CALIFORNIA ENVIRONMENTAL PROTECTION AGENCY

AIR RESOURCES BOARD

STAFF REPORT: INITIAL STATEMENT OF REASONS

PROPOSED MODIFICATIONS TO THE FLEET RULE FOR TRANSIT

AGENCIES AND NEW REQUIREMENTS FOR TRANSIT FLEET VEHICLES

Date of Release: January 7, 2005

Scheduled for Consideration: February 24-25, 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 the mention of trade names or

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

California Environmental Protection Agency

AIR RESOURCES BOARD

PROPOSED MODIFICATIONS TO THE FLEET RULE FOR TRANSIT AGENCIES AND

NEW REQUIREMENTS FOR TRANSIT FLEET VEHICLES

Staff Report

January 7, 2004
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TABLE OF CONTENTS

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

I. INTRODUCTION AND BACKGROUND...........................................................................4

A. Urban Buses and Transit Fleet Vehicles ................................................................................5

B. Engine Exhaust Emission Standards for Transit Fleet Vehicles and Urban Buses.........6

C. Amendments to the Fleet Rule for Transit Agencies............................................................8

II. NEED FOR REDUCTION OF DIESEL EXHAUST EMISSIONS..................................8

A. Diesel Particulate Matter ...........................................................................................................8

B. Ambient Air Quality Standards for Particulate Matter...........................................................9

C. Identification of Diesel Particulate Matter as a Toxic Air Contaminant..............................9

D. Physical and Chemical Characteristics of Diesel Particulate Matter................................10

E. Sources and Ambient Concentrations Of Diesel Particulate Matter.................................11

F. Health Effects of Diesel Particulate Matter...........................................................................12

G. Statewide Risk Reduction Goal of Diesel Risk Reduction Plan........................................12

H. Nitrogen Oxides and Reactive Organic Gas Emissions.....................................................13

III. NEED FOR MODIFICATIONS .........................................................................................13

A. Transit Fleet Vehicles: Addition to Scope.............................................................................13

B. Newly Formed Transit Agencies ............................................................................................14

C. Urban Bus Requirements for PM Reduction........................................................................15

D. 2004 to 2006 Diesel Hybrid-Electric Urban Bus Engine Exhaust Emission Standards 15

E. Renumbering Sections for the Fleet Rule for Transit Agencies........................................15

IV. SUMMARY OF PROPOSED REGULATIONS ..............................................................16

A. Transit Fleet Vehicle Requirements ......................................................................................16

1. Applicability..........................................................................................................................16

2. Fleet Requirements............................................................................................................17

a. Fleet NOx Average.......................................................................................................17

b. Fleet PM Reductions....................................................................................................18

B. Urban Bus Fleet Diesel PM Requirement.............................................................................18

C. 2004-2006 Urban Bus Diesel Hybrid-Electric Engine Emission Standard......................18

D. "Newly Formed" Transit Agency Requirements ..................................................................19

E. Extensions and Additional Definitions ...................................................................................19

V. PUBLIC OUTREACH AND ENVIRONMENTAL JUSTICE..........................................20

A. Environmental Justice..............................................................................................................21

1. Regulatory Proposal...........................................................................................................21

B. Outreach Efforts........................................................................................................................22

VI. ENGINE AND EMISSION INVENTORY.........................................................................23

A. Engine Inventory.......................................................................................................................23

B. Emission Inventory...................................................................................................................24

VII. TECHNOLOGICAL FEASIBILITY OF CONTROL MEASURE ...................................25

A. Availability of Ultra-low Sulfur Diesel Fuel............................................................................25

B. Verification of Diesel Emission Control Strategies..............................................................25

C. Diesel Emission Control Strategies for In-use Transit Fleet Vehicles..............................27

1. Hardware Diesel Emission Control Strategies...............................................................28

a. Passive (Catalyzed) Diesel Particulate Filter...........................................................28

b. Active Diesel Particulate Filter....................................................................................28
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c. Catalyzed Wire Mesh Flow Through Filter ...............................................................29

d. Diesel Oxidation Catalyst............................................................................................29

e. Selective Catalytic Reduction (SCR).........................................................................29

2. Fuel-based Diesel Emission Control Strategies............................................................30

a. Fuel-Water Emulsion....................................................................................................30

b. Fuel Additives................................................................................................................30

c. Biodiesel........................................................................................................................31

3. Combination Systems........................................................................................................31

4. In-Use Experience..............................................................................................................32

a. Diesel Oxidation Catalysts ..........................................................................................32

b. Diesel Particulate Filters..............................................................................................32

VIII. REGULATORY ALTERNATIVES....................................................................................33

A. Make No Change To Existing Regulations...........................................................................33

B. Require Transit Agencies to Purchase Only Alternative-Fuel Vehicles when Replacing

or Adding to their Fleets ..........................................................................................................34

C. Adopt Alternative Fuel Purchase Requirement and PM 2005 baseline reduction.........34

D. Include Transit Fleet Vehicles in a Rule for Public Agencies............................................35

E. Comparison of Emission Reductions from Alternatives .....................................................35

IX. ECONOMIC IMPACT.........................................................................................................36

A. Legal Requirement...................................................................................................................36

B. Affected Businesses.................................................................................................................36

C. Potential Impact on Businesses.............................................................................................36

D. Potential Impact on Business Competitiveness...................................................................37

E. Potential Impact on Employment ...........................................................................................37

F. Potential Impact on Business Creation, Elimination, or Expansion..................................37

G. Potential Cost to Local and State Agencies.........................................................................37

1. Implementation Scenarios ................................................................................................37

2. Implementation Costs........................................................................................................38

3. Cost Estimates for Replacing or Repowering Transit Fleet Vehicles.........................39

4. Cost Estimates for Diesel Particulate Filters (DPFs)....................................................40

H. Costs to Individuals ..................................................................................................................40

X. ENVIRONMENTAL IMPACT AND COST EFFECTIVENESS....................................41

A. Statewide Emission Benefits ..................................................................................................41

B. Impacts on the State Implementation Plan...........................................................................42

C. Health Benefits of Reductions of Diesel PM Emissions .....................................................42

1. Primary Diesel PM..............................................................................................................43

2. Secondary Diesel PM........................................................................................................43

D. Cost-Effectiveness of Proposed Regulation.........................................................................43

E. Benefit-Cost Analysis...............................................................................................................44

1. Value of Premature Deaths Avoided...............................................................................44

2. Cost of Avoiding Premature Deaths ................................................................................44

3. Comparison.........................................................................................................................45

F. Potential Negative Impacts .....................................................................................................45

1. NO2 Emissions from Diesel Particulate Filters...............................................................45

2. Diesel Oxidation Catalyst Emissions and Disposal......................................................47

3. Ash Management................................................................................................................48
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XI. ISSUES................................................................................................................................49

A. Cost is too high for agencies in low population counties ...................................................49

1. PM Emission Reductions ..................................................................................................50

2. Contract Operations ...........................................................................................................50

3. Financial Hardship..............................................................................................................50

B. Commuter Service Bus Definition..........................................................................................50

XII. STAFF RECOMMENDATION..........................................................................................51

XIII. REFERENCES...................................................................................................................52
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TABLES

Table 1. California Urban Bus and Heavy-Duty (HD)Truck New Engine Emission Standards

for NOx...................................................................................................................................7

Table 2. California Urban Bus and Heavy-Duty (HD)Truck New Engine Emission Standards

for PM.....................................................................................................................................7

Table 3. State and National Particulate MatterStandards. ...........................................................9

Table 4. Substances in Diesel Exhaust Listed by California as Toxic Air Contaminants.......11

Table 5. Estimated Exposure of Californians to Diesel Particulate Matter for 2000, 2010 and

2020 (ARB 2000a)..............................................................................................................12

Table 6. Fleet NOx Average Requirements for Transit Agencies (g/bhp-hr)...........................17

Table 7. Fleet Diesel PM Reduction Requirements for Transit Agencies (g/bhp-hr)..............18

Table 8. Workshop Locations and Times.......................................................................................22

Table 9. California Transit Fleet Vehicle Survey Population by Percent1.................................24

Table 10. Transit Fleet Vehicle Estimated Baseline Emissions....................................................24

Table 11. Diesel Emission Control Strategy Verification Levels ...................................................26

Table 12. Verified DECSs That May be Applicable to Transit Fleet Vehicles ............................27

Table 13. Diesel PM Emissions for Baseline and Proposed Scenarios......................................35

Table 14. NOx Emissions for Baseline and Proposed Scenarios ................................................35

Table 15. Total Costs for Staff's Proposal (In 2005 Dollars).........................................................38

Table 16. Annual Average Costs.......................................................................................................39

Table 17. Proposed Regulation PM Emission Reductions ............................................................41

Table 18. Proposed Regulation NOx Emission Reductions..........................................................41

Table 19. Proposed Regulation HC Emission Reductions ............................................................42

Table 20. Proposed Regulation CO Emission Reductions ............................................................42

Table 21. Summary of Relative Percent Impacts from Simulated NO2/NOx..............................46

APPENDICES

APPENDIX A: PROPOSED MODIFICATION TO THE FLEET RULE FOR TRANSIT

AGENCIES

APPENDIX B: DETAILED DESCRIPTION OF PROPOSED MODIFICATIONS

APPENDIX C: TRANSIT FLEET VEHICLE EMISSION INVENTORY

APPENDIX D: COST ANALYSIS METHODOLOGY
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LIST OF ACRONYMS

$/lb Dollars per pound

ug/m3 Micrograms per cubic meter

ARB, or the Board Air Resources Board

CalACT California Association for Coordinated Transportation, Inc.

CCR California Code of Regulations

CDC Clean diesel combustion

CNG Compressed natural gas

CO Carbon monoxide

DECS Diesel emission control system

DMV California Department of Motor Vehicles

DOC Diesel oxidation catalyst

DPF Diesel particulate filter

EGR Exhaust gas recirculation

EMFAC ARB’s on-road motor vehicle emissions estimation model

FBC Fuel-borne catalyst

FTA Federal Transit Administration

FTF Flow-through filter

g/bhp-hr Grams per brake horsepower-hour

GGT Golden Gate Bridge Highway and Transportation District

GVWR Gross vehicle weight rating

HC Hydrocarbon

HCCI Homogenous charge compression ignition

H&SC Health and Safety Code

HEB Hybrid-electric bus

lbs Pounds

lbs/day Pounds per day

LNG Liquefied natural gas

Low sulfur diesel fuel Diesel fuel with less than 15 ppmw sulfur content

LPG Liquefied propane gas

MY Model year

NMHC Non-methane hydrocarbons

NOx Oxides of nitrogen

NO2 Nitrogen dioxide

OEHHA Office of Environmental Health Hazard Assessment

PM Particulate matter

ppd Pounds per day

ppmw Parts per million by weight

ROG Reactive organic gases

SRP Scientific Review Panel

TAC Toxic air contaminant

tpd Tons per day

tpy Tons per year

U.S. EPA United States Environmental Protection Agency

ZEB Zero-emission bus
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EXECUTIVE SUMMARY

The Air Resources Board (ARB or “the Board”) seeks to provide clean, healthful

air to all the citizens of California. California’s commitment to providing clean

public transportation is an important part of achieving this goal. Public

transportation has important societal benefits, providing access to work and

education, reducing traffic congestion, and meeting mobility needs of the public.

In February 2000 the Board took steps to reduce emissions from public

transportation by establishing a new fleet rule for transit agencies and more

stringent emission standards for new urban bus engines and vehicles. The

regulations were designed to reduce oxides of nitrogen (NOx) and particulate

matter (PM) emissions from urban buses. The rule also promoted advanced

technologies by adopting a zero-emission bus (ZEB) demonstration and ZEB

acquisition requirements for larger transit agencies.

Diversification in public transit services has led to the increased use of smaller

and commuter service buses not subject to the existing fleet rule for transit

agencies. Therefore, staff believes it is necessary and appropriate to add

requirements for emission reductions from buses and trucks not covered under

the current rule.

In this rulemaking, staff is proposing to expand the fleet rule to include smaller

diesel and alternative-fuel buses, commuter buses, and heavy-duty trucks owned

or operated by transit agencies. The affected vehicles are called transit fleet

vehicles and would be subject to a fleet average NOx limit and PM reduction

requirement, phased in between 2007 and 2010. As a part of this change, staff

is proposing to add a definition for a commuter service bus, which is a

subcategory of a transit fleet vehicles. A commuter service bus is a bus that

would otherwise meet the definition of an urban bus except that its duty cycle

includes very little of the stop-and-go operations of an urban bus. In this case, a

commuter service bus will be classified as a transit fleet vehicle, not an urban

bus. This definition codifies existing policy based on a guidance issued in 2001.

Staff is also proposing several new sections to address various issues not

covered in prior amendments. The rule is currently silent on how new transit

agencies established after adoption of the rule in 2000 are to comply, thus staff is

including directions on compliance for new transit agencies. The current PM

reduction requirement does not allow for fleet growth following the final emission

reduction deadlines, thus staff is proposing to add a diesel fleet standard for

urban buses and transit fleet vehicles to allow for fleet growth while maintaining

emission reductions. The engine emission standard adopted for 2004 to 2006

model year diesel hybrid-electric urban buses in June 2004 is silent on engine

exhaust emission standards for non-methane hydrocarbon, carbon monoxide,

and formaldehyde, thus staff is proposing language for these standards. Finally,

staff is proposing to move and renumber the existing Fleet Rules for Transit
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Agencies (title 13, California Code of Regulations (CCR), sections 1956.2-

1956.4), currently located with the new engine emission standards, to new

sections set aside for controlling diesel particulate emissions from fleets.

The emission reductions obtained from this regulation will result in lower ambient

PM levels and reductions of exposure to primary and secondary diesel PM.

Lower ambient PM levels and reduced exposure, in turn, would result in a

reduction of the prevalence of the diseases attributed to PM and diesel PM,

including hospitalizations for cardio-respiratory disease, and premature deaths.

ARB staff estimates that in 2010 the proposed amendments would result in the

reduction of 44 pounds per day (lbs/day) of diesel PM, 380 lbs/day of NOx, 80

lbs/day of hydrocarbons (HC), and 80 lbs/day of carbon monoxide (CO)

emissions. In 2020, staff estimates reductions of 47 lbs/day of diesel PM, 620

lbs/day of NOx, 140 lbs/day of HC, and 100 lbs/day of CO emissions. The

proposed amendments, along with the more stringent new engine emission

standards identified in the Risk Reduction Plan to Reduce Particulate Matter

Emissions from Diesel-Fueled Engines and Vehicles (ARB 2000), reduce transit

fleet vehicle PM emissions by 43 percent and 81 percent in 2010 and 2020,

respectively, from the 2000 baseline emissions. NOx is reduced 29 percent in

2010 and 83 percent in 2020 from the 2000 baseline emissions.

The estimated cost of the proposed regulatory amendments is $0.90 to $1.90 per

pound of NOx and $42 to $88 per pound for PM. There are no associated costs

for business, only for local public transit agencies. Staff expects there will be

benefits to those businesses that produce or sell new vehicles or engines, and

retrofit technology.

ARB staff estimates that approximately 11 premature deaths would be avoided

by 2020 as a result of emission reductions obtained through this regulation. The

U.S. EPA has established $6.3 million (in 2000 dollars) for a 1990 income level

as the mean value of avoiding one death (U.S. EPA, 2003). Staff calculated the

value of avoiding one premature death, arriving at a range from $4 million to $6

million (in 2004 dollars). For the proposed regulation, the estimated cost of

control per premature death prevented is about $1.5 million to $2 million, which is

about three times lower than the U.S. EPA’s benchmark for value of avoided

death. This rule is, therefore, a cost-effective mechanism to reduce premature

deaths that would otherwise be caused by diesel emissions without this

regulation.

The proposed modifications, as described herein, are consistent with the

authority of the ARB to control emissions from mobile sources. To maintain

current emission reduction goals set by the Risk Reduction Plan to Reduce

Particulate Matter Emissions from Diesel-Fueled Engines and Vehicles (ARB

2000), as well as those set for urban buses in 2000, the ARB staff, therefore,

recommends that the Board adopt the proposed modifications to title 13, CCR,
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sections 1956.1, 1956.2, 1956.3, 1956.4, and 2020, and proposed new sections

2023, 2023.1, 2023.2, 2023.3 and 2023.4, as set forth in the proposed

Regulation Order in Appendix A.
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I. INTRODUCTION AND BACKGROUND

The Air Resources Board (ARB or “the Board”) seeks to provide clean, healthful

air to the citizens of California. California’s commitment to providing clean public

transportation is an important part of achieving this goal. Public transportation

has important societal benefits, including providing access to work and

education, reducing traffic congestion, and meeting the mobility needs of the

public, including the elderly and disabled.

California’s transit agencies are responsible for providing basic transportation

services for the public. Transit agencies provide both fixed-route service within

urban places, such as traditional urban bus and neighborhood routes, and

between urban places such as commuter routes, and non-fixed-route services

such as paratransit, dial-a-ride and charter services.

Most types of public transportation, however, are also sources of polluting engine

exhaust emissions. Oxides of nitrogen (NOx) and hydrocarbons (HC) contribute

to the atmospheric formation of ozone and fine particles. Carbon monoxide (CO)

is a colorless, odorless gas that reduces the ability of the body to transport

oxygen to cells. Diesel particulate matter (PM) is a toxic air contaminant – a

cancer-causing pollutant that also has significant short- and long-term negative

cardiovascular impacts. These emissions often occur within California’s most

populated areas. It is, therefore, vital to all Californians that the ARB continues

its efforts to reduce engine exhaust emissions from all sources.

In February 2000, the Board confirmed its established a new fleet rule for transit

agencies and more stringent emission standards for new urban bus engines and

vehicles: The Public Transit Bus Fleet Rule and Emission Standards for New

Urban Buses (ARB 1999, ARB 2000b). The multi-faceted regulations went

beyond the federal requirements for urban buses. The rules were designed to

reduce NOx and PM by setting fleet emission reduction requirements that

encouraged transit agencies to purchase cleaner buses and retrofit their existing

buses; and promoted advanced technologies by adopting requirements for zeroemission bus (ZEB) demonstrations and acquisition that are applicable to larger

transit agencies. New, more stringent mid- and long-term emission standards

were adopted that apply to new urban bus engines.

As a result of these rules, many transit agencies have installed natural gas

refueling infrastructure and purchased alternative-fuel urban buses; repowered

old diesel engines to engines meeting cleaner exhaust emission standards;

installed diesel particulate filters on diesel engines; and experimented with

developing technologies, such as hybrid-electric buses, NOx aftertreatment

systems and cleaner fuels. Many of California’s transit agencies consider

themselves to be innovators and incubators for advanced technologies.
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Since the rules were adopted, however, diversification in public transit services

has led to increased use of smaller local buses and larger commuter service

buses that do not meet the definition of urban bus and thus are not subject to the

existing Fleet Rule for Transit Agencies. In addition, the Board adopted the Risk

Reduction Plan to Reduce Particulate Matter Emissions from Diesel-fueled

Engines and Vehicles (ARB 2000a) and began an ambitious schedule of

adopting and implementing rules to reduce diesel PM emissions from all

California in-use vehicles and equipment. Staff therefore determined that it was

appropriate to expand the scope of the Fleet Rule for Transit Agencies to reduce

emissions from buses and trucks not within the current scope of the rule.

Staff’s proposal to amend the rule has five elements. First, staff is proposing

new NOx and PM fleet emission standards for buses and trucks owned and

operated by public transit agencies that are not urban buses, which staff terms

“transit fleet vehicles.” Second, staff is proposing new sections to address the

issue of a schedule for emission reductions for a new transit agency established

after adoption of the regulations. Third, staff is proposing to add a diesel PM

fleet standard applicable to urban buses to allow for fleet growth while

maintaining emission reductions. Fourth, staff is proposing clarifying language

for the adopted 2004 to 2006 model year diesel hybrid electric urban bus engine

standard to address non-methane hydrocarbon (NMHC), carbon monoxide (CO),

and formaldehyde emission standards. Finally, staff is proposing to move and

renumber the existing Fleet Rule for Transit Agencies [title 13, California Code of

Regulations (CCR), sections 1956.2-1956.4], currently located with engine

emission standards, to new sections set aside for rules controlling diesel

particulate emissions from fleets.

A. Urban Buses and Transit Fleet Vehicles

The Fleet Rule for Transit Agencies regulates urban buses that are owned or

leased by public transit agencies. An “urban bus” is a bus that is powered by a

heavy heavy-duty diesel engine, or of a type that would normally be powered by

a heavy heavy-duty diesel engine. These buses are generally 35 feet in length

or longer, although smaller chassis may have an urban bus engine installed if

necessary, in which case a smaller bus could be an “urban bus.” Urban buses

usually operate on a fixed route consisting of stops and starts as passengers are

routinely picked up and delivered to their destinations. Commuter bus operations

within metropolitan areas (such as the Yolo-Sacramento metropolitan area) that

consist of more than a few pick-up and drop-off stops are also considered to fall

within the definition of urban bus operation (ARB 2001b).

Diversification in public transit services has led to the increased use of buses not

subject to the current Fleet Rule for Transit Agencies. These vehicles typically

are greater than 8,500 lbs. gross vehicle weight rating (GVWR) but are smaller

than a typical urban bus and use a medium heavy-duty engine. In addition,

buses using heavy heavy-duty engines or buses that are charters or commuter
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buses having a few pick-up and drop-off stops may not meet the definition of an

urban bus. Traditional paratransit and dial-a ride services also utilize smaller

buses that are not currently subject to the rule. Several transit agencies only

operate buses and vehicles that do not meet the definition of urban bus. Staff

has defined these vehicles as “transit fleet vehicles.” Today, transit fleet vehicles

fueled by diesel and alternative fuel represent approximately one fourth of the

vehicles operated by public transit agencies.

B. Engine Exhaust Emission Standards for Transit Fleet Vehicles and

Urban Buses

ARB certifies new vehicles and engines to meet California's engine exhaust

emission standards based on how the vehicle or engine is operated, categorized

by service class. Types of service classes include passenger car, light-duty

truck, medium-duty vehicle, heavy-duty vehicle or engine, and urban bus. To be

certified, a vehicle must demonstrate that its emission control systems are

durable and comply with the applicable emission standards for the vehicle's

useful life. A vehicle or engine manufacturer determines under which emission

standard a vehicle or engine is to be certified, and vehicles and engines are not

legal for sale in California until certified by ARB. Certification is applied to either

the complete vehicle, "chassis certification," or the engine alone, "engine

certification," depending on the emission standard to which it is certified.

Heavy-duty engines used to power trucks and buses operated by transit

agencies, other than urban buses, are required to certify to California engine

exhaust emission standards (title 13, CCR, section 1956.8). As stated

previously, staff has termed these vehicles, when owned or operated by a transit

agency, as “transit fleet vehicles.” Transit fleet vehicles will continue to utilize

engines certified to the heavy-duty truck engine standards and not be required to

meet tighter urban bus engines that are found in title 13, CCR, section 1956.1.

Tables 1 and 2 provide a comparison of the California engine emission standards

for urban buses and transit fleet vehicles. A more detailed summary of the

California and federal heavy-duty truck and urban bus engine exhaust emission

standards is provided in Appendix C.
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Table 1. California Urban Bus and Heavy-Duty (HD)Truck New Engine

Emission Standards for NOx

Emission Standards (grams per brake horsepower-hour, g/bhp-hr)

Model Year Urban Bus HD Truck

1988 6.0 6.0

1990 6.0 6.0

1991 5.0 5.0

1996 4.0 5.0

1998 4.0 4.0

October 2002 2.2(1) 2.2(1)

2004 0.5(2), 2.2(3) 2.2(1)

2007 0.2 1.2(4)

2010 0.2(4) 0.2(4)

1. Nominal expected NOx level based on emission standards of 2.4 g/bhp-hr NOx plus non-methane hydrocarbons

(NMHC) or 2.5 g/bhp-hr NOx plus NMHC with 0.5 g/bhp-hr NMHC cap to take effect in October 2002 for those

engines subject to the Settlement Agreements between the heavy-duty engine manufacturers, the United States

Environmental Protection Agency (U.S. EPA), and ARB. As part of the Settlement Agreements, the federal heavyduty engine emission standards adopted for 2004 took effect in October 2002.

2. Standard applies to urban bus equipped with diesel-fuel, dual fuel, or bi-fuel, engines.

3. Standard applies to urban bus equipped with alternative-fueled engines. Nominal expected NOx level of 2.2 g/bhphr is based on ARB emission standards of 2.4 g/bhp-hr NOx plus NMHC or 2.5 g/bhp-hr NOx plus NMHC with 0.5

g/bhp-hr NMHC.

4. 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.

Table 2. California Urban Bus and Heavy-Duty (HD)Truck New Engine

Emission Standards for PM

Emission Standards (g/bhp-hr)

Model Year Urban Bus HD Truck

1988 0.6 0.6

1991 0.1 0.25

1993 0.1 0.25

1994 0.07 0.1

1996 0.05(1) 0.1

October 2002 0.01(2) 0.1

2007 0.01 0.01

1. In-use standard of 0.07 g/bhp-hr.

2. Standard applies to urban bus equipped with diesel-fuel, dual fuel, or bi-fuel, engines. Urban bus equipped with

alternative fueled engines may certify to optional standard of 0.03, 0.02, or 0.01 g/bhp-hr.
8

C. Amendments to the Fleet Rule for Transit Agencies

In the Fleet Rule for Transit Agencies, the Board set fleet-wide requirements for

urban buses applicable to each transit agency, requiring each transit agency to

consider its urban bus fleet as a whole to meet emission reduction goals. Each

transit agency was required to select a compliance path – either the “diesel” path

or the “alternative-fuel” path – by January 1, 2001. Path selection set the fuel

type for new urban bus purchases or leases through model year 2015. Transit

agencies on either path were required to achieve a maximum fleet average of 4.8

g/bhp-hr NOxas of October 1, 2002. The requirement was typically met by

retiring older buses or bus engines. The PM emission reduction requirement is

being met by replacement of older buses and bus engines and retrofit of diesel

engines with PM Filters. Future bus purchases must include 15 percent ZEBs for

the larger transit agencies. Large diesel path agencies are also required to

conduct a demonstration of ZEBs prior to implementation of the purchase

requirement.

The October 24, 2002, rule amendments were primarily focused on changing the

mechanism for PM reduction because of the unavailability of retrofit technology

for the oldest engines, and adopting an interim certification procedure for hybridelectric buses (HEBs) and vehicles (ARB 2002, ARB 2003). Further, any transit

agency on the diesel path and located in the South Coast Air Basin was allowed

to switch its fuel path to the alternative-fuel path, provided the transit agency was

in compliance with the rule. Additional changes allowed diesel path agencies to

purchase 2004 through 2006 MY alternative-fuel engines; provided a “financial

hardship” delay request mechanism for small transit agencies; repealed the

certification procedures for PM retrofit devices as duplicative of another recently

adopted rule; and made other conforming and clarifying changes.

The purpose of the June 24, 2004, rule amendments was to provide a

mechanism for manufacturers to certify diesel HEBs for the engine MY of 2004

through 2006 at 1.8 g/bhp-hr and allow diesel path transit agencies to purchase

those diesel HEBs (ARB 2004). To ensure that emission reductions were

maintained, transit agencies were required to prove they could offset the excess

NOx emissions from the difference between the 2004 to 2006 diesel emission

standard of 0.5 g/bhp-hr and the new allowed standard of 1.8 g/bhp-hr for HEBs.

In addition, the Board modified the ZEB demonstration requirements in

acknowledgment of the lag in technology compared to that projected in 2000

when the requirements were adopted.

II. NEED FOR REDUCTION OF DIESEL EXHAUST EMISSIONS

A. Diesel Particulate Matter

Particulate matter (PM) is the general term for tiny airborne particles. Diesel PM,

emitted from engines that burn diesel fuel, is a complex mixture that consists of
9

dry solid fragments, solid cores with liquid coatings and small droplets of liquid.

These tiny particles vary greatly in shape, size and chemical composition and

can be divided into several size fractions. Coarse particles are between 2.5 and

ten microns in diameter, and arise primarily from natural processes, such as

wind-blown dust or soil. Fine particles are less than 2.5 microns in diameter and

are produced mostly from combustion, or burning activities and are termed PM2.5.

Particles with an aerodynamic diameter less than or equal to a nominal ten

microns (about 1/7 the diameter of a single human hair) are termed PM10; PM10 is

a criteria air pollutant for which federal and state ambient air quality standards

have been set. Diesel PM is a subset of PM10.

B. Ambient Air Quality Standards for Particulate Matter

Both California and U.S. EPA have established standards for the amount of PM10

in the ambient air. These standards define the maximum amount of particles that

can be present in outdoor air without threatening the public's health and welfare.

California's current PM10 standard is more protective of human health than the

corresponding national standard. Standards for PM2.5 have also been

established to further protect public health (Table 3).

Table 3. State and National Particulate Matter Standards.

California Standard National Standard

PM10

Annual Arithmetic Mean 20 μg/m3 Annual Arithmetic Mean 50 μg/m3

24 Hour Average 50 μg/m3 24 Hour Average 150 μg/m3

PM2.5

Annual Arithmetic Mean 12 μg/m3 Annual Arithmetic Mean 15 μg/m3

24 Hour Average No separate

State standard

24 Hour Average 65 μg/m3

When the ARB sets California's ambient air quality standards, it designs them to

protect the most sensitive subpopulations, such as children, the elderly, or

people with pre-existing disease, such as cardiac patients or asthmatics.

C. Identification of Diesel Particulate Matter as a Toxic Air Contaminant

After ten years of extensive research and public outreach, ARB identified diesel

PM as a toxic air contaminant (TAC) in August 1998 (CalEPA 1998). As part of

the identification process, Office of Environmental Health Hazard Assessment

(OEHHA) evaluated the potential for diesel exhaust to affect human health.

OEHHA found that exposures to diesel PM resulted in an increased risk of

cancer and an increase in chronic non-cancer health effects, including a greater

incidence of cough, labored breathing, chest tightness, wheezing, and bronchitis

(OEHHA 1998). OEHHA estimated, based on available studies, that the

potential cancer risk for exposure to diesel PM in concentrations of one
10

microgram per cubic meter (μg/m3) ranged from 130 to 2400 excess cancers per

million. The ARB’s Scientific Review Panel (SRP) approved OEHHA’s

determinations concerning health effects and approved the range of risk for PM

from diesel-fueled engines, concluding that a value of 300 excess cancers per

million people, per μg/m3 of diesel PM, was appropriate as a point estimate of

unit risk for diesel PM.

OEHHA also concluded that exposure to diesel PM in concentrations exceeding

five μg/m3 can result in a number of long-term chronic health effects. The five

μg/m3 value is referred to as the chronic reference exposure value for diesel PM.

The SRP supported OEHHA’s conclusion and noted that the reference exposure

value may need to be lowered further as more data emerge on potential adverse

chronic effects of diesel PM.

D. Physical and Chemical Characteristics of Diesel Particulate Matter

Diesel PM is the non-gaseous portion of the exhaust from a diesel-fueled

compression ignition engine. 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. Diesel PM consists of several

constituents, including an elemental carbon fraction, a soluble organic fraction,

and a sulfate fraction. 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 (Table 4).
11

Table 4. Substances in Diesel Exhaust Listed by California as Toxic Air

Contaminants.

Acetaldehyde Manganese compounds

Acrolein Mercury compounds

Aniline Methanol

Antimony compounds Methyl Ethyl Ketone

Arsenic Naphthalene

Benzene Nickel

Beryllium compounds 4-Nitrobiphenyl

Biphenyl Phenol

Bis[2-ethylhexyl]phthalate Phosphorus

1,3-Butadiene Polycyclic organic matter,

Cadmium

Chlorine

Chlorobenzene

Chromium compounds

including polycyclic aromatic

hydrocarbons (PAHs) and their

derivatives

Cobalt compounds Propionaldehyde

Creosol isomers Selenium compounds

Cyanide compounds Styrene

Dibutylphthalate Toluene

Dioxins and dibenzofurans Xylene isomers and mixtures

Ethyl benzene o-Xylenes

Formaldehyde m-Xylenes

Inorganic lead p-Xylenes

Note: California Health and Safety Code section 39655 defines a TAC as "an air pollutant which may cause or

contribute to an increase in mortality or in serious illness, or which may pose a present or potential hazard to

human health."

E. Sources and Ambient Concentrations Of Diesel Particulate Matter

PM emissions from diesel-fueled vehicles and engines totaled about 28,000 tons

per year (tpy) in California as of 2000 (ARB 2000a). These emissions come from

a wide variety of sources including more than one million on-road and off-road

vehicles, about 16,000 stationary engines, and close to 50,000 portable engines.

On-road engines account for about 27 percent of the emissions, off-road engines

and portable engines about 71 percent, and the remaining two percent from

stationary engines. With full implementation of the current vehicle standards and

vehicle turnover, but not considering this control measure, diesel PM emissions

will still total about 22,000 tpy in 2010 and about 19,000 tpy in 2020.

In the year 2000, outdoor diesel PM concentrations were 1.8 μg/m3 and projected

to be 1.5 μg/m3 in 2010 after accounting for current regulations. After including

indoor concentrations of diesel PM, total exposure was 1.26 μg/m3 in 2000 and

projected to be 1.05 μg/m3 in 2010 (Table 5).
12

Table 5. Estimated Exposure of Californians to Diesel Particulate Matter

for 2000, 2010 and 2020 (ARB 2000a).

Estimated Average Air Exposure Concentration

(mg/m3 ) and Potential Risk

(excess cancers/million)

2000 2010 2020

Exposure

Location

Estimated

Average Air

Exposure

Concentration –

1990 (mg/m3) Conc. Risk Conc. Risk Conc. Risk

Outdoor Ambient 3.0 1.8 540 1.5 450 1.2 360

Indoor 2.0 1.2 360 1.0 300 0.8 240

Total 2.1 1.26 380 1.05 315 0.84 252

F. Health Effects of Diesel Particulate Matter

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).

Long-term ambient concentrations of PM10 are associated with increased risks of

all natural-cause 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). Initial findings indicate a clear correlation

between reduced lung function and more intense air pollution and high levels of

nitrogen dioxide (NO2), PM10, PM2.5, and acid vapor appear to be associated with

slower lung growth (Peters, et al., 1999).

G. Statewide Risk Reduction Goal of Diesel Risk Reduction Plan

As noted above, diesel PM is emitted from a variety of sources, including on- and

off-road diesel-fueled vehicles and stationary engines. On a statewide basis, the

average potential cancer risk associated with diesel PM emissions is 540

potential cases per million statewide, with the potential risk in the South Coast Air

Basin estimated to be 1,000 per million people. Compared to other air toxics the

Board has identified and controlled, diesel PM emissions are estimated to be

responsible for about 70 percent of the total ambient air toxics risk. In addition to

these general risks, diesel PM can also present elevated localized or near-source

exposures. Depending on the activity and nearness to receptors, these potential

risks can range from small to 1,500 per million or more.
13

The goal of the Board (ARB 2000) is to reduce diesel PM emissions and the

associated cancer risk by 75 percent in 2010 and 85 percent in 2020. The Fleet

Rule for Transit Agencies is one of a group of regulations being developed to

achieve the emission reduction goals of the ARB of protecting the health of

Californians by reducing the cancer risk from diesel PM and complying with legal

requirements to control a TAC. Other benefits associated with reducing diesel

PM emissions include increased visibility, less material damage from soiling of

surfaces, and reduced incidence of non-cancer health effects, such as bronchitis,

asthma, and allergy. The emission reductions obtained from this regulation will

result in lower ambient PM levels and significant reductions of exposure to

primary and secondary diesel PM. Lower ambient PM levels and reduced

exposure, in turn, would result in a reduction of the prevalence of the diseases

attributed to PM and diesel PM, including reduced incidences of hospitalizations

for cardio-respiratory disease, and prevention of premature deaths.

H. Nitrogen Oxides and Reactive Organic Gas Emissions

Emissions of NOx and Reactive Organic Gases (ROG) are precursors to the

formation of ozone in the lower atmosphere and secondary PM. Exhaust from

diesel engines contributes a substantial fraction of ozone precursors in any

metropolitan area. Secondary PM forms from the interaction of gases in the

atmosphere, including nitrates that result from diesel engine exhaust. Therefore,

reductions in NOx from diesel engines in urban areas would make a considerable

contribution to reducing exposures to ambient ozone and secondary PM.

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. ARB

has long established the need for reduction of emissions of NOx and other ozone

precursor chemicals from mobile sources.

III. NEED FOR MODIFICATIONS

This discussion will focus specifically on the need for the regulatory modifications

proposed in this initial statement of reasons.

A. Transit Fleet Vehicles: Addition to Scope

Diversification in public transit services has led to the increased use of buses that

are not subject to the current Fleet Rule for Transit Agencies. Transit agencies

have added long-distance routes to bring passengers from far-flung suburbs into

cities or to transit hubs. From cities or transit hubs, riders transfer to shorter,

local routes that use small buses and trolleys. California public transit agencies

today operate approximately 10,100 urban buses that are subject to the fleet

rule. In addition, in 2003 transit agencies operated approximately 5,400 buses

and trucks not subject to the fleet rule. These vehicles are fueled by gasoline,

diesel and alternative fuels. Of the 5,400 buses and trucks not subject to the
14

fleet rule, 4,100 are fueled by diesel fuel or alternative-fuels. These numbers are

expected to increase as California's population and density increase, thus

requiring both smaller and larger heavy-duty buses to meet both neighborhood

and commuter service needs.

The current Fleet Rule for Transit Agencies requires that transit agencies reduce

diesel PM and NOx emissions from their diesel and alternative-fueled urban

buses. Staff is proposing in this rule to add on emission reduction requirements

applicable to heavy-duty transit fleet vehicles fueled by diesel and alternativefuels. Staff is not proposing to include gasoline engines in this rule as they

produce no diesel PM and have lower NOx emissions as new certified engines

than diesel engines. Staff is proposing to include alternative-fuel engines as

required in the existing fleet rule.

As staff began implementing the newly finalized Fleet Rule for Transit Agencies

in 2001, we addressed the question of the definition of an urban bus. Some

transit agencies told ARB that they preferred or needed to use a large bus

configured more like a charter bus on commuter service routes and they felt that

these buses should not be classified as urban buses. Staff researched the issue

and responded with a letter dated December 20, 2001, that set forth guidance to

transit agencies. Staff determined that a bus used for commuter service is an

urban bus when its duty cycle is similar to that of a typical urban bus for at least

that part of its travel within a city or metropolitan area. In other words, if a bus

operates with more than a small number of drop-offs and pick-ups in a city or

metropolitan area for part of its route, then ARB determined that the bus would

be classified as an urban bus.

Staff is now proposing to codify existing guidance by adding a definition of

commuter service bus, which is not classified as an urban bus but would instead

be classified as a transit fleet vehicle. Staff's proposed definition does not

expand the scope of what ARB has previously classified as a commuter service

bus and thus maintains the integrity of previously adopted emission reductions

from urban buses.

B. Newly Formed Transit Agencies

Staff has been asked by newly formed transit agencies, which are either

successors under new ownership of existing transit agencies or new agencies

providing new services in new areas, to clarify how they are to comply with the

adopted rule. The current rule does not provide these new transit agencies with

direction on how to comply. Thus, staff is proposing regulations that establish

deadlines and set criteria for compliance with the fuel path and emission

reduction requirements for a new transit agency formed after 2001, which is

when the Fleet Rule For Transit Agencies was finalized.
15

C. Urban Bus Requirements for PM Reduction

At its October 2002 hearing, the Board modified the mechanism used by transit

agencies to reduce diesel PM emissions from urban buses in recognition of the

lack of available retrofit technology originally projected to be available for PM

reduction from certain diesel urban buses. After working with the transit

agencies, staff recognized that the new PM reduction requirements adopted in

2002 did not allow for fleet growth after 2007 (diesel path agencies) or 2009

(alternative-fuel path agencies) when the transit agencies were to have reduced

total fleet PM emissions to 15 percent of their January 1, 2002, baseline PM

emissions. With increases in demand for transit service, staff is proposing that

the final particulate emissions reduction requirement be based on the lowest

achievable particulate emission standard multiplied by the number of urban

buses in a transit agency’s urban bus fleet.

D. 2004 to 2006 Diesel Hybrid-Electric Urban Bus Engine Exhaust Emission

Standards

In the June 24, 2004, rule amendments, the Board provided a mechanism for

manufacturers to certify diesel HEBs for 2004 through 2006 model years and a

transit agency on the diesel path to purchase those diesel HEBs, provided the

transit agency offsets the excess NOx emissions between the adopted exhaust

emission standard of 0.5 g/bhp-hr for diesel engines and the new standard for

diesel HEBs of 1.8 g/bhp-hr NOx. The adopted standards also included a

requirement that the diesel HEBs be certified at the existing exhaust emission

particulate standard of 0.01 g/bhp-hr (ARB 2004). Staff inadvertently, however,

neglected to specify any other engine exhaust emission standards in the adopted

section and was informed recently that, as written, manufacturers would be

required to meet the 2004 diesel urban bus exhaust emission standards for

nonmethane hydrocarbons (NMHC), carbon monoxide (CO), and formaldehyde

found in title 13, CCR, section 1956.1 (a)(11). Manufacturers have further

informed staff that they could not meet the NMHC, CO, and formaldehyde

standards in section 1956.1(a)(11), which is not surprising as those standards

were crafted to match the expected engine technology to meet a NOx standard

of 0.5 g/bhp-hr. To correct its error, staff is therefore proposing to add language

to clarify the specific engine exhaust emission standards. For non-methane

hydrocarbon (NMHC) the proposed standard is 0.5 g/bhp-hr; for carbon

monoxide (CO) the proposed standard is 15.5 g/bhp-hr; and for formaldehyde

staff proposes to remove the requirement.

E. Renumbering Sections for the Fleet Rule for Transit Agencies

The existing Fleet Rule for Transit Agencies is located with engine emission

standards in title 13, CCR, sections 1956.2-1956.4. The engine emission

standard regulations are directed to new engine and vehicle manufacturers.
16

Recently, ARB set aside title 13, CCR, sections 2020-2027 for regulations that

control diesel emissions from existing in-use engines or fleets. Staff believes that

moving existing sections for the Fleet Rules for Transit Agencies to the new

sections for rules controlling diesel emissions from existing in-use engines or

fleets best serves the regulated transit community by co-locating all of the

regulations that focus on in-use engine exhaust emission reductions.

IV. SUMMARY OF PROPOSED REGULATIONS

Staff recommends that the Board adopt proposed amendments to title 13, CCR,

sections 1956.1, 1956.2, 1956.3, 1956.4, and 2020, and add sections 2023,

2023.1, 2023.2, 2023.3 and 2023.4, as set forth in Appendix A:

• Add transit fleet vehicles to the scope of the Fleet Rule for Transit

Agencies and require new NOx and PM fleet emission reduction

standards for these buses and trucks owned and operated by public

transit agencies.

• Provide explicit guidance in the rule for newly formed transit agencies,

established after adoption of the Fleet Rule for Transit Agencies.

• Modify the urban bus PM fleet reduction standard to allow for fleet growth

once transit agencies have met the mandated final PM reduction deadline.

• Modify the urban bus diesel HEB engine emission standard to clarify the

emission standards for non-methane hydrocarbon, carbon monoxide, and

formaldehyde.

• Move existing Fleet Rules for Transit Agencies (title 13, CCR, sections

1956.2-1956.4), currently housed with the engine emission standards, to

new sections set aside for controlling diesel particulate emissions from

fleets.

The proposed changes are summarized below. A detailed description of the all

the components is located in Appendix B.

A. Transit Fleet Vehicle Requirements

Staff proposes to add transit fleet vehicles to the scope of the Fleet Rule for

Transit Agencies and require new NOx and PM fleet emission reduction

standards for these buses and trucks owned and operated by public transit

agencies.

1. Applicability

Staff is proposing to define a transit fleet vehicle as an on-road vehicle greater

than 8,500 pounds gross vehicle weight rating (GVWR) powered by a heavy-duty

engine fueled by diesel or alternative fuel, owned or operated by a transit

agency, and which is not an urban bus. Transit agencies operating only gasoline

powered vehicles are not subject to this proposal.
17

In addition, staff is also proposing to add a new definition of a commuter service

bus, which is a bus that would otherwise meet the definition of an urban bus

except that its operations include very little of the stop-and-go operations of an

urban bus. The proposed definition is:

“Commuter Service Bus” means a passenger-carrying vehicle powered by

a heavy heavy-duty diesel engine, or of a type normally powered by a

heavy heavy-duty diesel engine, that is not otherwise an urban bus and

that operates on a fixed route primarily during peak commute hours and

has no more than ten stops per day excluding park-and-ride lots. A

commuter service bus is a transit fleet vehicle.”

2. Fleet Requirements

The proposal establishes a fleet average NOx standard and PM emission

reduction requirement for transit fleet vehicles, phased-in between 2007 and

2010 (Tables 6 and 7). Staff is not requiring transit agencies to select a fuel path

for transit fleet vehicles. Transit fleet vehicles would not be required to use ultralow sulfur diesel fuel until it becomes the only type of diesel fuel available in mid2006. New transit fleet vehicles would be subject to the heavy-duty diesel engine

emission standards, and not be subject to the new, more stringent urban bus

engine exhaust emission standards.

a. Fleet NOx Average

The proposal requires that a transit agency meet fleet NOx emission averages of

3.2 g/bhp-hr by December 31, 2007 and 2.5 g/bhp-hr by December 31, 2010 for

its transit fleet vehicles (Table 6). A transit agency calculates this value by

summing the NOx portion of the engine emission standard of each TFV and

dividing by the total number of transit fleet vehicles in its fleet. Staff expects

transit agencies to achieve this fleet standard through fleet turnover, repowering

older trucks, or retrofitting with a verified diesel emission control strategy (DECS)

that reduces NOx.

Table 6. Fleet NOx Average Requirements for Transit Agencies (g/bhp-hr)

Fleet Type Compliance Date

October 1,

2002

December 31,

2007

December 31,

2010

Urban Bus 4.81

Transit Fleet Vehicles 3.222.52

1Currently required in the Fleet Rule for Transit Agencies

2

Proposed
18

b. Fleet PM Reductions

The proposal requires that a transit agency reduce diesel PM emissions of its

transit fleet vehicles by 40 percent as of December 31, 2007 and 80 percent as

of December 31, 2010, compared to emissions as of January 1, 2005 (Table 7).

A transit agency calculates its diesel PM emission total by summing the PM

portion of the engine exhaust emission standard of each diesel-fueled transit fleet

vehicle. Staff expects that some reduction will occur with fleet turnover, but a

majority of the reductions will be achieved through retrofitting with a DECS or

repowering with a cleaner engine.

Table 7. Fleet Diesel PM Reduction Requirements for Transit Agencies

(g/bhp-hr)

Fleet Type Baseline Year Percent Reduction From Baseline

2004 2005 2007 2009 2010

Urban Bus1

Alternative Path 2002 20 40 60 853

Diesel Path 2002 40 60 853

TFV2

2005 40 803

1Currently required in the Fleet Rule for Transit Agencies

2

Proposed

3

In the final year of compliance and beyond the transit agency can meet a fleet average of 0.01

g/bhp-hr times the number of vehicles in the fleet.

B. Urban Bus Fleet Diesel PM Requirement

The current fleet diesel PM reduction requirements require transit agencies to

have reduced their total diesel PM emissions from their urban buses to 15

percent of their 2002 baselines as of 2007 (diesel path agencies) or 2009

(alternative-fuel path agencies), but are silent as to total diesel PM emissions

following those deadlines. In addition, the rule does not consider the situation of

a transit agency that meets the lowest possible diesel PM total without achieving

an 85 percent reduction from baseline. Staff proposes, as an option, that a

transit agency be able to meet a fleet average of 0.01 g/bhp-hr, in lieu of

achieving the value of 15 percent of the January 1, 2002, diesel PM emission

total. This new value would be calculated by a transit agency by multiplying the

value equal to the lowest achievable particulate emission standard of 0.01 g/bhphr by the number of urban buses.

C. 2004-2006 Urban Bus Diesel Hybrid-Electric Engine Emission Standard

Staff proposes to modify the adopted 2004 to 2006 diesel HEB engine exhaust

emission standards to enable manufacturers to certify diesel HEBs for 2004

through 2006. Staff is proposing to add engine exhaust emission standards of
19

0.5 g/bhp-hr NMHC and15.5 g/bhp-hr CO and delete the formaldehyde standard

from title 13, CCR, section 1956.1(a)(11)(B).

In order to certify a diesel HEB, some manufactures plan to utilize engines

already certified to the heavy-duty truck engine exhaust emission standards

found in title 13, CCR, section 1956.8. As there is no formaldehyde standard

required of heavy-duty truck engines, staff is proposing not to require a

formaldehyde standard for certification of diesel HEBs. Requiring such a

standard would add time and cost to the diesel HEB certification process and

would serve no useful purpose. The formaldehyde standard was adopted for an

engine that was expected to use selective catalytic reduction to meet the NOx

standard of 0.5 g/bhp-hr, which will not be used for these diesel HEBs.

Manufacturers are prohibited from using diesel urban bus engines, including HEB

engines, in the averaging, banking and trading program for PM.

D. "Newly Formed" Transit Agency Requirements

Staff proposes that a transit agency formed after the adoption of the Fleet Rule

for Transit Agencies be required to notify the Executive Officer in writing of its

existence and submit certain required reports to the Executive Officer. The new

transit agency would be required to choose a compliance path for its active fleet

and notify the Executive Officer within 120 days of formation of its intent to follow

either the diesel path or alternative path. A new transit agency that is a

successor to an existing transit agency would be required to follow the

compliance path of the transit agency out of which it has been formed.

The new transit agency would also be required to meet a specific NOx fleet

average and a diesel PM emission total reduction goal, which are specified in the

proposed rule. The emission reduction targets are set based on the date of

formation of the new transit agency and assume that the new transit agency

should be as clean as existing transit agencies. If, however, the new transit

agency was formed out of an already existing transit agency, then it must meet

the NOx fleet average and the diesel PM emission total of the urban buses and

transit fleet vehicles used in the transit operations of the existing transit agency

out of which the new transit agency was formed.

E. Extensions and Additional Definitions

Staff is proposing to allow the use of the compliance deadline extensions in the

existing urban bus rule for transit fleet vehicles. Applicable extensions include:

• an extension of the diesel PM emission requirements for one year due to the

unavailability of technology. A transit agency can apply annually;

• an extension for transit agencies in one hour ozone attainment areas from the

intermediate PM compliance deadlines; and,
20

• an extension for transit agencies with fewer than 30 vehicles (urban bus and

TFV) in their fleet for financial hardship. The fleet size was increased to

accommodate transit agencies with urban bus and transit fleet vehicles.

Staff is adding the following extension and exemption for transit fleet vehicles:

• an extension for a transit agency that is operating transit fleet vehicles under

contract (turnkey operations) for one year. Transit agencies may apply

annually; and,

• an exemption for low usage vehicle for transit fleet vehicles.

Staff is adding the following definitions:

• Commuter Service Bus is added as explained earlier to clarify when a bus is

an urban bus and when it is a transit fleet vehicle;

• Diesel PM Emission Total is defined and the used in the corresponding

sections;

• Low Usage Vehicle has been added to define transit fleet vehicles that get

little use. The corresponding category for urban buses is an emergency

contingency bus.

• New Transit Agency is defined to clarify the requirements for these transit

agencies;

• NOx Fleet Average is defined and used in corresponding sections;

• Retirement or Retire provides that ARB consider a vehicle or engine retired

only when it is sold out of state, the engine scrapped, or converted to use as

a low usage vehicle;

• Transit Fleet Vehicle is defined to provide the basis for the scope of the rule.

In addition, other definitions are moved from one section to another as part of the

movement of the Fleet Rule for Transit Agencies from sections 1956.2 to 1956.4

to sections 2023 to 2023.4.

V. PUBLIC OUTREACH AND ENVIRONMENTAL JUSTICE

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 more localized toxic pollution that is generated within our

communities. The ARB works to ensure that all individuals in California,

especially children and the elderly, can live, work and play in a healthful

environment that is free from harmful exposure to air pollution.
21

A. Environmental Justice

On December 13, 2001, the Board approved Environmental Justice Policies and

Actions,1 which formally established a framework for incorporating environmental

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

policy (ARB 2001a). “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

environmental justice issues have been raised more in the context of low-income

and minority communities because of past land use policies and the cumulative

impact of a concentration of emitting facilities in some neighborhoods.

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

Program and emphasized community health issues in our existing programs. To

provide people with the basic tools and information needed to understand and

participate in air pollution policy planning, permitting, and regulatory decisionmaking processes, ARB has published “The Public Participation Guide to Air

Quality Decision Making in California.”2

The Environmental Justice Policies are intended 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. Our outreach efforts,

described below, facilitate this objective.

1. Regulatory Proposal

Staff's proposal reduces diesel particulate matter, identified as a toxic air

contaminant, from transit buses. Transit services are predominantly located in

urbanized areas. Individuals from low income communities, along with elderly

and disabled people, are more likely to rely on transit services, and therefore

may be disproportionately exposed to diesel exhaust emissions from transit

buses.

By lowering the diesel PM emissions from transit buses, the exposure to toxic air

contaminants is reduced, therefore reducing cancer risk and exposure for

 

1

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

2

 Complete information on this program can be found at

http://www.arb.ca.gov/ch/public_participation.htm
22

individuals who use transit services and for those who reside in urbanized areas.

The staff's proposal (Section X) benefits these individuals and supports the Air

Resources Board's Environmental Justice goals.

B. Outreach Efforts

The ARB strives to involve the widest number of affected persons in the

development of its regulations. To this end, staff held informal public workshops

and meetings prior to publishing the notice and the staff report. For this rule,

staff conducted four sets of public workshops (Table 8) and additional focused

meetings. Notices for the workshops were mailed to more than 3,700 individuals

and companies and were posted to ARB’s Public Transit Agencies web site and

e-mailed to subscribers of ARB’s electronic listserves. Those workshops held in

Sacramento were webcast for individuals who could not travel to the meeting

locations. 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 Public Transit Agencies web

site.3 In addition, the web site provides background information and serves as a

portal to other web sites with related information.

Table 8. Workshop Locations and Times

Date Location Time

April 3, 2003 El Monte 2:00 – 5:00 PM

December 2, 2003 El Monte 1:30 – 3:00 PM

December 3, 2003 Sacramento 1:30 – 3:00 PM

May 17, 2004 Sacramento 1:30 – 3:00 PM

May 18, 2004 El Monte 1:30 – 3:00 PM

October 7, 2004 El Monte 1:30 – 3:00 PM

October 8, 2004 Sacramento 1:30 – 3:00 PM

Participants in the workshops included representatives from environmental

organizations, transit agencies, engine manufacturers, bus manufacturers, air

pollution control districts, cities and counties, the California Association for

Coordinated Transportation, California Transit Association, Regional Council of

Rural Counties, Manufacturers of Emission Controls Association, Engine

Manufacturers Association, California Department of Transportation, California

Natural Gas Vehicle Coalition, California Energy Commission, consultants, and

other parties interested in transit bus emissions.

Staff met with a number of the same stakeholders in focused meetings

throughout the rulemaking process to get feedback on staff’s proposed regulatory

 

3

 http://www.arb.ca.gov/msprog/bus/bus.htm
23

modifications. These stakeholders represented transit agencies, manufacturers

of buses and environmental organizations. Staff attended or made presentations

at the California Transit Association conference in November 2003 and

November 2004, the California Association for Coordinated Transportation

(Cal/ACT) conference in April 2004 and September 2004, and Rural County Task

Force Meetings. Staff also worked closely with small transit agencies, including

Amador County, Lake County, Mariposa County, Tehama County and many

other rural transit agencies. Alternatives were suggested to the proposed

regulation and explored by staff.

VI. ENGINE AND EMISSION INVENTORY

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

including a new survey of transit fleet vehicles in California (Appendix C). Staff

undertook a detailed survey to determine the engine make, model, model year,

and vehicle type of the transit fleet vehicles in California.

A. Engine Inventory

From April through December 2003, staff conducted a survey of both those

transit agencies subject to the Fleet Rule for Transit Agencies (reporting), as well

as transit agencies that are not subject to the rule because they operate no urban

buses (non-reporting). The survey was included in the annual reporting forms for

each reporting agency and distributed to the 250 Cal/ACT members, which

consist predominantly of small, rural, and paratransit agencies, the majority of

which were not subject to the existing Fleet Rule for Transit Agencies. Other

surveys were distributed as contacts were developed. Approximately 81 percent

of reporting transit agencies and 15 percent of the estimated non-reporting transit

agencies completed the survey. ARB staff gathered engine and fleet data from

2,187 vehicles and 91 transit agencies. Approximately 74 percent of the transit

fleet vehicles surveyed were operated by transit agencies currently subject to the

Fleet Rule for Transit Agencies.

ARB staff conducted a data extraction of the 2002 Department of Motor Vehicles

(DMV) database in January 2004 to further refine the estimate of the total

population of transit fleet vehicles. Using DMV data and survey information, staff

compared the fleet characteristics and determined the population of transit fleet

vehicles (non-urban buses and trucks) as approximately 5,410, of which

approximately 4,070 vehicles are fueled by diesel or alternative fuel; the rest are

gasoline or electric vehicles (Table 9). About ninety-nine percent (98.8 percent)

of the vehicle population was in revenue service (passenger carrying vehicles).

The truck population was 1.2 percent of the total population of transit fleet

vehicles. Details regarding the methodology and results are presented in

Appendix C.
24

Table 9. California Transit Fleet Vehicle Survey Population by Percent1

Gross Vehicle

Weight (GVW)

(lbs)

Diesel

percent

Gasoline

percent

Alternative

Fuel

percent

Electric

percent

Total

percent

8,500-14,000 15.6 7.5 2.9 0 26

14,001-33,000 47 17.4 7.1 0.2 71.7

>33,000 2.2 0 0 0 2.2

Total 64.8 24.9 10.0 0.2 99.92

1.These values represent transit fleet vehicles and do not include urban buses.

2.The total does not add up to 100 percent due to rounding

B. Emission Inventory

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

emissions-related and activity-related. 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 of the daily vehicle miles of travel, the distribution of travel by speed,

and the number of starts per vehicle per day by year. The on-road emission

inventory is then derived using a mathematical model named EMFAC.

ARB staff calculated the transit fleet vehicle emission inventory using a model

developed from EMFAC specifically incorporating the turnover rates for the

various types of transit fleet vehicles and emission factors for light, medium and

heavy heavy-duty truck engines. Gasoline vehicles were not included in the

emissions analysis (Appendix C).

The baseline emissions for the transit fleet vehicles (Table 10) gradually decline

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

model years.

Table 10. Transit Fleet Vehicle Estimated Baseline Emissions

Calendar

Year

NOX

(tpd)

PM

(lbs/day)

HC

(tpd)

COa

(tpd)

2000 4.48 158 0.99 0.78

2005 4.07 149 0.86 0.67

2010 3.47 133 0.70 0.57

2015 1.87 80 0.37 0.35

2020 0.81 77 0.14 0.22

a

 No emission factors are available for carbon monoxide (CO) from alternative fuel, and therefore values are lower than

expected.
25

VII. 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. In addition to technologies to reduce emissions in new engines, the

fields of exhaust aftertreatment and engine retrofitting are 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

Most 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 engines will require ultra-low sulfur diesel

fuel to enable proper functioning of the catalyzed diesel particulate filter (DPF)

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 ultralow sulfur diesel fuel beginning July 1, 2006. One refiner, BP, has been making

and selling ultra-low sulfur fuel in California since 2002, and 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 ultra-low sulfur diesel fuel, thus making the product

available by truck. BP is also selling ultra-low sulfur diesel fuel through its ARCO

stations that carry diesel fuel. Ultra-low sulfur diesel fuel will likely not be made

available through the pipeline distribution system until July 2006.

B. Verification of Diesel Emission Control Strategies

The Board adopted a procedure to verify diesel emission control strategies in

2003, codified in title 13, CCR, sections 2700 et seq.. The purpose of the

procedure is to verify strategies and systems that reduce diesel PM emissions

from in-use engines. Verification is an approval from ARB, which tells end users

that the verified device achieves advertised emission reductions and is durable.

The device manufacturer is required to provide a warranty for product useful life

and against engine damage caused by the DECS. To protect the end user, only

ARB-verified DECSs can be used in all of ARB’s mandated programs and most

of its voluntary programs.
26

ARB’s verification procedure is a multi-level verification system consisting of

three PM reduction levels and optional NOx reduction levels (Table 11).

Reductions in NOx are not required for verification, but ARB’s procedure

recognizes and verifies NOx reductions that are greater than or equal to 15

percent in five percent increments. This system has broadened both the

spectrum of control technologies available to participate in California’s diesel

emission control effort and the number and types of vehicles and engines that

can be controlled. This multi-level approach to verification is consistent with the

goal of achieving the maximum reductions in diesel PM emissions that are

economically and technologically feasible.

Table 11. Diesel Emission Control Strategy Verification Levels

Category PM Reduction

Level 1 ≥ 25 percent

Level 2 ≥ 50 percent

Level 3 > 85 percent, or 0.01 g/bhp-hr

Category NOx Reduction

Not verified <15 percent

Optional > 15 percent; in 5 percent

increments

The verification procedure requires considerable data to prove emission

reductions and durability, and any DECS that uses a fuel additive must

demonstrate that it is non-toxic in all media by going through a multimedia

assessment. ARB has received over 100 applications for verification, but not all

of those applications are actively moving forward for approval. As of November 1,

2004, ARB has verified four DPFs at Level 3, a fuel strategy and flow-throughfilter at Level 2, and three DOCs at Level 1 (Table 12). Not all of these DECSs

are applicable to transit fleet vehicles.
27

Table 12. Verified DECSs That May be Applicable to Transit Fleet Vehicles

E.O. Manufacturer & Product Date

Level 3

EO DE-04-001,

EO DE-04-002

Lubrizol PurifilterTM January 12, 2004

DE-04-005/DE04-005Donaldson DPM February 27,

2004/September 30,

2004

DE-04-006 Johnson Matthey CRTTM May 21, 2004

DE-03-001-03

DE-04-004-02

Cleaire LongviewTM1

July 26, 2004

Level 2

DE-04-008 Lubrizol's PuriNOxTM1 August 5, 2004

DE-04-011 Environmental Solutions

Worldwide

September 13, 2004

Level 1

Verification Letter Donaldson DCM November 7, 2002

DE-04-009 Donaldson DCM September 8, 2004

DE-04-010 Donaldson DCM September 8, 2004

1.Also verified for NOx reductions

The verification of a DECS specifies which engine family and vehicle operating

requirements the DECS be used for. The Executive Order or Verification Letter,

lists the engines by engine family and other conditions of verification, such as

minimum engine exhaust temperature. Additional evaluations by the

manufacturer may then be needed prior to installation of the DECS on a vehicle,

such as use of a datalogger that records engine exhaust temperatures over a

typical duty cycle.

This list is subject to change as additional systems are verified. The most current

list of verified DECSs, applicable engine families, as well as the 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 Transit Fleet Vehicles

A variety of retrofit strategies can be used for controlling emissions from in-use

diesel engines. The two main types of technologies discussed here are

hardware, add-on technologies such as diesel particulate filters (DPF) or

oxidation catalysts (DOC), and fuels or fuel additives. As discussed above, ARB

requires that a product be verified in order to claim PM or NOx emission

reductions. Devices certified under Vehicle Code 27156(h) for aftermarket parts

can be used on a vehicle but emission reductions cannot be claimed.
28

1. Hardware Diesel Emission Control Strategies

Currently, hardware DECSs consist of the DPF, including both passive and

active regenerated versions, and the DOC. Each of these types of technology

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 flowthrough-filter (FTF), was verified.

a. Passive (Catalyzed) Diesel Particulate Filter

A passive DPF reduces PM, CO and HC emissions through catalytic oxidation

and filtration. Most of the 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 DPF also reduces CO and HC by approximately the

same amount as the PM reduction. A passive 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.

Four 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. One, the Cleaire LongviewTM, is also verified for NOx reductions.

b. Active Diesel Particulate Filter

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

fuel to provide additional heat for particle oxidation, or adding a fuel-borne

catalyst or other reagent to initiate regeneration. Some active DPFs induce
29

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 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. Currently no active DPF systems have

been verified.

c. 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 like a DOC (diesel oxidation catalyst)

but achieves a greater PM reduction due to enhanced contact of PM with

catalytic surfaces and longer residency 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 from 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.

d. 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.

e. Selective Catalytic Reduction (SCR)

ARB has not verified any selective catalytic reduction DECS as of November 1,

2004. SCR catalysts that use ammonia as a NOx reductant have been used for

stationary source NOx control for a number of years. Urea may also used as the
30

source of ammonia for SCR catalysts, and such systems are commonly referred

to as Urea SCR systems. 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 will be introduced in 2004

or 2005 in Europe to comply with the EURO IV heavy-duty diesel emission

standards. The actual introduction dates in some countries will be earlier than

the EURO IV implementation requirements because of tax incentives in those

countries to promote early technology introduction (U.S. EPA 2004a). 

Although no SCR system is verified by ARB, transit agencies that received an

alternative NOx strategy exemption under title 13, CCR, section 1956.2(c)(8) or

(d)(9) were required to conduct a demonstration of an advanced NOx

aftertreatment system that could reduce NOx emissions by 70 percent or more

on buses operating in urban bus revenue service. Staff is monitoring the

demonstration of an ammonia SCR system on urban buses being conducted by

the seven transit agencies that received the exemption, led by the Santa Clara

Valley Transit Authority.

Three SCR NOx aftertreatment devices were selected, produced and installed by

Extengine, for demonstration on three urban buses. Initiated in October 2002,

VTA conducted baseline and emissions testing prior to placing the buses into

revenue service. Preliminary data submitted in January 2004 are favorable and

buses are operating in revenue service (VTA 2004).

2. Fuel-based Diesel Emission Control Strategies

Fuel-based DECSs utilize the fueling system and fuel for emission reductions.

All fuel-based DECSs 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 2002B);

Lubrizol has verified a fuel-water emulsion under the name PuriNOxTM.

b. Fuel Additives

A fuel additive is a substance designed to be added to fuel or fuel systems so

that it is present in-cylinder during combustion and its addition causes a

reduction in exhaust emissions. Fuel additives must be used with a Level 3 filter
31

unless proven safe when used without one. Additives can reduce the total mass

of PM, with variable effects on CO, NOx and gaseous HC production. In

published studies, PM reductions from fuel additives range 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) 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 widespread 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.

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 petroleumbased diesel fuel at any ratio. B20 is a biodiesel blend into petroleum-based

diesel fuel at 20 percent (ARB 2000a). Pure biodiesel is called B100.

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 2002a). While

biodiesel and biodiesel blends decrease PM, HC, and CO emissions, NOx

emissions increases 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.

Based on published studies, B20, which is a common concentration used in

California, is unlikely to reduce PM emissions enough to reach the Level 1

threshold of a minimum of 25 percent PM reduction. Although B20 meets the

definition of California diesel fuel, no biodiesel blend or B100 has been verified to

reduce emissions under the California program. In addition, in order to be

verified as a DECS, biodiesel fuel must also undergo a multimedia assessment,

just like any other alternative diesel fuel. At the time of this report, no biodiesel

blend or B100 has been verified in California as a DECS.

3. Combination Systems

Systems combining a hardware and fuel strategy are under development and inuse, although none have yet received verification from ARB. The U.S. EPA has
32

verified two combination systems under its voluntary program (U.S. EPA 2004b).

The U.S. EPA, however, 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 under go a multimedia assessment.

4. In-Use Experience

Around the world, public agencies 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 more than 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.

a. Diesel Oxidation Catalysts

In the past 20 years, over 250,000 DOCs have been installed primarily on

undergound mining and materials handling equipment, and more than 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) be retrofitted with

DOCs, resulting in more than 15,000 retrofits. In addition, over 3,000 trucks have

been retrofitted in Mexico and in Hong Kong about 40,000 heavy-duty vehicles

are beginning to be retrofitted (MECA 2002, 2004).

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 more than150,000 DPFs have been

retrofitted on heavy-duty vehicles worldwide (Kubsh, pers. comm.). One notable

program is Sweden’s Environmental Zone Program, which requires on- and offroad 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 policy in 2000 to require the retrofit

of all city-owned diesel trucks with DPFs by February 2004. By January 2003,

339 vehicles had been retrofitted with DPFs. To determine if the DPF worked

correctly, data loggers were installed on a subset of the retrofitted trucks and

exhaust temperatures were recorded. After 966,000 miles of in-use experience,

only a few DPF units demonstrated problems.
33

Los Angeles City’s sanitation department originally determined that 429 trucks

would be retrofitted with DPFs. However, many of these vehicles were retired or

in other ways removed from the fleet bringing the total number of trucks

retrofitted closer to 350. By 2004 the City has met its commitment to retrofit all

solid waste collection vehicles.

The City has been satisfied with the operation of the DPFs and is in the process

of retrofitting the remainder of the diesel fleet. The City of Los Angles has more

than 500 medium and heavy-duty diesel vehicles used for road maintenance and

other city activities. These included road maintenance vehicles such as asphalt

haulers, dump trucks, and tractors. All of these vehicles are scheduled to be

outfitted with DPFs. Scheduling issues prevented the City from retrofitting all

vehicles by 2004 as originally envisioned, however, progress has made toward

meeting the goal. As of October 2004, fewer than 200 trucks remained to be

retrofitted. The City expects these to be retrofitted with the appropriate retrofit

technology by June 2005 (Wilson, pers. comm.).

VIII. REGULATORY ALTERNATIVES

No alternative considered by the ARB would be more effective in carrying out the

purpose for which the regulation is proposed nor would be both as effective and

less burdensome to affected transit agencies than the proposed regulation. A

comparison of emission reductions from each regulatory alternative considered

can be found at the end of this section (Tables 13 and 14).

A. Make No Change To Existing Regulations

If the proposed regulations are not adopted, the emissions from transit fleet

vehicles, i.e., those buses and trucks not currently subject to the Fleet Rule for

Transit Agencies, will not be significantly reduced until 2020. With full

implementation of the proposed amendments, staff’s proposal reduces NOx

emissions by 0.04 tpd in 2010 and 0.31 tpd in 2020 and diesel PM emissions by

44 lbs/day in 2010 and 47 lbs/day in 2020 when compared to not adopting this

regulation (Tables 13 and 14). This proposed regulation will result in additional

benefits associated with reducing diesel PM emissions, such as 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.

In not adopting this regulation ARB would be disregarding the real health risks

caused by diesel PM. In consideration of the adverse health impacts and ARB’s

mandate to protect the public health of all Californians, therefore, this alternative

is not considered a reasonable option. Approximately 11 premature deaths

would not be prevented by 2020 if the proposed regulation is not adopted. ARB

staff does not recommend this alternative because it would result in greater PM
34

emissions and NOx emissions over the next few decades than the proposed

plan, thus adversely impacting the health of Californians.

B. Require Transit Agencies to Purchase Only Alternative-Fuel Vehicles

when Replacing or Adding to their Fleets

Staff evaluated the emission reductions and costs of requiring all new purchases

as of January 1, 2007, to be of alternative-fuel vehicles, as an alternative to

cleaning up the existing fleet. In this analysis, staff limited the useful life of

existing vehicles to ten years for vehicles less than 14,000 lbs GVWR, 15 years

for vehicles 14,000 to 33,000 lbs GVWR, and 22 years for vehicles greater than

33,000 lbs GVWR. At the end of the useful life, a diesel vehicle would need to be

replaced by an alternative-fueled vehicle. For the cost analysis, staff determined

the number of vehicles that would be replaced between 2008 and 2020 and

added up the incremental cost of purchasing alternative-fuel vehicle.

Infrastructure and fuel cost differentials were not added to the cost analysis.

The alternative-fuel replacement scenario emission reductions are estimated at

0.94. tpd of NOx in 2010 and 0.31 tpd in 2020 and diesel PM emissions at 15

lbs/day in 2010 and 7 lbs/day in 2020 (Table 13 and 14). This alternative

provides fewer emission reductions in 2010 and 2020 than staff's proposal

provides. Although this option provides more NOx emission reductions than

staff's proposal, the cost over the life of the rule is about $190 to $200 million, or

approximately 11 times higher than staff's proposal. In addition, many of the

transit agencies that will be newly subject to the Fleet Rule for Transit Agencies

because of the proposed expansion of scope are in rural areas where alternative

fuel is not available or the cost of infrastructure for alternative fuel is cost

prohibitive. This alternative is not as cost effective or as health protective as

staff’s proposal therefore staff does not recommend this alternative.

C. Adopt Alternative Fuel Purchase Requirement and PM 2005 baseline

reduction

Staff evaluated the emission reductions and costs of requiring all new purchases

as of January 1, 2007, to be of alternative-fuel vehicles as in Alternative B above.

In addition, staff included the diesel PM reduction requirements as in the

proposed regulation. The alternative fuel replacement plus PM reduction

scenario emission reductions are estimated at 0.94 tpd of NOx in 2010 and 0.31

tpd in 2020 and diesel PM emissions by 44 lbs/day in 2010 and 47 lbs/day in

2020 (Table 13 and 14).

Although this analysis showed the same PM reductions and more NOx

reductions as staff’s proposal, the cost is approximately 12 times higher than

staff's proposal. The estimated cost of this alternative ranges from $202 to $222

million over the life of the rule. As stated before, many of the transit agencies

newly subject to the Fleet Rule for Transit Agencies are in rural areas where
35

alternative fuel is not available or the cost of infrastructure for alternative fuel is

cost prohibitive. Staff does not recommend this alternative because it is not as

cost effective as staff’s proposal.

D. Include Transit Fleet Vehicles in a Rule for Public Agencies

Staff considered leaving the scope of the Fleet Rule for Transit Agencies

unchanged and including transit fleet vehicles in the scope of an upcoming rule

for public agencies. The Fleet Rule for Transit Agencies, however, uses a fleetbased reduction mechanism, which provides transit agencies with flexibility to

consider all of their vehicles when making decisions on how to comply. The

proposed rule for public agencies, on the other hand, will likely require owners to

apply best available control technology to each vehicle. Thus, staff decided that

it would make more sense for transit agencies to have only one type of

compliance mechanism for all of their vehicles and did not further analyze this

alternative. Staff therefore does not recommend this alternative, although it

could be crafted to be neutral with regards to emission reductions.

E. Comparison of Emission Reductions from Alternatives

Tables 13 and 14 summarize staff's analysis of estimated emission reductions

from each of the alternatives discussed above and compared to staff's proposal.

Table 13. Diesel PM Emissions for Baseline and Proposed Scenarios

Diesel PM Emissions (lbs/day)

Calendar

Year Staff’s

Proposal

No Change

(Baseline)

Alt-Fuel

Purchase

Requirement

Alt-Fuel

Purchase plus

PM Reduction

2000 158 158 158 158

2005 149 149 149 149

2010 90 133 118 90

2015 30 80 54 30

2020 30 77 77 30

Table 14. NOx Emissions for Baseline and Proposed Scenarios

NOx Emissions (tpd)

Calendar

Year Staff’s

Proposal

No Change

(Baseline)

Alt-Fuel

Purchase

Requirement

Alt-Fuel

Purchase plus

PM Reduction

2000 4.48 4.48 4.48 4.48

2005 4.07 4.07 4.07 4.07

2010 3.28 3.47 2.53 2.53

2015 1.52 1.87 1.21 1.21

2020 0.81 0.81 0.50 0.50
36

IX. ECONOMIC IMPACT

The proposed amendments require that transit agencies reduce fleet emissions

of NOx and diesel PM from their trucks and buses that are not otherwise

considered to be urban buses. Some transit agencies that do not own or operate

urban buses have not previously been subject to such requirements and they will

be subject to this rule for the first time. Staff believes that the proposed

regulation would cause no noticeable adverse impacts in California employment,

business status, or competitiveness.

A. Legal Requirement

Sections 11346.3 and 11346.5 of the Government Code require state agencies

proposing to adopt or amend any administrative regulation to assess the

potential for adverse economic impact on California business enterprises and

individuals. The assessment shall include consideration of the impact of the

proposed regulation on California jobs; on business expansion, elimination, or

creation; and on the ability of California businesses to compete in other states.

State agencies are also required to estimate the cost or savings to any state or

local agency or school district in accordance with instructions adopted by the

Department of Finance. This estimate is to include nondiscretionary costs or

savings to local agencies, and the costs or savings in federal funding to the state.

B. Affected Businesses

Companies affected would include manufacturers, distributors and installers of

buses, trucks, heavy-duty engines, engine retrofit kits, and emission control

systems. Most manufacturers of buses, trucks, and engines are located outside

of California. Many manufacturers of engine retrofit kits and emission control

systems are located in California, but staff did not do a comprehensive survey of

these companies because we believe they will experience only positive impacts.

There is at least one company in California that specializes in conversions of

standard diesel buses to alternative-fuel buses.

C. Potential Impact on Businesses

These proposed amendments create no direct costs for private sector

businesses. Staff discussed with transit agencies the use of private contractors

and determined that no private contractors will be directly impacted by this rule.

Staff expects that any impacts on businesses will be positive because the

regulation will result in a more rapid turnover of the newly regulated transit fleet

vehicles and in the installation of emission control systems.
37

D. Potential Impact on Business Competitiveness

The proposed amendments have no direct cost impact on businesses and thus

will have no negative impact on business competitiveness.

E. Potential Impact on Employment

Manufacturers, distributors and installers of exhaust after-treatment devices, and

fuel-conversion businesses located in California may increase their production

and sales volume, and thus create new jobs.

F. Potential Impact on Business Creation, Elimination, or Expansion

The proposed amendments could impact any of the companies involved in the

manufacture, production, distribution and installation of alternative fuel engines

and emission control systems that are sold in California. Many, but not all, of the

manufacturers that could benefit from the potential increase in business created

by requiring cleaner engines and buses are located outside of California. To the

extent that those businesses are located in California, the amendments could

lead to the creation or expansion of businesses in California. Businesses that

distribute or install alternative-fuel engines or emission control systems in

California are likely to expand their sales volumes.

G. Potential Cost to Local and State Agencies

The proposed regulation would impose fiscal impacts on local public transit

agencies and on the ARB. The transit agencies can all be expected to

experience relatively minor impacts due to additional record-keeping and auditing

requirements.

1. Implementation Scenarios

To determine implementation scenarios for costs, staff first evaluated existing

funding available for transit agencies. Transit agencies use Federal Transit

Administration (FTA) moneys and state and local matching funds to replace their

buses. A vehicle's service life determines when a transit agency can apply for

FTA funding, and the local transportation agency prioritizes which transportation

projects in its area obtain funding first (or in a fiscal year). Turnaround time for

funding in a rural area for an equivalent project (or bus) is longer than in an

urbanized area, due to competition for funds. A detailed description of the cost

analysis is found in Appendix D.

Staff evaluated fleet turnover supported by existing funding for buses using its

2003 survey data. The NOx fleet average was then calculated based on the

predicted fleet make up on December 31, 2007 and 2010. Because trucks do

not receive federal transportation funding, staff assumed that trucks do not turn
38

over and were still present in each implementation year. Staff estimated

approximately 6 buses and 44 trucks would require to be repowered to meet the

NOx requirements (Table 1, Appendix D).

Next, staff determined the fleet makeup for December 31, 2007 and 2010 to

determine the number of repowers or Level 3 DECS installations required to

meet the PM emission reductions. Although transit agencies have the flexibility

to use any DECS to reduce their fleet emissions, staff assumed a transit agency

would either repower a pre-1994 MY engine to a 1994 to 2002 MY engine plus a

DPF or would retrofit a vehicle with a 1994 to 2002 MY engine with a DPF,

because of the final 80 percent reduction requirement in 2010. Trucks and buses

in each implementation year were treated separately. Staff estimated that 1543

buses and 59 trucks would require retrofitting with a DPF, and 8 trucks would

require repowering, to meet the PM reduction requirement (Table 1, Appendix D).

2. Implementation Costs

All direct costs that will be required to comply with staff’s proposal and achieve

emissions reductions will only impact public transit agencies. Staff estimates that

the proposed regulation will cost $12.8 million to $26.7 million overall, with an

average estimate of just under $19 million (in 2005 dollars) over the lifetime of

the regulation (Table 15).

Table 15. Total Costs for Staff's Proposal (In 2005 Dollars)

Total Costs for PM & NOx

Low Medium High

Buses $11,873,233 $17,501,617 $25,120,541

Trucks $972,261 $1,232,940 $1,621,797

Total $12,845,494 $18,734,557 $26,742,339

Staff estimates that 95 percent of the costs are capital costs attributed to

retrofitting buses and a few trucks with DPFs and replacing a few bus and truck

engines with new or newer engines through engine repower or purchase of a

new or newer vehicle, to meet PM reduction requirements. Of the costs of the

DPFs, approximately 80 percent are capital costs with the rest attributed to

maintenance and filter cleaning. All of the estimated NOx implementation costs

are capital expenditures.

The first phase of the proposed regulation will be the most expensive at slightly

less than 80 percent of total estimated costs. Staff assumes that transit agencies

would not spend any money until the second half of 2007, since fleet operators

are not expected to have to pay for vehicles ordered, or engine conversions, or

other installations, until they are delivered or completed shortly before the

December 31, 2007 deadline. The same assumption applies to the 2010

compliance deadline.
39

The overall range of cost estimates above is equivalent to an annualized amount

ranging from $1.13 to $2.37 million, with a average annual amount of $1.66

million, over the 16 years from January 1, 2005 to December 31, 2020. These

values are in 2005 dollars.

The overall costs of this scenario can also be presented on an actual annual

basis. The values below represent 2005 dollars. The averages of the cost

estimates were used in Table 16.

Table 16. Annual Average Costs

Year Cost for PM Cost for NOx Total

2007 $11,364,611 $546,921 $11,911,533

2008 $333,469 $333,469

2009 $317,589 $317,589

2010 $3,461,223 $219,174 $3,680,397

2011 $379,504 $379,504

2012 $361,432 $361,432

2013 $344,221 $344,221

2014 $327,830 $327,830

2015 $312,219 $312,219

2016 $297,351 $297,351

2017 $283,192 $283,192

2018 $64,985 $64,985

2019 $61,891 $61,891

2020 $58,944 $58,944

Total $17,968,460 $766,097 $18,734,557

3. Cost Estimates for Replacing or Repowering Transit Fleet Vehicles

The used-bus market is relatively small, thus staff expects transit agencies will

opt to have new or newer engines installed in existing buses. The cost of

repowering a bus with a newer engine that was not designed to fit in its engine

compartment is highly variable. The relevant factors include the actual physical

configuration and the number of other systems (such as transmission, radiator, or

electronic control systems) which must be changed for a functional conversion.

Also, the required number of identical conversions can play a very significant role

in the cost estimate, as economies of scale and practice can reduce per-vehicle

engine replacement costs dramatically. The estimated costs for bus engine

replacements range from a low of $16,500 to a high of $70,000, depending on

such factors as whether the replacement is mechanical to mechanical, electronic

to electronic, or mechanical to electronic (the most expensive option).
40

In contrast, the used-truck market is extensive, and most of the trucks that are

designated for replacement are relatively unspecialized. Thus, staff’s economic

analysis assumes that trucks with older engines will be sold and replaced by a

newer truck. Staff interviewed truck sales staff who are familiar with the market

and determined that the residual value of a pre-1994 model year truck is about

$10,000, whereas the value of a 1994 to 2002 model year truck is about $25,000

to $30,000. Thus, the net cost of replacing a pre-1994 model year truck with a

1994 to 2002 model year truck is $15,000 to $20,000. Appendix D contains

additional details regarding the cost estimates for replacing or repowering a

transit fleet vehicle.

4. Cost Estimates for Diesel Particulate Filters (DPFs)

In this cost analysis, staff included only capital costs and annual filter cleaning

costs. Passive DPFs have been readily available for several years, and currently

prices are relatively stable. Estimates typically range from $7,000 to $8,000

installed, but could conceivably be as little as $6000 or as much as $11,000. A

number of the higher-emitting engines targeted by this regulation have EGR

valves, which means that active DPFs could be required; however, no product for

an EGR engine is verified yet. Staff expects that an active DPF will be

successfully verified in the near future, and well before the end of 2007. The

expected cost range of such prospective technology is less certain; the cost

analysis assumed a range of $8,500 to $20,000.

In addition, a DPF requires annual cleaning. Typically, this procedure is

outsourced, and ranges from $250 to $500 per year. Fleet operators may elect

to purchase a cleaning machine and take care of this themselves; the break-even

point for making this approach cost-effective is about 17 vehicles. Staff did not

analyze the cost of purchasing a cleaning machine, although it could be less

expensive for a larger agency than outsourcing the cleaning. Thus staff expects

that its cost estimate for DPF maintenance is high. See Appendix D for

additional details on the cost estimates for a DPF.

H. Costs to Individuals

Raising fares is one of the few ways transit operators can unilaterally raise

revenues. However, farebox revenues represent a minority of operating

expenses, and staff believes, based on discussions with transit operators, that

they are rarely used for capital expenditures. Of California transit agencies

operating 100 or more buses, the percentage of operating revenue from fares

ranges from 14.6 to 51.8 percent, with an average 31.75 percent. While riders

tend to be price-sensitive to fare increases, many agencies offer monthly passes

or discounts on purchases of set numbers of tickets or tokens that can reduce

rider costs. Staff was unable to provide a reasonable estimate of potential costs

to individuals because we can not predict if or how transit agencies would raise

fares.
41

X. ENVIRONMENTAL IMPACT AND COST EFFECTIVENESS

A. Statewide Emission Benefits

ARB staff estimates that in 2010 the proposed amendments would result in the

reduction of 44 pounds per day (lbs/day) of diesel PM, 380 lbs/day of NOx, 80

lbs/day of hydrocarbons (HC), and 80 lbs/day of carbon monoxide (CO)

emissions. In 2020, staff estimates reductions of 47 lbs/day of diesel PM, 620

lbs/day of NOx, 140 lbs/day of HC, and 100 lbs/day of CO emissions.

The proposed amendments, along with the more stringent engine emission

standards identified in the 2000 Diesel Risk Reduction Plan, reduce PM

emissions by 43 percent and 81 percent reduction in 2010 and 2020,

respectively, from the 2000 baseline emissions. NOx is reduced 29 percent in

2010 and 83 percent in 2020 from the 2000 baseline emissions (Tables 17 to

20).

Table 17. Proposed Regulation PM Emission Reductions

Calendar Diesel PM Emissions (lbs/day)

Year Baseline Proposal Reductions from

Baseline

2000 158 158 0

2005 149 149 0

2010 133 90 43

2015 81 30 51

2020 77 30 47

Table 18. Proposed Regulation NOx Emission Reductions

Calendar NOx Emissions (tpd)

Year Baseline Proposal Reductions from

Baseline

2000 4.48 4.48 0

2005 4.07 4.07 0

2010 3.47 3.28 0.19

2015 1.87 1.52 0.35

2020 0.81 0.50 0.31
42

Table 19. Proposed Regulation HC Emission Reductions

Calendar HC Emissions (tpd)

Year Baseline Proposal Reductions from

Baseline

2000 0.99 0.99 0

2005 0.86 0.86 0

2010 0.70 0.66 0.04

2015 0.37 0.26 0.11

2020 0.14 0.07 0.07

Table 20. Proposed Regulation CO Emission Reductions

Calendar CO Emissions (tpd)

Year Baseline Proposal Reductions from

Baseline

2000 0.78 0.78 0

2005 0.67 0.67 0

2010 0.57 0.53 0.04

2015 0.35 0.30 0.05

2020 0.22 0.17 0.05

B. Impacts on the State Implementation Plan

Currently several air basins are classified as nonattainment for the federal PM10

ambient air standard and have developed plans to meet this goal. This proposed

rule will assist those air basins in achieving and maintaining the standard. The

PM reductions will also serve as a down payment on future plans to achieve the

federal PM2.5 standards and California's more stringent standards. Most of the air

basins are in non-attainment for the state PM standards.

C. Health Benefits of Reductions of Diesel PM Emissions

Staff estimates that approximately 11 premature deaths will be avoided from the

implementation of this proposal. The proposed regulation is expected to reduce

PM emissions by a cumulative amount of 140 tons by the end of year 2020, and

therefore prevent an estimated 10 premature deaths (5 to 15, 95 percent

confidence interval (95% CI)) by year 2020. In addition, staff estimates that the

proposed regulation is expected to accrue a cumulative reduction of 620 tons of

NOx by the end of 2020, therefore avoiding an estimated 1 premature death (0 to

1, 95% CI).
43

1. Primary Diesel PM

Lloyd and Cackette estimated that, based on the Krewski et al. study4, 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 PM2.5 emissions corresponding to that PM2.5

concentration of 1.8 μg/m3 is 28,000 tpy (ARB, 2000b). Based on this

information, we estimate that reducing 14.11 tpy of diesel PM2.5 emissions would

result in one fewer premature death (28,000 tons/1,985 deaths). Comparing the

PM emissions before and after this regulation, the proposed regulation is

expected to reduce PM emissions by a cumulative amount of 140 tons by the

end of year 2020, and therefore prevent an estimated 10 premature deaths (5 to

15, 95% CI) by year 2020.

2. Secondary Diesel PM

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 that PM2.5 concentration of 0.81 μg/m3 is

1,641 tpd (598,965 tpy). Following the same approach as above, we estimate

that reducing 669 tons of NOx emissions would result in one fewer premature

death (598,965 tons/895 deaths). Therefore, with a cumulative NOx reduction of

620 tons by the end of 2020, an estimated 1 premature death (0 to 1, 95% CI)

would be avoided.

D. Cost-Effectiveness of Proposed Regulation

Staff determined that this rule is a cost-effective method of reducing PM and NOx

emissions when compared to other similar, recently adopted measures. Staff

developed low-cost and high-cost scenarios for calculating cost-effectiveness for

this proposal. For PM, the cost-effectiveness ratio is $85,000 per ton ($42 per

pound) for the low-cost estimate, and $176,000 per ton ($88 per pound) for the

high-cost estimate. For NOx, the cost-effectiveness ratio is $1,800 per ton

($0.90 per pound) for the low-cost estimate and $3,700 per ton ($1.90 per pound)

 

4

 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 et al., 1995)
44

for the high-cost estimate. The cost effectiveness values are similar to the cost

effectiveness of other recently adopted emission reduction measures.

In order to determine cost-effectiveness, ARB followed the following steps:

• For each year, note the annualized cost and the annual emission reductions.

• Allocate a portion of the costs to PM and the rest to NOx, in proportion to the

premature deaths prevented by the regulation. Since 91 percent of the

estimated deaths prevented by this regulation would be attributed to PM

emission reduction, we allocate 91 percent of these costs to PMemission

reductions and 9 percent to NOx reductions.

• Discount the cost in each year to 2004, using a 5 percent discount rate.

• Calculate the cost-effectiveness ratio in each year.

• Calculate a weighted average of these values, using the weights proportional

to the annual emission reductions.

E. Benefit-Cost Analysis

The benefit-cost analysis, as discussed below, is based on the estimated value

of avoiding one premature death, as well as the cost of control to prevent a

premature death.

1. Value of Premature Deaths Avoided

The U.S. EPA has established $6.3 million (in 2000 dollars) 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 dollars) 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 2004

dollars and discounted values of avoiding a premature death in the future back to

the year 2004. The U.S. EPA’s guidance on social discounting recommends

using both three and seven percent discount rates (U.S. EPA, 2000). Based on

these rates, and the annual avoided deaths as weights, the weighted average

value of reducing a future premature death, discounted back to the year 2004, is

around $4 million at the seven percent discount rate, and $6 million at three

percent.

2. Cost of Avoiding Premature Deaths

The average cost per premature death avoided is about $2 million using a 3
45

percent discount rate or about $1.5 million using a 7 percent discount rate.5

This calculation is similar to the one described above, except that we took a

weighted average of the cost of control, rather than the benefit of avoided

premature death. We allocated 91 percent of these costs to PM and the rest to

NOx, since 91 percent of the estimated deaths prevented by this regulation

would be attributed to PM emission reduction, and 9 percent to NOx reductions.

Using the same discount rates (3% and 7%) recommended by the U.S. EPA, we

discounted the cost in each year to 2004. The weighted average cost per

premature death avoided is then derived by using the annual premature deaths

avoided as weight.

3. Comparison

The social benefits of this regulation exceed the cost by a factor of about three.6

• Results using a 3 percent discount rate. The value of a premature death

avoided is about $6 million. The average cost per premature death avoided is

about $2 million.

• Results using a 7 percent discount rate. The value of a premature death

avoided is about $4 million. The average cost per premature death avoided is

about $1.5 million.

This rule is, therefore, a cost-effective mechanism to reduce premature deaths

that would otherwise be caused by diesel emissions without this regulation.

F. Potential Negative Impacts

Staff identified three potential negative impacts from this proposed rule.

1. NO2 Emissions from Diesel Particulate Filters

To the extent that transit agencies install diesel particulate filters on engines to

reduce diesel PM, there will be some impact from an increase in nitrogen dioxide

(NO2) emissions relative to the total NOx emissions from the tailpipe. 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 more stringent 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.

 

5

 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.

6

 The results presented here are point estimates. Their values are actually uncertain. Not all of

the uncertainties have been quantified, so it would be misleading to calculate and report a

confidence interval for the results.
46

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 helps to burn soot captured in the filter.

More NO2 is created than is actually used in the regeneration process and the

excess is emitted. The NO2 to 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.

In 2002, as part of the work to establish verification procedures, ARB conducted

an atmospheric modeling study that found that an NO2 to NOX emission ratio of

about 20 percent would nearly eliminate any impact of increased NO2 emissions.

The simulations were based on an assumed 90 percent market penetration of

diesel particulate filters with varying NO2/NOx ratios of 15, 20, 25, 30 and 50

percent (Table 21).

Table 21. Summary of Relative Percent Impacts from Simulated NO2/NOx

Diesel NO2/NOx 15% 20% 25% 30% 50%

24-hour O3

Exposure >

 90 ppb (%)

-3 -2 0 +2 +5

Summer

Peak 24-Hour

PM2.5

-3 N/A* N/A* -2 -1

Fall Peak 24-Hour

PM2.5

-6 N/A N/A -5 -3

Winter

Winter Peak 1-hr

Exposure NO2

(%)

+1 +6 +12 +18 +41

* N/A means the results were not available. However, the results can be estimated through

interpolation of NO2/NOx ratios between 15 and 30 percent.

The results of the study suggest that at a NO2/NOx ratio of 20 percent (twice the

baseline NO2/NOx ratio of a diesel engine without a passive catalyzed filter, used

in the simulation), population exposure to ozone levels above the 1-hour State

ozone standard would be reduced slightly. Simulated winter peak NO2 would

increase, but remain well below the state ambient air quality standard, and both
47

summer and fall PM 2.5 concentrations would decrease. The decrease in PM2.5

occurs because the filter reduces carbon particles and hydrocarbon emissions.

These reductions more than offset the increase in nitrates which are formed in

the atmosphere because of the higher NO2 emissions.

Based on this study, staff proposed a cap of 20 percent of NO2 to NOx emission

ratio be established for all verified diesel emission control technologies. To

ensure that the cap does not penalize retrofit strategies that reduce total NOx

emissions, the 20 percent cap is determined from the baseline (pre-control)

emissions.

In December 2003, the Board delayed the effective date of the 20 percent NO2

limit, which was to go into effect on January 1, 2004. This was necessary

because no Level 3 DECSs had been verified that met the NO2 limit, and the

implementation of upcoming retrofit regulations required the installation of a

verified system on certain vehicle fleets. Furthermore, questions had arisen

surrounding the accuracy of the assumptions that led to selection of the 20

percent limit and the nature of engine-out NO2 emissions. Therefore, the

effective date of the NO2 limit was delayed until January 1, 2007. This three-year

delay gives staff time to gather additional data and to develop an understanding

of the various aspects of the NO2 issue and gives manufacturers time for

additional research and development.

To address these issues the ARB created an NO2 working group committee

composed of scientists, health professionals, and manufacturers from around the

world. This group provided input to ARB on how to control emissions of NO2

from diesel retrofits. Their focus was on studying near-field NO2 exposure

scenarios, reevaluating the existing 20 percent NO2 limit in the verification

procedure, sharing emissions data, exploring technological issues, identifying

information needs, and evaluating regulatory alternatives.

The results of this work were presented at the International Diesel Retrofit

Advisory Committee meeting on October 5, 2004. Screening analyses have

indicated that the 20 percent NO2 limit would be sufficiently protective in nearfield exposure scenarios, as well as in regional ambient air quality scenarios.

Staff is now working on the rulemaking effort to refine the specific requirements

for verification to take into account these results while still allowing greater

application of retrofit PM reduction technologies to engines whose baseline NO2

exceeds 20 percent of their baseline NOx.

2. Diesel Oxidation Catalyst Emissions and Disposal

Two potential adverse environmental impacts of the use and disposal 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
48

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. Diesel oxidation catalysts are usually recycled, however, 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 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

Health and Safety Code, division 20; title 22, CCR, division 4.5; and title 40 of the

Code of Federal Regulations. Staff recommends 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.

ARB staff has consulted with personnel of the DTSC regarding management of

the ash from diesel particulate filters. 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.7

 

7

 Information can be obtained from local duty officers and from the website:

http://www.dtsc.ca.gov.
49

XI. ISSUES

Over the course of development of this proposal, staff has met many times with

various stakeholders and received written and verbal comments. Although staff

has considered each comment, not all issues could be resolved. Following is a

discussion of major outstanding issues.

A. Cost is too high for agencies in low population counties

Staff has received comments during workshops stating that in low population

counties, or rural areas, funding is not as available for bus purchases as in urban

areas. These transit agencies state that they cannot obtain funding from their

general county funds because the proposed regulations exceed general fund

capacities or contingencies. In addition, funding for the current vehicle

replacement program comes from the State Transportation Improvement

Program (STIP) and due to the state budget crisis, the 2004 STIP provides no

new programming capacity. As a result, some commenters contend that there

are no future capital funds to purchase transit vehicles.

Federal funds typically pay for most of the cost of a new transit bus - the Federal

Transit Administration (FTA) pays 80-83 percent of the purchase cost of a new

bus. The remaining cost is made up from local and state transportation funds

such as operational revenues, local sales tax, state fuel tax and state

transportation accounts. The transportation planning agencies prioritize project

categories and assign funding to each category. Transportation projects can

include planning projects, streets and highways, bridges, public transit, rail

projects, ferry operations, pedestrian and bicycle facilities, and other services

and projects.

To address the funding issue, staff worked with the California Association for

Coordinated Transportation, the Regional Council of Rural Counties, and rural

transportation agencies. Staff evaluated approximately 20 transit agencies that

were located in communities with a population of less than 50,000, and that are

not subject to the current fleet rule for transit agencies (see Appendix C for the

list). The fleet size of these transit agencies ranges from one to thirteen transit

fleet vehicles, with an average of six. These transit agencies primarily own and

operate buses that are eligible for FTA and state and local matching funds.

Some of the local transit agencies rely on private contracts or "turnkey

operations" for their fleets. Staff evaluated existing extensions and added

extensions to provide a sufficient safety net for rural counties. The following

discussion details how the regulation supports small transit fleets.
50

1. PM Emission Reductions

A small transit agency located in a 1-hour ozone attainment area is eligible for an

extension on the PM reduction requirement. The transit agency may delay

compliance with the intermediate 2007 PM requirement, extending their

compliance to the final compliance date on December 31, 2010. This extension

provides the opportunity for the a transit agency to delay or forego the installation

of a diesel emission control strategy on a TFV or urban bus and take advantage

of the purchase of a 2007 or newer vehicle that is certified to the most stringent

particulate engine exhaust emission standard.

2. Contract Operations

It was brought to staff's attention that a few smaller communities do not own their

fleets but contract for "turnkey" operations. Staff has added a new extension for

transit agencies operating transit fleet vehicles through contract. The transit

agency may apply annually to extend their compliance deadlines to allow for the

termination of a vehicle lease, maintenance/lease, turnkey, or service contract

operations of transit fleet vehicles.

3. Financial Hardship

An extension is provided for transit agencies with fewer than 30 vehicles (urban

bus and TFV) that can not meet the compliance deadlines as a result of financial

hardship. A transit agency can apply for an extension of a compliance deadline

based on financial hardship. Financial hardship must be documented, including

an analysis of the cost of compliance, the sources of available funds, and the

shortfall between funds available and the cost of compliance. The transit agency

must also specify the date and means by which compliance will be achieved in

the request for a delay. This information provides for a case-by-case analysis of

each transit agency's situation.

In summary, staff believes that modifications made to the proposed requirements

provide for a sufficient safety net for rural counties.

B. Commuter Service Bus Definition

Transit agencies requested that staff develop a new definition that would exclude

over-the-road coaches in commuter service from the definition of an urban bus.

After meeting with transit agency, staff proposed a definition based on the engine

type (heavy-heavy duty engine) and the duty cycle (number of stops). Staff has

received comments that the definition of "Commuter Service Bus" should instead

focus more on the style of the vehicle, such as a motor coach with features such

as only one door, reading lights, reclining seats, and luggage racks.
51

ARB focused on urban bus emissions for the development of the original fleet

rule for transit agencies in 2000 because the duty cycle of an urban bus

generates high levels of emissions. When an over-the-road coach is operated

like an urban bus it emits the same or more emissions, especially as a 45 ft.

motor coach is typically not equipped with an engine certified to the urban bus

engine emission standard. Staff's definition of "Commuter Service Bus" focuses

on the duty cycle of the bus not on how the bus looks. Therefore, staff believes

the proposed definition is appropriate for this type of vehicle. Staff also is

concerned that changing the definition to focus more on the features of a motor

coach than its duty cycle would potentially expand the number of buses that are

not treated as urban buses and thus could result in excess emissions.

XII. STAFF RECOMMENDATION

ARB staff recommends that the Board adopt the proposed modifications to title

13, CCR, sections 1956.1, 1956.2, 1956.3, 1956.4, and 2020, and proposed new

sections 2023, 2023.1, 2023.2, 2023.3 and 2023.4, set forth in the proposed

Regulation Order in Appendix A. These new requirements will reduce NOx and

PM emissions and are consistent with the Board's Risk Reduction Plan to

Reduce Particulate Matter Emissions from Diesel-Fueled Engines and Vehicles

(ARB 2000).
52

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