition, staff conducted a temperature exhaust study to determine 

the percentage of vehicles that would be amenable to passive diesel emission control 

systems. A summary of this study is provided in Section VI.E. The on-road emission 

inventory is then derived using a mathematical model developed by ARB named 

EMission FACtor (or EMFAC). 

Staff calculated the emission inventory for public agency and private utility vehicles 

using the EMFAC model. Certain parameters such as vehicle age distribution, 

population and turn over (useful life) were updated based on the surveys staff did to 

support this regulatory purpose and incorporated into the revised inventory (Appendix 

B). Gasoline vehicles, alternative fueled and vehicles less than 14,001 lbs GVWR were 

not included in the emissions analysis. 

The baseline emissions for pubic agency and private utility vehicles (Table 7) gradually 

decline over time naturally with the introduction of cleaner engines in the 2007 and 2010 

model years. 
14

Table 7. Baseline Public Agency and Private Utility Inventory (Tons Per Year) 

Calendar Year PM NOx HC CO 

2000 165 4061 365 895 

2005 140 4148 103 837 

2010 93 3680 84 730 

2015 63 3093 72 644 

2020 45 2676 59 600 

V. SUMMARY OF PROPOSED CONTROL MEASURE 

Staff recommends that the Board adopt new sections 2022 and 2022.1, as set forth in 

Appendix A. The core of this proposal is a requirement that each municipality and 

private utility apply best available control technology (BACT) to its on-road heavy-duty 

diesel vehicles to reduce diesel PM emissions and associated health impacts according 

to the rule’s schedule. The proposed rule is based on the proposed control measure 

listed in the Diesel Risk Reduction Plan (ARB 2000). 

A. Scope and Applicability 

The proposed rule applies to municipalities and private utilities that own or operate one 

or more diesel-fueled on-road vehicles with a GVWR greater than 14,000 lbs, powered 

by a heavy-heavy or medium-heavy duty 1960 to 2006 MY engines. Medium and heavy 

heavy-duty diesel trucks have the highest diesel PM emissions when compared to all 

medium duty/light heavy-duty trucks and thus focusing on these vehicles is a costeffective mechanism for diesel PM reduction, as will be discussed later. The regulation 

does not apply to emergency vehicles described in the California Vehicle Code 27156.2 

or military tactical vehicles which in general are exempt from certain air pollution control 

requirements. It also does not include solid waste collection vehicles, school buses, 

transit buses or off-road vehicles which are subject to separate state regulations or 

programs. Gasoline vehicles are excluded if they do not meet the standards specified 

in these regulations. 

A municipality is defined in section 2020, title 13 of the California Code of Regulations 

(CCR) as a city, county, city and county, special district, or a public agency of the United 

States of America or the State of California, and any department, division, public 

corporation, or public agency of this State or of the United States, or two or more 

entities acting jointly, or the duly constituted body of an Indian reservation or rancheria. 

A utility is a new definition proposed by the regulation and is defined as a privatelyowned company that provides the same or similar services for water, natural gas, and 

electricity as a utility operated by a municipality. 
15

B. Best Available Control Technology (BACT) 

The proposed rule requires that a municipality or utility reduce diesel PM emissions 

through application of BACT by the applicable implementation dates. 

BACT is defined in this section as one of four compliance options: 

(1) Use of a engine or power system certified to the 0.01 g/bhp-hr particulate emission 

standard; or 

(2) Use of an engine or power system certified to the 0.1 g/bhp-hr particulate emission 

standard, in conjunction with the highest level verified diesel emission control strategy 

(DECS); or 

(3) Use of an alternative-fuel, heavy-duty pilot-ignition, or gasoline engine; or 

(4) Use of an existing engine used in conjunction with the highest level verified DECS. 

A public agency or utility that chooses to repower a vehicle with an engine certified to 

the 0.01 g/bhp-hr PM standard (option 1), would use an engine certified to either the 

optional 0.01 g/bhp-hr particulate emission standard as specified in title 13, CCR, 

section 1956.8(a)(2), or the 0.01 g/bhp-hr particulate emission standard as specified in 

title 13, CCR, section 1956.8(a), when it becomes effective in 2007. This option has a 

greater cost, as it entails either purchasing a replacement vehicle or engine (also called 

engine repowering), but may be preferred by a public agency or utility when the vehicle 

being replaced is nearing the end of its useful life. Engines certified to 0.01 g/bhp-hr 

PM, however, will not be generally available for vehicles until the 2007 MY. 

A public agency or utility that chooses to repower a vehicle with an engine certified to a 

0.1 g/bhp-hr particulate emission standard (option 2) as specified in title 13, CCR 

section 1956.8, must also install the highest level DECS that is verified in accordance 

with 13 CCR section 2702(f). The DECS must be the highest level that the retrofit 

manufacturer or authorized dealer agrees that can be used on that engine. 

No additional controls are required to reduce diesel PM emissions from alternativefueled or gasoline vehicles (option 3) because, by definition, alternative-fuel or gasoline 

vehicles do not emit diesel PM. Staff wanted to ensure that only the cleanest alternative 

fueled or gasoline engines would be considered BACT, therefore for MY 2004-2006 

alternative fueled engines must be certified to the optional reduced emission standards 

specified in title 13 CCR section 1956.8(a)(2)(A). Similarly, in order for gasoline 

engines to be considered BACT, they must be certified to the 2005 model year and later 

emission standards for heavy-duty Otto cycle engines specified in title 13 CCR section 

1956.8(c)(1)(B) and 1976(b)(1)(F). Beginning in 2007, both alternative fuel and 

gasoline engines will be required to meet the stringent standards set for diesel fueled 

engines. A certified dual-fuel engine, however, uses both diesel fuel and an alternativefuel, and is not considered to meet BACT because of the relatively high proportion of 
16

diesel fuel used. Thus an owner with a dual-fuel vehicle must still comply with the rule, 

for example by installation of a verified diesel particulate filter. A heavy-duty pilotignition engine is treated like an alternative-fuel engine in this rule because of its 

relatively low proportion of diesel fuel compared to alternative-fuel usage. This engine 

would use diesel fuel in less than ten percent of its duty cycle for engine ignition and 

cannot operate or idle solely on diesel fuel at any time. It should be noted at this time 

no such engine is currently certified in California. 

The last option (4 above) is to install a verified DECS to meet the BACT requirement. 

This is the least expensive option. If a municipality or utility plans to comply using this 

option, the technology must be verified by ARB. Several DECSs have received 

approval under the Verification Procedure for In-Use Strategies to Control Emissions 

from Diesel Engines (title 13, CCR, sections 2700-2710). 

Under this procedure, diesel PM control devices can be verified to one of three levels: 

Level 1, greater than 25 diesel PM reduction; Level 2, greater than 50 percent; and 

Level 3, 85 percent and greater diesel PM reduction. BACT is determined by Level, not 

by percent emission reduction. Thus a technology that reduces diesel PM by, for 

example, 45 percent is equivalent, under this rule, to one that reduces diesel PM by 25 

percent. Both get the same credit in this rule as Level 1 DECS. Table 8 shows the PM 

emission levels which result when the three levels of verified devices are applied to 

various engine model years. A DECS can also be optionally verified to reduce NOx 

emissions by a minimum of 15 percent reduction. ARB has verified a few DECS that 

are verified to reduced PM and NOx emissions. 

Table 8. Potential Reductions from the Use of DECSs. 

PM Emissions (g/bhp-hr) 

Engine MYs 

New 

Engine 

Particulate 

Standard 

(g/bhp-hr) 

Level 3 Level 2 Level 1 

1960 – 1987 None 85% 

reduction 

50% 

reduction 

25% 

reduction 

1988 – 1990 0.6 0.09 0.30 0.45 

1991 – 1993 0.25 0.04 0.13 0.19 

1994 – 2006 0.1 0.02 0.05 0.08 

2007+ 0.01 NA NA NA 

In this rule, BACT is evaluated on a vehicle-by-vehicle basis. A municipality or utility 

must evaluate the highest level DECS that can be installed and operated successfully 

for each combination of an engine and vehicle. If a Level 3 DECS is available for the 

engine, this option must be applied to the engine provided the DECS manufacturer or 

authorized dealer agrees that the DECS will work in that vehicle. A municipality or utility 

is required to investigate the highest level DECS appropriateness to a particular vehicle, 

prior to installation of a lower level DECS. If a Level 3 is not available or feasible, then a 
17

Level 2 option must be explored. A device verified to this level, for example, might be 

employed for those vehicles that do not have the appropriate PM to NOx ratio or 

exhaust temperature for a Level 3 DECS such as a passive diesel particulate filter. 

A Level 1 DECS is acceptable only if it is the only option available for the engine or 

application. It should be noted that the regulation does not allow 1960 to 1987 MY 

engines (Group 1) to use Level 1 technology, unless the municipality or utility is located 

in a county meeting the “low-population” definition. If no DECS is verified and feasible, 

the municipality or utility may apply for an implementation delay, as discussed later, but 

will eventually have to repower or otherwise replace the engine with one meeting the 

0.01 g/bhp-hr PM standard, an alternative fuel engine, a heavy-duty pilot ignition, or 

gasoline engine. Technologies to meet the BACT option are discussed in more detail in 

Section VI. 

The general approach of applying BACT is consistent with the solid waste collection 

vehicle rule previously adopted by the Board. 

C. Implementation Schedule 

Staff proposes two different implementation schedules. The first is for all municipalities 

or utilities (Table 9). The second is an optional schedule that a municipality or utility, 

located in a specified low population county may elect to follow (Table 11). The 

purpose of the optional schedule is to reduce costs by lengthening the compliance 

period. 

1. General Schedule 

Table 9. Implementation Schedule for 1960 to 2006 MY Engines 

Group Engine MY 

Percentage of Group to 

Use Best Available 

Control Technology 

Compliance 

Deadline 

1a 1960 – 1987 20 

60 

100 

December 31, 2007 

December 31, 2009 

December 31, 2011 

2 1988 – 2002 20 

60 

100 

December 31, 2006 

December 31, 2008 

December 31, 2010 

3 2003 – 2006 50 

100 

December 31, 2009 

December 31, 2010 a

Group 1: A municipality or utility not use Level 1 technology as BACT 

Currently, the higher emitting, mechanically controlled, MY 1960 to 1987 engines 

(Group 1), are more difficult to retrofit. The best option to reduce PM emissions from 

these vehicles may be to purchase a new vehicle with a 2007 MY engine. Although 

replacement with a new 2007 MY vehicle is not required by this rule, staff has adjusted 
18

the starting implementation date for this group to December 31, 2007, to allow owners 

to take advantage of these engines. This compliance mechanism would produce the 

largest overall reductions in diesel PM emissions. 

A municipality or utility could also replace a 1960 to 1987 MY engine with a newer 

mechanically controlled engine (i.e., MY 1991-1993), and then retrofit this engine with 

the highest level verified DECS. This would result in the engine moving from the Group 

1 to the Group 2 in the compliance schedule. 

Group 2, or 1988 through 2002 MY engines, begin implementation in December 31, 

2006, one year earlier than the Group 1 engines. ARB has verified Level 3, Level 2 and 

Level 1 DECS for all MY engines in this group, thus an earlier compliance deadline is 

justified. 

Vehicles with 2003 to 2006 MY engines (Group 3) are to be brought into compliance by 

the end of 2010. This group currently comprises the smallest portion of the fleet (four 

percent) and exhaust gas recirculation (EGR) is widely used on these engines to control 

NOx emissions. Currently there is one Level 3 passive DPF verified for use with an 

engine that employs exhaust gas recirculation (EGR). However, there are several level 

1 and one level 2 currently verified DECS for this MY group. 

2. Municipality or Utility Located in a Low Population County 

Staff recognizes that a municipality located in a low population county may have less 

access to revenue sources such as vehicle license fees, road tax, property taxes, sales 

taxes, etc. than those located in other areas in the state and utilities have fewer 

customers. Therefore, staff proposes a special, optional implementation schedule for 

public agencies and utilities located in counties with populations below 125,000 as of 

July 1, 2005, based upon 2001 population projections by the California Department of 

Finance. These counties are considered “low population” and are listed in Table 10. 

Figure 1 shows a map where these counties are located with the overlay of the 

California air districts in bold. 
19

Table 10. Low Population Counties: Populations Under 125,000 

COUNTY Projected Population as of 

July 2005 

ALPINE 1,300 

SIERRA 3,700 

MODOC 10,100 

TRINITY 13,800 

MONO 14,200 

INYO 18,800 

MARIPOSA 19,600 

PLUMAS 21,900 

COLUSA 24,200 

DEL NORTE 31,500 

GLENN 31,800 

AMADOR 37,600 

LASSEN 39,800 

SISKIYOU 47,200 

CALAVERAS 47,800 

TUOLUMNE 62,200 

TEHAMA 63,400 

SAN BENITO 63,600 

YUBA 66,000 

LAKE 69,200 

SUTTER 90,400 

MEDOCINO 95,500 

NEVADA 106,300 

1

Reference: State of California, Department of Finance, Interim County Population 

Projections.Sacramento, California, June 2001 
20

Figure 1. Map Showing Locations of Low Population Counties 
21

These municipalities or utilities may follow the alternate compliance schedule provided 

below (Table 11): 

Table 11. Implementation Schedule for a Municipality or Utility Located in a LowPopulation County 

Group Engine Model Years

Percentage of 

Group to Use Best 

Available Control 

Technology 

Compliance 

Deadline, 

 as of 

December 31st

1 1960 – 1987 20 

40 

60 

80 

100 

2009 

2011 

2013 

2015 

2017 

2 1988 – 2002 20 

40 

60 

80 

100 

2008 

2010 

2012 

2014 

2016 

3 2003 – 2006 

(Includes dual-fuel 

and bi-fuel engines) 

20 

40 

60 

80 

100 

2011 

2012 

2013 

2014 

2015 

At the request of Regional Council of Rural Counties6

, staff also included a special 

provision that allows the use of Level 1 DECS on 1960 to 1987 (Group 1) engines for 

municipalities or utilities located in low population counties. 

3. Municipalities or Utilities Located in a Low Population County Accelerated 

Turnover Option 

Many municipalities located in low population counties stated they still would be unable 

to comply with the rule even with the extended implementation schedule. Therefore, 

based on this input from low population counties, Regional Council of Rural Counties 

and several Air Pollution Control Districts, staff developed the accelerated turnover 

option. 

This option requires that a municipality or utility located in a low population county 

commit to retiring all their 1993 and older engines by December 31, 2020. An owner 

could elect to retire the vehicle or repower the vehicle with a 1994 or newer engine to 

comply. This option also requires that the owner apply BACT to their total fleet by 

December 31, 2025. The municipality or utility must notify the ARB by July 31, 2008, if 

 

6

 Regional Council of Rural Counties letter to ARB dated November 9, 2004, September 9, 2004, and 

September 7, 2005. 
22

this compliance option is selected. The municipality or utility would still be required to 

comply with all other requirements of the rule such as record keeping. 

D. Calculating Fleet Size for Implementation 

The total number of vehicles comprising a fleet may vary from year to year because of 

new purchases and retirement of older vehicles, thus complicating the calculation of the 

number of vehicles that must be in compliance each year. Staff has therefore 

developed formulas to specify how an owner must calculate the number of vehicles to 

be brought into compliance each year. 

To determine compliance during the phase-in, the municipality or utility needs to 

calculate its fleet size January 1st of each year where a compliance deadline is 

applicable. For example, the first compliance date is January 1, 2006. The following 

equations are used to calculate fleet size for any given year. 

Total number (by group) of municipality or utility’s fleet vehicles (#MUVby group) is equal to 

the total number of engines subject to the rule (#Enginesby group) including gasoline or 

alternative fueled engines that meets the definition of BACT, plus the number of 

vehicles retired in the previous year (TotRetireby group), beginning with January 1st of the 

initial applicable compliance deadline. For example, for Group 2 vehicles, only vehicles 

retired in the 2006 calendar year or later would be counted as retired. Note also that, 

under this proposed rule, "retirement" means that the engine is scrapped, sold out of 

state, or converted for use in a "low usage vehicle." If an engine (or vehicle) has BACT 

applied prior to sale, it may be counted as a retired vehicle; however an engine (or 

vehicle) that is simply sold within the state is not included in the calculation as a retired 

vehicle, but disappears from the fleet in the annual count of engines. This is shown in 

equation (1) below: 

(1) #MUVby group = #Enginesby group + TotRetireby group 

 

The total number of vehicles that must be phased in during a given year by group 

(TotVehby group) is calculated by taking the percentage of vehicles that must meet BACT 

for that particular year (Group%BACT) multiplied by the municipality’s or utility’s total 

fleet number as of January 1st of that compliance year (#MUFVby group) from equation (1). 

This is shown by equation (2). 

(2) TotVehby group= Group%BACT * (#MUVby group) 

After the first year of compliance, to calculate how many additional vehicles are required 

to meet BACT by the next compliance deadline (TotAddCompby group), then the total 

vehicles are calculated as shown in equation (1) and (2), then the number of vehicles in 

already in compliance (TotBACTby group) and the number of vehicles which have been 

removed the model year group by retirement in prior years (TotRetireby group) are 

subtracted. Again, only engines that have been retired through scrapping, sale out of 

state or has had BACT applied if sold within the state can be counted as retired. All 
23

engines retired since the initial compliance year (for example, 2006 for Group 2) may be 

included in ToTRetire. This is shown in equation (3). 

(3) TotAddCompby group= TotVehby group– TotBACTby group- TotRetireby group

In the final compliance year for each group, all remaining vehicles must be brought into 

compliance. If the number of vehicles to be brought into compliance is not equal to a 

whole number (TotAddComp), the municipality or utility is expected to round to the 

nearest whole vehicle. A municipality should round up when the fractional part of 

number of additional vehicles to be brought into compliance (TotAddComp) is greater 

than or equal to one-half of a vehicle, and round down to the nearest vehicle when the 

fractional part of TotAddComp is less than one-half of a vehicle. It should be noted, 

gasoline vehicles that do not meet the emission standards specified for BACT are 

excluded from the initial total fleet number (#MUVby group); while gasoline engines 

meeting the requirements for BACT are counted in the total fleet number and are 

counted as a compliant vehicle for determining TotBACTby group in Equation 3. 

Five sample fleet size calculations are given in Appendix E to illustrate various cases a 

municipality or utility might experience. 

E. Compliance Extensions 

Under a variety of conditions, owners may be justified in requesting and receiving 

compliance extensions. During the public workshop process, staff identified six different 

circumstances that would potentially justify a request for a compliance extension: early 

implementation, no verified DECS, fleets located in a low population county, dual-fuel or 

bi-fuel vehicle, engines near retirement, and participation in an experimental DECS 

project. 

1. Early Implementation 

Many public agencies and utilities have proactively taken steps to reduce emissions 

from their vehicles through early application of BACT. Staff proposes to give some 

allowance to these fleets in the following two situations. 

If a municipality or utility has applied BACT to 50 percent of its vehicles in Group 1 (MY 

1960 – 1987) before December 31, 2007, the owner may delay 100 percent compliance 

of the Group 1 vehicles to December 31, 2012. Likewise, if a municipality or utility 

applied BACT to 50 percent of its vehicles in Group 2 (MY 1988 – 2002) before 

December 31, 2006, the owner may delay 100 percent compliance of the Group 2 

vehicles to December 31, 2012. A municipality or utility may count each vehicle that 

meets BACT, as defined in section 2022.1(b) as of January 1, 2005 as a compliant 

vehicle. This allows a municipality or utility that has previously converted a vehicle to 

alternative fuel, for example, to subtract this vehicle out of the calculation for additional 

vehicles required to be brought into compliance for a given calendar year. 
24

A municipality or utility that implements early will not be required to install a higher level 

DECS if one becomes available between the time the DECS is installed early and the 

mandated compliance date. A compliance extension for early implementation allows 

municipalities and utilities to stretch out implementation beyond required dates while at 

the same time implementing early in at least half of the vehicles. In addition, 

municipalities and utilities may qualify for incentive funding based on early 

implementation because it is voluntary and occurs prior to the mandated implementation 

dates. 

2. No Verified Diesel Emission Control Strategy 

Staff proposes to allow a municipality or utility a delay in implementing BACT if no 

verified DECS exists for an engine and application. This delay recognizes the higher 

cost of an engine repower or replacement and provides the owner additional time to 

plan for this cost. In addition, during the time allowed for a delay, effective DECS may 

become verified. This extension applies only after the owner has applied DECS to 

every applicable engine. 

Two methods of granting delays are proposed. Either the Executive Officer would grant 

a blanket one-year compliance extension or, if the municipality or utility may apply for a 

compliance extension. Staff proposes the Executive Officer grant a one-year 

implementation delay without requiring documentation as to the unavailability of verified 

technology in the event no DECS has been verified for a specific engine or application, 

or one is not commercially available, by ten months prior the implementation date for 

that group. 

In the second case, a DECS could be verified for an engine, but not able to be used in a 

specific application. In this case, staff proposes an owner may apply no later than July 

31st of the year for which he or she is requesting an extension. The owner must provide 

documentation that all verified DECSs have been investigated and shown not to work 

on a particular engine or set of engines, or for that vehicle’s particular application. 

Evidence convincing to ARB would include, for example, a letter from a DECS 

manufacturer showing evidence of data collected that demonstrates the DECS will not 

function on that particular vehicle because of its duty cycle. Other examples of justified 

reasons for an owner applying for an implementation delay would be if the engine is 

under an original engine warranty and application of a DECS would void that warranty, 

or if a DECS is not commercially available. In these cases, the documentation should 

be provided to validate the need for a delay. 

ARB has an existing procedure for responding to requests for extension as codified in 

title 17, CCR, section 60030. Within 90 days after the application is accepted for filing, 

the Executive Officer will issue his/her approval or disapproval of the compliance 

extension request. 

Staff proposes, however, that an owner not be granted extensions indefinitely because 

there are other BACT options. Staff proposes that if no DECS for a specific engine or 
25

application is available through 2012 for MY 1960 to 1987 (Group 1) engines, the owner 

would be required to use one of the following BACT: an engine that achieves the 0.01 

g/bhp-hr PM standard, a newer 1988 to 2002 (Group 2) engine that can use a verified 

DECS or an alternative-fueled, heavy-duty pilot ignition or gasoline engine, by 

December 31, 2011. Similarly, for MY 1988 to 2002 engines, compliance extensions 

are not given for longer than to December 31, 2011. The municipality or utility would, 

therefore, be required to employ another BACT by December 31, 2012. No compliance 

extensions are proposed for MY 2003 to 2006 (Group 3) engines. 

3. Dual Fuel or Bi-Fuel Engine 

Staff proposes that a dual-fuel and bi-fuel engine of any model year implement BACT 

according to the 2003 to 2006 MY engine compliance schedule in recognition of its 

relatively lower certified NOx emissions and because many public agencies purchased 

these vehicles as part of programs to reduce NOx emissions. A delayed 

implementation schedule for these vehicles allows public agencies to plan for the 

additional cost of a retrofit. A public or utility fleet vehicle with a dual-fuel engine 

retrofitted with a verified level 3 diesel particulate filter is in compliance with the BACT 

requirement. 

4. Engine Near Retirement 

Staff proposes to allow a compliance extension for engines within one year of 

retirement. Retirement, as discussed earlier, refers in this regulation to sale outside of 

the State of California, scrappage of the engine, or conversion to use only in a lowusage vehicle7

. If the engine is within one year of retirement as of the applicable 

compliance date, then staff proposes that the owner could take advantage of a one year 

delay for compliance. Similarly, if an installed DECS fails and it cannot be repaired, and 

the vehicle is within one year of retirement, the DECS would not be required to be 

replaced or upgraded. In the case of this compliance extension, staff envisions that the 

only case in which this would be used is in the final compliance year. In previous years, 

the owner needs to apply a DECS to all applicable engines. 

5. Use of Experimental Diesel Emission Control Strategy 

 

Many municipalities and utilities have participated in demonstrations of experimental 

technology designed to reduce diesel PM. This regulation requires the use of verified 

DECS, and by its nature an experimental technology will not have received verification. 

Staff, therefore, proposes a municipality or utility be allowed to install experimental 

technology on no more than twenty vehicles or ten percent of the fleet (whichever is 

less) for testing and evaluation. Each vehicle being used for the demonstration would 

be deemed to be in compliance with this rule for the duration of the experiment, 

provided the experimental technology reduces diesel PM and a valid experimental 

permit has been obtained from ARB. At the termination of the experiment, the 

 

7

 A low usage vehicle is defined in the proposed regulation as a vehicle that is operated for fewer than 

1000 miles or 50 hours per year, based on a five-year rolling average. 
26

experimental technology would be removed, unless it has received appropriate 

verification from ARB, and replaced with the verified DECS as required, within six 

months of termination of the experiment. No experimental DECS may be used after 

December 31, 2012, to meet the BACT requirement. 

These provisions provided in sections V.E.1-5 are consistent with the previously 

adopted rule for the Solid Waste Collection Vehicles. 

6. Accelerated Turnover Option 

Staff has included an Accelerated Turnover Option for municipalities or utilities located 

in low population counties. To participate in this option, these municipalities or utilities 

must notify ARB in writing by July 31, 2008. This date is six months prior to the first 

implementation deadline for municipalities or utilities located in low population counties. 

If a fleet elects to participate in this option, they would send a letter to the ARB 

indicating that they would be participating in this option. The fleet would then be 

required to label all their trucks by December 31, 2006, as participating in the 

“accelerated turnover option”. The fleet would not be required to do anything to their 

vehicles until 2020, when they would be required to retire all their vehicles with engines 

1993 and older, and replace these with vehicles with engines newer than 1994. The 

fleet could also repower all their vehicles with 1993 engines with 1994 and newer 

engines to comply with this option. Then the fleet would not do anything until 2025, 

when they would be required to apply BACT all their vehicles. 

F. Diesel Emission Control Strategy Special Circumstances 

Staff has included in the proposed rule provision to address special circumstances that 

may arise during its implementation. 

1. Fuel Strategy DECS 

A municipality or utility must apply the highest level DECS available for a particular 

engine. There could be a situation where a fuel based strategy may be the highest level 

DECS for a small number of vehicles in a municipality or utility’s fleet. Some fuel based 

DECS strategies require the fuel be stored in a dedicated tank, and for a small number 

of vehicles the infrastructure cost could be unreasonable. Therefore, staff has included 

a provision where a fleet could request the use of a lower level non fuel-based DECS on 

these vehicles where the highest level DECS would only be a fuel based strategy. For 

example, say a fleet has 100 vehicles and 90 could use a level 3 passive diesel 

particulate filter and 10 meet the criteria to use a level 2 diesel emulsified fuel. Use of 

this fuel would require installation of a dedicated fuel tank. In this case, the fleet could 

request to use a level 1 diesel emission control strategy for these 10 vehicles provided 

they are not in the oldest group of vehicles (1960 to 1987 engine MY). 
27

Another situation could exist where a fleet decides to use a fuel based DECS across its 

entire fleet. However, the highest level DECS for certain vehicles within the fleet may 

be a Level 3 hardware device. In this case, the fleet could request to use a lower DECS 

on the few vehicles that are amenable to a Level 3 DECS, in order to accommodate a 

minimum Level 2 fuel based DECS across the entire fleet. 

2. Failure or Damage of a DECS 

For various reasons, a DECS might fail or be damaged during the lifetime of an engine. 

The intent of this regulation is to reduce diesel PM emissions for the life of an engine. 

Staff proposes if a DECS fails or is damaged while it is within its warranty period, the 

municipality or utility be allowed to repair or replace the DECS with the same or 

comparable DECS, as provided under the DECS manufacturer’s warranty. If, however, 

the DECS fails or is damaged outside of its manufacturer-provided warranty, staff 

proposes the municipality or utility would then be required to install the highest verified 

level DECS available. For example, if a vehicle initially is retrofitted with a Level 1 

DECS or another BACT, and a Level 2 or Level 3 DECS becomes available after the 

Level 1 DECS warranty expires and the DECS fails, then the municipality or utility would 

be required to upgrade the DECS to the higher level DECS. 

3. Discontinuation of Fuel as a DECS 

If a municipality or utility chooses to discontinue use of fuel verified as a DECS under 

section 2022.1(b) of the proposed regulation, it would be required to use another BACT. 

In the event another BACT is not commercially available within 30 days from the date of 

discontinuation of a fuel verified as a DECS, a compliance plan must be submitted to 

the Executive Officer no later than 30 days after discontinuation of the use of the fuel 

verified as a DECS. This plan must demonstrate how the municipality or utility will bring 

its vehicles into compliance within six months. 

4. Limited Use of a Level 1 DECS 

While use of a Level 1 DECS is allowed in most cases when no level 2 or 3 DECS is 

available, the relatively low level of PM reduction (25 percent) is a concern. 

Widespread use of Level 1 DECSs would not achieve the goals of 75 percent diesel PM 

reduction by 2010 and 85 percent diesel PM reduction by 2020. Therefore, staff 

proposes to allow a municipality or utility to use a Level 1 DECS for a limited time period 

as a BACT. The time limit for Group 2 (MY 1988 – 2002) is ten years. 

A municipality or utility is not allowed to use a Level 1 DECS on MY 1960-1987 (Group 

1) engines due to their extremely high PM emission rates. An owner would be required 

to apply at least a Level 2, Level 3 or another BACT to these engines. If no DECS is 

verified or available for Group 1 vehicles, then the owner would be eligible to apply for a 

compliance extension, after which the owner would have to repower or replace the 

engine as per sections 2022.1 (b)(1), or (b)(2). Alternatively, a municipality or utility 

could repower a vehicle with a newer engine such that it would be amenable to a 
28

verified DECS. It should be noted that the regulation does allow Level 1 DECS to be 

used on 1960-1987 (Group 1) engines located in low population counties to meet 

BACT. However, the use of a Level 1 DECS even on these engines would be limited to 

ten years. This provision was provided at the request of the Regional Council of Rural 

Counties and several air pollution control districts. This would provide a certain level of 

PM reduction for the oldest trucks and allow additional time for agencies or utilities 

located in low population counties to procure newer vehicles that could be amenable to 

higher level DECS. 

Staff proposes that the time limit for use of a Level 1 DECS on Group 3 (MY 2003-2006) 

vehicles be five years since it is anticipated there will be level 3 or 2 technologies 

available for most engines during the rule’s implementation timeframe. Therefore, it is 

proposed that a fleet owner be required to upgrade a level 1 DECS after five years, 

since these vehicles will be in the fleet for a very long time. 

G. Record Keeping Requirement 

Municipalities and utilities must keep records as required by the regulation, and make 

those records available for inspection during enforcement audits by ARB personnel. 

Certain records as described by section 2022.1(f) must be kept at the terminal where 

the vehicle normally resides and others must be kept in the vehicle. If a municipality or 

utility is found to be out of compliance with this record keeping requirement, 

enforcement actions may be initiated. 

1. Records Accessible at Terminal 

Records to be kept at the facility where the vehicle normally resides (or other 

centralized location) include a list of the vehicles covered by the proposed regulation 

that identifies each vehicle by type, engine manufacturer, engine model, engine model 

year, series, engine family, and status as a low usage vehicle (if applicable). That 

information must be tied to specific DECS that are installed in each vehicle. 

DECS information required includes the type of DECS, its serial number, manufacturer, 

model, level, and date of installation, or first date of use if a fuel DECS. The reason for 

choosing a Level 1 or Level 2 verified DECS must also be maintained. If a Level 3 

verified DECS is available, then the DECS manufacturer or authorized dealer must 

provide reasoning for not using that DECS. DECS maintenance records would also 

need to be available. In the case of fuel or fuel additives used as a DECS, purchase 

records would need to be kept for the most current two years worth of purchases. 

If a municipality is following the implementation schedule in for a low population county, 

then it must maintain documentation affirming that the vehicles are not at any time 

operated in a metropolitan statistical area as defined by the U.S. Census Bureau. 
29

2. Records Kept in Vehicle 

Staff also proposes that a municipality or utility be required to keep certain information 

in the vehicle, which can be accessed during roadside inspections. In order to have 

vehicle records easily accessible, ARB proposes a label with the required information 

be affixed to the driver’s side door jam, or another location known by the driver and 

readily visible to an inspector. 

For a vehicle with an installed DECS, the information required is the same as that 

required under the Verification Procedure in section 2706 (g). This includes the 

manufacturer’s name, address, and phone number; the DECS family name; product 

serial number, month and year of manufacture plus the date of installation of the DECS, 

or date of first use if the DECS is a fuel. 

Staff believes this information is needed to enforce the rule. Without this information, an 

inspector might have to dismantle a muffler housing, for example, to determine that a 

diesel particulate filter was installed. In addition, other regulations require certain 

records be kept in vehicles, such as manifests, therefore staff believes it is not 

unreasonable to require these records be kept in vehicles. 

3. Requirement for Transfer of Records 

The regulation requires that once a vehicle is in compliance it must remain in 

compliance with this regulation. Therefore, if ownership of a vehicle is transferred, the 

seller shall give these records to the buyer, or a third party sales representative. 

H. Contractor Compliance Requirement 

Staff has proposed that municipalities and utilities include compliance contract language 

when hiring a private company for services that a municipality or utility would normally 

provide. For instance, because many municipalities do street sweeping, a contract to 

provide this service would be subject to this condition. The compliance contract 

language is in section 2202.1(g) and proposes that municipalities and utilities add a 

statement in all contracts that a company is in compliance with all applicable air 

pollution control laws in order to be considered for bid. A similar provision was adopted 

in the solid waste collection vehicle rule where it was discovered many existing 

contracts already have boiler plate language similar to this one proposed. This simply 

provides another level of back-up that both municipalities and contractors are required 

to comply with all existing air pollution control regulations, local ordinances, and any 

future retrofit rules for private companies. 
30

I. Non-Compliance and Enforcement 

To ensure compliance with this rule, ARB staff will inspect the records and verify 

installation of DECS during inspections under the Periodic Smoke Inspection Program8

. 

If a fleet is in non-compliance with the regulation a penalty of up to $1,000 per vehicle 

per day can be imposed. If further investigation determines the municipality or utility 

neglected or intentionally violated the regulation, penalties of up to $10,000 per vehicle 

per day may be imposed. 

VI. TECHNOLOGICAL FEASIBILITY OF CONTROL MEASURE 

Reducing emissions from diesel engines is an area of active research and development. 

Engine manufacturers are close to deploying engines that meet the California and 

federal 2007 engine standards for demonstration in fleets, and they are developing 

technologies to further reduce NOx emissions for the 2010 standards. The field of 

exhaust aftertreatment, or retrofitting engines, is growing rapidly, spurred both by the 

research and development ongoing to new engines and by California’s diesel emission 

reduction regulations. Based on its evaluation of the technology available today and an 

assessment of technology likely to be available in the near future, staff is confident that 

the proposed control measure is technologically feasible. The following sections 

describe the availability and feasibility of various exhaust emission control technologies. 

A. Availability of Ultra-low Sulfur Diesel Fuel 

Many diesel emission control technologies are adversely affected by sulfur in the fuel. 

Ultra-low sulfur (15 ppmw or less sulfur content) diesel fuel is therefore required for 

effective functioning of many, although not all, diesel emission control strategies 

(DECS). New, 2007 MY engines will require ultra-low sulfur diesel fuel to enable proper 

functioning of the catalyzed diesel particulate filter that manufacturers will use to reduce 

diesel PM emissions to 0.01 g/bhp-hr. 

The U.S. EPA and California adopted regulations that mandate the sale of ultra-low 

sulfur diesel fuel beginning July 1, 2006. One refiner, BP, has been making and selling 

ultra-low sulfur fuel in California since 2002. California transit agencies subject to the 

Fleet Rule for Transit Agencies have been required to use the fuel since July 1, 2002. 

Some cities have also been using ultra-low sulfur diesel fuel since it became widely 

available in 2002 when BP certified fuel resellers to handle the low sulfur diesel fuel, 

thus making the product available by truck. BP is also selling low sulfur diesel fuel 

through its ARCO stations that carry diesel fuel. By July 2006, ultra-low sulfur diesel 

fuel will be available statewide through the pipeline distribution system. 

 

8

 Details of ARB’s Period Smoke Inspection Program can be found at 

http://www.arb.ca.gov/msprog/hdvip/hdvip.htm 
31

B. Verification of Diesel Emission Control Strategies 

The Board adopted a procedure to verify diesel emission control strategies in 2002, 

codified in title 13, California Code of Regulations, Section 2700 et seq. Verification is a 

stamp of approval from ARB, which tells end users that the verified device achieves 

advertised emission reductions and is durable. The manufacturer is required to provide 

a warranty that includes coverage of engine damage caused by the DECS. To protect 

the end user, only ARB-verified DECS can be used in all of ARB’s mandated programs 

and most of its voluntary programs. 

ARB has received over one hundred applications for verification, but not all of those 

applications are active. The procedure requires considerable data to prove emission 

reductions and durability. Any DECS that uses a fuel additive must also demonstrate 

that it is non-toxic in all media by going through a multimedia assessment. As of 

September 2, 2005, ARB has verified the DECS shown in the tables below. Not all of 

these DECS are applicable to public or utility fleet vehicles. 

Table 12. Verified Level 3 DECS 

Product Name 

Technology 

Type 

PM 

Reduction 

NOx 

Reduction Applicability 

Cleaire Flash and 

Catch CRT DPF 85% 25% 

1994+ on-road (limited - Cummins defeat 

device); 15 ppm sulfur diesel. 

Cleaire Flash and 

Catch DPX DPF 85% 25% 

1994+ on-road (limited - Cummins defeat 

device); 15 ppm sulfur diesel. 

Cleaire Longview 

Lean NOx 

Catalyst 

and DPF 85% 25% 

1993-2003 model year on-road; 15 ppm 

sulfur diesel. 

CleanAIR 

Systems PERMIT DPF 85% N/A 

Stationary emergency generators; 15 

ppm sulfur diesel. 

Donaldson DPF 85% N/A 1994-2002 on-road; 15 ppm sulfur diesel. 

International 

Truck and Engine 

Corporation DPX DPF 85% N/A 

1994-2003 on-road Navistar 

(International); 15 ppm sulfur diesel. 

Johnson Matthey 

CRT DPF 85% N/A 

1994-2004 on-road; 2002-2006 

Cummins ISM and ISB with EGR;15 ppm 

sulfur diesel or B20. 

Johnson Matthey 

CCRT DPF 85% N/A 

1994-2004 on-road; 2002-2006 

Cummins ISM and ISB with EGR;15 ppm 

sulfur diesel. 

Johnson Matthey 

EGRT EGR/DPF 85% 40% 

2000 International DT-466, 2000 

Cummins ISM 2001 Cummins ISB, 2001 

Cummins ISC, 2001 Cummins ISL, 2001 

MY DDC - 50, and 2001 DDC - 60. onroad; 15 ppm sulfur diesel. 

Lubrizol ECS 

Purifilter DPF 85% N/A 1994-2003 on-road; 15 ppm sulfur diesel. 

Lubrizol ECS 

Unikat Combifilter DPF 85% 

1996-2004 off-road; 15 ppm sulfur diesel 

or carb diesel. 
32

Table 13. Verified Level 2 DECS 

Product Name 

Technology 

Type 

PM 

Reduction 

NOx 

Reduction Applicability 

Environmental 

Solutions 

Worldwide 

Particulate 

Reactor 

Flow 

Through 

Filter 50% N/A 1991-1993 on-road, CARB diesel. 

Lubrizol PuriNOx 

Alternative 

Fuel 50% 15% 1988-2003 on-road. 

Lubrizol AZ 

Purimuffler/Purifier 

DOC + Alt 

Fuel 50% 20% 1996-2002 off-road; PuriNOx 

Table 14. Verified Level 1 DECS 

Product Name 

Technology 

Type PM Reduction 

NOx 

Reduction Applicability 

Cleaire Flash 

and Match DOC 25% 25% 

1993+ on-road (limited – Cummins 

defeat device); 15 ppm sulfur diesel or 

CARB diesel. 

Donaldson DOC 25% N/A 

1988-1990 on-road; 15 ppm sulfur 

diesel or CARB diesel. 

Donaldson 

DOC + 

crankcase 

filter 25% N/A 

1988-1990 on-road; 15 ppm sulfur 

diesel or CARB diesel. 

Donaldson 

DOC + 

crankcase 

filter 25% n.a 

1991+ on-road/1996 + off-road port 

equipment; CARB diesel. 

Donaldson DOC 25% n.a 1991+ on-road; 15 ppm sulfur diesel. 

Donaldson 

DOC + 

crankcase 

filter 25% n.a 

1994+ on-road/1996 + off-road port 

equipment; 15 ppm sulfur diesel. 

Extengine 

DOC + 

SCR 25% 80% 

1991-1995 Cummins 5.9 liter off-road; 

15 ppm sulfur diesel or CARB diesel. 

Lubrizol ECS AZ 

Purifier & 

Purifmuffler DOC 25% N/A 

1991-2003 Cummins and Navistar onroad; 15 ppm sulfur diesel. 1973-1993 

DDC 2 stroke; CARB diesel. 

Lubrizol ECS AZ 

Purifier & 

Purifmuffler DOC 25% N/A 

1996-2002 off-road; 15 ppm sulfur 

diesel. 

In order to determine if a particular DECS will work with a specific engine and vehicle 

combination, the conditions contained in the Executive Order or Verification Letter must 

be followed. The EO or Verification Letter lists the engines by engine family and other 

conditions of verification, such as minimum engine exhaust temperature. Additional 

evaluations may then be needed, such as use of a datalogger that records engine 

exhaust temperatures over a typical duty cycle. 
33

This list is subject to changes as additional systems are verified. The most current list 

of verified DECS, applicable engine families, as well as the EO and verification letters 

may be found on our web site at: 

http://www.arb.ca.gov/diesel/verdev/verdev.htm 

C. Diesel Emission Control Strategies for In-use Public and Utility Fleet Vehicles 

A variety of retrofit strategies can be used for controlling emissions from in-use diesel 

engines. The main types of technologies discussed here are hardware, add-on 

technologies such as diesel particulate filters (DPF), flow through filters (FTF), or 

oxidation catalysts (DOC), and fuels or fuel additives. 

1. Hardware Diesel Emission Control Strategies 

Currently, hardware DECS consist of the DPF, including both passive and active 

regenerated versions, and the DOC. Each of these technology types has been used in 

both on- and off-road vehicles and equipment for many years. More recently, another 

device, a catalyzed wire mesh filter, also known as a flow-through-filter (FTF), was 

developed and verified. 

a. Diesel Particulate Filter 

A passive DPF reduces PM, and catalyzed DPFs will also reduce CO and HC 

emissions through catalytic oxidation and filtration. Most DPFs sold in the United States 

use substrates consisting either of a ceramic wall-flow monolith or a silicon carbide 

substrate. These substrates are either coated with a catalyst material, typically a 

platinum group metal, or a separate catalyst is installed upstream of the particulate filter. 

The filter is positioned in the exhaust stream to trap or collect a significant fraction of the 

particulate emissions while allowing the exhaust gases to pass through the system. 

Effective operation of a DPF requires a balance between PM collection and PM 

oxidation, or regeneration. The volume of PM generated by a diesel engine will fill up 

and plug a DPF over time; thus the trapped PM must be burned off or "regenerated" 

periodically. Regeneration is accomplished by either raising the exhaust gas 

temperature or by lowering the PM ignition temperature through the use of a catalyst. 

The type of filter technology that uses a catalyst to lower the PM ignition temperature is 

termed a passive DPF, because no outside source of energy is required for 

regeneration. 

Verified passive DPFs have demonstrated reductions in excess of 90 percent for PM, 

although the ARB verification Level 3 lists 85 percent PM reduction as its minimum 

level. A passive catalyzed DPF also reduces CO and HC by approximately the same 

amount as the PM reduction. A passive catalyzed DPF is a very attractive means of 

reducing diesel PM emissions because of the combination of high reductions in PM 

emissions and minimal operation and maintenance requirements. 
34

Several passive DPF systems have been verified in California for use on a variety of 

diesel applications including the most popular engine series of the major engine 

manufacturers for model-year engines 1993 to 2004. The Executive Orders or EOs 

include restrictions for these verifications and a list of applications and engine families 

for which the device has been approved. These EOs are available at 

http://www.arb.ca.gov/diesel/verdev/verdev.htm

An active DPF system uses an external source of heat to oxidize the PM. The most 

common methods of generating additional heat for oxidation involve electrical 

regeneration by passing a current through the filter medium, injecting and burning 

additional fuel to provide additional heat for particle oxidation, or adding a fuel-borne 

catalyst or other reagent to initiate regeneration. Some active DPFs induce 

regeneration automatically on-board the vehicle or equipment when a specified 

backpressure is reached. Others use an indicator, such as a warning light, to alert the 

operator that regeneration is needed, and require the operator to initiate the 

regeneration process. Some active systems collect and store diesel PM over the 

course of a full shift and are regenerated at the end of the shift with the vehicle or 

equipment shut off. A number of the filters are removed and regenerated externally at a 

regeneration station. 

For applications in which the engine-out PM is relatively high, and/or the exhaust 

temperature is relatively cool, actively regenerating systems may be more effective than 

a passive DPF. Because active DPFs are not dependent on the heat carried in the 

exhaust for regeneration, they potentially have a broader range of application than 

passive DPFs. ARB has verified Lubrizol ECS Unikat Combifilter for certain off-road 

applications (Executive Order DE-04-012, dated December 13, 2004). This filter is an 

actively regenerated non-catalyzed diesl particulate filter that is regenerated via an 

electrically-heated regeneration system. Currently, no active DPF systems are verified 

for on-road applications, although retrofit manufacturers are currently conducting field 

studies to verify such systems. 

b. Catalyzed Wire Mesh Flow Through Filter 

Flow-through filters (FTF) employ a catalyzed wire mesh substrate that has an intermix 

of flow channels creating turbulent flow conditions. Unlike a DPF, in which only gases 

can pass through the substrate, the FTF does not physically trap and accumulate PM. 

Instead, it acts list a DOC but achieves a greater PM reduction due to enhanced contact 

of PM with catalytic surfaces and longer residence times. Any particles that are not 

oxidized within the FTF flow out with the rest of the exhaust and do not accumulate. 

Consequently, the filtration efficiency of an FTF is lower than that of a DPF, but the FTF 

is much less susceptible to plugging because of high PM emissions and low exhaust 

temperatures. Therefore, this type of filter may be suitable for specific duty cycles 

where a typical DPF would not be applicable. 

The ARB has verified the Environmental Solutions Worldwide (ESW) Particulate 

ReactorTM system for specific 1991 through 1993 model year diesel engines used in on-
35

road applications operating on standard CARB diesel fuel. The Particulate ReactorTM 

system employs a catalyzed wire mesh substrate to achieve at least a 50 percent 

reduction in particulate matter emissions, qualifying it for a Level 2 verification. Specific 

engine families and conditions for which the Particulate ReactorTM has been approved 

may be found in the Executive Order DE-04-011 (September 13, 2004) and its 

attachment. 

c. Diesel Oxidation Catalyst 

A DOC reduces emissions of CO, HC, and the soluble organic fraction of diesel PM 

through catalytic oxidation alone. Exhaust gases are not filtered in DOCs. In the 

presence of catalytic material and oxygen, CO, HC, and the soluble organic fraction of 

the PM undergo a chemical reaction and are converted into carbon dioxide and water. 

Some manufacturers integrate HC traps (zeolites) and sulfate suppressants into their 

oxidation catalysts. HC traps enhance HC reduction efficiency at lower exhaust 

temperatures and sulfate suppressants minimize the generation of sulfates at higher 

exhaust temperatures. A DOC may reduce total PM emissions by up to 30 percent. 

On November 7, 2002, the ARB verified three Donaldson Company DECSs (Verification 

Letter November 7, 2002). The first system consists of the Donaldson DCM DOC 

muffler with 6000 Series catalyst formulation plus closed loop crankcase with 

Donaldson SpiracleTM. The second system consists of the same Donaldson DOC but 

with the 6100 Series catalyst formulation. The third system resembles the second 

system but is applicable to different model year vehicles. 

In September 2004, ARB extended the verification of the DCM DOC muffler with 6000 

Series catalyst formulation alone and the DCM DOC muffler with the Donaldson 

SpiracleTM closed crankcase filtration system used with California diesel fuel or fuel with 

a lower sulfur content for model years 1988-1990 (DE-04-009 September 8, 2004). 

2. Fuel-based Diesel Emission Control Strategies 

Fuel-based DECS utilize the fueling system and fuel for emission reductions. All fuelbased DECS must undergo an assessment of multimedia toxicity effects by the 

California Environmental Policy Council as required by Health and Safety Code 43830.8 

prior to ARB verification. 

a. Fuel-Water Emulsion 

A demonstrated alternative to diesel fuel that reduces both PM and NOx emissions is an 

emulsion of diesel fuel and water. The process blends water into diesel fuel along with 

an additive to keep the mixture from separating. The water is suspended in droplets 

within the fuel, creating a cooling effect on the fuel that decreases NOx emissions. A 

fuel-water emulsion creates a leaner fuel environment in the engine, thus lowering PM 

emissions also (U.S. EPA 2002). 
36

Lubrizol's PuriNOxTM is verified by the ARB for 1988 through 2003 MY diesel engines 

used in on-road applications (Executive Order, DE-04-008, dated August 5, 2004). 

PuriNOxTM is an emulsified diesel fuel that achieves at least 50 percent reduction in PM 

and 15 percent reduction of NOx and is categorized as a Level 2 system. PuriNOxTM is 

verified as an emulsified mix of water and CARB diesel fuel. It is verified for use with 

Luribrizol ECS DOC (Executive Order, DE-04-007, dated October 29, 2004) for certain 

off-road engines; however it is not verified for use with any on-road hardware DECS. 

Lubrizol requires that fleets that use PuriNOxTM must install a recirculation pump in the 

products’ storage tank and vehicles fueled with product must be used on a daily basis. 

b. Fuel Additives 

A fuel additive is a substance designed to be added to fuel or fuel system so that it is 

present in-cylinder during combustion and its addition causes a reduction in exhaust 

emissions. Additives can reduce the total mass of PM, with variable effects on PM, CO, 

oxides of nitrogen (NOx) and gaseous HC production. The range of PM reductions that 

have been published in studies of fuel additives is from 15 to 50 percent reduction in 

mass. Most additives are fairly insensitive to fuel sulfur content and will work with a 

range of sulfur concentrations as well as different fuels and other fuel additives 

(DieselNet 2002). 

A fuel-borne catalyst (FBC) is a substance that is added to diesel fuel in order to aid in 

soot oxidation in DPFs by decreasing the ignition temperature of solid carbon. An FBC 

can be used in conjunction with both passive and active filter systems to aid system 

performance, and decrease mass PM emissions. FBC/DPF systems are in wide spread 

use in Europe in both on-road and off-road, mobile and stationary applications and 

typically achieve a minimum of 85 percent reduction in PM emissions. 

No fuel additive is currently verified by ARB, although some retrofit manufacturers are 

actively pursing verification. Fuel additives must be used with a Level 3 filter unless 

proven safe when used without one. 

c. Biodiesel 

Biodiesel is a mono-alkyl ester-based oxygenated fuel made from vegetable oils, such 

as oilseed plants or used vegetable oil, or animal fats. It has similar properties to 

petroleum-based diesel fuel, and can be blended into petroleum-based diesel fuel at 

any ratio. B20 is a biodiesel blend into petroleum-based diesel fuel at 20 percent. Pure 

biodiesel is called B100. B20, which is a common concentration used in California, 

would not reduce PM emissions enough to reach the Level 1 threshold of a minimum of 

25 percent PM reduction. In order for a hardware DECS to be used with a biodiesel 

blended fuel, the DECS manufacturer must specifically request verification on this fuel. 

ARB has verified Johnson-Matthey, Inc. CRT Particulate Filter for use with B20 

(Executive Order DE-04-06-05, dated August 15, 2005.) ARB is encouraging other 

hardware DECS manufacturers to similarly apply for verification of their hardward DECS 

on biodiesel blends. 
37

Using publicly available data, the U.S. EPA analyzed the impacts of biodiesel on 

exhaust emissions from heavy-duty on-road engines (U.S. EPA 2002). While biodiesel 

and biodiesel blends decrease PM, HC, and CO emissions, NOx emissions, increase 

proportionally with the increase of biodiesel fraction. For B20, the NOx increase is 

reported to be two percent, with reductions of ten percent PM, 21 percent HC, and 11 

percent CO. In addition, the U.S. EPA states a B20 blend is predicted to reduce fuel 

economy by one to two percent. The data were qualified with conclusions that the 

impact of biodiesel on emissions varied depending on the type of biodiesel (soybean, 

rapeseed, or animal fats) and the quality of the diesel fuel used in biodiesel blends. 

Although B20 meets the definition of California diesel fuel, no biodiesel blend or B100 

has been verified to reduce emissions under California’s program. In order to be 

verified as a DECS, biodiesel fuel, like other alternative diesel fuel, must undergo a 

multimedia assessment. 

3. Combination Systems 

Systems combining a hardware and fuel strategy are under development and in-use. In 

order to receive ARB verification, the hardware and fuel strategy must be approved 

together as a system. As previously discussed, ARB has verified Lubrizol ECS’s 

PuriNox and DOC together as a combination system (Executive Order DE-04-007). 

The U.S. EPA has verified two combination systems under its voluntary program (U.S. 

EPA 2004b). Clean Diesel Technologies, Inc manufactures the two products U.S. EPA 

has verified. One is the Platinum Plus Purifier System, which is a fuel borne catalyst 

plus DOC verified for on-road, medium-heavy and heavy-heavy duty, 4 cycle, 1988 – 

2003 MY, turbocharged or naturally aspirated engines. The other is the Platinum Plus 

Fuel Borne Catalyst/Catalyzed Wire Mesh Filter (FBC/CWMF) System, which is verified 

for on-road, medium-heavy duty, 4 cycle, 1991 to 2003 MY, non-EGR, turbocharged or 

naturally aspirated engines. The U.S. EPA does not assign a level for PM reduction as 

California does, but describes the fuel-borne catalyst plus DOC as achieving 25 to 50 

percent PM reduction and the fuel-borne catalyst plus wire mesh filter as achieving 55 

to 76 percent PM reduction. ARB is currently evaluating these systems under 

California's program. Because these systems use a fuel additive, they must to undergo 

a multimedia assessment prior to receiving verification. 

4. In-Use Experience 

Around the world, counties and cities have long required the reduction of in-use and 

new diesel engine emissions, with a focus on reducing diesel PM. Retrofitting offroad 

diesel engines with DOCs has been taking place for over 20 years; particulate filters 

have been in use for over ten years. In Europe and Asia, mandates have been in place 

and are working to clean up the air. 
38

a. Diesel Oxidation Catalysts 

In the past 20 years, over 250,000 DOCs have been installed primarily on underground 

mining and materials handling equipment, and over 40,000 DOCs have been installed 

on urban buses and on-road trucks in the U.S. and Europe. The U.S. EPA’s urban bus 

retrofit/rebuild program required that urban buses with engines older than 1994 MY 

(1995 MY in California) retrofit with DOCs, resulting in over 15,000 retrofits. In addition, 

over 3,000 trucks have been retrofitted in Mexico and in Hong Kong about 40,000 urban 

buses are beginning to be retrofitted (MECA 2002, 2004b). 

b. Diesel Particulate Filters 

The use of DPFs is not as widespread as DOCs in part because of the requirement for 

very low fuel sulfur content for effective operation of a DPF. Nevertheless, MECA 

estimated that over 130,000 DPFs have been retrofitted on heavy-duty vehicles 

worldwide (MECA 2000a). One notable program is Sweden’s Environmental Zone 

Program, which requires on- and off-road vehicles operating in specified urban areas to 

be retrofitted. In the U.S., California and New York have taken the lead in aggressive 

programs to reduce diesel PM through the use of DPFs. In addition, the City of Los 

Angeles adopted a motion in 2000 to require the retrofit of all city-owned diesel trucks 

with DPFs by February 2004. 

As of September 2005, the City of Los Angeles has outfitted approximately 370 diesel 

Solid Waste Collection Vehicles (SWCV), 252 dual fuel (liquefied natural gas and 

diesel) SWCV, and 487 general service vehicles (e.g. asphalt haulers, dump trucks, 

sweepers, and tractors) with DPFs. The City of LA has stated that they have been 

satisfied with their retrofit experience, and have had few maintenance or performance 

problems associated with vehicles installed DPFs (Wilson, pers. comm.). 

Several other public fleets have retrofitted or are actively investigating the applicability 

of passive DPFs in their in-use vehicles with grant money from the Carl Moyer and ERC 

programs. These include City of Azusa, City of Chino, Los Angeles County, City of Los 

Angeles Airports, Rancho California Water District, City of Cucamonga, Riverside 

County, City of Riverside, City of Pasadena and City of San Diego. 
39

D. Engine Technology for Public and Utility Fleet Vehicles 

1. Current Engine Availability 

Heavy-duty engines sold in California are required to meet the engine exhaust 

standards shown below in Table 15. 

Table 15. Emission Standards for New Heavy-Duty Engines 

Emissions Standards (g/bhp-hr) 

Model Year NOx PM 

Diesel Derived Engines 

1988-1989 6.0 0.60 

1990 6.0 0.60 

1991-1993 5.0 0.25 

1994-1997 5.0 0.10 

1998-2003 4.0 0.10 

October 2002 2.2 (a) 0.10 

2004-2006 2.2 (a) 0.10 

2007-2009 1.2 (b) 0.01 

2010 and 

subsequent 0.20 0.01 

Otto Cycle Engines 

NHMC+NOx PM 

2005-2007 1.0(c) n/a 

NOx PM 

2008 and 

subsequent 0.20 0.01 

a. Nominal NOx value of 2.2 g/bhp-hr is based on emission standards of 2.4 g/bhp-hr for NOx plus 

non-methane hydrocarbons (NMHC) or 2.5 g/bhp-hr NOx plus NMHC with 0.5 g/bhp-hr NMHC cap, 

which took effect in October 2002 for those engines subject to U.S. EPA Consent Decrees and the 

California Settlement Agreements. The Consent Decree-complying engines had to comply with 

2004 standards by October 1, 2002. 

b. Between 2007 and 2009, U.S. EPA requires 50 percent of heavy-duty diesel engine family 

certifications to meet the 0.2 g/bhp-hr NOx standard. Averaging is allowed, and it is expected that 

most engines will conform to the fleet NOx average of approximately 1.2 g/bhp-hr. 

c. A manufacturer may request to certify to the Option 1 or Option 2 federal NOx plus NMHC 

standards as set forth in 40 CFR §86.005-10(f). For engine families certified to the Option 1 or 2 

federal standards the Family Emission Limit must not exceed 1.5 g/bhp-hr. 

Beginning with the 2007 model year, every heavy-duty engine will have to meet the 0.01 

g/bhp-hr PM standard and lower NOx emission standards. The following websites 

provides information on MY 2005 and 2006 California certified engines: 

http://www.arb.ca.gov/msprog/onroad/cert/mdehdehdv/2005/2005.php

http://www.arb.ca.gov/msprog/onroad/cert/mdehdehdv/2006/2006.php
40

2. Future Engine Availability (2007 – 2009) 

a. Diesel-fueled Engines 

All major manufactures have announced that they will be using exhaust gas 

recirculation (EGR) to meet the 2007 NOx emission standard and diesel particulate 

filters to meet the particulate standard. EGR causes a portion of the exhaust gases to 

circulate through a heat exchanger to cool the exhaust before reintroducing the gases 

into the engine intake manifold. EGR has been used in some engines since 2003, but 

engine manufacturers have further refined the systems to allow lower NOx emissions. 

Caterpillar, Cummins, and DDC plan to offer a full line of medium- and heavy-duty 

diesel engines; International focuses on the school bus and collection vehicle engine 

markets; and Mack/Volvo focuses on engines for collection vehicles. 

Dual fuel systems for collection vehicles are no longer available in the U.S., as Clean 

Air Power, the sole manufacturer of these systems, has concentrated its efforts in 

Europe. Increased interest in its product may, however, prompt Clean Air Power to 

develop and certify in California a 2007 product for collection vehicles. 

The Diesel hybrid-electric is another technology that reduces both emissions and fuel 

use and that will be available in 2007. While not classified by ARB as an alternative-fuel 

technology, diesel hybrid-electric technology achieves lower emissions and better fuel 

economy than equivalently sized diesel buses or trucks. Emissions testing studies at 

ARB and other facilities indicate a fuel consumption reduction of 25 percent and NOx 

emission reduction of about 50 percent for diesel-fueled hybrid-electric buses (HEBs) 

compared to conventional diesel transit buses. This technology is being applied 

primarily in delivery vehicles and transit buses. 

b. Alternative-fuel Engines 

Manufacturers of natural gas engines are likely to be able to meet the upcoming 2007 

standard with three-way catalyst aftertreatment technology similar to that being used on 

passenger cars. Cummins, through its joint partnership with Westport Innovations, 

Cummins Westport Inc., and John Deere has stated they will offer alternative fuel 

products to meet the 2007 emission standards. Although we have only preliminary 

data, it appears that these manufacturers of alternative-fuel engines or systems will 

certify to the more stringent 2010 0.20 g/bhp-hr NOx and 0.01 g/bhp-hr PM standards. 

John Deere currently only certifies urban bus and medium heavy-duty natural gas 

engines, but is developing a heavy heavy-duty engine that could be suitable for use in 

waste collection vehicles. John Deere has stated is intends to produce a 250-325 

horsepower, 9 liter natural gas engine meeting the 0.20 g/bhp-hr NOx level by 2007. 

This engine could be used in transit buses, school buses, and refuse trucks. 
41

Cummins will be marketing the natural gas engines developed by Cummins Westport 

Inc. Cummins is currently providing bids on both diesel and natural gas buses for 2007. 

Cummins Westport Inc. has partnered with U.S. DOE's NREL to develop a lower 

emission version of the L Gas Plus (8.9 L) engine for use in medium-duty trucks, refuse 

trucks, and urban buses. This engine is scheduled to be commercially available in 

early-2007. The SCAQMD is also currently sponsoring a project with Cummins to 

commercialize the C Gas Plus engine (8.2 L) to 0.2 g/bhp-hr NOx by 2007. 

In 2004, Ford and General Motors stated that they would no longer be producing their 

smaller CNG engines used in cutaway vehicles. As a result, BAT Technologies, Clean 

Energy, and Teleflex/GFI Control Systems have jointly proposed a contract with the 

SCAQMD and the state of New York to "develop and certify in California a retrofit 

system that converts 2005 and subsequent model year gasoline-powered Ford Crown 

Victoria and E-450 cutaway vehicles to dedicated CNG operation" (South Coast Air 

Quality Management District, 2004). It is anticipated that once retrofitted, the engines 

will meet SULEV emission levels. This technology is scheduled to be certified by 

mid-year 2005. 

ISE Corporation currently offers a California-certified gasoline hybrid electric bus and is 

developing hybrid electric systems with compressed natural gas, diesel, and hydrogen 

fuels, also for urban buses. While ISE focuses on the urban bus market, it is 

considering expanding into other vocations that use heavy heavy-duty engines, such as 

waste collection vehicles. 

c. Gasoline Engines 

Emission standards for heavy duty Otto-cycle engines used in heavy-duty vehicles over 

14,000 GVWR for model year 2007 are 1.0 g/bhp-hr NMHC+NOx with no PM standard. 

Beginning in model year 2008 the emission standards are lowered to 0.20 g/bhp-hr for 

NOx and 0.01 g/bhp-hr for PM. It is expected that only minor modifications to current 

gasoline engine technology will be required to meet these standards. 

3. Engine Availability (2010 and beyond) 

Engine technology for 2010 will most likely rely upon selective catalytic reduction (SCR), 

NOx adsorbers, and further improvements in engine technology to reduce NOx 

emissions. 

Two aftertreatment technologies that will most likely play a large role in meeting the 

2010 NOx standard are selective catalytic reduction (SCR) and the NOx adsorber. 

SCR catalysts use ammonia as a NOx reductant to reduce stationary sources 

emissions. Urea may also used as the source of ammonia. In recent years, 

considerable effort has been invested in developing urea SCR systems that could be 

applied to heavy-duty diesel vehicles with low sulfur diesel fuel. Urea SCR systems are 

being used to comply with the EURO IV heavy-duty diesel emission standards 
42

(U.S. EPA, 2004b). U.S. manufacturers are working on SCR systems for vehicles that 

could be used in 2010. 

Unlike catalysts, which continuously convert NOx to N2, NOx adsorbers are materials 

that store NOx under lean conditions and release and catalytically reduce the stored 

NOx under rich conditions. NO and NO2 are acidic oxides and can be trapped on basic 

oxides. Fuel sulfur can be converted to stable sulfates providing competition with NOx 

for storage sites, thus poisoning the catalysts, therefore low sulfur fuel is required. 

E. ARB Exhaust Temperature Study 

From October 2003 to July 2004, ARB conducted an exhaust temperature study to 

evaluate the various vehicle types that are typically used by municipalities and/or 

utilities. The study’s goal was to determine what percent of the vehicles have the 

operational characteristics to use DECS that rely on exhaust temperature to function 

properly. 

Based upon the study, ARB determined that at least 56% of the vehicles meet the 

criteria for Level 3 passive DPFs, 67% of the vehicles meet the temperature criteria for 

the Level 2 Flow Through Filter, and 96% met the temperature criteria for a Level 1 

DOCs. Details of the study can be found in Appendix D. Overall the study shows 

nearly all vehicles could use a temperature dependent DECS; provided adequate space 

is available for device installation. 

F. Implementation Assistance 

Staff is committed to provide the necessary compliance assistance to fleets for 

successful implementation of the rule. Upon adoption of the rule, staff is prepared to 

conduct statewide workshops, develop compliance guidance documents, sample 

recordkeeping forms and labels to assist fleets with implementation. All these activities 

are consistent with ARB’s efforts with other fleets rules already adopted. In addition, 

staff is also working on developing an interactive web-based “look-up” table to help 

fleets identify verified DECS that may be applied to a vehicle based upon engine 

manufacturer and model-year. 

VII. REGULATORY ALTERNATIVES 

Staff believes the proposed regulation is the most cost efficient method for reducing 

diesel PM from municipality and utility fleet vehicles. A comparison of emission 

reductions from each regulatory alternative considered can be found at the end of this 

section (Table 16). 
43

A. Do Not Adopt This Regulation 

Not adopting this regulation would disregard the adverse health risk posed by diesel 

PM. In consideration of the potential health impacts discussed earlier, and ARB’s 

mandate to protect the public health of all Californians, this alternative is not considered 

a reasonable option. ARB staff does not recommend this alternative because it would 

result in approximately 80 percent greater PM emissions over the next few decades 

than the proposed plan, thus adversely impacting the health of Californians. 

With full implementation of this control measure, the estimated reduction in diesel PM 

ranges from 78 percent in 2010, to 84 percent in 2020, when compared to the 2000 PM 

baseline. The recommended actions in this plan will reduce the localized risks 

associated with activities that expose nearby individuals to diesel PM emissions. This 

diesel PM control measure will result in additional benefits associated with reducing 

diesel PM emissions, including reducing NOx emissions by 35% percent from baseline 

in 2020, reducing ambient fine PM levels, increasing visibility, reducing material damage 

due to soiling of surfaces, and reducing incidences of non-cancer health effects, such 

as bronchitis and asthma. 

B. Rely on Voluntary Programs 

The federal rules for new diesel engines will not be implemented for several years and 

do not affect existing vehicles. The U.S. EPA developed the Voluntary Diesel Retrofit 

Program to reduce diesel PM emissions in the immediate future. The program 

addresses pollution from diesel construction equipment and heavy-duty vehicles on the 

road today by providing a voluntary certification program for technology. Participation is 

voluntary and available incentive funds are currently limited. The U.S. EPA program is 

not sufficient for meeting ARB’s overall goals. 

The Carl Moyer Program is a California program which encourages use of cleaner 

engines by funding the incremental cost of repower, retrofit, or purchase of new, cleaner 

engines. Although the Moyer Program is funded at approximately $140 million per year 

for the next 10 years, participation is still voluntary, available incentive funds are limited 

and it does not require fleets to clean up their existing fleet. 

Therefore, given the over 1.2 million diesel engines in California, reliance on purely 

voluntary programs is inadequate for meeting California’s risk reduction goals. ARB 

staff does not recommend this alternative because it would result in only minor diesel 

PM emission reductions. 

C. Require Repowered Engines or New Vehicle Purchases 

Another alternative staff considered, which would result in similar reductions in diesel 

PM emissions, is to require all public and utility fleet vehicles to repower with diesel 

engines certified to the 0.01 g/bhp-hr particulate standard beginning in 2007. This 

option is significantly more expensive than the proposed alternative. The estimated 
44

capital cost of repowering all engines in 2007 is approximately $650 million, which is 

three times higher than the $213 million cost to implement this proposed regulation, for 

a similar reduction in diesel PM. The estimated cost could be even higher than this as 

many vehicles cannot be repowered. A repower may be incompatible with older engine 

and drive train technology or the size of the engine compartment, thus the owner would 

have to purchase a new vehicle to accomplish the lower PM emissions. 

Staff predicts a complete turnover of public and utility vehicles by 2020 would reduce 

diesel PM emissions by up to 90 percent. This is an estimated reduction of 0.06 tpd, 

which is slightly higher than the recommended alternative in 2020 (Table 16). ARB staff 

does not recommend mandating this as the sole option, however, because of the high 

cost of implementation compared to the amount of PM emissions reduced and 

significantly poorer cost effectiveness. 

D. Require Alternative Fuel 

The last alternative staff considered but did not recommend was the requirement to 

repower all applicable vehicles with alternative fueled engines. This would have 

resulted in the same PM reductions as the alternative to repower with all 2007 engines; 

however it may result in a small NOx benefit from 2007 to 2009. ARB staff does not 

recommend mandating this as the sole option, however, because of the limited 

alternative fueled engine availability for public and utility fleet vehicles, and the high cost 

of implementation compared to the amount of PM emissions reduced and significantly 

poorer cost effectiveness. 

Table 16. Diesel PM Reductions by Alternative Compared to the Proposal. 

Regulatory Alternatives Reductions (tons/day) 

Year Proposal 

(tpd) Adopt 

Nothing Voluntary Repower to 0.01 Engine 

Alt Fuel 

Engines 

2010 0.15 0 n.q. 0.13 0.13

2020 0.05 0 n.q. 0.06 0.06

n.q. – not quantified 

VIII. ECONOMIC IMPACT 

The total discounted cost of the rule in 2005 dollars for all municipalities and utilities is 

$213 million. This cost is to apply BACT to approximately 31,076 vehicles (estimated to 

be in the fleet in 2006). The cost per vehicle is estimated at $6,857. This is lower than 

the estimated cost per truck of $13,000 for implementation of the solid waste collection 

vehicle rule adopted by the Board in 2003. 
45

A. Legal Requirement 

Sections 11346.3 and 11346.5 of the Government Code require state agencies to 

assess the potential for adverse economic impacts on California business enterprises 

and individuals when proposing to adopt or amend any administrative regulation. The 

assessment shall include a consideration of the impact of the proposed regulation on 

California jobs, business expansion, elimination, or creation, and the ability of California 

business to compete. 

State agencies are also required to estimate the cost or savings to any state or local 

agency and school districts in accordance with instruction adopted by the Department of 

Finance. This estimate is to include any nondiscretionary costs or savings to local 

agencies and the costs or savings in federal funding to the state. 

B. Affected Manufacturers 

No manufacturer will incur any direct costs as a result of this proposed rule because it 

only applies to government agencies and utilities that operate fleets, and their choices 

on purchasing existing engines and emission control technologies. 

C. Estimated Costs to Investor-Owned Private Utilities 

Staff estimates a total of 209 private utilities operating an estimated 3,979 vehicles as of 

2004 will be impacted by this regulation. Staff collected data from the four largest 

investor-owned private utilities that provide natural gas, electricity and/or water services 

in California. These four large utilities account for 3,130 vehicles that are subject to this 

rule. In addition, staff identified about twenty additional utilities with 664 vehicles from 

the ARB PSIP database. Lastly, staff identified about 185 small water companies from 

the California Public Utilities Commission’s (CPUC) lists. Telephone contact with these 

small water companies shows that on average they have about one vehicle per 

company that may be impacted by this regulation. 

Staff does not have access to financial records for any investor-owned utilities; therefore 

the number of vehicles owned by a company was used as a surrogate to determine 

small business status. The criteria staff used for a small business was a company that 

owns fewer than 15 vehicles. Based on these criteria, staff determined that all small 

water companies would be considered small businesses, which is 88 percent of the total 

companies potentially directly affected by this regulation but less than one percent of 

the total California municipal and utility fleet vehicles. 

1. Retrofit Implementation Scenario 

Staff assumed utility vehicle owners would choose the least expensive of the best 

available control technologies to comply with this regulation. Staff, therefore, assumed 

a diesel emission control strategy would be employed in lieu of more expensive options 

of repowering or replacing the vehicle or engine, unless that was the only option 
46

available to those vehicles or the fleet operator needed to replace the vehicle in the 

near future for other reasons. Typically, particulate matter (PM) emissions and exhaust 

temperatures dictate the type of diesel emission control strategy a vehicle can use. 

Based on available data on DECS currently available to the vehicle fleet, staff created a 

“most-likely” retrofit scenario to determine an average economic impact (Table 17). 

This scenario is based on those DECS that are expected to be available during the 

implementation period (Table 18). DECS include Level 3 verified diesel particulate 

filters; Level 2 verified flow through filters and a fuel-water emulsified fuel; and Level 1 

verified technology of a diesel oxidation catalysts. Table 18 also includes an active 

DPF9

. The only other technologies available to these vehicles are engine repower or 

replacement. The scenario assumes more Level 1 technologies will be verified, and for 

current verified Level 1, 2 and 3 technologies to have verifications extended to 

additional MY engines. 

 

9

 Active DPFs do not rely on exhaust temperature for regeneration, thereby having a wide range of retrofit 

applications. 
47

Table 17. Most-Likely Verification Retrofit Scenariog 

(Applies to Municipal and Utility Fleets) 

Group MY %BACT 

Implementation 

Date Level 1a Level 2d Level 3 Repower

20% 12/31/2007 10% 8% 

60% 12/31/2009 28% 

100% 12/31/2011 11% 33% 1 1960-

1987e

Delay 12/31/2012 10% 

20% 12/31/2006 5% 5% 8% 

60% 12/31/2008 2% 10% 25% 

100% 12/31/2010 35% 2a 1988-

1993 

Delay 12/31/2011 10% 

20% 12/31/2006 5% 5% 8% 

60% 12/31/2008 2% 10% 25% 

100% 12/31/2010 35% 2b 1994- 

2002d, f

Delay 12/31/2011 10% 

50% 12/31/2009 20% 30% 3 2003-

2006b,c 100% 12/31/2010 20% 30% 

Notes: 

a

Assumes current Level 1 verification will be extended to 1960-1993 model years.

b

Assumes current Level 3 verification will be extended to 2003-2006 model years. c

Assumes current Level 1 verification will be extended to 2003-2006 model years.

d

Assumes current Level 2 verification will be extended to all model years e

Assumes a Level 3 verification will be available for some 1960-1987 model 

years.

f

Assumes a Level 3 active DPF verification will be available for some 1988-2002 

model years. 

g

Percentage add to 100% for each model year group 

2. Implementation Costs 

The initial cost per truck will vary depending on the best available control technology 

used for the truck. The initial costs listed in this section are based on capital and 

operation and maintenance costs applied to the retrofit scenarios discussed in the 

previous paragraph. Capital costs per vehicle and technology are listed in Table 18. 

Staff assumed that the only capital cost required for the fuel-water emulsion option is for 

one fuel re-circulation pump per terminal since it is assumed that fleets that use this 

operation already have an existing fuel tank on-site. No additional cost was added for 

those DECS that specify use of ultra-low sulfur fuel because the federal and state ultra 

low sulfur diesel fuel rule will be effective for all on-road diesel vehicles as of July 1, 

2006 (six months prior to the first implementation deadline). 
48

Table 18. Average Capital Costs for Diesel Emission Control Strategies 

COST DESCRIPTION 

DECS Low High Average 

Passive Diesel Particulate Filter $6,000 $11,000 $8,500 

Diesel Oxidation Catalyst $1,000 $2,000 $1,500 

Flow Though Filter $3,500 $6,500 $5,000 

Fuel Recirculation Pump/Terminal $1,000 $10,000 $4,00010

Lean Nox Catalyst with DPF $13,000 $17,000 $15,000 

Active DPF $10,000 $12,500 $11,000 

EGR+DPF $14,000 $18,000 $16,000 

Table 19. Incremental Annual Operation and Maintenance Costs for a Retrofitted 

Municipality or Utility Vehicle 

Cost 

Description 

Average Cost for 

Passive and 

Active DPF and 

Oxidation 

Catalyst 

Average Cost for 

Fuel-Water 

Emulsion 

Average Cost 

Savings for 

Engine Repowerc

Maintenance $33 a $0 <$176> 

Fuelb $0 $355 <$264> 

Total: $33 $355 <$440> 

Notes: 

a

Includes increased cleaning and maintenance estimated at 1 hour for diesel particulate filters and 

oxidation catalyst crankcase filter replacement interval required once per three years based upon low 

mileage accumulation. 

b

Incremental fuel cost if a fuel-based DECS is selected. c

Decreased maintenance and fuel costs are associated with the use of new engines. 

The average total statewide dollar costs were then derived from the application of the 

average discounted capital costs plus the average operation and maintenance costs 

from FY 2006 to 2022 for the most-likely retrofit implementation scenario, totaling 

approximately $28,390,000 (Table 20) for the retrofit of the total number of utility 

vehicles expected to be in the fleet in 2006 (approximately 4,140 vehicles). 

Staff developed average capital costs for each BACT option listed in the most-likely 

retrofit scenario (Table 17). Staff surveyed various retrofit manufacturers and installers 

to get an average cost for a level 1, 2, and 3 DECS. Staff also surveyed engine 

dealerships and fleets to get an average cost to repower a diesel vehicle. These capital 

 

10 Based upon most common size fuel pump utilized by fleets, Lubrizol 2004. 
49

costs were discounted over the period of ten years for the DECS or repower. See small 

businesses section below for complete description of how costs were derived and 

Appendix C for more detailed retrofit cost assumptions. 

Table 20. Average Total Statewide Costs of Most-Likely DECS Verification 

Implementation Scenarios for Utilities 

Fiscal 

Year 

Discounted Average 

Annual Capital Costs (in 

2005 dollars) 

Average Annual 

O&M Costs (in 2005 

dollars) 

Total Average 

Annual Cost (in 2005 

dollars) 

2006 $333,000 $35,000 $368,000 

2007 $806,000 $53,000 $859,000 

2008 $1,520,000 $43,000 $1,563,000 

2009 $2,188,000 $19,000 $2,207,000 

2010 $2,932,000 -$22,000 $2,910,000 

2011 $3,162,000 -$39,000 $3,123,000 

2012 $3,115,000 -$60,000 $3,056,000 

2013 $2,912,000 -$56,000 $2,856,000 

2014 $2,721,000 -$52,000 $2,669,000 

2015 $2,543,000 -$49,000 $2,494,000 

2016 $2,208,000 -$64,000 $2,144,000 

2017 $1,811,000 -$70,000 $1,742,000 

2018 $1,303,000 -$59,000 $1,244,000 

2019 $828,000 -$47,000 $781,000 

2020 $323,000 -$24,000 $299,000 

2021 $87,000 -$13,000 $75,000 

2022 $0 $0 $0 

Total: $28,792,000 -$405,000 $28,390,000 

 

Capital and operation and maintenance costs will vary depending on the year of 

implementation, due to the phase-in schedule. Staff expects the costs to be borne by 

the end user, since this is a regulation requiring retrofits of in-use vehicles. 

D. Potential Impact on Utilities 

The average cost per vehicle for small utilities and typical utilities are the same. The 

average investor-owned private utility company has approximately five vehicles to which 

this rule applies, while the four largest investor-owned utilities have an average of 783 

vehicles each to which this rule applies. Staff chose to calculate the average cost using 

five vehicles. The average size for a typical fleet was calculated by taking the total 

number utility vehicles (4,140) and subtracting the percentage of vehicles owned by 

large utilities (79%). This number (869) was then divided by 205 which is the number of 

private utilities if the four largest utilities are not included. 

Staff assumed 22 percent of the vehicles would fall under 1960-1987 MY (Group 1) 

engines, 74 percent of the vehicles would fall under 1988-2002 MY (Group 2) engines, 
50

and 4 percent would fall under the 2003-2006 MY (Group 3) engines for implementation 

phase-in, based on survey information. The capital costs, and operating and 

maintenance costs are listed in Table 21 for the years of implementation, FYs 2006 to 

2011. 

Table 21. Initial and Annual Costs Average Small Utility with 5 Vehicles 

Fiscal 

Year 

Discounted Average 

Annual Capital Costs (in 

2005 dollars) 

Average Annual 

O&M Costs (in 

2005 dollars)

Total Average 

Annual Cost (in 

2005 dollars) 

2006 $402 $43 $444 

2007 $974 $64 $1,038 

2008 $1,836 $51 $1,888 

2009 $2,642 $23 $2,665 

2010 $3,541 -$26 $3,514 

2011 $3,819 -$47 $3,772 

In order to arrive at the discounted capital costs for the small/typical business, staff 

annualized the capital costs by multiplying the net present value of the capital costs by 

the capital recovery factor.11 Staff assumed a lifetime of the DECS based on a 

minimum lifetime of ten years with an annual interest rate of seven percent.12 It is quite 

likely that a DECS will last much longer in a well-maintained vehicle, as some DECSs 

have been operating for over ten years on solid waste collection vehicles in Europe.13 

To determine the operation and maintenance costs in current dollars, staff multiplied the 

yearly costs by the net present value factor. Also, the operation and maintenance costs 

are higher than would be expected with just hardware DECS used, because the fuelwater emulsion DECS is included the overall operation and maintenance costs at an 

average of $355 per vehicle annually, and not all utilities will utilize this option. 

 

11 Net Present Value is the cost multiplied by 1/(1+r)^(n+1), where r = the annual interest rate, and n = the 

number of years in the future. For example, FY2004-2005 is considered to be n = 0, and for FY 2005-

2006 n = 1. Capital Recovery Rate Factor is (r*(1+r)^N)/[(1+r)^N-1], where r = the annual interest rate, 

and N = lifetime of project (in years) (Linsley, 1977). 12 For federal decision-making, Office of Management and Budget suggests using this annual interest 

rate. (OMB Circulate A-94, http://www.whitehouse.gov/omb/circulars/a094/a094.html) 13 Bauner, David. March 2002. Raw data submitted to ARB for contract to determine European retrofit 

experience. 
51

E. Potential Impact on Businesses 

The regulation allows municipalities and utilities a variety of options to meet the 

proposed regulation requirements. The proposed regulation may have some cost 

impact on companies involved in the manufacture and production of engines and 

vehicles by creating the need for new engines and vehicles. 

While this regulation applies to existing businesses and uses technology from existing 

businesses, it may lead to the creation of businesses. Businesses that may be created 

include those that manufacture DECS and those that install, repair, or clean DECS. 

Staff believes businesses will be altered or augmented in lieu of creating new 

businesses. Some used trucks businesses; however, may be adversely affected 

because these businesses may experience a reduction in demand for their used truck 

services. Staff believes, however, that these businesses are likely to change their 

business focus to refurbishment and upgrading of engines for resale. 

Specific to the retrofit requirements, California businesses capable of performing engine 

retrofits will be positively affected with increased workload. There are seven DECS 

manufacturers located in California that may be positively affected by this regulation. 

F. Potential Impact on Business Competitiveness 

The proposed regulation is not expected to impact the ability of California businesses to 

compete with businesses in other states because utilities generally do not compete with 

each other because each has their own specific service territories. As indicated above, 

many of the businesses that produce the products needed to meet the proposal are 

located in other states. By requiring new, clean technology, this proposal may actually 

provide new opportunities for California businesses engaged in advanced technology. 

Utilities providing water, natural gas and electricity services will remain in California to 

provide effective and efficient services to their customers. 

G. Potential Impact on Employment 

The proposed regulation will likely create a market for manufacturers of heavy-duty 

diesel or natural gas engines, vehicles, and emission control systems. For those 

businesses located in California, the creation of new jobs is expected to meet this 

demand. Services to retrofit existing public and utility vehicles are expected to create 

new opportunities for existing businesses. 

H. Potential Impact on Business Creation, Elimination or Expansion 

The proposed regulation could impact California companies involved in the manufacture 

and production of engines, vehicles, and DECS. Currently seven DECS manufacturers 

and numerous OEM dealerships are located in California. Allowing new, cleaner engine 

and vehicle purchases as a means to meet the diesel PM control measure could create 
52

new business opportunities for manufacturers of heavy-duty diesel, natural gas, or 

gasoline engines, vehicles, and DECS. 

I. Potential Costs to Local Agencies 

The proposed regulation is expected to have a significant impact on public agencies 

statewide that own and operate diesel-fueled vehicles. The average total statewide 

dollar costs for local agencies (i.e., city, county and special districts) were derived from 

the application of the average discounted capital costs plus the average operation and 

maintenance costs from FYs 2006 to 2022. Implementing the retrofit scenario (Table 

17) would cost approximately $156.6 million for the retrofit of approximately 22,839 

vehicles expected to in the fleet by 2006. Capital costs were discounted over the period 

of ten years for the DECS. 

The average discounted costs for the first year of implementation in FY 2006 are 

$2,030,000 (Table 22). The average annual costs are based on discounted average 

capital costs plus average operation and maintenance costs (Table 18 and 19) for the 

most-likely DECS verification implementation scenario. 

In order to arrive at the discounted capital costs for the proposed regulation, staff 

annualized the capital costs by multiplying the net present value of the capital costs by 

the capital recovery factor.14 Staff assumed a lifetime of the DECS based on a 

minimum lifetime of ten years with an annual interest rate of seven percent.15 It is quite 

likely a DECS will last much longer in a well-maintained vehicle, as some DECS have 

been operating for over ten years in vehicles in Europe without replacement.16 

To determine the operation and maintenance costs in 2005 dollars, staff multiplied the 

yearly costs by the net present value factor. The cost analysis assumes a fleet 

composition of 22 percent of the Group 1 vehicles; 74 percent of the Group 2 vehicles; 

and 4 percent of the Group 3 vehicles, and a retrofit scenario shown in Table 17. Staff 

estimates 22,839 vehicles are owned by local public agencies throughout California, 

and 3,087 vehicles would be brought into compliance in FY 2006. 

 

14 Net Present Value is the cost multiplied by 1/(1+r)^(n+1), where r = the annual interest rate, and n = the 

number of years in the future. For example, FY2003-2004 is considered to be n = 0, and for FY 2004-

2005 n = 1. Capital Recovery Rate Factor is (r(1+r)^N)/[(1+r)^N-1], where r = the annual interest rate, 

and N = lifetime of project (in years) (Linsley, 1977). 15 For federal decision-making, Office of Management and Budget suggests using this annual interest 

rate. (OMB Circulate A-94, http://www.whitehouse.gov/omb/circulars/a094/a094.html) 16 Bauner, David. March 2002. Raw data submitted to ARB for contract to determine European retrofit 

experience. 
53

Table 22. Average Local Government Costs to Implement Public and Utility Fleet 

Vehicle Regulation 

Fiscal 

Year 

Number of 

Vehicles 

Retrofit 

Discounted 

Annual Capital 

Costs (in 2005 

dollars) 

Average 

Annual O&M 

Costs (in 2005 

dollars) 

Total Average 

Annual Cost 

(in 2005 

dollars) 

2005 0 $0 $0 $0 

2006 3,087 $1,835,000 $195,000 $2,030,000 

2007 3,416 $4,448,000 $292,000 $4,740,000 

J. Potential Costs to State Agencies 

Two separate costs may pertain at the state government level: costs to state agencies 

that own diesel vehicles to bring the vehicles into compliance, and costs for the ARB to 

implement and enforce the regulations. ARB estimates three additional staff will be 

required to enforce the regulation and to provide guidance for implementation. The cost 

for three additional ARB staff is approximately $300,000 annually. Staff anticipates the 

need for added staff beginning FY 2005. 

According, to DMV registration data, the State of California owns approximately 1,275 

diesel-fueled vehicles as of 2004; however this number is expected to grow to 

approximately 1,327 vehicles by 2006. The total cost to the state just to bring these 

vehicles into compliance is approximately $9.1 million. If we include the cost to the 

state to implement and enforce the regulation, the initial discounted cost for FY 2006 

would be $418,000. Assuming the cost of compliance is discounted over ten years, the 

estimated cost of compliance for California for current fiscal year and the next two fiscal 

years are shown below (Table 23): 

Table 23. Average Costs to the State to Implement Municipality and Utility Fleet 

Regulation 

Fiscal 

Year 

Number of 

Vehicles 

Retrofit 

Discounted 

Annual 

Capital Costs 

(in 2005 

dollars) 

Average 

Annual O&M 

Costs17 (in 

2005 dollars) 

Total 

Average 

Annual Cost 

(in 2005 

dollars) 

2005 0 $0 $300,000 $300,000 

2006 179 $107,000 $311,000 $418,000 

2007 198 $258,000 $317,000 $575,000 

Most state agencies will have to absorb the cost of compliance in their general budget 

since they do not charge specific fees for services provided by their diesel vehicles 

(e.g., CalTrans freeway sweeping.) 

 

17 O&M costs include vehicle retrofit costs and costs to implement and enforce the regulation. 
54

K. Cost to Federal Agencies 

Staff was unable to determine the exact number of vehicles owned by the federal 

government operating in California, since most are not registered by the DMV. 

However, the United States Postal Service, several military bases, and the federal 

General Services Administration submitted survey data on their vehicles subject to the 

rule. Based on these, staff estimated the total federal fleet vehicles subject to the rule is 

2,663 as of 2004. This number is expected to grow to approximately 2,771 by 2006. 

The total cost for federal agencies discounted to 2005 dollars is estimated at $19 

million. 

L. Cost to Municipalities and Utilities Located in Low Population Counties 

Municipalities and utilities located in low population counties typically have older 

vehicles. Based on an analysis DMV data, approximately 1,070 municipal and utility 

vehicles subject to the rule are registered in low population counties. Forty-six percent 

(46%) are Group 1 vehicles, 54% are Group 2 vehicles, and less than 1% are Group 3 

vehicles. The majority of Group 1 vehicles will likely be replaced as shown in the retrofit 

scenario in Table 17 since these are less amenable to retrofit. The total discounted cost 

for these fleets is estimated at $9.2 million if they do not select any optional compliance 

schedule. 

Based on discussion with these fleets and the Regional Council of Rural Counties, staff 

assumes most fleets will take advantage of the optional implementation schedule in 

Table 11 or the accelerated turnover option. This would result in a lower discounted 

total cost since the full implementation period is extended out a minimum six years 

(depending what option is selected.) 

M. Cost to the Average Household for Utilities 

Utilities have the ability to pass the cost of compliance on to their ratepayers. Some 

special districts also provide services on a fee basis (i.e., water district) and may be 

able to pass on the cost of compliance to their ratepayers. A utility ratepayer may 

eventually pay higher costs for natural gas, electric or water services. 

To estimate an order of magnitude for the cost to an individual ratepayer, staff 

calculated the average increase to an individual ratepayer for the largest utility in 

California. This utility owns approximately 1,472 vehicles subjected to the regulation as 

reported to ARB in 2004 (this number is estimated to grow to 1,531 vehicles by 2006). 

The total cost of compliance discounted to 2005 dollars is $10.5 million. If this cost was 

equally distributed to the 4,756,159 utility’s customer accounts18, it would result in a one 

time increase per ratepayer of $2.20. 

 

18 California Public Utility Commission 2001 Utility Electric Sales 
55

IX. ENVIRONMENTAL IMPACT AND COST-EFFECTIVENESS 

The proposed regulation would provide cost-effective diesel PM emission reductions 

throughout California, especially at the neighborhood level. The air quality benefits 

statewide would be not only from reduction of diesel PM emissions, but also from 

reduction of CO, NOx, and HC emissions. Staff calculated the average cost per diesel 

PM pound reduced by 2010 is about $159 and the average cost per NOx pound 

reduced is $11.47 

The cost-effectiveness of this regulation is higher than other similar PM control 

measures; however the health benefits of the regulations provides a cost savings as 

discussed in section IX.C. 

A. Statewide Emission Benefits 

ARB staff estimates the proposed diesel PM control measure would result in the 

reduction of between 0.15 tpd of diesel PM emissions in 2010 and 0.05 tpd diesel PM 

reduced in 2020 (Table 24). The reduction of diesel PM emissions attributed to this 

regulation peaks around 2010 because the majority of vehicles are expected to meet 

the diesel PM control measure by 2010 (except for about 1,070 vehicles located in lowpopulation counties, which have a later final implementation date). After 2010 the 

benefits attributed to this regulation decline to 0.05 tpd in 2020 as vehicles are retired 

and replaced with new engines that meet the federal 2007 0.01 g/bhp-hr PM standard. 

Table 24. Statewide Diesel PM Emission Reduction Benefits. 

Calendar Year Baseline Inventory 

(tpd) 

 Diesel PM Retrofit 

Reduction (tpd) 

 % Reduction from 

Baseline 

2006 0.36 0.02 6% 

2010 0.25 0.15 60% 

2015 0.17 0.10 59% 

2020 0.12 0.05 42% 

Other air quality benefits also exist as a result of the use of the various BACT, including 

reduced emissions of CO, HC, and NOx. The reductions in HC are also accounted for 

in the State Implementation Plan. Based on expected reduction capabilities from the 

various DECS that might be used (Table 25), reductions of up to 1.18 tons of CO per 

day (Table 26), 0.15 tons of HC per day (Table 27), and 0.30 tons of NOx per day 

(Table 28) will be realized . 
56

Table 25. Other Pollutant Reductions 

Emission Reduction (Percent) 

Diesel Emission Control Strategy PMa

 CO HC NOx

Passive Diesel Particulate Filter 85 90b 95b 0c

Fuel-Water Emulsionh 50 35d 60d 50d

Average Diesel Oxidation Catalyst 25 47e, f 76e, f 0c

a

Verified Level Reduction Goals for ARB. Strategies will not be verified without meeting this standard at a 

minimum. 

b

Allansson, R, Cooper, BJ, Thoss, JE, Uusimaki, A, Walker, AP, Warren, JP. 2001. European Experience 

of High Mileage Durability of Continuously Regenerating Diesel Particulate Filter Technology. SAE. 

2001-01-0480. 

c

Majewski, W. Addy. 2001. Diesel Net Technology Guide: Diesel Particulate Traps. www.dieselnet.com. d

Diesel Net Technology Guide: Emission Control Technologies, 1998. www.dieselnet.com. e

Diesel Net Technology Guide: Diesel Oxidation Catalyst, 1999. www.dieselnet.com. f

Khair, Magdi; McKinnon, Dale L. Performance Evaluation of Advanced Emission Control Technonlogies 

for Diesel Heavy-Duty Engines. SAE. 1999-01-3564. h

Fuel-water emulsion increases CO and HC emissions. Although can be verified alone for the purposes 

of simplifying calculations, assumed it would be used in conjunction with a diesel oxidation catalyst to 

decrease impact of increase. Choose least decrease to account for offset of increase from fuel-water 

emulsion.

Table 26. Statewide Diesel CO Emission Reduction Benefits 

Calendar Year Baseline Inventory (tpd) Diesel CO Reduction (tpd)

2006 2.2 0.17 

2010 2.0 1.18 

2015 1.8 0.85 

2020 1.6 0.46 

Table 27. Statewide Diesel HC Emission Reduction Benefits 

Calendar Year Baseline Inventory (tpd) Diesel HC Reduction (tpd)

2005 0.27 0.02 

2010 0.23 0.15 

2015 0.20 0.11 

2020 0.16 0.05 
57

Table 28. Statewide Diesel NOx Emission Reduction Benefits 

Calendar Year Baseline Inventory (tpd) Diesel NOx Reduction (tpd)

2006 11.2 0.03 

2010 10.1 0.30 

2015 8.5 0.18 

2020 7.3 0.09 

B. Impacts on the State Implementation Plan for PM10

The draft State Implementation Plan (SIP) for in the San Joaquin Valley projects 

attainment for the federal PM10 standard by 2010. As a “serious” nonattainment area, 

the San Joaquin Valley must use best available control measures for all sources of 

PM10 and must also achieve five percent annual emission reductions in PM10 and its 

precursors. The San Joaquin Valley has ten percent of the statewide municipal and 

utility vehicles and will see a benefit of 0.02 tpd of PM reduced by 2010. In addition, the 

NOx and volatile organic carbon (VOC) benefits of the proposed rule are contained in 

the plan, as they are precursors to secondary PM formation. 

The South Coast air basin is also classified as “serious” for PM10 but its attainment 

deadline is 2006, before most of the benefits of the proposed rule will be achieved. 

Nonetheless, the proposed rule will help that District maintain compliance with the 

federal PM10 standard. The rule also serves as a down payment on future plans to 

achieve the federal PM2.5 standards and California’s own, more stringent standards. 

Thirty-five percent of California’s public and utility fleet vehicles are in the South Coast 

region. By 2010, the proposed rule will reduce emissions from those vehicles by 0.05 

tpd. 

All other PM10 nonattainment areas in California will benefit from the proposed rule in a 

general way. Every district except Lake County is in nonattainment for the California 

PM10 standard. In addition, four other areas in California are nonattainment for the 

federal PM10 standards: Owens Valley, Searles Valley, Coachella Valley, and Imperial 

Valley. 

For ozone SIPs there is a similar situation. The ARB adopted the statewide element and 

approved the comprehensive SIP for the South Coast Air Basin and the PM10 SIP for 

the Coachella Valley on October 23, 2003. ARB submitted the South Coast and 

Coachella SIPs to U.S. EPA on January 9, 2004. 
58

As with PM10, all other ozone nonattainment areas in California will benefit from the 

proposed rule in a general way as it reduces the precursors to ozone formation (see 

Tables 27 and 28). 

C. Health Benefits of Reductions of Diesel PM Emissions 

This section examines the health benefits of reducing diesel PM emission and provides 

an analysis of the number of premature deaths prevented by the reduction of diesel PM. 

It also provides the cost savings to society for each prevented premature death. In 

addition, a brief discussion of health benefits of reducing ozone precursors is included. 

Staff estimates that approximately 40 premature deaths will be avoided from the 

implementation of this proposal. The proposed regulation is expected to reduce PM2.5

emissions by a cumulative amount of 538 tons by the end of year 2022, and therefore 

prevent an estimated 38 premature deaths (19 - 57, 95 percent confidence interval 

(95% CI)) by year 2022. In addition, staff estimates that the proposed regulation is 

expected to accrue a cumulative reduction of 1,005 tons of NOx by the end of 2022, 

therefore avoiding an estimated 2 premature deaths (1 – 2, 95% CI). 

Lloyd and Cackette estimated that, based on the Krewski et al. study19, a statewide 

population-weighted average diesel PM2.5 exposure of 1.8 μg/m3 resulted in a mean 

estimate of 1,985 premature deaths per year in California (Lloyd/Cackette, 2001). The 

diesel PM emissions corresponding to the direct diesel ambient population-weighted PM 

concentration of 1.8 μg/m3 is 28,000 tons per year (ARB, 2000). Based on this 

information, we estimate that reducing 14.11 tons per year of diesel PM emissions 

would result in one fewer premature death (28,000 tons/1,985 deaths). 

Comparing the PM2.5 emissions before and after this regulation, the proposed 

regulation is expected to reduce PM2.5 emissions by a cumulative amount of 538 tons 

by the end of year 2022, and therefore prevent an estimated 38 premature deaths (19 - 

57, 95 percent confidence interval (95% CI)) by year 2022. 

Lloyd and Cackette also estimated that indirect diesel PM2.5 exposures at a level of 

0.81 μg/m3

 resulted in a mean estimate of 895 additional premature deaths per year in 

California, above those caused by directly emitted formed diesel PM. The NOx 

emission levels corresponding to the indirect diesel ambient PM concentration of 

0.81 μg/m3 is 1,641 tpd (598,965 tpy). Following the same approach as above, we 

 

19 Although there are two mortality estimates in the report by Lloyd and Cackette – one based on work by 

Pope et al. and the other based on Krewski et al., we selected the estimate based on the Krewski’s work. 

For Krewski et al., an independent team of scientific experts commissioned by the Health Effects Institute 

conducted an extensive reexamination and reanalysis of the health effect data and studies, including 

Pope et al. The reanalysis resulted in the relative risk being based on changes in mean levels of PM2.5, 

as opposed to the median levels from the original Pope et al. study. The Krewski et al. reanalysis 

includes broader geographic areas than the original study (63 cities vs. 50 cities). Further, the U.S. EPA 

has been using Krewski’s study for its regulatory impact analyses since 2000. (Krewski et al., 2000) 

(Pope, 1995) 
59

estimate that reducing 669 tons of NOx emissions would result in one fewer premature 

death (598,965 tons/895 deaths). Therefore, with a NOx reduction of 1,005 tons that is 

expected to accumulate by the end of 2022, an estimated 2 deaths (1 – 2, 95% CI) 

would be avoided. 

1. Social Benefit - Cost Analysis 

As discussed below, staff calculated the value of avoiding one premature death, as well 

as the estimated cost of control to prevent a premature death 

The U. S. EPA has established $6.3 million (in 2000 $) for a 1990 income level as the 

mean value of avoiding one death (U.S. EPA, 2003). As real income increases, people 

may be willing to pay more to prevent premature death. The U.S. EPA further adjusted 

the $6.3 million value to $8 million (in 2000 $) for a 2020 income level. Assuming that 

real income grew at a constant rate from 1990 and will continue at the same rate until 

2020, we adjusted the value of avoiding one death for income growth. We then updated 

the value to 2005 dollars and discounted values of avoiding a premature death in the 

future back to the year 2005. The U.S. EPA’s guidance of social discounting 

recommends using both three and seven percent discount rates (U.S. EPA, 2000). 

Based on these rates, and the annual avoided deaths, the weighted average value of 

reducing a future premature death, discounted back to the year 2005, is around $5 

million at seven percent discount rate, and $7 million at three percent. 

The ARB calculates the cost of avoiding a premature death, following these steps: 

• For each year, note the annualized cost and the annual premature deaths avoided. 

• Allocate a portion of the costs to PM and the rest to NOx, in proportion to the 

premature deaths prevented by the regulation. Since 96% of the estimated deaths 

prevented by this regulation would be attributed to PM emission reduction, we 

allocate 96% of these costs to PM2.5 emission reductions and 4% to NOx reductions. 

• Take the time value of money into account, by discounting the cost in each year to 

2005, using a 3 percent discount rate and a 7 percent discount rate. 

• Calculate a cost per premature death avoided in each year. 

• Calculate a weighted average of these values, using the weights proportional to the 

annual premature deaths avoided. 

• Results using a 3 percent discount rate. The average cost per premature death 

avoided is about $4 million.20

• Results using a 7 percent discount rate. The average cost per premature death 

avoided is about $3 million. 

The results presented here are point estimates. Their values are actually uncertain. 

For example, we reported the confidence interval on the number of premature deaths 

 

20 The value is the same whether the premature deaths avoided result from reductions of PM or 

reductions of NOx. That is because the costs allocated to each pollutant are proportional to the number 

of premature deaths avoided. Thus, the ratio of cost to deaths comes out the same for both pollutants. 
60

avoided. Not all of the uncertainties are quantified, so it would be misleading to 

calculate and report a confidence interval for the results of the valuation calculations. 

2. Health Benefit From Reduced Ambient Ozone Levels 

Emissions of NOx and ROG are precursors to the formation of ozone in the lower 

atmosphere. Exhaust from diesel engines contributes a substantial fraction of ozone 

precursors in any metropolitan area. Therefore, reductions in NOx from diesel engines 

in urban areas would make a considerable contribution to reducing exposures to 

ambient ozone. Controlling emissions of ozone precursors would reduce the 

prevalence of the types of adverse respiratory effects associated with ozone exposure 

and would reduce hospital admissions and emergency visits for respiratory effects. 

D. Cost-Effectiveness of Proposed Regulation 

The estimated average cost-effectiveness of this proposed diesel PM emission 

reduction regulation is approximately $159/lb of PM reduced annually from fiscal years 

2006 to 2010. The costs and emission reductions associated with this regulation and 

how they were derived are discussed in Appendix C. Both capital costs, such as the 

purchase and installation of a DECS, and O & M costs, such as incremental fuel cost for 

fuel DECS, are included in this analysis. This cost-effectiveness does not include a 

number of benefits and costs, which could not be quantified. These benefits and costs 

are described in the assumptions section in Appendix C as well. 

E. Potential Negative Impacts 

Certain potential negative impacts could be associated with elements of this proposed 

regulation. Those potential negative impacts are discussed below. 

1. Creation Of Nitrogen Dioxide By Passive Catalyzed Diesel Particulate Filters 

Nitrogen dioxide (NO2) is a component of NOx and its presence in the atmosphere can 

be correlated with emissions of NOx. There has been a steady decline in NO2 values 

over the years due primarily to the implementation of tighter controls on both mobile and 

stationary sources. However, statewide emission trends still predict NOx levels of 761 

tons/day per year from on-road diesel vehicles by year 2010. 

At higher concentrations than are normally found in the atmosphere, NO2 is an acute 

irritant. Health effects from prolonged exposure to NO2 include upper respiratory 

problems, bronchitis, and pulmonary edema, and NO2 has been linked to causes of 

severe asthma and bronchial infections in children. 

Measurements of NOX emissions (NO and NO2) from heavy-duty diesel vehicles 

equipped with passive catalyzed filters have shown an increase in the NO2 fraction, 

though total NOX emissions remain approximately the same. Passive catalyzed filters 

oxidize NO to NO2, which burns soot captured in the filter. More NO2 is created than is 

actually used in the regeneration process and the excess is emitted. In fact, the NO2 to 
61

NOX ratios could range from 20 to 70 percent, depending on factors such as the diesel 

particulate filter system, sulfur level in diesel fuel, and the duty cycle. Diesels without 

passive catalyzed filters typically emit less than 10 percent NO2 as a fraction of total 

NOx. 

Based on an ARB study conducted in 2002 (ARB 2002), a cap of 20 percent of NO2 to 

NOx emission ratio was established for all verified diesel emission control technologies, 

to assume that measured NO2 emission caused no increase in ambient air pollution. In 

December 2003, the Board made the decision to delay the effective date of the 20 

percent NO2 limit, which was to go into effect on January 1, 2004, to provide more time 

for manufacturers of DECS to reduce the NO2 fraction. ARB established a working 

group comprised of scientists, health professionals, and manufacturers around the 

world to re-evaluate the limit. Staff is now working on the rulemaking effort to refine the 

NO2 specific requirements for verification. ARB staff held a workshop to propose an 

alternative limit. Details of the workshop can be found at 

http://www.arb.ca.gov/diesel/verdev/mailoutmsc0504.pdf. 

2. Diesel Oxidation Catalysts 

Two potential adverse environmental impacts of the use of diesel oxidation catalysts 

have been identified. First, as is the case with most processes that incorporate catalytic 

oxidation, the formation of sulfates increases at higher temperatures. Depending on the 

exhaust temperature and sulfur content of the fuel, the increase in sulfate particles may 

offset the reductions in soluble organic fraction emissions. Using low sulfur diesel fuel 

can minimize this effect. Second, a diesel oxidation catalyst could be considered a 

“hazardous waste” at the end of its useful life depending on the materials used in the 

catalytic coating. However, diesel oxidation catalysts are usually recycled for their 

precious metal content and thus are not managed as hazardous wastes in practice. 

Recycling also reduces any potential impact on landfill capacity. 

3. Ash Management 

Diesel particulate filter technology may generate a new hazardous waste stream. The 

carbonaceous component of the PM captured by the filter is burned off when the filter 

regenerates. Any inorganic components left behind after regeneration as ash in the 

filter must eventually be cleaned from the filter. Based on preliminary data from two 

samples, the ash may be classified as hazardous waste because of its zinc content. 

Ash collected from a diesel engine using a typical lubrication oil and no fuel additives 

has been analyzed and is primarily composed of oxides of the following elements: 

calcium, zinc, phosphorus, silicon, sulfur, and iron. Zinc is the element of primary 

concern because, if present in high enough concentration, it can make a waste a 

hazardous waste. Title 22, CCR, section 66261.24 establishes two limits for zinc in a 

waste: 250 milligrams per liter for the Soluble Threshold Limit Concentration and 5,000 

milligrams per kilogram for the Total Threshold Limit Concentration. The presence of 
62

zinc at or above these levels would cause a sample of ash to be characterized as a 

hazardous waste. 

Under California law, it is the generator's responsibility to determine whether their waste 

is hazardous or not. Applicable hazardous waste laws are found in the HS&C, division 

20; title 22, CCR, division 4.5; and title 40 of the Code of Federal Regulations. Staff 

recommends that owners who install a diesel particulate filter on a vehicle contact both 

the manufacturer of the DECS and the California Department of Toxic Substances 

Control (DTSC) for advice on waste management. 

DTSC personnel have advised ARB that it has a list of facilities that accept waste from 

businesses that qualify as a conditionally exempt small quantity generator. Such a 

business can dispose of a specific quantify of hazardous waste at certain Household 

Hazardous Waste events, usually for a small fee. An owner who does not know 

whether or not he qualifies or who needs specific information regarding the identification 

and acceptable disposal methods for this waste should contact the California DTSC.21 

X. ISSUES 

Over the course of development of this proposal, staff has met with various 

stakeholders and received written and verbal comments. Although staff has considered 

each comment, not all issues could be resolved while achieving ARB’s goals to reduce 

diesel PM emissions from public and utility vehicles. Following is a discussion of major 

outstanding issues. 

A. Low Population Definition 

Staff has proposed an extended compliance schedule municipalities or utilities located 

in counties with populations 125,000 or less. Several fleets located in counties with 

populations over 125,000 but less than 300,000 still have the same fiscal limitations 

needs as smaller “rural” counties. Counties with population greater than 125,000 but 

less than 300,000 are listed below (Table 29): 

 

21 Information can be obtained from local duty officers and from the website: http://www.dtsc.ca.gov.
63

Table 29. Counties with Populations Between 125,000 to 300,000 

County Population 

HUMBOLDT 132,500 

NAPA 135,700 

KINGS 149,600 

MADERA 152,600 

IMPERIAL 182,500 

SHASTA 185,700 

EL DORADO 187,000 

YOLO 188,600 

BUTTE 235,000 

MERCED 239,900 

MARIN 257,600 

SANTA CRUZ 284,500 

SAN LUIS OBISPO 287,000 

Several of these counties include urban areas. If these counties are included in the 

current definition of low population they would account for 17% of the rule’s benefit. 

Staff does not believe these mid size counties should be treated as rural counties with a 

delayed implementation schedule. Other provision of the rule, such as low use vehicle 

exemption, and exclusion of dedicated snow removal equipment, may help reduce the 

cost of the rule to these counties. 

B. Biodiesel 

The biodiesel industry and entities subject to the Federal Energy Policy Act (EPAct) 

expressed concerns that implementation of the rule would functionally preclude the use 

of biodiesel. This is a concern for public fleets such as the military since these agencies 

are using biodiesel blends in their heavy duty trucks to accumulate alternative fuel 

credits for compliance with EPAct. This concern was raised several times during 

outreach activities when no DECS was verified for use with biodiesel blends; however 

since this time, ARB has verified the Johnson-Matthey CRT with the use of B20 (EO 

DE-04-006-05). Based on this staff is confident that other DECS manufacturers will 

also apply for extension of existing DECS verifications to be used with biodiesel blends 

dispelling the concerns raised earlier in the rulemaking process. 

The biodiesel industry has also requested several times to allow biodiesel blends to be 

considered BACT in the rule. Since ARB is mandating the application of BACT on inuse engines, biodiesel and biodiesel blends could only be considered BACT if the fuel 

goes through ARB’s verification procedure. This would ensure the user that the fuel 

would carry the same warranty as other DECS against damage to the engine. Other 

impediments to the use of biodiesel blends have been the lack of fuel specifications for 
64

the neat fuel. ARB has formed a Biodiesel Working Group to facilitate the development 

of possible biodiesel specifications. This group consists of a broad range of 

stakeholders, including biodiesel producers, distributors, petroleum refiners, 

regulatory agencies, and biodiesel end users. Information of this effort can be found at 

http://www.arb.ca.gov/fuels/diesel/altdiesel/altdiesel.htm

C. Alternative Compliance Plan or Alternative Early Compliance Plan 

Several commentors have requested the inclusion of alternative compliance plans or 

early compliance plans. The rationale behind this request is that some municipalities or 

utilities have proactively purchased alternative fuel engines or retrofitted their vehicles 

with BACT. Therefore, the early implementation of BACT should generate credits that 

would allow delaying the proposed implementation schedule. Staff evaluated this 

proposal, but believed that implementation of such a provision would be too difficult to 

enforce. Staff also noted that many municipalities and/or utilities applied BACT to 

vehicles with the use of grant money. Therefore, no early credit can be given, since 

most grant money is also tied to emission reduction requirements. Therefore these 

alternative implementation options were not included in the regulation. 

D. Cost to Local Government Agencies 

Several government agencies that do not have the ability to collect fees have stated that 

the cost of compliance for this rule is too high. Staff believes based on the variety of 

verified DECS available, and the phased-in implementation makes the rule technically 

feasible and cost effective. The concept of BACT is to give owners several options to 

choose from whether it is staggering their new vehicle purchases with already 

complying engines, repowering older vehicles with cleaner engines, or retrofit existing 

engines with verified technology. BACT is a much more attractive option to accelerated 

fleet turnover because it does give the owner the choice of less costly options. Staff 

also tried to stagger implementation schedules that were more in line with fleets’ routine 

plans for vehicle replacement and engine repowering. In addition, staff built in several 

extensions based on technology unavailability and low population county concerns. 

Any further relaxing of the proposal would not deliver the near term needs of reducing 

the public’s exposure to diesel PM. 

E. Applicability of Proposed Rule to Federal Agencies 

The United States Postal Service (USPS) has submitted several comment letters 

presenting a legal argument that while other governmental fleets may be regulated, 

federal fleets like USPS may not be regulated until privately-owned fleets are similarly 

regulated citing section 118(a) of Clean Air Act (CAA). ARB’s legal staff determined 

that USPS’s reading of this statute is not consistent with the statute itself and is also 

inconsistent with other provisions of the CAA. In cases regarding the applicability of 

state and local regulations to federal agencies, the courts have held that Congress 

waived its sovereign immunity with respect to independent state or local air pollution 
65

control laws. Therefore, staff has determined that federal fleets including the USPS are 

subject to the proposed regulation. 

XI. SUMMARY AND STAFF RECOMMENDATION 

ARB staff recommends the Board adopt new sections 2022, and 2022.1, title 13, 

chapter 1, article 4, CCR, in its entirety. The regulation is set forth in the proposed 

regulation order in Appendix A. 
66

XII. REFERENCES 

Abbey, David E., Nishino, Naomi, McDonnell, William F., Burchette, Raoul J., Knutsen, 

Synnove F., Beeson, W. Lawrence, Yang, Jie X. 1999. Long-term Inhalable Particles 

and Other Air Pollutants Related to Mortality in Nonsmokers. Am J Respir Crit Care 

Med. 159:373-382. 

ARB. January 8, 2002. Impact of Altering NO2/NO Splits in NOx Emissions From Diesel 

Sources Equipped with PM Traps and Recommended Mitigation Methods. First Draft of 

Issue Paper. 

ARB. 2001. Policies and Actions for Environmental Justice. 

http://www.arb.ca.gov/ch/ejpolicies_121301.pdf. 

ARB. June 30, 2000a. Neighborhood Assessment Program Work Plan. 

http://www.arb.ca.gov/ch/programs/nap/napworkplan.pdf

ARB 2000b. Air Resources Board. October 2000. Risk Reduction Plan to 

Reduce Particulate Matter Emissions from Diesel-Fueled Engines and Vehicles. 

http://www.arb.ca.gov/diesel/documents/rrpapp.htm

Allansson, R, Cooper, BJ, Thoss, JE, Uusimaki, A, Walker, AP, Warren, JP. 2001. 

European Experience of High Mileage Durability of Continuously Regenerating Diesel 

Particulate Filter Technology. SAE. 2001-01-0480. 

 

Beeson, W. Lawrence, Abbey, David E., Knutsen, Synnove F. 1998. Long-term 

Concentrations of Ambient Air Pollutants and Incident Lung Cancer in California Adults: 

Results from the AHSMOG Study. Environmental Health Perspectives. 106: 813-822. 

Dab, William, Segala, Claire, Dor, Frederic, Festy, Bernard, Lameloise, Phillipe, Le 

Moullec, Yvon, Le Tertre, Alain, Medina, Sylvia, Quenel, Phillipe, Wallaert, Benoit, 

Zmirou, Denis. 2000. Air Pollution and Health: Correlation or Causality? The Case of 

the Relationship between Exposure to Particles and Cardiopulmonary Mortality. Journal 

of the Air and Waste Management Association. 51: 220-235. 

Diesel Net. 1998. Diesel Net Technology Guide: Emission Control Technologies. 

www.dieselnet.com. 

Diesel Net 1999. Diesel Net Technology Guide: Diesel Oxidation Catalyst. 

www.dieselnet.com. 

DieselNet 2002. DieselNet. March 2002. Technical Guide: Diesel Filter Systems, Traps 

with Fuel Additives. Revision 2000.02b. 

www.dieselnet.com. 

 
67

Krewski et al. 2000. Krewski D.; Burnett R.; Goldberg M.; Hoover K.; Stemiatychi 

J.; Jerrett M.; Abrahamovicz M.; White W. Reanalysis of the Harvard Six Cities 

Study and the American Cancer Society Study of Particulate Air Pollution and 

Mortality, Health Effects Institute, Cambridge, Massachusetts; 2000. 

http://es.epa.gov/ncer/science/pm/hei/Rean-ExecSumm.pdf 

Khair, Magdi; McKinnon, Dale L. Performance Evaluation of Advanced Emission 

Control Technonlogies for Diesel Heavy-Duty Engines. SAE. 1999-01-3564. 

Lloyd and Cackette. 2001. Lloyd, A.C.; Cackette, T.A.; Diesel Engines: 

Environmental Impact and Control; J Air Waste Manage. Assoc. 2001, 51: 809- 

847. 

http://www.arb.ca.gov/research/seminars/lloyd/AWMA2001/JAWMADieselCritical 

Review.pdf 

Majewski, W. Addy. 2001. Diesel Net Technology Guide: Diesel Particulate Traps. 

www.dieselnet.com. 

McDonnell, William F., Nishino-Ishikawa, Naomi, Petersen, Floyd F., Chen, Lie Hong, 

Abbey, David E. 2000. Relationships of mortality with the fine and coarse fractions of 

long-term ambient PM10 concentrations in nonsmokers. Journal of Exposure Analysis 

and Environmental Epidemiology. 10: 427-436. 

Manufacturers of Emission Controls Association (MECA). March 2000a. 

Emission Control Retrofit of Diesel-Fueled Vehicles. Washington, D.C. 

MECA. November 9, 2000b. MECA Independent Cost Survey for Emission Control 

Retrofit Technologies. Washington, DC. 

MECA. June 9, 2004. Response to ARB Questions Provided to MECA During the 

ARB/SCAQMD/MECA May 18, 2004 Meeting. 

Office of Environmental Health Hazard Assessment (OEHHA). May 1998. Health Risk 

Assessment for Diesel Exhaust (Public and Scientific Review Panel Review Draft). 

Office of Environmental Health Hazard Assessment, California Environmental 

Protection Agency. ftp.arb.ca.gov/carbis/regact/diesltac/partb.pdf. 

Parsons. 2001. Improved Diesel Emissions Performance: Fleet Upgrade Strategies. 

Regional Workshop Fighting Urban Air Pollution: From Plan to Action. February 12 – 

14, 2001. www.worldbank.org January 17, 2002. 

Peters, A; Dockery, DW; Muller, JE; Mittleman, MA. 2001. Increased Particulate Air 

Pollution and the Triggering of Myocardial Infarction Circulation 103: 2810-2815. 

Pope et al, 1995. Pope, C.A.; Thun, M.J.; Namboodiri, M.M.; Dockery, D.W.; 

Evans, J.S.; Speizer, F.E.; Heath, C.W. Particulate Air Pollution as a Predictor of 
68

Mortality in Prospective Study of U.S. Adults, Am. J. Respir. Crit. Care Med.; 

1995. 

South Coast Air Quality Management District Board. December 3, 2004. Board Meeting, 

Agenda Number 4 

TIAX LLC. March 17, 2003. California Public Fleet Heavy-Duty Vehicle and Equipment 

Inventory Final Report. 

U. S. EPA. May 2000a. Draft Regulatory Impact Analysis for the Proposed Heavy-duty 

Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements 

Rule. EPA420-D-00-001. Washington, D.C. 

U.S. EPA 2000b. United States Environmental Protection Agency. September 

2000, Guidelines for Preparing Economic Analyses. EPA240-R-00-003 

http://www.epa.gov/opei/pubsinfo.htm

U.S. EPA 2002. United States Environmental Protection Agency. October 2002, A 

Comprehensive Analysis of Biodiesel Impacts on Exhaust Emissions, Draft Technical 

Report. EPA420-P-02-001. 

U.S. EPA 2003. United States Environmental Protection Agency. April 2003. 

United States Environmental Protection Agency, Assessment and Standards 

Division, Office of Transportation and Air Quality, Draft Regulatory Impact 

Analysis: Control of Emissions of Air Pollution from Nonroad Diesel Engines and 

Fuel. EPA420-R-03-008. CD-ROM. Research Triangle Park, North Carolina. 

http://www.epa.gov/otaq/cleaner-nonroad/r03008.pdf

U.S. EPA 2004a. Draft Diesel Retrofit Technology A Cost Effective Method to Reduce 

Particulate Matter Emissions from Heavy Duty Diesel Engines. 

United States Department of Energy. 2005. www.eere.energy.gov/cleancities An 

Internet web page listing Clean Cities alternative-fueled fleets. 

U.S. EPA. March 2004b. Highway Diesel Progress Review Report 2.