oEPA
Office of Transportation EPA420-R-03-015
and Air Quality December 2003
United States
Environmental Protection
Agency
Final Regulatory Support
Document: Control of
Emissions from
Highway Motorcycles
> Printed on Recycled Paper
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EPA420-R-03-015
December 2003
Final Regulatory Support Document:
Control of Emissions from
Highway Motorcycles
Assessment and Standards Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
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Table of Contents
Executive Summary
CHAPTER 1: Air Quality, Health and Welfare Concerns
1.1 - Ozone 1-1
1.1.1 - General Background 1-1
1.1.2 - Health and Welfare Effects of Ozone and Its Precursors 1-3
1.1.3 - Additional Health and Welfare Effects of VOC and NOx Emissions 1-7
1.1.4 - Attainment and Maintenance of the 1-Hour and 8-Hour Ozone NAAQS ... 1-7
1.1.4.1 - 1-Hour Ozone Nonattainment Areas and Concentrations 1-8
1.1.4.2 - 8-Hour Ozone Levels: Current and Future Concentrations 1-11
1.1.5 - Other Ozone Welfare Effects 1-19
1.2 - Particulate Matter 1-19
1.2.1 - General Background 1-19
1.2.2 - Health and Welfare Effects of PM 1-20
1.2.3 - PM Nonattainment 1-21
1.2.3.1 - Current PM10 Nonattainment 1-21
1.2.3.2 - CurrentPM25Nonattainment 1-23
1.2.3.3 - Risk of Future PM25 Violations 1-24
1.2.4 - Particulate Matter and Visibility Degradation 1-32
1.3 - Air Toxics 1-35
1.3.1 -Benzene 1-35
1.3.2 - 1,3-Butadiene 1-37
1.3.3 - Formaldehyde 1-38
1.3.4 - Acetaldehyde 1-39
1.3.5 - Acrolein 1-40
1-41
1.4 - Inventory Contributions 1-41
1.4.1 - Inventory Contribution 1-41
1.4.2 - Inventory Impacts on a Per Vehicle Basis 1-44
1.5 - Other Health and Environmental Effects 1-45
1.5.1 - Acid Deposition 1-45
1.5.2 - Eutrophication and Nitrification 1-45
CHAPTER 2: Industry Characterization
2.1- Manufacturers 2-1
2.2 - Sales and Fleet Size 2-3
2.3 - Usage 2-5
2.4 - Current Trends 2-5
2.5 - Customer Concerns 2-6
2.5.1 - Performance 2-6
2.5.2 - Cost 2-6
2.5.3 - Consumer Modifications 2-7
2.5.4 - Safety 2-7
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CHAPTERS: Technology
3.1 - Introduction to Spark-Ignition Engine Technology 3-1
3.1.1 -Basics of Spark-Ignition Four-Stroke Engines 3-1
3.1.2 - Basics of Spark-ignition Two-stroke Engines 3-2
3.1.3 - Engine Calibration 3-3
3.1.3.1 - Air-fuel ratio 3-3
3.1.3.2 - Spark-timing: 3-4
3.1.3.3 - Fuel Metering 3-5
3.1.4 - Gaseous Fuels 3-6
3.2 - Exhaust Emissions and Control Technologies 3-6
3.2.1 - Combustion chamber design 3-7
3.2.2 - Exhaust gas recirculation 3-7
3.2.3 - Secondary air 3-7
3.2.4 - Catalytic Aftertreatment 3-8
3.2.4.1 - System cost 3-9
3.2.4.2 - Packaging constraints 3-9
3.2.4.3 - Two-Stroke Aftertreatment 3-9
3.2.5 - Multiple valves and variable valve timing 3-10
3.2.6 - Advanced Emission Controls 3-11
3.3 - Evaporative Emissions 3-13
3.3.1 Sources of Evaporative Emissions 3-13
3.3.1.1 - Diurnal and Running Loss Emissions 3-14
3.3.1.2 - Hot Soak Emissions 3-15
3.3.1.3 - Refueling Emissions 3-15
3.3.1.4-Permeation 3-15
3.3.2 Evaporative Emission Controls 3-16
3.3.2.1 Fuel Tanks 3-16
3.3.2.2 Fuel Hoses 3-17
4.1 - Exhaust Emission Control from Motorcycles 4-1
4.1.1 - Class I and II Motorcycles 4-3
4.1.1.1 - Class I Motorcycles Above 50cc and Class II Motorcycles 4-3
4.1.1.2 - Class I Motorcycles Under 50cc 4-4
4.1.2 - Class III Motorcycles 4-6
4.1.2.1 - Tier-1 Standards 4-6
4.1.2.2 - Analysis of EPA Certification Data 4-9
4.1.2.3 - Tier-2 Standards 4-11
4.1.2.5 - Conclusion 4-15
4.1.3 - Impacts on Noise, Energy, and Safety 4-16
4.2 - Permeation Evaporative Emission Control from Motorcycles 4-22
4.2.1 Baseline Technology and Emissions 4-22
4.2.1.1 Fuel Tanks 4-23
4.2.1.2 Fuel Hoses 4-25
4.2.2 Permeation Reduction Technologies 4-26
4.2.2.1 Fuel Tanks 4-26
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4.2.2.2 Fuel Hoses 4-36
4.2.2.3 Material Properties 4-39
4.2.3 Test Procedures 4-43
4.2.3.1 Fuel Tanks 4-43
4.2.3.2 Fuel Hoses 4-45
4.2.4 Conclusion 4-45
4.2.5 Impacts on Noise, Energy, and Safety 4-45
CHAPTER 5: Costs of Control
5.1 - Methodology 5-1
5.2 Costs for Permeation Evaporative Emission Control 5-3
5.2.1 - Technologies and Estimated Costs for Permeation Control 5-3
5-3
5.2.2 - Operating Cost Savings for Permeation Control 5-5
5.2.3 - Compliance Costs for Permeation Emission Control 5-5
5.3 - Exhaust Emission Control for Class III Highway Motorcycles 5-6
5.3.1 - Research and Development Costs 5-7
5.3.2 - Technologies and Estimated Costs for Class III Exhaust Emission Control . . 5-9
5.3.2 - Compliance Costs for Class III Exhaust Emission Control 5-13
5.3.3 - Total Costs for Class III Exhaust Emission Control 5-14
5.4 - Exhaust Emission Control for Highway Motorcycles Under 50cc 5-19
5.5 - Highway Motorcycle Aggregate Costs 5-21
CHAPTER 6: Emissions Inventory
6.1- General Methodology 6-1
6.1.1 - Highway Motorcycle Exhaust Emissions 6-1
6.1.2 - Highway Motorcycle Evaporative Emissions 6-1
6.1.2.1 - Permeation Emissions 6-2
6.1.2.2 - Diurnal Emissions 6-2
6.1.2.3 - Refueling Emissions 6-4
6.2 - Effect of Emission Controls by Engine/Vehicle Type 6-5
6.2.1 - Exhaust Emissions 6-5
6.2.1.1 - Inputs for the Inventory Calculations 6-5
6.2.1.2 - Reductions Due to the Standards 6-10
6.2.1.3 - Per Equipment Emissions from On-highway Motorcycles 6-11
6.2.2 - Evaporative Emissions 6-13
6.2.2.1 - Inputs for the Inventory Calculations 6-13
6.2.2.2 Permeation Emissions Inventory and Reductions 6-14
6.2.2.3 Per Motorcycle Permeation Emissions 6-15
6.2.2.4 Other Evaporative Emissions 6-16
CHAPTER 7 Cost Per Ton
7.1 - Cost Per Ton for Exhaust and Permeation Control 7-1
7.1.1 - Introduction 7-1
7.1.2 - Permeation Evaporative Emission Control for Motorcycles 7-1
7.1.3 - Exhaust Emission Control for Motorcycles 7-2
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7.2 - Cost Per Ton for Other Mobile Source Control Programs 7-4
7.3 - 20-Year Cost and Benefit Analysis 7-5
CHAPTER 8: Small Business Flexibility Analysis
8.1 - Requirements of the Regulatory Flexibility Act 8-1
8.2 - Need For and Objectives of the Rule 8-3
8.3 - Issues Raised by the Public Comments 8-3
8.4 - Description of Affected Entities 8-4
8.5 - Projected Reporting, Recordkeeping, and Other Compliance Requirements of the
Regulation 8-5
8.6 - Steps to Minimize Significant Economic Impacts on Small Entities 8-6
8.61 Delay of Implementation Timing of the Standards 8-6
8.6.2 Broader Engine Families 8-7
8.6.3 Averaging, Banking, and Trading 8-7
8.6.4 Reduced Certification Data Submittal and Testing Requirements 8-7
8.6.5 Hardship Provisions 8-7
8.7 - Conclusion 8-8
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Executive Summary
This Final Regulatory Support Document provides economic, technical, cost, and
environmental analyses of the new permeation evaporative and exhaust emission standards for
highway motorcycles. The anticipated emission reductions will translate into meaningful, long-
term improvements in air quality in many areas of the U.S. Overall, the new requirements will
reduce individual exposure to dangerous pollutants and provide much needed assistance to states
and regions facing ozone and particulate air quality problems that are causing a range of adverse
health effects, especially in terms of respiratory impairment and related illnesses.
Chapter 1 reviews information related to the health and welfare effects of the pollutants of
concern. Chapter 2 contains an overview of the affected manufacturers, including some
description of the range of vehicles/engines involved and their place in the market. Chapter 3
covers a broad description of engine and permeation evaporative emission control technologies,
including a wide variety of approaches to reducing emissions. Chapter 4 summarizes the
available information specifically providing a technical justification for the feasibility of the
standards. Chapter 5 applies cost estimates to the projected technologies. Chapter 6 presents the
calculated contribution of these sources to the nationwide emission inventories with and without
the new standards. Chapter 7 compares the costs and the emission reductions for an estimate of
the cost-effectiveness of the rulemaking. Chapter 8 presents our Small Business Flexibility
Analysis, which evaluates the impact of the rule on small businesses.
Market Overview
This regulation is designed to achieve emission reductions from highway motorcycles.
Even though there are tangible and intangible benefits associated with reducing emissions from
this source, control to the levels in these regulations has generally not been brought about by
market forces. From an overall perspective these are a relatively small portion of the overall
inventory for HC and NOx. This document will show that technology exists to achieve these
significant reductions from motorcycles and demonstrates that this control would be inexpensive
on a cost per ton basis. Presented below is a brief summary of the key factors pertaining to this
analysis and reference to more substantive discussions in later chapters when available.
Emissions Overview
The primary source of evaporative emissions is permeation through the walls of plastic fuel
tanks and rubber hoses. Fewer than ten percent of motorcycles use plastic fuel tanks, although
there is an indication that a larger fraction of motorcycles may be using plastic fuel tanks in the
future. Motorcycles generally use rubber fuel hose which has permeation rates several orders of
magnitude higher than typical automotive fuel lines.
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Exhaust emissions from motorcycles have been the subject of a Federal emission control
program for about twenty-five years. However, it has been over two decades since EPA last
reviewed these requirements. Technology has progressed over these years and indeed the nature
of the business and market forces are substantially different. The technology used and available
for most highway motorcycles now is far advanced beyond that called for by the 1980 era
Federal standards. Thus, there is a need for an update. Also, today, highway motorcycles are
predominantly a national and international commodity and importing and exporting of product is
the norm. Thus, harmonization of emission standards and control requirements is a key need for
industry with the added benefit of lower consumer cost.
Alternatives
In developing the permeation evaporative emission standards we looked at several
alternatives for potential emission control strategies and programs. In considering alternatives,
we investigated a wide range of technologies and considered various test procedures and
implementation dates. In addition, we established a emission credit program designed to give
manufacturers flexibility in what technology they use to comply with the standards. As required
by section 202(a)(3)(E) of the Clean Air Act (CAA, or "the Act"), we also considered "the need
to achieve equivalency of emission reductions between motorcycles and other motor vehicles to
the maximum extent practicable."
For permeation emission control of plastic fuel tanks, we identified a number of
technologies that could be used to meet the standards. These technologies include surface
treatments such as fluorination or sulfonation, low permeability barrier materials, and
construction using low permeability materials. In some cases manufacturers will be able to
certify to the permeation standards by design, if they elect to do so, by implementing designs
consistent with available data. For permeation emission control through hoses, we identify a
number of low permeability materials that could be used as either barriers or as construction
materials for the fuel lines. Hoses using these materials are used in automotive applications
today.
With regard to highway motorcycle exhaust emissions, the alternatives focus primarily on
meeting statutory requirements while at the same time tailoring the program to the way
motorcycles are produced, sold, and used. The evaluation of program alternatives focused
heavily on identifying options that would lead to the largest emission reductions available at the
lowest cost taking into account these factors. Consultations with industry made it clear that
harmonization with the California program was critical and that international harmonization was
also valuable when possible. From the engineering and users perspective, optimal design meant
establishing a program which permitted manufacturers and users technology choices to be
applied within the program. The alternatives considered by EPA looked at harmonization, lead
time, and emission credit averaging programs. For under 50cc motorcycles international
harmonization and adequate lead time were key as these drove cost and emission control
technology considerations. For 50 cc and larger motorcycles, California harmonization and
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emission credit averaging had a first order impact on cost and consumer choice. The actual
program and control technology options are discussed further in later chapters of this document.
Emission Standards
Evaporative Emissions
We are finalizing new permeation emission standards for motorcycle fuel tanks and hoses
that begin in 2008. These standards are presented in Table 1 and represent more than a 90
percent reduction in permeation from new motorcycles.
Table 1
Evaporative Emission Standards
Evaporative Emission
Component
Fuel Tank Permeation
Hose Permeation
Emission Standard
1.5 g/m2/day
15 g/m2/day
Test Gasoline
10%Ethanol
10%Ethanol
Test Temperature
40°C (104°F)
23°C (73°F)
Exhaust Emissions
We are adopting new exhaust emission standards for highway motorcycles. Motorcycles
come in a variety of two- and three-wheeled configurations and styles, but for the most part they
are two-wheeled, self-powered vehicles. Federal regulations currently define a motorcycle as
"any motor vehicle with a headlight, taillight, and stoplight and having: two wheels, or three
wheels and a curb mass less than or equal to 793 kilograms (1749 pounds)" (see 40 CFR
86.402-98). Note that if any motorcycle or motorcycle-like vehicle that can't be defined as a
motor vehicle (for example, if its top speed is less than 25 miles per hour), it would fall under
requirements that apply to nonroad recreational vehicles. Highway motorcycles include a
category referred to as "dual use" or "dual-sport," meaning that their designs incorporate features
that allow riders to use them both for street and off-highway application. Highway motorcycles
are operated on public roadways predominantly during warmer weather and often in or near
urban areas where they can contribute to ozone formation and ambient CO and PM levels.
Table 2 shows the new standards for highway motorcycles.
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Table 2
Highway Motorcycle Exhaust Emission Standards
Class
Class I
Class II
Class III
Engine Size (cc)
0-169
170-279
280 and above
Implementation
Date
2006
2006
2006
2010
HC
(g/km)
1.0
1.0
—
—
HC+NOx
fe/km)
1.4 (optional)
1.4 (optional)
1.4
0.8
CO (g/km)
12.0
12.0
12.0
12.0
Projected Impacts
The following paragraphs and tables summarize the projected emission reductions and costs
associated with the new emission standards. See the detailed analysis later in this document for
further discussion of these estimates. Table 3 contains the projected emissions from
motorcycles. Projected figures compare the estimated emission levels with and without the
emission standards (both the exhaust and permeation standards) for 2020.
Table 3
2020 Projected Emissions Inventories
(thousand short tons)
Exhaust and Permeation HC
base
case
79
with
standards
31
percent
reduction
61%
Exhaust NOx
base
case
14
with percent
standards reduction
7 50%
Table 4 summarizes the projected costs to meet the new emission standards. This is our best
estimate of the cost associated with adopting new technologies to meet the new emission
standards. The analysis also considers total operating costs, including maintenance and fuel
consumption. All costs are presented in 2001 dollars.
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Table 4
Estimated Average Cost Impacts of the New Emission Standards
Category
tank permeation
hose permeation
aggregate
Highway motorcycles <50cc
Highway motorcycles >50cc
Highway motorcycles >50cc
Standard
Date
2008
2006
2006
2010
Increased Production
Cost per Vehicle*
$0.17
$1.68
$1.85
$44
$30
$45**
Lifetime Operating Costs
per Engine (NPV)
($0.30)
($6.23)
($6.52)
($8)
—
—
* The estimated long-term costs for highway motorcycles >50cc decrease by about 35 percent.
** Costs presented are incremental to the first-phase standards.
We also calculated the cost per ton of emission reductions for the new standards. We
attributed the entire cost of the program to the control of ozone precursor emissions (HC or NOx
or both). Table 5 presents the discounted cost-per-ton estimates for the various engines factoring
in the effect of reduced operating costs such as fuel savings.
Table 5
Estimated Cost-per-Ton of the New Emission Standards
Engine Type
tank permeation
hose permeation
aggregate
Highway Motorcycles <50cc
Highway Motorcycles >50cc
Highway Motorcycles >50cc
Date
2008
2006
2006
2010
Pollutant
HC
HC
HC+NOx
HC+NOx
Discounted
Reductions
per Vehicle
(short tons)
0.003
0.017
0.02
0.02
0.03
0.03
Discounted Cost per Ton
Without Fuel Savings
$205
$98
$103
$2,130
$1,150
$1,550
With Fuel Savings
($158)
($265)
($260)
$1,750
$1,150
$1,550
Table 6 presents the annualized emission reductions, cost to manufacturers and fuel savings
for the twenty year period after the standards take effect based on a seven percent discount rate.
Because of the different implementation dates for the exhaust and permeation evaporative
emission standards, the aggregate is based on a 22 year (rather than twenty year) annualized cost.
Therefore, the aggregate is not equal to the sum of the costs for the two different standards.
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Table 6
Estimated Annualized Emission Reductions, Costs to Manufacturers,
and Annualized Fuel Savings Due to the New Motorcycle Standards
Standard
Exhaust
Permeation Evap
Aggregate
Annualized Emission
Reductions (tons/year)
18,100HC+NOx
11, 400 HC only
29,000 HC+NOx
Annualized Cost
to Manufacturers
(millions/year)
$32.0
$1.4
$33.4
Annualized Fuel
Savings
(millions/year)
$0.2
$4.2
$3.7
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CHAPTER 1: Air Quality, Health and Welfare Concerns
Highway motorcycles generate a complex mixture of HC and NOx emissions that contribute
to the formation of ground-level ozone. Along with SOx emissions from the sulfur content of
gasoline, these emissions are also involved in atmospheric transformation of secondary particle
formation. Highway motorcycle emissions also contribute to direct PM and air toxic emissions.
These pollutants cause a range of adverse health and welfare effects, especially in terms of
respiratory impairment and related illnesses. This chapter describes the health and
environmental effects related to these emissions. This chapter also presents our estimates of the
contribution these engines make to our national air inventory.1
Air quality modeling and monitoring data presented in this chapter indicate that a large
number of our citizens are affected by these emissions. Based on the most recent monitoring
data available (1999-2001), ozone and PM air quality problems are widespread in the United
States. There are about 111 million people living in counties exceeding the 8-hour ozone
National Ambient Air Quality Standard (NAAQS) and over 70 million people living in counties
with PM25 levels exceeding the PM25 NAAQS,. Figure 1-1 illustrates the widespread nature of
these problems by showing the areas that exceed the 8-hour ozone and the PM25 NAAQS. Also
shown are Class 1 areas, which have particular needs for reductions in haze.
The new federal highway motorcycle emission standards are another component of the
effort by Federal, State, local and Tribal governments to reduce the health related impacts of air
pollution and to reach attainment of the National Ambient Air Quality Standard (NAAQS) for
ozone and PM. They will also help reduce exposure to air toxics and improve other
environmental conditions such as atmospheric visibility.
1.1 - Ozone
1.1.1 - General Background
This section reviews health and welfare effects of ozone and describes the air quality
information that forms the basis of our conclusion that ozone concentrations in many areas
across the country face a significant risk of exceeding the ozone standard into the year 2030.
Information on air quality was gathered from a variety of sources, including monitored ozone
concentrations from 1999-2001, air quality modeling forecasts conducted for this rulemaking
and other state and local air quality information.
Ground-level ozone, the main ingredient in smog, is formed by the reaction of volatile
organic compounds (VOCs) and nitrogen oxides (NOx) in the atmosphere in the presence of heat
and sunlight. These pollutants, often referred to as ozone precursors, are emitted by many types
of pollution sources, including on-highway and nonroad motor vehicles and engines, power
plants, chemical plants, refineries, makers of consumer and commercial products, industrial
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Figure 1-1. Air Quality Problems are Widespread
Areas
£££?] Federal Class! Areas (Visibility) "^
Q^ Counties Exceeding 8-hr Ozone NAAQS
| | Counties Exceeding PM2.5 NAAQS
^| Counties Exceeding Both NAAQS
Air quality data derived from AQS (1999-2001)
with data handling per Agency guidance except PM2 5 data
includes monitors with complete data in at least 10 quarters.
facilities, and smaller "area" sources. VOCs are also emitted by natural sources such as
vegetation. Hydrocarbons are a set of compounds that are very similar to, but slightly different
from, VOCs, and to reduce mobile-source VOC levels we set maximum limits for HC
emissions.2 Oxides of nitrogen are emitted largely from motor vehicles, off-highway equipment,
power plants, and other sources of combustion.
The science of ozone formation, transport, and accumulation is complex. Ground-level
ozone is produced and destroyed in a cyclical set of chemical reactions involving NOx, VOC,
heat, and sunlight. Many of the chemical reactions that are part of the ozone-forming cycle are
sensitive to temperature and sunlight. When ambient temperatures and sunlight levels remain
high for several days and the air is relatively stagnant, ozone and its precursors can build up and
produce more ozone than typically would occur on a single high temperature day. Further
complicating matters, ozone also can be transported into an area from pollution sources found
hundreds of miles upwind, resulting in elevated ozone levels even in areas with low VOC or
NOx emissions. As a result, differences in NOx and VOC emissions and weather patterns
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contribute to daily, seasonal, and yearly differences in ozone concentrations and differences from
city to city.
These complexities also have implications for programs to reduce ozone. For example,
relatively small amounts of NOx enable ozone to form rapidly when VOC levels are relatively
high, but ozone production is quickly limited by removal of the NOx. Under these conditions,
NOx reductions are highly effective in reducing ozone while VOC reductions have little effect.
Such conditions are called "NOx-limited." Because the contribution of VOC emissions from
biogenic (natural) sources to local ambient ozone concentrations can be significant, even some
areas where man-made VOC emissions are relatively low can be NOx-limited.
When NOx levels are relatively high and VOC levels relatively low, NOx forms inorganic
nitrates (i.e., particles) but relatively little ozone. Such conditions are called "VOC-limited."
Under these conditions, VOC reductions are effective in reducing ozone, but NOx reductions can
actually increase local ozone under certain circumstances. Even in VOC-limited urban areas,
NOx reductions are not expected to increase ozone levels if the NOx reductions are sufficiently
large. The highest levels of ozone are produced when both VOC and NOx emissions are present
in significant quantities on clear summer days.
Rural areas are almost always NOx-limited, due to the relatively large amounts of biogenic
VOC emissions in such areas. Urban areas can be either VOC- or NOx-limited, or a mixture of
both, in which ozone levels exhibit moderate sensitivity to changes in either pollutant.
Ozone concentrations in an area also can be lowered by the reaction of nitric oxide with
ozone, forming nitrogen dioxide (NO2); as the air moves downwind and the cycle continues, the
NO2 forms additional ozone. The importance of this reaction depends, in part, on the relative
concentrations of NOx, VOC, and ozone, all of which change with time and location.
1.1.2 - Health and Welfare Effects of Ozone and Its Precursors
Exposure to ambient ozone contributes to a wide range of adverse health effects, which are
discussed in detail in the EPA Air Quality Criteria Document for Ozone.3 Effects include lung
function decrements, respiratory symptoms, aggravation of asthma, increased hospital and
emergency room visits, increased medication usage, inflammation of the lungs, as well as a
variety of other respiratory effects. People who are particularly at risk for high ozone exposures
include healthy children and adults who are active outdoors. Susceptible subgroups include
children, people with respiratory disease, such as asthma, and people with unusual sensitivity to
ozone.
Based on a large number of scientific studies, EPA has identified several key health effects
caused when people are exposed to levels of ozone found today in many areas of the country.
Short-term (1 to 3 hours) and prolonged exposures (6 to 8 hours) to higher ambient ozone
concentrations have been linked to lung function decrements, respiratory symptoms, increased
hospital admissions and emergency room visits for respiratory problems.4'5'6'7'8'9 Repeated
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exposure to ozone can make people more susceptible to respiratory infection and lung
inflammation and can aggravate preexisting respiratory diseases, such as asthma.10'n'12'13'14 It
also can cause inflammation of the lung, impairment of lung defense mechanisms, and possibly
irreversible changes in lung structure, which over time could lead to premature aging of the
lungs and/or chronic respiratory illnesses, such as emphysema and chronic bronchitis.15'16> 17'18
Adults who are outdoors and active during the summer months, such as construction
workers and other outdoor workers, also are among those most at risk of elevated exposures.19
This is because they typically are active outside, playing and exercising, during the summer
when ozone levels are highest.20'21 For example, summer camp studies in the Eastern U.S. and
southeastern Canada have reported significant reductions in lung function in children who are
active outdoors.22'23'24'25'26> 27'28'29 Further, children are more at risk of experiencing health
effects than adults from ozone exposure because their respiratory systems are still developing.
These individuals, as well as people with respiratory illnesses such as asthma, especially
asthmatic children, can experience reduced lung function and increased respiratory symptoms,
such as chest pain and cough, when exposed to relatively low ozone levels during prolonged
periods of moderate exertion.30'31'32'33
The 8-hour NAAQS is based on well-documented science demonstrating that more people
experience adverse health effects at lower levels of exertion, over longer periods, and at lower
ozone concentrations than addressed by the 1-hour ozone standard.34 Attaining the 8-hour
standard will greatly limit ozone exposures of concern for the general population and
populations most at risk, including children active outdoors, outdoor workers, and individuals
with pre-existing respiratory disease, such as asthma.
New research suggests additional serious health effects beyond those that were known when
the 8-hour ozone standard was set. Since 1997, over 1,700 new health and welfare studies have
been published in peer-reviewed journals.35 Many of these studies investigate the impact of
ozone exposure on such health effects as changes in lung structure and biochemistry,
inflammation of the lungs, exacerbation and causation of asthma, respiratory illness-related
school absence, hospital and emergency room visits for asthma and other respiratory causes, and
premature mortality. EPA is currently evaluating these and other studies as part of the ongoing
review of the air quality criteria and NAAQS for ozone. A revised Air Quality Criteria
Document for Ozone and Other Photochemical Oxidants will be prepared in consultation with
the EPA's Clean Air Scientific Advisory Committee (CASAC).
Key new health information falls into four general areas: development of new-onset asthma,
hospital admissions for young children, school absence rates, and premature mortality.
Examples of new studies in these areas are briefly discussed below.
Aggravation of existing asthma resulting from short-term ambient ozone exposure was
reported prior to the 1997 decision and has been observed in studies published since.36'37 More
recent studies now suggest a relationship between long-term ambient ozone concentrations and
the incidence of new-onset asthma. In particular, such a relationship in adult males (but not in
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females) was reported by McDonnell et al. (1999).38 Subsequently, McConnell et al. (2002)
reported that incidence of new diagnoses of asthma in children is associated with heavy exercise
in communities with high concentrations of ozone (i.e., mean 8-hour concentration of 59.6
ppb).39 This relationship was documented in children who played three or more sports and was
not statistically significant for those children who played one or two sports.1 The larger effect of
high activity sports than low activity sports and an independent effect of time spent outdoors also
in the higher ozone communities strengthened the inference that exposure to ozone may modify
the effect of sports on the development of asthma in some children.
Previous studies have shown relationships between ozone and hospital admissions in the
general population. A new study in Toronto reports a significant relationship between 1-hour
maximum ozone concentrations and respiratory hospital admissions in children under two.40
Given the relative vulnerability of children in this age category, we are particularly concerned
about the findings from the literature on ozone and hospital admissions.
Increased respiratory disease that are serious enough to cause school absences has been
associated with 1-hour daily maximum and 8-hour average ozone concentrations in studies
conducted in Nevada in kindergarten to 6th grade 41 and in Southern California in grades 4 to 6.42
These studies suggest that higher ambient ozone levels may result in increased school
absenteeism.
The ambient air pollutant most clearly associated with premature mortality is PM, with
dozens of studies reporting such an association. However, repeated ozone exposure may be a
contributing factor for premature mortality, causing an inflammatory response in the lungs which
may predispose elderly and other sensitive individuals to become more susceptible to the adverse
health effects of other air pollutants, such as PM.43'44 Although the findings in the past have been
mixed, the findings of three recent analyses suggest that ozone exposure is associated with
increased mortality. Although the National Morbidity, Mortality, and Air Pollution Study
(NMMAPS) did not find an effect of ozone on total mortality across the full year, Samet et al.
(2000), who conducted the NMMAPS study, did report an effect after limiting the analysis to
summer when ozone levels are highest.45 Similarly, Thurston and Ito (1999) have reported
associations between ozone and mortality.46 Toulomi et al., (1997) reported that 1-hour
maximum ozone levels were associated with daily numbers of deaths in 4 cities (London,
Athens, Barcelona, and Paris), and a quantitatively similar effect was found in a group of 4
additional cities (Amsterdam, Basel, Geneva, and Zurich).47
In 2002, questions were raised about the default convergence criteria and standard error
calculations made using generalized additive models (GAM), which has been commonly used in
recent time-series epidemiologic studies. A number of time-series studies were reanalyzed using
alternative methods, typically GAM with more stringent convergence criteria and an alternative
In communities with high ozone (i.e., mean 8-hour concentration of 59.6 ppb) the relative risk of
developing asthma in children playing three or more sports was 3.3. (95% CI 1.9 - 5.8) compared with children
playing no sports.
1-5
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model such as generalized linear models (GLM) with natural smoothing splines, and the results
of the reanalyses have been compiled and reviewed in a recent Health Effects Institute (HEI)
publication.48 In most, but not all, of the reanalyzed studies, it was found that risk estimates
were reduced and confidence intervals increased with the use of GAM with more stringent
convergence criteria or GLM analyses; however, the reanalyses generally did not substantially
change the findings of the original studies, and the changes in risk estimates with alternative
analysis methods were much smaller than the variation in effects across studies. The HEI review
committee concluded:
a. While the number of studies showing an association of PM with
mortality was slightly smaller, the PM association persisted in the
majority of studies.
b. In some of the large number of studies in which the PM association
persisted, the estimates of PM effect were substantially smaller.
c. In the few studies in which investigators performed further sensitivity
analyses, some showed marked sensitivity of the PM effect estimate to
the degree of smoothing and/or the specification of weather.49
It is important to note that the estimates derived from the long-term exposure studies and the
time-series studies employing generalized linear models or other parametric methods, as well as
case-crossover studies, are not affected.
In addition to human health effects, ozone adversely affects crop yield, vegetation and forest
growth, and the durability of materials. These effects are discussed in the Ozone Criteria
Document and Staff Paper. Because ground-level ozone interferes with the ability of a plant to
produce and store food, plants become more susceptible to disease, insect attack, harsh weather
and other environmental stresses. Ozone causes noticeable foliage damage in many crops, trees,
and ornamental plants (i.e., grass, flowers, shrubs) and causes reduced growth in plants. Studies
indicate that current ambient levels of ozone are responsible for damage to forests and
ecosystems (including habitat for native animal species). Ozone chemically attacks elastomers
(natural rubber and certain synthetic polymers), textile fibers and dyes, and, to a lesser extent,
paints. For example, elastomers become brittle and crack, and dyes fade after exposure to ozone.
1.1.3 - Additional Health and Welfare Effects of VOC and NOx Emissions
Volatile organic compounds emissions are detrimental not only for their role in forming
ozone, but also for their role as air toxics. Some VOCs emitted from highway motorcycles are
toxic compounds. At elevated concentrations and exposures, human health effects from air
toxics can range from respiratory effects to cancer. Other health impacts include neurological
developmental and reproductive effects. The lexicologically significant VOCs emitted in
substantial quantities from the engines that are the subject of this rule are discussed in more
detail in Section 1.3, below.
1-6
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In addition to NOx's role as an ozone and PM precursor, NOx emissions by themselves are
associated with a wide variety of other health and welfare effects.50 51 Nitrogen dioxide can
irritate the lungs and lower resistance to respiratory infection (such as influenza). NOx
emissions are an important precursor to acid rain that may affect both terrestrial and aquatic
ecosystems. Atmospheric deposition of nitrogen leads to excess nutrient enrichment problems
("eutrophication") in the Chesapeake Bay and several nationally important estuaries along the
East and Gulf Coasts. Eutrophication can produce multiple adverse effects on water quality and
the aquatic environment, including increased algal blooms, excessive phytoplankton growth, and
low or no dissolved oxygen in bottom waters. Eutrophication also reduces sunlight, causing
losses in submerged aquatic vegetation critical for healthy estuarine ecosystems. Deposition of
nitrogen-containing compounds also affects terrestrial ecosystems. Nitrogen fertilization can
alter growth patterns and change the balance of species in an ecosystem. In extreme cases, this
process can result in nitrogen saturation when additions of nitrogen to soil over time exceed the
capacity of plants and microorganisms to utilize and retain the nitrogen. These environmental
impacts are discussed further in Sections 1.5.1 and 1.5.2, below.
Elevated levels of nitrates in drinking water pose significant health risks, especially to
infants. Studies have shown that a substantial rise in nitrogen levels in surface waters is highly
correlated with human-generated inputs of nitrogen in those watersheds.52 These nitrogen inputs
are dominated by fertilizers and atmospheric deposition. Nitrogen dioxide and airborne nitrate
also contribute to pollutant haze, which impairs visibility and can reduce residential property
values and the value placed on scenic views.
1.1.4 - Attainment and Maintenance of the 1-Hour and 8-Hour Ozone NAAQS
As illustrated in Figure 1-1, unhealthy ozone concentrations - i.e., those exceeding the level
of the 8-hour standard which is requisite to protect public health with an adequate margin of
safety - occur over wide geographic areas, including most of the nation's major population
centers. Highway motorcycle emissions contribute to ozone precursors in metropolitan areas
during the ozone season.
In analyzing ozone concentrations in counties, we calculate design values. An ozone design
value is the concentration that determines whether a monitoring site meets the NAAQS for
ozone. Because of the way they are defined, design values are determined based on 3
consecutive-year monitoring periods. For example, an 8-hour design value is the fourth highest
daily maximum 8-hour average ozone concentration measured over a three-year period at a given
monitor. The full details of these determinations (including accounting for missing values and
other complexities) are given in Appendices H and I of 40 CFR Part 50. As discussed in these
appendices, design values are truncated to whole part per billion (ppb). Due to the precision
with which the standards are expressed (0.08 parts per million (ppm) for the 8-hour), a violation
of the 8-hour standard is defined as a design value greater than or equal to 0.085 ppm. We
follow this convention in these analyses.
1-7
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For a county, the design value is the highest design value from among all the monitors with
valid design values within that county. If a county does not contain an ozone monitor, it does
not have a design value. Thus, our analysis may underestimate the number of counties with
design values above the level of NAAQS. For the purposes of defining the current design value
of a given area, the 1999-2001 design values were chosen to provide the most recent set of air
quality data for identifying areas likely to have an ozone problem in the future. The 1999-2001
design values are listed in the air quality technical support document prepared for our recent
Notice of Proposed Rulemaking proposing more stringent emission standards for nonroad diesel
engines and the diesel fuel used in those engines (the Nonroad proposal, 68 FR 28328, May 23,
2003).53
1.1.4.1 - 1-Hour Ozone Nonattainment Areas and Concentrations
The 1-hour ozone NAAQS is 0.12 ppm daily maximum 1-hour concentration, not to be
exceeded more than once per year on average. Currently, there are about 114 million people
living in 53 1-hour ozone nonattainment areas covering 223 counties.54
-------
Table 1.1-1
1-Hour Ozone Extreme and Severe Nonattainment Areas
Nonattainment Area
Los Angeles South Coast Air Basin,
CAa
Chicago-Gary-Lake County, IL-IN
Houston-Galveston-Brazoria, TX
Milwaukee-Racine, WI
New York-New Jersey -Long Island,
NY-NJ-CT
Southeast Desert Modified AQMA, CA
Baltimore, MD
Baton Rouge, LA
Philadelphia- Wilmington-Trenton, PA-
NJ-DE-MD
Sacramento, CA
San Joaquin Valley, CA
Ventura County, CA
Washington, DC-MD-VA
Total Population
Attainment
Date
December 3 l,2010a
December 3 1,2007
December 3 1,2007
December 3 1,2007
December 3 1,2007
December 3 1,2007
2005
2005
2005
2005
2005
2005
2005
2000
Population
(millions)
14.6
8.8
4.7
1.8
19.2
1.0
0.8
0.6
6.3
2.0
3.2
0.7
4.5
1999-2001
Measured
Violation?
Yes
No
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
70 million
a Extreme 1-Hour nonattainment areas. All other areas are severe nonattainment areas.
Source: "One-hour Ozone and PM 10 Nonattainment Status and Air Quality Data Update," Memorandum from
Patricia Koman to Docket A-2000-2, August 11, 2003, Docket A-2000-02, Document IV-B-07
Of the 53 areas in nonattainment for the 1-hour ozone NAAQS, there are 1 extreme and 12
severe 1-hour ozone nonattainment areas with a total affected population of 70 million. These
areas are shown in Table 1.1-1. Each of the areas is adopting additional measures to address
specific emission reduction shortfalls in attainment. State Implementation Plans submitted for
New York, Houston, the South Coast Basin, Philadelphia, and Baltimore are based on the local
ozone modeling and other evidence. The San Joaquin Valley will need additional reductions to
attain and maintain the standards. There is some risk that New York will fail to attain the
standard by 2007, and thus a transferred risk that Connecticut will also fail. A similar situation
exists in Southern California, where attainment of the South Coast is a precondition of the ability
of downwind to reach attainment by their respective attainment dates.
1-9
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The Los Angeles (South Coast Air Basin) ozone attainment demonstration is fully
approved, but it is based in part on reductions from new technology measures that have yet to be
identified (as allowed under CAA Section 182(e)(5)). The 2007 attainment demonstration for
the Southeast Desert area is also approved. However, a transport situation exists between the
Southeast Desert areas and the South Coast Air Basin, such that attainment in the Southeast
Desert depends on progress in reducing ozone levels in the South Coast Air Basin.
Even if the SIPs were approved and all shortfalls were filled in an area, there would still be
a risk that ozone levels in that area could still exceed the NAAQS. EPA's approval of an
attainment demonstration generally indicates our belief that a nonattainment area is reasonably
likely to attain by the applicable attainment date with the emission controls in the SIP. However,
such approval does not indicate that attainment is certain. Moreover, no ozone forecasting is 100
percent certain, so attainment by these deadlines is not certain, even though we believe it is more
likely than not. There are significant uncertainties inherent in predicting future air quality, such
as unexpected economic growth, unexpected vehicle miles traveled (VMT) growth, the year-to-
year variability of meteorological conditions conducive to ozone formation, and modeling
approximations. There is at least some risk in each of these areas that even assuming all
shortfalls are filled, attainment may not be reached by the applicable dates without further
emission reductions. The Agency's mid-course review in the SIP process—as well as the Clean
Air Act's provisions for contingency measures—is part of our strategy for dealing with some of
these uncertainties, but does not ensure successful attainment.
Many other 1-hour ozone nonattainment areas continue to experience exceedances.55
Approximately 51 million people are living in counties with measured air quality violating the 1-
hour NAAQS in 1999-2001.2 In addition, the ability of states to maintain the ozone NAAQS
once attainment is reached has proved challenging, and the recent recurrence of violations of the
NAAQS in some other areas increases the Agency's concern about continuing maintenance of
the standard. Recurrent nonattainment is especially problematic for areas where high population
growth rates lead to significant annual increases in vehicle trips and vehicle miles traveled
(VMT). Moreover, ozone modeling conducted for Nonroad Diesel proposal predicts
exceedances in 2020 and 2030 (without additional controls), which adds to the Agency's
uncertainty about the prospect of continued attainment for these areas. These highway
motorcycle standards will help these areas reduce their levels of ambient ozone concentrations
and maintain the NAAQS.
Typically, county design values (and thus exceedances) are consolidated where possible into design
values for consolidated metropolitan statistical areas (CMSA) or metropolitan statistical areas (MSA). Accordingly,
the design value for a metropolitan area is the highest design value among the included counties, and counties that
are not in metropolitan areas would be treated separately. However, for this section, we examined data on a county
basis, not consolidating into CMSA or MSA. Designated nonattainment areas may contain more than one county,
and some of these counties are experiencing recent exceedances, as indicated in the table. Further, the analysis is
limited to areas with monitors. See US EPA 2003. Air Quality Data Analysis 1999-2001: Technical Support
Document for Regulatory Actions. Table 1. Docket Number A-2001-28, Number II-A-196
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The serious and extreme 1-hour ozone nonattainment areas described above are expected to
need additional reductions to attain the ozone standard. While the standards in this rule will take
effect after the date by which some of these areas are expected to attain the ozone standard and
will not be fully phased-in until later, they will assist states in maintaining the standard in later
years.
1.1.4.2 - 8-Hour Ozone Levels: Current and Future Concentrations
As described above in Section 1.1.2, the 8-hour NAAQS is based on well-documented
science demonstrating that more people experience adverse health effects at lower levels of
exertion, over longer periods, and at lower ozone concentrations, than addressed by the 1-hour
ozone standard.56 The 8-hour standard greatly limits ozone exposures of concern for the general
population and sensitive populations. This section describes the current measured 8-hour
concentrations and describes our modeling to predict future 8-hour ozone concentrations.
1.1.4.2.1 - Current 8-hour Ozone Concentrations
Based upon the measured data from years 1999 - 2001, there are 291 counties with
measured values that violate the 8-hour ozone NAAQS, with a total affected population of about
111 million.57 These areas are shown in Figure 1-1. Of these, 61 million people live in counties
that meet the 1-hour standard but violate the 8-hour standard. There may be additional areas
above the level of the NAAQS for which no monitoring data are available. An additional 37
million people live in 155 counties that have air quality measurements within 10 percent of the
level of the standard. Finally, approximately 48 million people lived in counties with at least a
week (7 days) of 8-hour ozone concentrations measurements at or above 0.085 ppm in 2000.
Approximately 8 million people lived in counties experiencing 20 days and 4 million
experienced 40 days of 8-hour ozone concentrations at or above 0.085 ppm in 2000. See the Air
Quality Technical Support Document (AQ TSD) prepared for our Nonroad proposal for more
details about the counties and populations experiencing various levels of measured 8-hour ozone
• 58
concentrations.
1.1.4.2.2 - Risk of Future 8-Hour Ozone Violations
Based on our air quality modeling performed for our Nonroad Diesel proposal, we
anticipate that there will continue to be a need for reductions in ozone concentrations in the
future. In this section we briefly describe that air quality modeling including the non-emission
inventory inputs. We then discuss the results of the modeling. This modeling is described in
more detail in Chapter 3 of the draft Regulatory Impact Analysis for our Nonroad Diesel
proposal.59
Method
The air quality modeling performed for our Nonroad Diesel proposal was based upon the
same modeling approach used in the EPA's air quality assessment of the Clear Skies legislation,
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with the addition of updated inventory estimates for 1996, 2020 and 2030. Further discussion of
this modeling, including evaluations of model performance relative to predicted future air
quality, is provided in the Air Quality Modeling Technical Support Document (AQ Modeling
TSD) for our Nonroad Diesel proposal.60
The Comprehensive Air Quality Model with Extension (CAMx) was utilized to estimate
base and future-year ozone concentrations over the Eastern and Western U.S. for the various
emissions scenarios. CAMx simulates the numerous physical and chemical processes involved
in the formation, transport, and destruction of ozone. CAMx is a photochemical grid model that
numerically simulates the effects of emissions, advection, diffusion, chemistry, and surface
removal processes on pollutant concentrations within a three-dimensional grid. This model is
commonly used for purposes of determining attainment/non-attainment as well as estimating the
ozone reductions expected to occur from a reduction in emitted pollutants.
The regional ozone analyses used the modeling domains are those used previously for the
Ozone Transport Assessment Group (OTAG) and the on-highway passenger vehicle Tier 2
rulemaking.
The simulation periods modeled by CAMx included several multi-day periods when
ambient measurements were representative of ozone episodes over the eastern and western U.S.
A simulation period, or episode, consists of meteorological data characterized over a block of
days that are used as inputs to the air quality model. Three multi-day meteorological scenarios
during the summer of 1995 were used in the model simulations over the Eastern U.S.: June 12-
24, July 5-15, and August 7-21. Two multi-day meteorological scenarios during the summer of
1996 were used in the model simulations over the western U.S.: July 5-15 and July 18-31. In
general, these episodes do not represent extreme ozone events but, instead, are generally
representative of ozone levels near local design values. Each of the emissions scenarios were
simulated for the selected episodes.
The meteorological data required for input into CAMx (wind, temperature, vertical mixing,
etc.) were developed by separate meteorological models. For the eastern U.S., the gridded
meteorological data for the three historical 1995 episodes were developed using the Regional
Atmospheric Modeling System (RAMS), version 3b.
The modeling results provide information on our calculations of the number of people
estimated to live in counties in which ozone monitors are predicted to exceed design values or to
be within 10 percent of the design value in the future. We also provide specific information
about the number of people who would repeatedly experience levels of ozone of potential
concern over prolonged periods, i.e., over 0.085 ppm ozone 8-hour concentrations over a number
of days.
The determination that an area is at risk of exceeding the ozone standard in the future was
made for all areas with current design values greater than or equal to 0.085 ppm (or within a 10
percent margin) and with modeling evidence that concentrations at and above this level will
1-12
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persist into the future. Additional details for this analysis are provided in the AQ TSD and AQ
Modeling TSD for the Nonroad Diesel Proposal.61
The inventories that underlie the ozone modeling conducted for this rulemaking include
reductions from all current or committed federal, State and local controls. The modeling does
not examine the prospect of areas attaining or maintaining the ozone standard with possible
future controls (i.e., controls beyond current or committed federal, State and local controls).
Therefore, Tables 1.1-2 and 1.1-3 below should be interpreted as indicating what areas are at risk
of ozone violations in 2020 or 2030 without additional federal or State measures that may be
adopted and implemented after this rulemaking is finalized. We expect many of the areas listed
in Table 1.1-1 will adopt additional emission reduction programs, but we are unable to quantify
or rely upon future reductions from additional State programs since they have not yet been
adopted.
Results
Areas presented in Table 1.1-2 and 1.1-3 have monitored 1999-2001 air quality data
indicating violations of the 8-hour ozone NAAQS, or are within 10 percent of the standard, and
are predicted to have exceedances in 2020 or 2030.
Table 1.1-2 lists the counties with 2020 and 2030 projected 8-hour ozone design values (4th
maximum concentration) that violate the 8-hour standard. Counties are marked with an "V" in
the table if their projected design values are greater than or equal to 85 ppb. The current 3-year
average design values of these counties is also listed. Because we can project future design
values only for counties that have current design values, this list is limited to those counties with
ambient monitoring data sufficient to calculate current design values.
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Table 1.1-2. Counties with 2020 and 2030 Projected Ozone Design Values
in Violation of the 8-Hour Ozone Standarda
State
CA
CA
CA
CA
CA
CA
CA
CT
CT
CT
GA
GA
GA
IL
IN
MD
MI
MI
NJ
NJ
NJ
NJ
NJ
NJ
NJ
NY
NY
NY
PA
PA
TX
TX
WI
County
Fresno
Kern
Los Angeles
Orange
Riverside
San Bernardino
Ventura
Fairfield
Middlesex
New Haven
Bibb
Fulton
Henry
Cook
Lake
Harford
Macomb
Wayne
Camden
Gloucester
Hudson
Hunterdon
Mercer
Middlesex
Ocean
Bronx
Richmond
Westchester
Bucks
Montgomery
Galveston
Harris
Kenosha
1999-2001
Design Value
(vob)
108
109
105
77
111
129
101
97
99
97
98
107
107
88
90
104
88
88
103
101
93
100
105
103
109
83
98
92
105
100
98
110
95
Number of Violating Counties
Population of Violating Counties'5
2020
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
30
42.930.060
2030
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
32
46.998.413
Population
in 2000
799,407
661,645
9,519,338
2,846,289
1,545,387
1,709,434
753,197
882,567
155,071
824,008
153,887
816,006
119,341
5,376,741
484,564
218,590
788,149
2,061,162
508,932
254,673
608,975
121,989
350,761
750,162
510,916
1,332,650
443,728
923,459
597,635
750,097
250,158
3,400,578
149.577
Populations are based on 2020 and 2030 estimates from the U.S. Census.
Source: US EPA (2003) Air Quality Data Analysis 1999-2001, Technical
This document is available in Docket A-2001-28, Document No. II-A-196
Support Document for Regulatory Actions
, Appendix A, "Base case."
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Table 1.1-3 lists the counties with 2020 and 2030 projected 8-hour ozone design values that
do not violate the annual standard, but are within 10 percent of it. Counties are marked with an
"X" in the table if their projected design values are greater than or equal to 77 ppb, but less 85
ppb. Counties are marked with a "V" in the table if their projected design values are greater than
or equal to 85 ppb. The current 3-year average design values of these counties are also listed.
These are counties that are not projected to violate the standard, but to be close to it.
Table 1.1-3
Counties with 2020 and 2030 Projected Ozone Design Values
within Ten Percent of the 8-Hour Ozone Standard"
State
AR
AZ
CA
CA
CA
CO
CT
DC
DE
GA
GA
GA
GA
GA
GA
GA
GA
IL
IN
IN
LA
LA
LA
LA
LA
LA
LA
LA
LA
LA
County
Crittenden
Maricopa
Kings
Merced
Tulare
Jefferson
New London
Washington
New Castle
Bibb
Coweta
DeKalb
Douglas
Fayette
Fulton
Henry
Rockdale
McHenry
Lake
Porter
Ascension
Bossier
Calcasieu
East Baton Rou
Iberville
Jefferson
Livingston
St Charles
St James
St John The Ba
1999-2001
Design Value
(traM
92
85
98
101
104
81
90
94
97
98
96
102
98
99
107
107
104
83
90
90
86
90
86
91
86
89
88
86
83
86
2020
X
X
X
X
X
X
X
X
X
V
X
X
X
X
V
V
X
X
X
X
X
X
X
X
X
X
X
X
X
2030
X
X
X
X
X
X
X
X
X
V
X
X
X
X
V
V
X
X
V
X
X
X
X
X
X
X
X
X
X
X
Population
in 2000
50,866
3,072,149
129,461
210,554
368,021
527,056
259,088
572,059
500,265
153,887
89,215
665,865
92,174
91,263
816,006
119,341
70,111
260,077
484,564
146,798
76,627
98,310
183,577
412,852
33,320
455,466
91,814
48,072
21,216
43,044
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State
LA
MA
MA
MD
MD
MD
MD
MD
MD
MI
MI
MI
MI
MI
MI
MO
MO
MS
MS
MS
NJ
NJ
NJ
NJ
NY
NY
NY
NY
NY
OH
OH
PA
PA
PA
PA
PA
PA
RI
RI
TN
County
West Baton Rou
Barnstable
Bristol
Anne Arundel
Baltimore
Cecil
Harford
Kent
Prince Georges
Benzie
Macomb
Mason
Muskegon
Oakland
St Clair
St Charles
St Louis
Hancock
Harrison
Jackson
Cumberland
Monmouth
Morris
Passaic
Bronx
Erie
Niagara
Putnam
Suffolk
Geauga
Lake
Allegheny
Delaware
Lancaster
Lehigh
Northampton
Philadelphia
Kent
Washington
Shelby
1999-2001
Design Value
(rob)
88
96
93
103
93
106
104
100
97
89
88
91
92
84
85
90
88
87
89
87
97
94
97
89
83
92
87
89
91
93
91
92
94
96
96
97
88
94
92
93
2020
X
X
X
X
X
X
V
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
2030
X
X
X
X
X
X
V
X
X
X
V
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Population
in 2000
21,601
222,230
534,678
489,656
754,292
85,951
218,590
19,197
801,515
15,998
788,149
28,274
170,200
1,194,156
164,235
283,883
1,016,315
42,967
189,601
131,420
146,438
615,301
470,212
489,049
1,332,650
950,265
219,846
95,745
1,419,369
90,895
227,511
1,281,666
550,864
470,658
312,090
267,066
1,517,550
167,090
123,546
897,472
1-16
-------
State
TX
TX
TX
TX
TX
TX
TX
VA
VA
VA
WI
WI
WI
WI
WI
WI
WI
WI
County
Brazoria
Collin
Dallas
Denton
Jefferson
Montgomery
Tarrant
Alexandria City
Arlington
Fairfax
Door
Kewaunee
Manitowoc
Milwaukee
Ozaukee
Racine
Sheboygan
Waukesha
1999-2001
Design Value
ftrob')
91
99
93
101
85
91
97
88
92
95
93
89
92
89
95
87
95
86
Number of Counties within 10%
Population of Counties within 10%b
2020
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
79
40.465.492
2030
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
82
44.013.587
Population
in 2000
241,767
491,675
2,218,899
432,976
252,051
293,768
1,446,219
128,283
189,453
969,749
27,961
20,187
82,887
940,164
82,317
188,831
112,646
360.767
a Populations are based on 2020 and 2030 estimates from the U.S. Census.
Source: US EPA (2003) Air Quality Data Analysis 1999-2001, Technical
This document is available in Docket A-2001-28, Document No. II-A-196
Support Document for Regulatory Actions
, Appendix A "Base Case."
This air quality modeling suggests that without emission reductions beyond those already
required under promulgated regulations and approved SIPs, ozone nonattainment will likely
persist into the future. With reductions from programs already in place, the number of counties
violating the ozone 8-hour standard is expected to decrease in 2020 to 30 counties where 43
million people are projected to live. Thereafter, exposure to unhealthy levels of ozone is
expected to begin to increase again. In 2030 the number of counties violating the ozone 8-hour
NAAQS is projected to increase to 32 counties where 47 million people are projected to live. In
addition, in 2030, 82 counties where 44 million people are projected to live will be within 10
percent of violating the ozone 8-hour NAAQS.
Based on our modeling, we are also able to provide a quantitative prediction of the number
of people anticipated to reside in counties in which ozone concentrations are predicted for 8-hour
periods to be in the range of 0.085 to 0.12 ppm and higher on multiple days. Our analysis relies
on projected county-level population from the U.S. Department of Census for the period
representing each year analyzed.
1-17
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For each of the counties analyzed, we determined the number of days for periods on which
the highest model-adjusted 8-hour concentration at any monitor in the county was predicted, for
example, to be equal to or above 0.085 ppm. We then grouped the counties which had days with
ozone in this range according to the number of days this was predicted to happen, and summed
their projected populations.
We estimate that in 2020 53 million people are predicted to live in counties with at least 2
days with 8-hour average concentrations of 0.085 ppm or higher. This baseline will increase in
2030 to 56 million people are predicted to live in counties with at least 2 days with 8-hour
average concentrations of 0.085 ppm or higher. About 30 million people live in counties with at
least 7 days of 8-hour ozone concentrations at or above 0.085 ppm in 2020 and 2030 without
additional controls. Approximately 15 million people are predicted to live in counties with at
least 20 days of 8-hour ozone concentrations at or above 0.085 ppm in 2020 and 2030 without
additional controls.
EPA is still developing the implementation process for bringing the nation's air into
attainment with the ozone 8-hour NAAQS. EPA's current plans call for designating ozone 8-
hour nonattainment areas in April 2004. EPA is planning to propose that States submit SIPs that
address how areas will attain the 8-hour ozone standard within three years after nonattainment
designation regardless of their classification. EPA is also planning to propose that certain SIP
components, such as those related to reasonably available control technology (RACT) and
reasonable further progress (RFP), be submitted within 2 years after designation. We therefore
anticipate that States will submit their attainment demonstration SIPs by April 2007. Section
172(a)(2) of the Clean Air Act requires that SIP revisions for areas covered only under subpart 1
of part D, Title I of the Act demonstrate that the nonattainment areas will attain the ozone 8-hour
standard as expeditiously as practicable but no later than five years from the date that the area
was designated nonattainment. However, based on the severity of the air quality problem and
the availability and feasibility of control measures, the Administrator may extend the attainment
date "for a period of no greater than 10 years from the date of designation as nonattainment."
Based on these provisions, we expect that most or all areas covered under subpart 1 will have to
attain the ozone standard in the 2007 to 2014 time frame. For areas covered under subpart 2, the
maximum attainment dates will range from 3 to 20 years after designation, depending on an
area's classification. Thus, we anticipate that areas covered by subpart 2 will attain in the 2007
to 2024 time period.
The HC and NOx emission reductions expected from the new highway motorcycle
standards will assist States in their effort to meet and maintain the 8-hour ozone NAAQS, both
for areas that are expected to be in nonattainment and those that are at risk of being in
nonattainment in the future.
It should be noted that while reductions in NOx and VOC levels generally and provide
significant ozone-related health benefits, this may not always be the case at the local level. Due
to the complex photochemistry of ozone production, NOx emissions lead to both the formation
and destruction of ozone, depending on the relative quantities of NOx, VOC, and ozone catalysts
1-18
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such as the OH and HO2 radicals. In areas dominated by fresh emissions of NOx, ozone
catalysts are removed via the production of nitric acid which slows the ozone formation rate.
Because NOx is generally depleted more rapidly than VOC, this effect is usually short-lived and
the emitted NOx can lead to ozone formation later and further downwind. The terms "NOx
disbenefits" or "ozone disbenefits" refer to the ozone increases that can result from NOx
emissions reductions in these localized areas. According to the NARSTO Ozone Assessment,
these disbenefits are generally limited to small regions within specific urban cores and are
surrounded by larger regions in which NOx control is beneficial.62 Historically, NOx reductions
have been very successful at reducing regional/national ozone levels.
1.1.5 - Other Ozone Welfare Effects
Ozone at these levels can have other welfare effects, with damage to plants being of most
concern. Plant damage affects crop yields, forestry production, and ornamentals. The adverse
effect of ozone on forests and other natural vegetation can in turn cause damage to associated
ecosystems, with additional resulting economic losses. Prolonged ozone concentrations of 0.10
ppm can be phytotoxic to a large number of plant species, and can produce acute injury and
reduced crop yield and biomass production. Ozone concentrations within the range of 0.05 to
0.10 ppm have the potential over a longer duration of creating chronic stress on vegetation that
can result in reduced plant growth and yield, shifts in competitive advantages in mixed
populations, decreased vigor, and injury. Ozone effects on vegetation are presented in more
detail in Chapter 5, Volume II of the 1996 Ozone Criteria Document.
1.2 - Particulate Matter
1.2.1 - General Background
Particulate matter (PM) represents a broad class of chemically and physically diverse
substances. It can be principally characterized as discrete particles that exist in the condensed
(liquid or solid) phase spanning several orders of magnitude in size. PM10 refers to particles with
an aerodynamic diameter less than or equal to a nominal 10 micrometers. Fine particles refer to
those particles with an aerodynamic diameter less than or equal to a nominal 2.5 micrometers
(also known as PM2 5), and coarse fraction particles are those particles with an aerodynamic
diameter greater than 2.5 microns, but less than or equal to a nominal 10 micrometers. Ultrafine
PM refers to particles with diameters of less than 100 nanometers (0.1 micrometers). The health
and environmental effects of PM are in some cases related to the size of the particles.
Specifically, larger particles (> 10 micrometers) tend to be removed by the respiratory clearance
mechanisms whereas smaller particles are deposited deeper in the lungs.
Fine particles are formed in two ways. They can be directly emitted from combustion
sources. They can also be formed secondarily from gaseous precursors such as sulfur dioxide,
oxides of nitrogen, or organic compounds.63 These particles are generally composed of sulfate,
nitrate, chloride, ammonium compounds, organic carbon, elemental carbon, and metals. Fine
1-19
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particles can remain in the atmosphere for days to weeks and travel through the atmosphere
hundreds to thousands of kilometers.
Coarse particles typically result from mechanical crushing or grinding in both natural and
anthropogenic sources. They include resuspended dusts, plant material, and crustal material
from paved roads, unpaved roads, construction, farming, and mining activities. In contrast to
fine particles, coarse particles deposit to the earth within minutes to hours and within tens of
kilometers from the emission source.
1.2.2 - Health and Welfare Effects of PM
Scientific studies show ambient PM contributes to a series of adverse health effects. These
health effects are discussed in detail in the EPA Air Quality Criteria Document for PM as well as
the draft updates of this document released in the past year.64 In addition, EPA recently released
its final "Health Assessment Document for Diesel Engine Exhaust" (the "Diesel HAD"), which
also reviews health effects information related to diesel exhaust as a whole including diesel PM,
which is one component of ambient PM.65
As detailed in these documents, health effects associated with short-term variation in
ambient particulate matter (PM) have been indicated by epidemiologic studies showing
associations between exposure and increased hospital admissions for ischemic heart disease,66
heart failure,67 respiratory disease,68'69'70'71 including chronic obstructive pulmonary disease
(COPD) and pneumonia.72'73'74 Short-term elevations in ambient PM have also been associated
with increased cough, lower respiratory symptoms, and decrements in lung function.75'76'77
Short-term variations in ambient PM have also been associated with increases in total and
cardiorespiratory daily mortality in individual cities78'79'80'81 and in multi-city studies.82'83'84
Studies examining populations exposed to different levels of air pollution over a number of
years, including the Harvard Six Cities Study and the American Cancer Society Study suggest an
association between exposure to ambient PM2 5 and premature mortality.85'86 Two studies further
analyzing the Harvard Six Cities Study's air quality data have also established a specific
influence of mobile source-related PM25 on daily mortality87 and a concentration-response
function for mobile source-associated PM25 and daily mortality.88 Another recent study in 14
U.S. cities examining the effect of PM10 on daily hospital admissions for cardiovascular disease
found that the effect of PM10 was significantly greater in areas with a larger proportion of PM10
coming from motor vehicles, indicating that PM10 from these sources may have a greater effect
on the toxicity of ambient PM10 when compared with other sources.89 Additional studies have
associated changes in heart rate and/or heart rhythm in addition to changes in blood
characteristics with exposure to ambient PM.90
The health effects of PM10 are similar to those of PM25, since PM10 includes all of PM2 5 plus
the coarse fraction from 2.5 to 10 micrometers in size. EPA also evaluated the health effects of
PM between 2.5 and 10 micrometers in the draft revised Criteria Document. As discussed in the
1-20
-------
Diesel HAD and other studies, most diesel PM is smaller than 2.5 micrometers.91 Both fine and
coarse fraction particles can enter and deposit in the respiratory system.
PM also causes adverse impacts to the environment. Fine PM has been clearly associated
with the impairment of visibility over urban areas and large multi-State regions. Other
environmental impacts occur when particles deposit onto soils, plants, water or materials. For
example, particles containing nitrogen and sulphur that deposit on to land or water bodies may
change the nutrient balance and acidity of those environments. Finally, PM causes soiling and
erosion damage to materials, including culturally important objects such as carved monuments
and statues. It promotes and accelerates the corrosion of metals, degrades paints, and
deteriorates building materials such as concrete and limestone. Components of particulate
matter (e.g., sulfuric or nitric acid) also contribute to acid deposition, nitrification of surface soils
and water eutrophication of surface water.
1.2.3 - PM Nonattainment
1.2.3.1 - Current PM10 Nonattainment
The current NAAQS for PM10 was first established in 1987. The primary (health-based) and
secondary (public welfare based) standards for PM10 include both short- and long-term NAAQS.
The short-term (24 hour) standard of 150 ug/m3 is not to be exceeded more than once per year on
average over three years. The long-term standard specifies an expected annual arithmetic mean
not to exceed 50 ug/m3 averaged over three years.
Currently, 29 million people live in PM10 nonattainment areas, including moderate and
serious areas. There are currently 56 moderate PM10 nonattainment areas with a total population
of 6.6 million.92 The attainment date for the initial moderate PM10 nonattainment areas,
designated by law on November 15, 1990, was December 31, 1994. Several additional PM10
nonattainment areas were designated on January 21, 1994, and the attainment date for these areas
was December 31, 2000.
There are 8 serious PM10 nonattainment areas with a total affected population of 22.7
million. According to the Act, serious PM10 nonattainment areas must attain the standards no
later than 10 years after designation. The initial serious PM10 nonattainment areas were
designated January 18, 1994 and had an attainment date set by the Act of December 31, 2001.
The Act provides that EPA may grant extensions of the serious area attainment dates of up to 5
years, provided that the area requesting the extension meets the requirements of Section 188(e)
of the Act. Five serious PM10 nonattainment areas (Phoenix, Arizona; Clark County (Las
Vegas), NV; Coachella Valley, South Coast (Los Angeles), and Owens Valley, California) have
received extensions of the December 31, 2001 attainment date and thus have new attainment
dates of December 31, 2006.
Many PM10 nonattainment areas continue to experience exceedances. Of the 29 million
people living in designated PM10 nonattainment areas, approximately 25 million people are
1-21
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living in nonattainment areas with measured air quality violating the PM10 NAAQS in 1999-
2001. Among these are the seven serious areas listed in Table 1.2-1 and 4 moderate areas:
Nogales, AZ, Imperial Valley, CA, Mono Basin, CA, and El Paso, TX.
Serious
Table 1.2-1
Nonattainment Areas
Area
Owens Valley, CA
Phoenix, AZ
Clark County, NV (Las Vegas)
Coachella Valley, CA
Los Angeles South Coast Air Basin, CA
San Joaquin Valley, CA
Walla Walla, WA
Washoe County, NV (Reno)
Total Population
Attainment
Date
December 3 1,2006
December 3 1,2006
December 3 1,2006
December 3 1,2006
December 3 1,2006
2001
2001
2001
2000
Population
7,000
3,111,876
1,375,765
225,000
14,550,521
3,080,064
10,000
339,486
1999-2001 Measured
Violation
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
22.7 million
In addition to these designated nonattainment areas, there are 19 unclassified areas, where
8.7 million live, for which States have reported PM10 monitoring data for 1999-2001 period
indicating a PM10 NAAQS violation. An official designation of PM10 nonattainment indicates
the existence of a confirmed PM10 problem that is more than a result of a one-time monitoring
upset or a result of PM10 exceedances attributable to natural events. We have not yet excluded
the possibility that one or the other of these is responsible for the monitored violations in 1999-
2001 in these 19 unclassified areas. We adopted a policy in 1996 that allows areas whose PM10
exceedances are attributable to natural events to remain unclassified if the State is taking all
reasonable measures to safeguard public health regardless of the sources of PM10 emissions.
Areas that remain unclassified areas are not required to submit attainment plans, but we work
with each of these areas to understand the nature of the PM10 problem and to determine what best
can be done to reduce it.
1.2.3.2 - Current PM2 5 Nonattainment
The NAAQS for PM25 were established in 1997 (62 Fed. Reg., 38651, July 18, 1997). The
short term (24-hour) standard is set at a level of 65 jig/m3 based on the 98th percentile
concentration averaged over three years. (The air quality statistic compared to the standard is
referred to as the "design value.") The long-term standard specifies an expected annual
arithmetic mean not to exceed 15 ug/m3 averaged over three years.
1-22
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Current PM25 monitored values for 1999-2001, which cover counties having about 75
percent of the country's population, indicate that at least 65 million people in 129 counties live
in areas where annual design values of ambient fine PM violate the PM2 5 NAAQS. There are an
additional 9 million people in 20 counties where levels above the NAAQS are being measured,
but there are insufficient data at this time to calculate a design value in accordance with the
standard, and thus determine whether these areas are violating the PM2 5 NAAQS. In total, this
means that 37 percent of the counties and 64 percent of the national population are in areas with
monitored levels above the NAAQS. Furthermore, an additional 11 million people live in 41
counties that have air quality measurements within 10 percent of the level of the standard, with
complete data. These areas, although not currently violating the standard, will also benefit from
the additional reductions from this rule in order to ensure long term maintenance.
As shown in Table 1.2-2, of the 74 million people currently living in counties with
measurements above the NAAQS (15 ug/m3), 22 million live in counties above 20 ug/m3.
Absent additional controls, our modeling predicts there will continue to be large numbers of
people living in counties with PM levels above the standard.
Table 1.2-2
1999/2001 Monitored Population" Living in Counties with Annual Average15 PM2 5
Concentrations Shown (70 Percent of Total U.S. Population)
Measured 1999/2000 Annual
Average PM2 5
Concentration
(Hg/m3)
(A)
>25
>20 <=25
>15 <— 20
<=15
Number of Counties
Within The Concentration
Range
3
10
136
402
2000 Population Living
in Monitored Counties
Within The
Concentration Range
(Millions, 2000 Census
Data)
12.8
9.2
52.3
115.6
Percent of 2000
Monitored Population
Living in Counties
Within The
Concentration Range0
(C)
7
5
27
61
a Monitored population estimates represent populations living in monitored counties (with community based monitors)
based on monitors with at least 10 quarter with at least 11 samples per quarter between 1999 and 2001.
b Annual average represents the monitor reading with the highest average in each monitored county.
0 The monitored population is 189.2 million (as reflected in column C, where C=B/Monitored Population). Total
monitored population is 191 million; the Census total county-based 2000 population is 272.7 million.
1.2.3.3 - Risk of Future PM25 Violations
In conjunction with our Nonroad Diesel proposal, we performed a series of PM air quality
modeling simulations for the continental U.S. The model outputs from the 1996, 2020 and 2030
baselines, combined with current air quality data, were used to identify areas expected to exceed
the PM2 5 NAAQS in 2020 and 2030. These areas became candidates for being determined to be
1-23
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residual exceedance areas which will require additional emission reductions to attain and
maintain the PM2 5 NAAQS. This modeling supports the conclusion that there is a broad set of
areas with predicted PM25 concentrations at or above 15 ug/m3 between 1996 and 2030 without
additional emission reductions.
The air quality modeling performed for this rule was based upon an improved version of the
modeling system used in the HD Engine/Diesel Fuel rule with the addition of updated inventory
estimates for 1996, 2020 and 2030. A national-scale version of the REgional Model System for
Aerosols and Deposition (REMSAD) was utilized to estimate base and future-year PM
concentrations over the contiguous U.S. for the various emissions scenarios. Version 7 of
REMSAD was used for this analysis. REMSAD was designed to calculate the concentrations of
both inert and chemically reactive pollutants in the atmosphere that affect annual particulate
concentrations and deposition over large spatial scales.3 More detailed information is included
in the AQ Modeling TSD for our Nonroad Diesel proposal.93
This air quality modeling suggests that the present widespread number of counties with
annual averages above 15 ug/m3 is likely to persist in the future in the absence of additional
controls. For example, in 2020 based on emission controls currently adopted or expected to be
in place, we project that 66 million people will live in 79 counties with average PM25 levels at
and above 15 ug/m3. In 2030, the number of people projected to live in areas exceeding the
PM25 standard is expected to increase to 85 million in 107 counties. An additional 24 million
people are projected to live in counties within 10 percent of the standard in 2020, which will
decrease to 17 million people in 2030.
Table 1.2-3 lists the counties with 2020 and 2030 projected annual PM25 design values that
violate the annual standard. Counties are marked with an "V" in the table if their projected
design values are greater than or equal to 15.05 ug/m3. The current 3-year average design values
of these counties are also listed. Recall that we project future design values only for counties
that have current design values, so this list is limited to those counties with ambient monitoring
data sufficient to calculate current 3-year design values.
Table 1.2-3
Counties with 2020 and 2030 Projected Annual PM2.5
Design Values in Violation of the Annual PM2.5 Standard."
State
AL
County
DeKalb
1999-2001
Design Value
(ug/m3)
16.8
2020
2030
V
Population
in 2000
64,452
Given the potential impact of the porposed rule on secondarily formed particles it is important to employ
a Eulerian model such as REMSAD. The impact of secondarily formed pollutants typically involves primary
precursor emissions from a multitude of widely dispersed sources, and chemical and physical processes of pollutants
that are best addressed using an air quality model that employs an Eulerian grid model design.
1-24
-------
State
AL
AL
AL
AL
AL
AL
AL
AL
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CA
CT
DE
DC
GA
GA
GA
GA
GA
GA
GA
GA
GA
GA
GA
GA
GA
GA
GA
IL
County
Houston
Jefferson
Mobile
Montgomery
Morgan
Russell
Shelby
Talladega
Fresno
Imperial
Kern
Los Angeles
Merced
Orange
Riverside
San Bernardino
San Diego
San Joaquin
Stanislaus
Tulare
New Haven
New Castle
Washington
Bibb
Chatham
Clarke
Clayton
Cobb
DeKalb
Dougherty
Floyd
Fulton
Hall
Muscogee
Paulding
Richmond
Washington
Wilkinson
Cook
1999-2001
Design Value
(ug/m3)
16.3
21.6
15.3
16.8
19.1
18.4
17.2
17.8
24
15.7
23.7
25.9
18.9
22.4
29.8
25.8
17.1
16.4
19.7
24.7
16.8
16.6
16.6
17.6
16.5
18.6
19.2
18.6
19.6
16.6
18.5
21.2
17.2
18
16.8
17.4
16.5
18.1
18.8
2020
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
2030
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
Population
in 2000
88,787
662,047
399,843
223,510
111,064
49,756
143,293
80,321
799,407
142,361
661,645
9,519,338
210,554
2,846,289
1,545,387
1,709,434
2,813,833
563,598
446,997
368,021
824,008
500,265
572,059
153,887
232,048
101,489
236,517
607,751
665,865
96,065
90,565
816,006
139,277
186,291
81,678
199,775
21,176
10,220
5,376,741
1-25
-------
State
IL
IL
IL
IL
IN
IN
IN
IN
KY
KY
LA
LA
MD
MD
MD
MA
MI
MS
MO
MT
NJ
NJ
NY
NY
NC
NC
NC
NC
NC
NC
NC
NC
NC
OH
OH
OH
OH
OH
OH
County
Du Page
Madison
St Clair
Will
Clark
Lake
Marion
Vanderburgh
Jefferson
Kenton
East Baton Rouge
West Baton Rouge
Baltimore
Prince Georges
Baltimore City
Suffolk
Wayne
Jones
St Louis City
Lincoln
Hudson
Union
Bronx
New York
Catawba
Davidson
Durham
Forsyth
Gaston
Guilford
McDowell
Mecklenburg
Wake
Butler
Cuyahoga
Franklin
Hamilton
Jefferson
Lawrence
1999-2001
Design Value
(ug/m3)
15.4
17.3
17.4
15.9
17.3
16.3
17
16.9
17.1
15.9
14.6
14.1
16
17.3
17.8
16.1
18.9
16.6
16.3
16.4
17.5
16.3
16.4
17.8
17.1
17.3
15.3
16.2
15.3
16.3
16.2
16.8
15.3
17.4
20.3
18.1
19.3
18.9
17.4
2020
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
2030
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
Population
in 2000
904,161
258,941
256,082
502,266
96,472
484,564
860,454
171,922
693,604
151,464
412,852
21,601
754,292
801,515
651,154
689,807
2,061,162
64,958
348,189
18,837
608,975
522,541
1,332,650
1,537,195
141,685
147,246
223,314
306,067
190,365
421,048
42,151
695,454
627,846
332,807
1,393,978
1,068,978
845,303
73,894
62,319
1-26
-------
State
OH
OH
OH
OH
OH
OH
OH
PA
PA
PA
PA
SC
SC
TN
TN
TN
TN
TN
TX
TX
UT
VA
WV
WV
WV
WV
WV
WI
County
Lucas
Mahoning
Montgomery
Scioto
Stark
Summit
Trumbull
Allegheny
Delaware
Philadelphia
York
Greenville
Lexington
Davidson
Hamilton
Knox
Shelby
Sullivan
Dallas
Harris
Salt Lake
Richmond City
Brooke
Cabell
Hancock
Kanawha
Wood
Milwaukee
1999-2001
Design Value
(ug/m3)
16.7
16.4
17.6
20
18.3
17.3
16.2
21
15
16.6
16.3
17
15.6
17
18.9
20.4
15.6
17
14.4
15.1
13.6
14.9
17.4
17.8
17.4
18.4
17.6
14.5
Number of Violating Counties
Population of Violating Counties"
2020
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
79
65,821,078
2030
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
107
85,525,624
Population
in 2000
455,054
257,555
559,062
79,195
378,098
542,899
225,116
1,281,666
550,864
1,517,550
381,751
379,616
216,014
569,891
307,896
382,032
897,472
153,048
2,218,899
3,400,578
898,387
197,790
25,447
96,784
32,667
200,073
87,986
940.164
a The proposal differs based on updated information; however, we believe that the net results would approximate future
emissions, although we anticipate the design value improvements would be slightly smaller.
b Populations are based on 2020 and 2030 estimates. See US EPA (2003) Air Quality Data Analysis 1999-2001,
Technical Support Document for Regulatory Actions This document is available in Docket A-2001-28, Document
No. II-A-196, Appendix A for details, "Base case."
Table 2.1-4 lists the counties with 2020 and 2030 projected annual PM2 5 design values that
do not violate the annual standard, but are within 10 percent of it. Counties are marked with an
"X" in the table if their projected design values are greater than or equal to 13.5 5 ug/m3, but less
1-27
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than 15.05 ug/m3. Counties are marked with an "V" in the table if their projected design values
are greater than or equal to 15.05 ug/m3. The current design values of these counties are also
listed.
1-28
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Table 2.1-4
Counties with 2020 and 2030 Projected Annual PM2.5 Design Values
within Ten Percent of the Annual PM2.5 Standard.3
State
AL
AL
AL
AL
AL
AR
AR
CA
CA
CA
CA
CA
CT
DE
GA
IL
IL
IL
IN
IN
IN
IN
IN
IN
IN
KY
KY
KY
KY
KY
KY
KY
KY
LA
LA
LA
County
Alabama
DeKalb
Houston
Madison
Mobile
Crittenden
Pulaski
Butte
Imperial
Kings
San Joaquin
Ventura
Fairfield
Sussex
Hall
Du Page
Macon
Will
Elkhart
Floyd
Howard
Marion
Porter
Tippecanoe
Vanderburgh
Bell
Boyd
Bullitt
Campbell
Daviess
Fayette
Kenton
Pike
Caddo
Calcasieu
East Baton Rouge
1999-2001
Design Value
Cue/m3)
15.5
16.8
16.3
15.5
15.3
15.3
15.9
15.4
15.7
16.6
16.4
14.5
13.6
14.5
17.2
15.4
15.4
15.9
15.1
15.6
15.4
17
13.9
15.4
16.9
16.8
15.5
16
15.5
15.8
16.8
15.9
16.1
13.7
12.7
14.6
2020
X
X
V
X
X
X
X
X
X
X
V
X
X
V
X
X
X
V
X
X
X
X
X
X
X
X
X
X
2030
X
V
V
X
V
X
X
X
V
X
V
X
X
X
V
V
X
V
X
X
X
V
X
X
V
X
X
X
X
X
X
V
X
X
X
V
Population
in 2000
14,254
64,452
88,787
276,700
399,843
50,866
361,474
203,171
142,361
129,461
563,598
753,197
882,567
156,638
139,277
904,161
114,706
502,266
182,791
70,823
84,964
860,454
146,798
148,955
171,922
30,060
49,752
61,236
88,616
91,545
260,512
151,464
68,736
252,161
183,577
412,852
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State
LA
LA
LA
LA
MD
MA
MA
MI
MS
MS
MS
MS
MS
MO
MO
MO
MO
MO
NJ
NJ
NY
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
NC
OH
OH
OH
OH
County
Iberville
Jefferson
Orleans
West Baton Rouge
Baltimore
Hampden
Suffolk
Kalamazoo
Forrest
Hinds
Jackson
Jones
Lauderdale
Jackson
Jefferson
St Charles
St Louis
St Louis City
Mercer
Union
Bronx
Alamance
Cabarrus
Catawba
Cumberland
Durham
Forsyth
Gaston
Guilford
Haywood
McDowell
Mitchell
Orange
Wake
Wayne
Butler
Lorain
Mahoning
Portage
1999-2001
Design Value
(ug/m3)
13.9
13.6
14.1
14.1
16
14.1
16.1
15
15.2
15.1
13.8
16.6
15.3
13.9
15
14.6
14.1
16.3
14.3
16.3
16.4
15.3
15.7
17.1
15.4
15.3
16.2
15.3
16.3
15.4
16.2
15.5
14.3
15.3
15.3
17.4
15.1
16.4
15.3
2020
X
X
X
X
V
X
X
X
V
X
X
X
V
X
X
V
X
X
V
X
X
X
X
V
X
X
X
X
V
X
X
X
2030
X
X
X
V
V
X
V
X
X
X
X
V
X
X
X
X
X
V
X
V
V
X
X
V
X
V
V
V
V
X
V
X
X
V
X
V
X
V
X
Population
in 2000
33,320
455,466
484,674
21,601
754,292
456,228
689,807
238,603
72,604
250,800
131,420
64,958
78,161
654,880
198,099
283,883
1,016,315
348,189
350,761
522,541
1,332,650
130,800
131,063
141,685
302,963
223,314
306,067
190,365
421,048
54,033
42,151
15,687
118,227
627,846
113,329
332,807
284,664
257,555
152,061
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-------
State
OH
PA
PA
PA
PA
PA
PA
PA
SC
sc
SC
sc
TN
TN
TN
TN
TN
TX
UT
VA
VA
VA
VA
WV
WV
WV
WV
WI
WI
County
Trumbull
Berks
Cambria
Dauphin
Delaware
Lancaster
Washington
York
Georgetown
Lexington
Richland
Spartanburg
Davidson
Roane
Shelby
Sullivan
Sumner
Dallas
Salt Lake
Bristol City
Richmond City
Roanoke City
Virginia Beach Cit
Berkeley
Marshall
Ohio
Wood
Milwaukee
Waukesha
1999-2001
Design Value
rue/m31)
16.2
15.6
15.3
15.5
15
16.9
15.5
16.3
13.9
15.6
15.4
15.4
17
17
15.6
17
15.7
14.4
13.6
16
14.9
15.2
13.2
16
16.5
15.7
17.6
14.5
14.1
Number of Counties within 10%
Population of Counties within 10%b
2020
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
V
X
70
23,836,367
2030
V
X
X
X
V
X
X
V
X
V
X
X
V
X
V
V
X
V
V
X
V
X
X
X
X
X
V
V
X
64
16,870,324
Population
in 2000
225,116
373,638
152,598
251,798
550,864
470,658
202,897
381,751
55,797
216,014
320,677
253,791
569,891
51,910
897,472
153,048
130,449
2,218,899
898,387
17,367
197,790
94,911
425,257
75,905
35,519
47,427
87,986
940,164
360.767
a The proposal differs based on updated information; however, we believe that the net results would approximate future
emissions, although we anticipate the design value improvements would be slightly smaller.
b Populations are based on 2020 and 2030 estimates. See US EPA (2003) Air Quality Data Analysis 1999-2001,
Technical Support Document for Regulatory Actions This document is available in Docket A-2001-28, Document
No. II-A-196, Appendix A, "Base case" for details.
While the final implementation process for bringing the nation's air into attainment with the
PM2 5 NAAQS is still being completed in a separate rulemaking action, the basic framework is
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well defined by the statute. EPA's current plans call for designating PM2 5 nonattainment areas
in late-2004. Following designation, Section 172(b) of the Clean Air Act allows states up to 3
years to submit a revision to their state implementation plan (SIP) that provides for the
attainment of the PM25 standard. Based on this provision, states could submit these SIPs in late-
2007. Section 172(a)(2) of the Clean Air Act requires that these SIP revisions demonstrate that
the nonattainment areas will attain the PM2 5 standard as expeditiously as practicable but no later
than 5 years from the date that the area was designated nonattainment. However, based on the
severity of the air quality problem and the availability and feasibility of control measures, the
Administrator may extend the attainment date "for a period of no greater than 10 years from the
date of designation as nonattainment." Therefore, based on this information, we expect that most
or all areas will need to attain the PM25 NAAQS in the 2009 to 2014 time frame, and then be
required to maintain the NAAQS thereafter.
This emission control program for highway motorcycles is another component of the effort
by federal, state and local governments to reduce the health related impacts of air pollution and
to reach attainment of the NAAQS for and particulate matter as well as to improve other
environmental conditions such as atmospheric visibility. The emission reductions associated
with these standards will help these areas in maintaining the standards.
1.2.4 - Particulate Matter and Visibility Degradation
Visibility can be defined as the degree to which the atmosphere is transparent to visible
light.94 Visibility impairment has been considered the "best understood and most easily
measured effect of air pollution."95 Visibility degradation is often directly proportional to
decreases in light transmittal in the atmosphere. Scattering and absorption by both gases and
particles decrease light transmittance. Haze obscures the clarity, color, texture, and form of what
we see. Fine particles are the major cause of reduced visibility in parts of the U.S. Visibility is
an important effect because it has direct significance to people's enjoyment of daily activities in
all parts of the country. Visibility is also highly valued in significant natural areas such as
national parks and wilderness areas, because of the special emphasis given to protecting these
lands now and for future generations.
The size and chemical composition of particles strongly affect their ability to scatter or
absorb light. The same particles (sulfates, nitrates, organic carbon, smoke, and soil dust)
comprising PM2 5, which are linked to serious health effects and environmental effects can also
significantly degrade visual air quality. Sulfates contribute to visibility impairment especially on
the haziest days across the U.S., accounting in the rural Eastern U.S. for more than 60 percent of
annual average light extinction on the best days and up to 86 percent of average light extinction
on the haziest days. Nitrates and elemental carbon each typically contribute 1 to 6 percent of
average light extinction on haziest days in rural Eastern U.S. locations.96
Visibility effects are manifest in two principal ways: (1) as local impairment (e.g., localized
hazes and plumes) and (2) as regional haze. The emissions from engines covered by this rule
contribute to both types of visibility impairment.
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Local-scale visibility degradation is commonly in the form of either a plume resulting from
the emissions of a specific source or small group of sources, or it is in the form of a localized
haze such as an urban "brown cloud." Plumes are comprised of smoke, dust, or colored gas that
obscure the sky or horizon relatively near sources. Impairment caused by a specific source or
small group of sources has been generally termed as "reasonably attributable."
The second type of impairment, regional haze, results from pollutant emissions from a
multitude of sources located across a broad geographic region. It impairs visibility in every
direction over a large area, in some cases over multi-state regions. Regional haze masks objects
on the horizon and reduces the color and contrast of nearby objects.97
On an annual average basis, the concentrations of non-anthropogenic fine PM are generally
small when compared with concentrations of fine particles from anthropogenic sources.98
Anthropogenic contributions account for about one-third of the average extinction coefficient in
the rural West and more than 80 percent in the rural East.99 In the Eastern U.S., reduced
visibility is mainly attributable to secondarily formed particles, particularly those less than a few
micrometers in diameter (e.g., sulfates). While secondarily formed particles still account for a
significant amount in the West, primary emissions contribute a larger percentage of the total
particulate load than in the East. Furthermore, it is important to note that even in those areas
with relatively low concentrations of anthropogenic fine particles, such as the Colorado plateau,
small increases in anthropogenic fine particle concentrations can lead to significant decreases in
visual range. This is one of the reasons mandatory Federal Class I areas have been given special
consideration under the Clean Air Act. The 156 mandatory Federal Class I areas are displayed
on the map in Figure 2-1 above.
Without the effects of pollution, a natural visual range is approximately 140 miles (230
kilometers) in the West and 90 miles (150 kilometers) in the East. However, over the years, in
many parts of the U.S., fine particles have significantly reduced the range that people can see. In
the West, the current range is 33 to 90 miles (53 to 144 kilometers), and in the East, the current
range is only 14 to 24 miles (22 to 38 kilometers).100
Based upon the light-extinction coefficient, a unitless visibility index or deciview can be
calculated.101'4 As shown in Table 1.2-5, in 2030 we estimate visibility in the East to be about
20.54 deciviews (or visual range of 50 kilometers) on average, with poorer visibility in urban
areas, compared to the visibility conditions without man-made pollution of 9.5 deciviews (or
visual range of 150 kilometers). Likewise, we estimate visibility in the West to be about 8.83
4 To quantify changes in visibility, the analysis presented in this chapter computes a light-extinction
coefficient based on the work of Sisler (1996), which shows the total fraction of light decreased per unit distance.
This coefficient accounts for the scattering and absorption of light by both particles and gases, and accounts for the
higher extinction efficiency of fine particles compared to coarse particles. Visibility can be described in terms of
visual range, light extinction or deciview. Visibility impairment also has a temporal dimension in that impairment
might relate to a short-term excursion or to longer periods (e.g., worst 20 percent of days or annual average levels).
4 cont-d...More detailed discussions of visibility effects are contained in the EPA Criteria Document for PM.
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deciviews (or visual range of 162 kilometers) in 2030, compared to the visibility conditions
without anthropogenic pollution of 5.3 deciviews (or visual range of 230 kilometers). Thus, in
the future, a substantial percent of the population may experience unacceptable visibility
impairment in areas where they live, work and recreate.
Table 1.2-5
Summary of Future National (48 state) Baseline Visibility
Conditions Absent Additional Controls (Deciviews)
Regions"
Eastern U.S.
Urban
Rural
Western U.S.
Urban
Rural
Predicted 2020
Visibility
(annual average)
20.27
21.61
19.73
8.69
9.55
8.5
Predicted 2030
Visibility
(annual average)
20.54
21.94
19.98
8.83
9.78
8.61
Natural Background
Visibility
9.5
5.3
a Eastern and Western Regions are separated by 100 degrees north longitude. Background visibility conditions
differ by region.
The emissions from highway motorcycles contribute to this visibility impairment through
their direct and indirect PM emissions.
In the 1990 Clean Air Act amendments, Congress provided additional emphasis on regional
haze issues (see section 169B). There are 156 Mandatory Federal Class I areas that are in need
of additional action to reduce regional haze. These areas include many of our best known and
most treasured natural areas, such as the Grand Canyon, Yosemite, Yellowstone, Mount Rainier,
Shenandoah, the Great Smokies, Acadia, and the Everglades. More than 280 million visitors
come to enjoy the scenic vistas and unique natural features in these and other park and
wilderness areas each year.
In 1999 EPA finalized a rule that calls for States to establish goals and emission reduction
strategies for improving visibility in the 156 mandatory Class I national parks and wilderness
areas. In that rule, EPA established a "natural visibility" goal.102 EPA also encouraged the
States to work together in developing and implementing their air quality plans. The regional
haze program is focused on long-term emissions decreases from the entire regional emissions
inventory comprised of major and minor stationary sources, area sources and mobile sources.
The regional haze program is designed to improve visibility and air quality in our most treasured
natural areas so that these areas may be preserved and enjoyed by current and future generations.
At the same time, control strategies designed to improve visibility in the national parks and
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wilderness areas will improve visibility over broad geographic areas, including other recreational
sites, our cities and residences. For mobile sources, there may also be a need for a Federal role
in reduction of those emissions, in particular, because mobile source engines are regulated
primarily at the Federal level.
The regional haze program calls for states to establish goals for improving visibility in
national parks and wilderness areas to improve visibility on the haziest 20 percent of days and to
ensure that no degradation occurs on the clearest 20 percent of days (64 FR 35722. July 1,
1999). The rule requires states to develop long-term strategies including enforceable measures
designed to meet reasonable progress goals toward natural visibility conditions. Under the
regional haze program, States can take credit for improvements in air quality achieved as a result
of other Clean Air Act programs, including national mobile-source programs.5 The highway
motorcycle standards in this rule will assist states in meeting their goals under the regional haze
program.
1.3 - Air Toxics
In addition to the human health and welfare impacts described above, emissions from the
engines covered by this rule also contain several other substances that are known or suspected
human or animal carcinogens, or have serious noncancer health effects.103 These include
benzene, 1,3-butadiene, formaldehyde, acetaldehyde, and acrolein. This section describes the
health effects of these air toxics. Additional information can also be found in the Technical
Support Document four our final Mobile Source Air Toxics rule.104 The HC limits for highway
motorcycles will help reduce emissions of these harmful pollutants.
1.3.1 - Benzene
Benzene is an aromatic hydrocarbon which is present as a gas in both exhaust and
evaporative emissions from mobile sources. For gasoline-powered highway vehicles, the
benzene fraction of TOG varies depending on control technology (e.g., type of catalyst) and the
levels of benzene and other aromatics in the fuel, but is generally higher than for diesel engines,
about three to five percent. The benzene fraction of evaporative emissions from gasoline
vehicles depends on control technology and fuel composition and characteristics (e.g., benzene
level and the evaporation rate) and is generally about one percent.105
The EPA's IRIS database lists benzene as a known human carcinogen (causing leukemia at
5 Although a recent court case, American Corn Growers Association v. EPA, 291F.3d 1(D.C .Cir 2002),
vacated the Best Available Retrofit Technology (BART) provisions of the Regional Haze rule, the court denied
industry's challenge to EPA's requirement that state's SIPS provide for reasonable progress towards achieving
natural visibility conditions in national parks and wilderness areas and the "no degradation" requirement. Industry
did not challenge requirements to improve visibility on the haziest 20 percent of days. The court recognized that
mobile source emission reductions would need to be a part of a long-term emission strategy for reducing regional
haze. A copy of this decision can be found in Docket A-2000-01, Document IV- A-113.
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high, prolonged air exposures) by all routes of exposure.106 It is associated with additional health
effects including genetic changes in humans and animals and increased proliferation of bone
marrow cells in mice.107'108 EPA states in its IRIS database that the data indicate a causal
relationship between benzene exposure and acute lymphocytic leukemia and suggest a
relationship between benzene exposure and chronic non-lymphocytic leukemia and chronic
lymphocytic leukemia. Respiration is the major source of human exposure and at least half of
this exposure is attributable to gasoline vapors and automotive emissions. A number of adverse
noncancer health effects including blood disorders, such as preleukemia and aplastic anemia,
have also been associated with low-dose, long-term exposure to benzene.
Respiration is the major source of human exposure to benzene. Long-term respiratory
exposure to high levels of ambient benzene concentrations has been shown to cause cancer of the
tissues that form white blood cells. Among these are acute nonlymphocytic leukemia,6 chronic
lymphocytic leukemia and possibly multiple myeloma (primary malignant tumors in the bone
marrow), although the evidence for the latter has decreased with more recent studies.109'110
Leukemias, lymphomas, and other tumor types have been observed in experimental animals
exposed to benzene by inhalation or oral administration. Exposure to benzene and/or its
metabolites has also been linked with genetic changes in humans and animals111 and increased
proliferation of mouse bone marrow cells.112 The occurrence of certain chromosomal changes in
individuals with known exposure to benzene may serve as a marker for those at risk for
contracting leukemia.113
The latest assessment by EPA places the excess risk of developing acute nonlymphocytic
leukemia at 2.2 x 10"6 to 7.7 x 10"6/|ig/m3. In other words, there is a risk of about two to eight
excess acute nonlymphocytic leukemia cases in one million people exposed to 1 i-ig/m3 over a
lifetime (70 years).114 This range of unit risk represents the maximum likelihood estimate of
risk. Upper bound cancer risk is above 10 in a million across the entire U.S. EPA projects a
median nationwide reduction in ambient concentrations of benzene from mobile sources of about
46 percent between 1996 and 2007, as a result of current and planned control programs based on
the analysis referenced earlier examining these pollutants in the 1996 to 2007 time frame based
on the analysis of hazardous air pollutants in the 1996 to 2007 time frame referenced earlier.
Leukemia is a blood disease in which the white blood cells are abnormal in type or number. Leukemia
may be divided into nonlymphocytic (granulocytic) leukemias and lymphocytic leukemias. Nonlymphocytic
leukemia generally involves the types of white blood cells (leukocytes) that are involved in engulfing, killing, and
digesting bacteria and other parasites (phagocytosis) as well as releasing chemicals involved in allergic and immune
responses. This type of leukemia may also involve erythroblastic cell types (immature red blood cells).
Lymphocytic leukemia involves the lymphocyte type of white bloods cell that are responsible for the immune
responses. Both nonlymphocytic and lymphocytic leukemia may, in turn, be separated into acute (rapid and fatal)
and chronic (lingering, lasting) forms. For example; in acute myeloid leukemia (AML) there is diminished
production of normal red blood cells (erythrocytes), granulocytes, and platelets (control clotting) which leads to
death by anemia, infection, or hemorrhage. These events can be rapid. In chronic myeloid leukemia (CML) the
leukemic cells retain the ability to differentiate (i.e., be responsive to stimulatory factors) and perform function; later
there is a loss of the ability to respond.
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A number of adverse noncancer health effects, blood disorders such as preleukemia and
aplastic anemia, have also been associated with low-dose, long-term exposure to benzene.115'116
People with long-term exposure to benzene may experience harmful effects on the blood-
forming tissues, especially the bone marrow. These effects can disrupt normal blood production
and cause a decrease in important blood components, such as red blood cells and blood platelets,
leading to anemia (a reduction in the number of red blood cells), leukopenia (a reduction in the
number of white blood cells), or thrombocytopenia (a reduction in the number of blood platelets,
thus reducing the ability for blood to clot). Chronic inhalation exposure to benzene in humans
and animals results in pancytopenia,7 a condition characterized by decreased numbers of
circulating erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes
(blood platelets).117'118 Individuals that develop pancytopenia and have continued exposure to
benzene may develop aplastic anemia,8 whereas others exhibit both pancytopenia and bone
marrow hyperplasia (excessive cell formation), a condition that may indicate a preleukemic
state.11912° The most sensitive noncancer effect observed in humans is the depression of absolute
lymphocyte counts in the circulating blood.121
1.3.2 - 1,3-Butadiene
1,3-Butadiene is formed in engine exhaust by the incomplete combustion of fuel. It is not
present in engine evaporative emissions because it is not present in any appreciable amount in
fuel. 1,3-Butadiene accounts for less than one percent of total organic gas exhaust from mobile
sources.
EPA earlier identified 1,3-butadiene as a probable human carcinogen in its IRIS database.122
Recently EPA redesignated 1,3-butadiene as a known human carcinogen.123'124'125 The specific
mechanisms of 1,3-butadiene-induced carcinogenesis are unknown. However, it is virtually
certain that the carcinogenic effects are mediated by genotoxic metabolites of 1,3-butadiene.
Animal data suggest that females may be more sensitive than males for cancer effects; but more
data are needed before reaching definitive conclusions on potentially sensitive subpopulations.
The unit cancer risk estimate is 0.08/ppm or 3x10-5 per |ig/m3 (based primarily on linear
Pancytopenia is the reduction in the number of all three major types of blood cells (erythrocytes, or red
blood cells, thrombocytes, or platelets, and leukocytes, or white blood cells). In adults, all three major types of
blood cells are produced in the bone marrow of the vertebra, sternum, ribs, and pelvis. The bone marrow contains
immature cells, known as multipotent myeloid stem cells, that later differentiate into the various mature blood cells.
Pancytopenia results from a reduction in the ability of the red bone marrow to produce adequate numbers of these
mature blood cells.
8 Aplastic anemia is a more severe blood disease and occurs when the bone marrow ceases to function,
i.e.,these stem cells never reach maturity. The depression in bone marrow function occurs in two stages -
hyperplasia, or increased synthesis of blood cell elements, followed by hypoplasia, or decreased synthesis. As the
disease progresses, the bone marrow decreases functioning. This myeloplastic dysplasia (formation of abnormal
tissue) without acute leukemias known as preleukemia. The aplastic anemia can progress to AML (acute
mylogenous leukemia).
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modeling and extrapolation of human data). In other words, it is estimated that approximately 30
persons in one million exposed to 1 i-ig/m3 1,3-butadiene continuously for their lifetime (70
years) would develop cancer as a result of this exposure. The human incremental lifetime unit
cancer risk (incidence) estimate is based on extrapolation from leukemias observed in an
occupational epidemiologic study.126 A twofold adjustment to the epidemiologic-based unit
cancer risk was applied to reflect evidence from the rodent bioassays suggesting that the
epidemiologic-based estimate may underestimate total cancer risk from 1,3-butadiene exposure
in the general population. Upper bound cancer risk is above 10 in a million across the entire
U.S. EPA projects a median nationwide reduction in ambient concentrations of benzene from
mobile sources of about 46 percent between 1996 and 2007, as a result of current and planned
control programs.
1,3-Butadiene also causes a variety of reproductive and developmental effects in mice; no
human data on these effects are available. The most sensitive effect was ovarian atrophy
observed in a lifetime bioassay of female mice.127 Based on this critical effect and the
benchmark concentration methodology, an RfC (i.e., a chronic exposure level presumed to be
"without appreciable risk" for noncancer effects) was calculated. This RfC for chronic health
effects was 0.9 ppb.
1.3.3 - Formaldehyde
Formaldehyde is the most prevalent aldehyde in engine exhaust. It is formed from
incomplete combustion of both gasoline and diesel fuel. In a recent test program which
measured toxic emissions from several nonroad diesel engines, ranging from 50 to 480
horsepower, formaldehyde consistently accounted for well over 10 percent of total exhaust
hydrocarbon emissions.128 Formaldehyde accounts for far less of total exhaust hydrocarbon
emissions from gasoline engines, although the amount can vary substantially by duty cycle,
emission control system, and fuel composition. It is not found in evaporative emissions.
EPA has classified formaldehyde as a probable human carcinogen based on limited evidence
for carcinogenicity in humans and sufficient evidence of carcinogenicity in animal studies, rats,
mice, hamsters, and monkeys.129' 13° Epidemiological studies in occupationally exposed workers
suggest that long-term inhalation of formaldehyde may be associated with tumors of the
nasopharyngeal cavity (generally the area at the back of the mouth near the nose), nasal cavity,
and sinus.131 Studies in experimental animals provide sufficient evidence that long-term
inhalation exposure to formaldehyde causes an increase in the incidence of squamous (epithelial)
cell carcinomas (tumors) of the nasal cavity.132'133'134 The distribution of nasal tumors in rats
suggests that not only regional exposure but also local tissue susceptibility may be important for
the distribution of formaldehyde-induced tumors.135 Research has demonstrated that
formaldehyde produces mutagenic activity in cell cultures.136
The upper confidence limit estimate of a lifetime extra cancer risk from continuous
formaldehyde exposure is about 1.3 * 10"5/|ig/m3. In other words, it is estimated that
approximately 10 persons in one million exposed to 1 i-ig/m3 formaldehyde continuously for their
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lifetime (70 years) would develop cancer as a result of this exposure. The agency is currently
conducting a reassessment of risk from inhalation exposure to formaldehyde based on new
information including a study by the Chemistry Industry Institute of Toxicology.137'138 Upper
bound cancer risk is above 10 in a million for more than one hundred million Americans. EPA
projects a median nationwide reduction in ambient concentrations of benzene from mobile
sources of about 43 percent between 1996 and 2007, as a result of current and planned control
programs (Cook et al., 2002).
Formaldehyde exposure also causes a range of noncancer health effects. At low
concentrations (e.g. 0.05-2.0 ppm), irritation of the eyes (tearing of the eyes and increased
blinking) and mucous membranes is the principal effect observed in humans. At exposure to 1-
11 ppm, other human upper respiratory effects associated with acute formaldehyde exposure
include a dry or sore throat, and a tingling sensation of the nose. Sensitive individuals may
experience these effects at lower concentrations. Forty percent of formaldehyde-producing
factory workers reported nasal symptoms such as rhinitis (inflammation of the nasal membrane),
nasal obstruction, and nasal discharge following chronic exposure.139 In persons with bronchial
asthma, the upper respiratory irritation caused by formaldehyde can precipitate an acute
asthmatic attack, sometimes at concentrations below 5 ppm.140 Formaldehyde exposure may also
cause bronchial asthma-like symptoms in non-asthmatics.141 142
Immune stimulation may occur following formaldehyde exposure, although conclusive
evidence is not available. Also, little is known about formaldehyde's effect on the central
nervous system. Several animal inhalation studies have been conducted to assess the
developmental toxicity of formaldehyde: The only exposure-related effect noted in these studies
was decreased maternal body weight gain at the high-exposure level. No adverse effects on
reproductive outcome of the fetuses that could be attributed to treatment were noted. An
inhalation reference concentration (RfC), below which long-term exposures would not pose
appreciable noncancer health risks, is not available for formaldehyde at this time. The Agency is
currently conducting a reassessment of risk from inhalation exposure to formaldehyde.
1.3.4 - Acetaldehyde
Acetaldehyde is a saturated aldehyde that is found in engine exhaust and is formed as a
result of incomplete combustion of both gasoline and diesel fuel. In a recent test program which
measured toxic emissions from several nonroad diesel engines, ranging from 50 to 480
horsepower, acetaldehyde consistently accounted for over 5 percent of total exhaust hydrocarbon
emissions.143 Acetaldehyde accounts for far less of total exhaust hydrocarbon emissions from
gasoline engines, although the amount can vary substantially by duty cycle, emission control
system, and fuel composition. It is not a component of evaporative emissions.
Acetaldehyde is classified as a probable human carcinogen. Studies in experimental
animals provide sufficient evidence that long-term inhalation exposure to acetaldehyde causes an
increase in the incidence of nasal squamous cell carcinomas (epithelial tissue) and
adenocarcinomas (glandular tissue)'144' 145> 146> 147> 148 The upper confidence limit estimate of a
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lifetime extra cancer risk from continuous acetaldehyde exposure is about 2.2 x 10"6 /|ig/m3. In
other words, it is estimated that about 2 persons in one million exposed to 1 i-ig/m3 acetaldehyde
continuously for their lifetime (70 years) would develop cancer as a result of their exposure. The
Agency is currently conducting a reassessment of risk from inhalation exposure to acetaldehyde.
Upper bound cancer risk is above one in a million for more than one hundred million Americans.
EPA projects a median nationwide reduction in ambient concentrations of benzene from mobile
sources of about 36 percent between 1996 and 2007, as a result of current and planned control
programs
EPA's IRIS database states that noncancer effects in studies with rats and mice showed
acetaldehyde to be moderately toxic by the inhalation, oral, and intravenous routes (EPA, 1988).
Similar conclusions have been made by the California Air Resources Board.149 The primary
acute effect of exposure to acetaldehyde vapors is irritation of the eyes, skin, and respiratory
tract. At high concentrations, irritation and pulmonary effects can occur, which could facilitate
the uptake of other contaminants. Little research exists that addresses the effects of inhalation of
acetaldehyde on reproductive and developmental effects. The in vitro and in vivo studies
provide evidence to suggest that acetaldehyde may be the causative factor in birth defects
observed in fetal alcohol syndrome, though evidence is very limited linking these effects to
inhalation exposure. Long-term exposures should be kept below the reference concentration of 9
l-ig/m3 to avoid appreciable risk of these noncancer health effects (EPA, 1988).
Acetaldehyde has been associated with lung function decrements in asthmatics. In one
study, aerosolized acetaldehyde caused reductions in lung function and bronchoconstriction in
asthmatic subjects.150
1.3.5 - Acrolein
In a recent test program which measured toxic emissions from several nonroad diesel
engines, ranging from 50 to 480 horsepower, acrolein accounted for about 0.5 to 2 percent of
total exhaust hydrocarbon emissions.151 Acrolein accounts for far less of total exhaust
hydrocarbon emissions from gasoline engines, although the amount can vary substantially by
duty cycle, emission control system, and fuel composition. It is not a component of evaporative
emissions.
Acrolein is extremely toxic to humans from the inhalation route of exposure, with acute
exposure resulting in upper respiratory tract irritation and congestion. The Agency developed a
reference concentration for inhalation (RfC) of acrolein of 0.02 |ig/m3 in 1993. The hazard
quotient is greater than one for most of the U.S. population, indicating a potential for adverse
noncancer health effects.
Although no information is available on its carcinogenic effects in humans, based on
laboratory animal data, EPA considers acrolein a possible human carcinogen.152
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1.4 - Inventory Contributions
1.4.1 - Inventory Contribution
The contribution of emissions from highway motorcycles to the national inventories of
pollutants associated with the health and public welfare effects described in this chapter are
considerable. Emission estimates for highway motorcycles were developed using information on
the emission levels of current motorcycles and updated information on motorcycle use provided
by the motorcycle industry. A more detailed description of the modeling and our estimation
methodology can be found in the Chapter 6 of this document.
Baseline emission inventory estimates for the years 1996 and 2020 for highway motorcycles
are summarized in Tables 1.4-1 through 1.4-3 for VOC, NOx, and PM, respectively.9 The
estimates shown for highway motorcycles are baseline estimates and do not account for the
impact of the standards adopted today. These tables show the relative contributions of the
different mobile-source categories to the overall national mobile-source inventory. Highway
motorcycles contribute about 0.6 percent, 0.1 percent, and less than 0.1 percent of mobile source
VOC, NOx, and PM emissions, respectively, in the year 1996. Our inventory projections for
2020 for highway motorcycles show that emissions are expected to increase over time if left
uncontrolled. The projections for 2020 indicate that motorcycles are expected to contribute 2.3
percent, 0.3 percent, and 0.1 percent of mobile source VOC, NOx, and PM emissions,
respectively, in the year 2020. Population growth and the effects of other regulatory control
programs are factored into these projections.
9 The inventories cited in Tables 1.4-1 through 1.4-4 were developed for the Nonroad Diesel Rulemaking.
(See 68 FR 28328, published May 23, 2003.) The inventories for recreational marine engines greater than 50
horsepower, nonroad spark-ignition engines greater than 25 horsepower, and recreations spark-ignition engines have
been updated using the latest version of EPA's NONROAD model to account for the new standards adopted by EPA
in late 2002. (See 67 FR 68242, published November 8, 2002.)
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Table 1.4-1
Annual VOC Baseline Emission Levels for Mobile and Other Source Categories
a,b
Category
Highway Motorcycles
Highway Light-duty
Highway Heavy-duty
Land-based Nonroad Diesel
Recreational Marine Diesel <50 hp
Recreational Marine Diesel >50 hp
Recreational Marine SI
Nonroad SI <25 hp
Nonroad SI >25hp
Recreational SI
Commercial Marine Diesel
Commercial Marine SI
Locomotive
Aircraft
Total Nonroad
Total Highway
Total Mobile Sources
Stationary Point and Area Sources
Total Man-Made Sources
Mobile Source Percent of Total
1996
VOC
short tons
47,368
4,635,410
608,607
221,403
128
1,199
804,488
1,330,229
85,701
308,285
31,545
960
48,381
176,394
3,008,713
5,291,385
8,300,098
10,249,136
18,549,234
45%
%of
mobile
source
0.6%
55.8%
7.3%
2.7%
0.0%
0.0%
9.7%
16.0%
1.0%
3.7%
0.4%
0.0%
0.6%
2.1%
36%
64%
100%
—
—
—
%of
total
0.3%
25.0%
3.3%
1.2%
0.0%
0.0%
4.3%
7.2%
0.5%
1.7%
0.2%
0.0%
0.3%
1.0%
16%
29%
45%
55%
2020
VOC
short tons
86,520
1,755,119
226,641
96,855
108
1,531
380,891
650,158
12,265
339,098
37,290
998
36,546
239,654
1,795,394
2,068,280
3,863,674
9,648,376
13,512,050
29%
%of
mobile
source
2.2%
45.4%
5.9%
2.5%
0.0%
0.0%
9.9%
16.8%
0.3%
8.8%
1.0%
0.0%
0.9%
6.2%
46%
54%
100%
—
—
—
%of
total
0.6%
13.0%
1.7%
0.7%
0.0%
0.0%
2.8%
4.8%
0.1%
2.5%
0.3%
0.0%
0.3%
1.8%
13%
15%
29%
71%
a These are 48-state inventories. They
b The mobile source estimates include
do not include Alaska and Hawaii.
both exhaust and evaporative emissions.
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Table 1.4-2
Annual NOV Baseline Emission Levels for Mobile and Other Source Categories a
Category
Highway Motorcycles
Highway Light-duty
Highway Heavy-duty
Land-based Nonroad Diesel
Recreational Marine Diesel <50 hp
Recreational Marine Diesel >50 hp
Recreational Marine SI
Nonroad SI <25 hp
Nonroad SI >25hp
Recreational SI
Commercial Marine Diesel
Commercial Marine SI
Locomotive
Aircraft
Total Nonroad
Total Highway
Total Mobile Sources
Stationary Point and Area Sources
Total Man-Made Sources
Mobile Source Percent of Total
1996
NOx
short tons
7,284
4,427,634
4,626,004
1,583,664
523
33,468
33,304
63,584
273,099
4,297
959,704
6,428
921,556
165,018
4,044,645
9,060,922
13,105,567
11,449,752
24,555,319
53%
%of
mobile
source
0.1%
33.8%
35.3%
12.1%
0.0%
0.3%
0.3%
0.5%
2.1%
0.0%
7.3%
0.0%
7.0%
1.3%
31%
69%
100%
—
—
—
%of
total
0.0%
18.0%
18.8%
6.4%
0.0%
0.1%
0.1%
0.3%
1.1%
0.0%
3.9%
0.0%
3.8%
0.7%
16%
37%
53%
47%
2020
NOx
short tons
14,059
1,264,342
696,911
1,140,727
682
47,675
61,749
100,119
43,322
17,129
819,201
4,551
612,722
228,851
3,076,728
1,975,312
5,052,040
10,050,213
15,102,253
33%
%of
mobile
source
0.3%
25.0%
13.8%
22.6%
0.0%
0.9%
1.2%
2.0%
0.9%
0.3%
16.2%
0.1%
12.1%
4.5%
61%
39%
100%
—
—
—
%of
total
0.1%
8.4%
4.6%
7.6%
0.0%
0.3%
0.4%
0.7%
0.3%
0.1%
5.4%
0.0%
4.1%
1.5%
20%
13%
33%
67%
' These are 48-state inventories. They do not include Alaska and Hawaii.
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Table 1.4-3
Annual PM-2.5 Baseline Emission Levels for Mobile and Other Source Categories
a,b
Category
Highway Motorcycles
Highway Light-duty
Highway Heavy-duty
Land-based Nonroad Diesel
Recreational Marine Diesel <50 hp
Recreational Marine Diesel >50 hp
Recreational Marine SI
Nonroad SI <25 hp
Nonroad SI >25hp
Recreational SI
Commercial Marine Diesel
Commercial Marine SI
Locomotive
Aircraft
Total Nonroad
Total Highway
Total Mobile Sources
Stationary Point and Area Sources
Total Man-Made Sources
Mobile Source Percent of Total
1996
PM-2.5
short tons
184
57,534
172,965
176,510
62
815
35,147
24,130
1,374
7,968
36,367
1,370
20,937
27,891
332,571
230,683
563,254
1,653,392
2,216,646
25%
%of
mobile
source
0.0%
10.2%
30.7%
31.3%
0.0%
0.1%
6.2%
4.3%
0.2%
1.4%
6.5%
0.2%
3.7%
5.0%
59%
41%
100%
—
—
—
%of
total
0.0%
2.6%
7.8%
8.0%
0.0%
0.0%
1.6%
1.1%
0.1%
0.4%
1.6%
0.1%
0.9%
1.3%
15%
10%
25%
75%
2020
PM-2.5
short tons
434
47,136
24,806
124,334
70
1,162
26,110
29,998
2,302
9,963
41,365
1,326
16,727
30,024
283,381
72,376
355,757
1,712,004
2,067,761
17%
%of
mobile
source
0.1%
13.2%
7.0%
34.9%
0.0%
0.3%
7.3%
8.4%
0.6%
2.8%
11.6%
0.4%
4.7%
8.4%
80%
20%
100%
—
—
—
%of
total
0.0%
2.3%
1.2%
6.0%
0.0%
0.1%
1.3%
1.5%
0.1%
0.5%
2.0%
0.1%
0.8%
1.5%
14%
4%
17%
83%
a These are 48-state inventories. They do not include Alaska and Hawaii.
b Excludes natural and miscellaneous sources.
1.4.2 - Inventory Impacts on a Per Vehicle Basis
In addition to the general inventory contributions described above, motorcycles have much
higher emissions than cars on a per vehicle basis. A highway motorcycle driven 10 miles emits
as many hydrocarbon emissions as a current passenger car driven for 210 miles. The per engine
emissions are important because they mean that operators of these engines and vehicles, as well
1-44
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as those who work in their vicinity, are exposed to high levels of emissions, many of which are
air toxics. These effects are described in more detail in the next section.
1.5 - Other Health and Environmental Effects
1.5.1 - Acid Deposition
Acid deposition, or acid rain as it is commonly known, occurs when SO2 and NOx react in
the atmosphere with water, oxygen, and oxidants to form various acidic compounds that later fall
to earth in the form of precipitation or dry deposition of acidic particles.153 It contributes to
damage of trees at high elevations and in extreme cases may cause lakes and streams to become
so acidic that they cannot support aquatic life. In addition, acid deposition accelerates the decay
of building materials and paints, including irreplaceable buildings, statues, and sculptures that
are part of our nation's cultural heritage. To reduce damage to automotive paint caused by acid
rain and acidic dry deposition, some manufacturers use acid-resistant paints, at an average cost
of $5 per vehicle—a total of $61 million per year if applied to all new cars and trucks sold in the
U.S.
Acid deposition primarily affects bodies of water that rest atop soil with a limited ability to
neutralize acidic compounds. The National Surface Water Survey (NSWS) investigated the
effects of acidic deposition in over 1,000 lakes larger than 10 acres and in thousands of miles of
streams. It found that acid deposition was the primary cause of acidity in 75 percent of the
acidic lakes and about 50 percent of the acidic streams, and that the areas most sensitive to acid
rain were the Adirondacks, the mid-Appalachian highlands, the upper Midwest and the high
elevation West. The NSWS found that approximately 580 streams in the Mid-Atlantic Coastal
Plain are acidic primarily due to acidic deposition. Hundreds of the lakes in the Adirondacks
surveyed in the NSWS have acidity levels incompatible with the survival of sensitive fish
species. Many of the over 1,350 acidic streams in the Mid-Atlantic Highlands (mid-Appalachia)
region have already experienced trout losses due to increased stream acidity. Emissions from
U.S. sources contribute to acidic deposition in eastern Canada, where the Canadian government
has estimated that 14,000 lakes are acidic. Acid deposition also has been implicated in
contributing to degradation of high-elevation spruce forests that populate the ridges of the
Appalachian Mountains from Maine to Georgia. This area includes national parks such as the
Shenandoah and Great Smoky Mountain National Parks.
1.5.2 - Eutrophication and Nitrification
Nitrogen deposition into bodies of water can cause problems beyond those associated with
acid rain. The Ecological Society of America has included discussion of the contribution of air
emissions to increasing nitrogen levels in surface waters in a recent major review of causes and
consequences of human alteration of the global nitrogen cycle in its Issues in Ecology series.154
Long-term monitoring in the United States, Europe, and other developed regions of the world
shows a substantial rise of nitrogen levels in surface waters, which are highly correlated with
human-generated inputs of nitrogen to their watersheds. These nitrogen inputs are dominated by
fertilizers and atmospheric deposition.
1-45
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Human activity can increase the flow of nutrients into those waters and result in excess
algae and plant growth. This increased growth can cause numerous adverse ecological effects
and economic impacts, including nuisance algal blooms, dieback of underwater plants due to
reduced light penetration, and toxic plankton blooms. Algal and plankton blooms can also
reduce the level of dissolved oxygen, which can also adversely affect fish and shellfish
populations. This problem is of particular concern in coastal areas with poor or stratified
circulation patterns, such as the Chesapeake Bay, Long Island Sound, or the Gulf of Mexico. In
such areas, the "overproduced" algae tends to sink to the bottom and decay, using all or most of
the available oxygen and thereby reducing or eliminating populations of bottom-feeder fish and
shellfish, distorting the normal population balance between different aquatic organisms, and in
extreme cases causing dramatic fish kills.
Collectively, these effects are referred to as eutrophication, which the National Research
Council recently identified as the most serious pollution problem facing the estuarine waters of
the United States.155 Nitrogen is the primary cause of eutrophi cation in most coastal waters and
estuaries.156 On the New England coast, for example, the number of red and browntides and
shellfish problems from nuisance and toxic plankton blooms have increased over the past two
decades, a development thought to be linked to increased nitrogen loadings in coastal waters.
We believe that airborne NOx contributes from 12 to 44 percent of the total nitrogen loadings to
United States coastal water bodies. For example, some estimates assert that approximately one-
quarter of the nitrogen in the Chesapeake Bay comes from atmospheric deposition.
Excessive fertilization with nitrogen-containing compounds can also affect terrestrial
ecosystems.10 Research suggests that nitrogen fertilization can alter growth patterns and change
the balance of species in an ecosystem, providing beneficial nutrients to plant growth in areas
that do not suffer from nitrogen over-saturation. In extreme cases, this process can result in
nitrogen saturation when additions of nitrogen to soil over time exceed the capacity of the plants
and microorganisms to utilize and retain the nitrogen. This phenomenon has already occurred in
some areas of the U.S.
10 Terrestrial nitrogen deposition can act as a fertilizer. In some agricultural areas, this effect can be
beneficial.
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Notes to Chapter 1
1. The air quality modeling data presented in this chapter was developed for our proposed
rulemaking proposing standards for nonroad diesel engines and their fuels. See 68 FR 28328,
May 23, 2003. Additional information about the air quality modeling and other aspects of the
health and welfare impacts of the pollutants described in this chapter can be found in the Draft
Regulatory Impact Analysis prepared for that proposal. A copy of that document can be found in
Docket A-2001-28, Document III-B-01. It is also available on EPA's web-based electronic
docket as OAR-2003-0012-0025.
2. For more information about VOC and HC, see U.S. EPA (1997), Conversion Factors for
Hydrocarbon Emission Components, Report No. NR-002. This document is available in Docket
A-2000-02, Document IV-A-26.
3. U.S. EPA (1996). Air Quality Criteria for Ozone and Related Photochemical Oxidants,
EPA/600/P-93/004aF. Docket No. A-99-06. Document Nos. II-A-15 to 17. More information
on health effects of ozone is also available at
http:/www.epa.gov/ttn/naaqs/standards/ozone/s.03.index.html.
4. Bates, D.V.; Baker-Anderson, M.; Sizto, R. (1990) Asthma attack periodicity: a study of
hospital emergency visits in Vancouver. Environ. Res. 51: 51-70.
5. Thurston, G.D.; Ito, K.; Kinney, P.L.; Lippmann, M. (1992) A multi-year study of air
pollution and respiratory hospital admissions in three New York State metropolitan areas:
results for 1988 and 1989 summers. J. Exposure Anal. Environ. Epidemiol. 2:429-450.
6. Thurston, G.D.; Ito, K.; Hayes, C.G.; Bates, D.V.; Lippmann, M. (1994) Respiratory
hospital admissions and summertime haze air pollution in Toronto, Ontario: consideration of the
role of acid aerosols. Environ. Res. 65: 271-290.
7. Lipfert, F.W.; Hammerstrom, T. (1992) Temporal patterns in air pollution and hospital
admissions. Environ. Res. 59: 374-399.
8. Burnett, R.T.; Dales, R.E.; Raizenne, M.E.; Krewski, D.; Summers, P.W.; Roberts, G.R.;
Raad-Young, M.; Dann,T.; Brook, J. (1994) Effects of low ambient levels of ozone and sulfates
on the frequency of respiratory admissions to Ontario hospitals. Environ. Res. 65: 172-194.
9. U.S. EPA (1996). Air Quality Criteria for Ozone and Related Photochemical Oxidants,
EPA/600/P-93/004aF. Docket No. A-99-06. Document Nos. II-A-15 to 17. (See page 9-33)
10. U.S. EPA (1996). Air Quality Criteria for Ozone and Related Photochemical Oxidants,
EPA/600/P-93/004aF. Docket No. A-99-06. Document Nos. II-A-15 to 17. (See page 7-167)
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11. Devlin, R. B.; McDonnell, W. F.; Mann, R.; Becker, S.; House, D. E.; Schreinemachers,
D.; Koren, H. S. (1991) Exposure of humans to ambient levels of ozone for 6.6 hours causes
cellullar and biochemical changes in the lung. Am. J. Respir. Cell Mol. Biol. 4: 72-81.
12. Koren, H. S.; Devlin, R. B.; Becker, S.; Perez, R.; McDonnell, W. F. (1991) Time-
dependent changes of markers associated with inflammation in the lungs of humans exposed to
ambient levels of ozone. Toxicol. Pathol. 19: 406-411.
13. Koren, H. S.; Devlin, R. B.; Graham, D. E.; Mann, R.; McGee, M. P.; Horstman, D. H.;
Kozumbo, W. J.; Becker, S.; House, D. E.; McDonnell, W. F.; Bromberg, P. A. (1989a) Ozone-
induced inflammation in the lower airways of human subjects. Am. Rev. Respir. Dis. 139: 407-
415.
14. Schelegle, E.S.; Siefkin, A.D.; McDonald, RJ. (1991) Time course of ozone-induced
neutrophilia in normal humans. Am. Rev. Respir. Dis. 143:1353-1358.
15. U.S. EPA (1996). Air Quality Criteria for Ozone and Related Photochemical Oxidants,
EPA/600/P-93/004aF. Docket No. A-99-06. Document Nos. II-A-15 to 17. (See page 7-171)
16. Hodgkin, I.E.; Abbey, D.E.; Euler, G.L.; Magie, A.R. (1984) COPD prevalence in
nonsmokers in high and low photochemical air pollution areas. Chest 86: 830-838.
17. Euler, G.L.; Abbey, D.E.; Hodgkin, I.E.; Magie, A.R. (1988) Chronic obstructive
pulmonary disease symptom effects of long-term cumulative exposure to ambient levels of total
oxidants and nitrogen dioxide in California Seventh-day Adventist residents. Arch. Environ.
Health 43: 279-285.
18. Abbey, D.E.; Petersen, F.; Mills, P.K.; Beeson, W.L. (1993) Long-term ambient
concentrations of total suspended particulates, ozone, and sulfur dioxide and respiratory
symptoms in a nonsmoking population. Arch. Environ. Health 48: 33-46.
19. U.S. EPA. (1996). Review of National Ambient Air Quality Standards for Ozone,
Assessment of Scientific and Technical Information, OAQPS Staff Paper, EPA-452/R-96-007.
Docket No. A-99-06. Document No. II-A-22.
20. U.S. EPA (1996). Air Quality Criteria for Ozone and Related Photochemical Oxidants,
EPA/600/P-93/004aF. Docket No. A-99-06. Document Nos. II-A-15 to 17. More information
on health effects of ozone is also available at
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23. Avol, E. L.; Trim, S. C.; Little, D. E.; Spier, C. E.; Smith, M. N.; Peng, R.-C.; Linn, W. S.;
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55. For more details about the counties and populations experiencing various levels of
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61. US EPA (2003) Air Quality Data Analysis 1999-2001, Technical Support Document for
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64. U.S. EPA (1996) Air Quality Criteria for Paniculate Matter - Volumes I, II, and III,
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75. Schwartz, 1; Dockery, D. W.; Neas, L. M.; Wypij, D.; Ware, J. H.; Spengler, J. D.;
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97. National Research Council, 1993. Protecting Visibility in National Parks and Wilderness
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98. National Research Council, 1993. Protecting Visibility in National Parks and Wilderness
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100. See 64 FR 35722, July 1, 1999.
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103. EPA recently finalized a list of 21 Mobile Source Air Toxics, including VOCs, metals,
and diesel particulate matter and diesel exhaust organic gases (collectively DPM+DEOG). 66
FR 17230, March 29, 200. This materials is available in Docket No. A-2000-01, Documents
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104. See our Mobile Source Air Toxics final rulemaking, 66 FR 17230, March 29, 2001, and
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106. U.S. EPA (2000). Integrated Risk Information System File for Benzene. This material is
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Monooxygenases and Bioactivation of Toxic Compounds. New York: Plenum Press, pp. 415-
434.
118. Goldstein, B.D. (1988). Benzene toxicity. Occupational medicine. State of the Art
Reviews. 3: 541-554.
119. Aksoy, M., S. Erdem, and G. Dincol. (1974). Leukemia in shoe-workers exposed
chronically to benzene. Blood 44:837.
120. Aksoy, M. and K. Erdem. (1978). A follow-up study on the mortality and the
development of leukemia in 44 pancytopenic patients associated with long-term exposure to
benzene. Blood 52: 285-292.
121. Rothman, N., G.L. Li, M. Dosemeci, W.E. Bechtold, G.E. Marti, Y.Z. Wang, M. Linet,
L.Q. Xi, W. Lu, M.T. Smith, N. Titenko-Holland, L.P. Zhang, W. Blot, S.N. Yin, and R.B.
Hayes (1996). Hematotoxicity among Chinese workers heavily exposed to benzene. Am. J. Ind.
Med. 29: 236-246.
122. U.S. EPA (1987). Integrated Risk Information System File of Butadiene. This material is
available electronically at http://www.epa.gov/iris/subst/0139.htm A copy of this document is
available in Docket A-2000-02, Document IV-A-33.
123. U.S. EPA. (2002). Health Assessment of 1,3-Butadiene. Office of Research and
Development, National Center for Environmental Assessment, Washington Office, Washington,
DC. Report No. EPA600-P-98-001F. This document is available in Docket A-2001-28,
Document No. II-A-116. This document is also available at
http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=54499 .
124. U.S. EPA (2002). Health Assessment of 1,3-Butadiene. Office of Research and
Development, National Center for Environmental Assessment, Washington Office, Washington,
DC. Report No. EPA600-P-98-001F. This document is available in Docket A-2001-28,
Document No. II-A-116. This document is also available at
http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=54499 .
125. U.S. EPA (1998). A Science Advisory Board Report: Review of the Health Risk
Assessment of 1,3-Butadiene. EPA-SAB-EHC-98-003. This document is available in Docket A-
2000-02, Document IV-A-34. It is also available at http://www.epa.gov/sab/pdf/ehc9903.pdf
126. Delzell E. Sathiakumar N. Hovinga M. Macaluso M. Julian J. Larson R. Cole P. Muir DC.
A follow-up study of synthetic rubber workers. [Journal Article] Toxicology. 113(1-3): 182-9,
1996Oct28.
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127. Bevan, C; Stadler, JC; Elliot, GS; et al. (1996) Subchronic toxicity of 4-vinylcyclohexene
in rats and mice by inhalation. Fundam. Appl. Toxicol. 32:1-10.
128. Southwest Research Institute. (2002). Nonroad Duty Cycle Testing for Toxic Emissions.
Prepared for the U.S. Environmental Protection Agency, Office of Transportation and Air
Quality, September 2002. Report No. SwRI 08.5004.05. A copy of this report is available in
Docket A-2001-28, Document II-A-38.
129. U.S. EPA (1987). Environmental Protection Agency, Assessment of health risks to
garment workers and certain home residents from exposure to formaldehyde, Office of Pesticides
and Toxic Substances, April 1987. This document is available in Docket A-2001-28, Document
No. II-A-93.
130. U.S. EPA (1991). Integrated Risk Information System File of Formaldehyde. This
material is available electronically at http ://www. epa. gov/iris/subst/0419.htm . A copy of this
document is available in Docket A-2000-02, Document IV-A-35.
131. Blair, A., P.A. Stewart, R.N. Hoover, et al. (1986). Mortality among industrial workers
exposed to formaldehyde. J. Natl. Cancer Inst. 76(6): 1071-1084.
132. Kerns, W.D., K.L. Pavkov, D.J. Donofrio, EJ. Gralla and J.A. Swenberg. (1983).
Carcinogenicity of formaldehyde in rats and mice after long-term inhalation exposure. Cancer
Res. 43:4382-4392.
133. Albert, R.E., A.R. Sellakumar, S. Laskin, M. Kuschner, N. Nelson and C.A. Snyder.
Gaseous formaldehyde and hydrogen chloride induction of nasal cancer in the rat. J. Natl.
Cancer Inst. 68(4): 597-603.
134. Tobe, M., T. Kaneko, Y. Uchida, et al. (1985) Studies of the inhalation toxicity of
formaldehyde. National Sanitary and Medical Laboratory Service (Japan), p. 1-94.
135. Clement Associates, Inc. (1991). Motor vehicle air toxics health information, for U.S. EPA
Office of Mobile Sources, Ann Arbor, MI, September 1991. This document is available in
Docket A-2000-01, Document No. II-A-49.
136. Ulsamer, A. G., J. R. Beall, H. K. Kang, et al. (1984). Overview of health effects of
formaldehyde. In: Saxsena, J. (ed.) Hazard Assessment of Chemicals - Current Developments.
NY: Academic Press, Inc. 3:337-400.
137. Chemical Industry Institute of Toxicology (1999). Formaldehyde: Hazard
Characterization and Dose-Response Assessment for Carcinogenicity by the Route of Inhalation.
Revised Edition. A copy of this document is available in Docket A-2000-02, Documents IV-A-
36 and IV-A-37.
138. Blair, A., P. Stewart, P.A. Hoover, et al. (1987). Cancers of the nasopharynx and
oropharynx and formaldehyde exposure. J. Natl. Cancer Inst. 78(1): 191-193.
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139. Wilhelmsson, B. and M. Holmstrom. (1987). Positive formaldehyde PAST after
prolonged formaldehyde exposure by inhalation. The Lancet: 164.
140. Burge, P.S., M.G. Harries, W.K. Lam, I.M. O'Brien, and P.A. Patchett. (1985).
Occupational asthma due to formaldehyde. Thorax 40:225-260.
141. Hendrick, D.J., RJ. Rando, DJ. Lane, and MJ. Morris (1982). Formaldehyde asthma:
Challenge exposure levels and fate after five years. J. Occup. Med. 893-897.
142. Nordman, H., H. Keskinen, and M. Tuppurainen. (1985). Formaldehyde asthma - rare or
overlooked? J. Allergy din. Immunol. 75:91-99.
143. Southwest Research Institute. (2002). Nonroad Duty Cycle Testing for Toxic Emissions.
Prepared for the U.S. Environmental Protection Agency, Office of Transportation and Air
Quality, September 2002. Report No. SwRI 08.5004.05. A copy of this report is available in
Docket A-2001-28, Document II-A-38.
144. U.S. EPA (1988). Integrated Risk Information System File of Acetaldehyde. This
material is available electronically at http ://www. epa. gov/iris/subst/0290.htm . A copy of this
document is available in Docket A-2000-02, Document IV-A-38.
145. Feron, VJ. (1979). Effects of exposure to acetaldehyde in Syrian hamsters simultaneously
treated with benzo(a)pyrene or diethylnitrosamine. Prog. Exp. Tumor Res. 24: 162-176.
146. Feron, V.J., A. Kruysse and R.A. Woutersen. (1982). Respiratory tract tumors in hamsters
exposed to acetaldehyde vapour alone or simultaneously to benzo(a)pyrene or
diethylnitrosamine. Eur. J. Cancer Clin. Oncol. 18: 13-31.
147. Woutersen, R.A. and L.M. Appelman. (1984). Lifespan inhalation carcinogenicity study
of acetaldehyde in rats. III. Recovery after 52 weeks of exposure. Report No. V84.288/190172.
CIVO-Institutes TNO, The Netherlands. A copy of this document is available in Docket A-
2000-02.
148. Wouterson, R., A. Van Garderen-Hoetmer and L.M. Appelman. 1985. Lifespan (27
months) inhalation carcinogenicity study of acetaldehyde in rats. Report No. V85.145/190172.
CIVO-Institutes TNO, The Netherlands.
149. California Air Resources Board (CARB) (1992). Preliminary Draft: Proposed
identification of acetaldehyde as a toxic air contaminant, Part B Health assessment, California
Air Resources Board, Stationary Source Division, August, 1992. A copy of this document is
available in Docket A-2000-01, Document II-A-34.
150. Myou, S.; Fujimura, M.; Nishi, K.; et al. (1993) Aerosolized acetaldehyde induces
histamine-mediated bronchoconstriction in asthmatics. Am Rev Respir Dis 148(4 Pt 1): 940-3.
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151. Southwest Research Institute. (2002). Nonroad Duty Cycle Testing for Toxic Emissions.
Prepared for the U.S. Environmental Protection Agency, Office of Transportation and Air
Quality, September 2002. Report No. SwRI 08.5004.05. A copy of this report is available in
Docket A-2001-28, Document II-A-38.
152. U.S. EPA (1994). Integrated Risk Information System File of Acrolein. This material is
available electronically at http://www.epa.gov/iris/subst/0364.htm . A copy of this document is
available in Docket A-2000-02, Document IV-A-39.
153. Much of the information in this subsection was excerpted from the EPA document, Human
Health Benefits from Sulfate Reduction, written under Title IV of the 1990 Clean Air Act
Amendments, U.S. EPA, Office of Air and Radiation, Acid Rain Division, Washington, DC
20460, November 1995, Air Docket A-2000-01, Document No. II-A-32.
154. Vitousek, Peter M., John Aber, Robert W. Howarth, Gene E. Likens, et al. 1997. Human
Alteration of the Global Nitrogen Cycle: Causes and Consequences. Issues in Ecology. Published
by Ecological Society of America, Number 1, Spring 1997.
155. National Research Council, 1993. Protecting Visibility in National Parks and Wilderness
Areas. National Academy of Sciences Committee on Haze in National Parks and Wilderness
Areas. National Academy Press, Washington, DC. This book can be viewed on the National
Academy Press website at http://www.nap.edu/books/0309048443/html/.
156. Much of this information was taken from the following EPA document: Deposition of Air
Pollutants to the Great Waters-Second Report to Congress., Office of Air Quality Planning and
Standards, June 1997, EPA-453/R-97-011. This document is available in Docket A-2000-02,
Document IV-A-40. The Third Report is available in Docket A-99-06, Document No. IV-A-06.
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CHAPTER 2: Industry Characterization
To accurately assess the potential impact of this emission control program, it is important to
understand the nature of the affected industries. This chapter describes relevant background
information related to highway motorcycles. Portions of this industry characterization were
developed in part under contract with RTI International1 as well as independent analyses
conducted by EPA through interaction with the industry and other sources. The complete report
from RTI International is available in the public docket.
Motorcycles come in a variety of two- and three-wheeled configurations and styles. For the
most part, however, they are two-wheeled self-powered vehicles designed for operation on paved
roadway surfaces. Federal regulations currently define a motorcycle as "any motor vehicle with
a headlight, taillight, and stoplight and having: two wheels, or three wheels and a curb mass less
than or equal to 793 kilograms (1749 pounds)." (See 40 CFR 86.402-98). By using the term
"motor vehicle," this definition includes only those vehicles that can achieve speeds of 25mph or
greater. Thus, most small scooters are considered to be highway motorcycles, but mopeds and
motorized bicycles are not. Vehicles that can be used both on and off-highway, called dual-
purpose or dual-sport motorcycles, are also covered by the current regulation.
Both EPA and California regulations sub-divide highway motorcycles into classes based on
engine displacement. Table 2.1-1 below shows how these classes are defined by EPA.
Table 2.1-1
Motorcycle Classes
Motorcycle
Class
Class I
Class II
Class III
Engine Displacement
(cubic centimeters)
(f-169
170 - 279
280 and greater
' This rule extends Class I to include <50cc.
2.1 - Manufacturers
Six companies account for about 95 percent of all motorcycles sold (Honda, Harley-
Davidson/Buell, Yamaha, Kawasaki, Suzuki, and BMW). All of these companies except Harley-
Davidson and BMW also manufacture off-road motorcycles and ATVs for the U.S. market.
From 1996 to 2000, Harley-Davidson produced more on-road motorcycles than any other
manufacturer and accounted for nearly 30 percent of total production by the six largest firms.
Honda accounted for 23.2 percent of total production by the six largest firms and Yamaha
accounted for 18.4 percent. Kawasaki and Suzuki each accounted for approximately 13 percent
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of production by the six largest firms, while BMW accounted for 2.7 percent. As a whole, these
firms increased production steadily in 1997, 1998, 1999, and 2000. In 2001, these firms are
continued producing over 90 percent of all highway motorcycles manufactured for the US
market.
Many other companies make up the remaining few percent of sales. Many of these are
small U.S. companies manufacturing anywhere from a couple dozen to a couple thousand
motorcycles, although importers and U.S. affiliates of larger international companies also
contribute to the remaining few percent. Excluding the six large manufacturers noted above, the
manufacturers with certified 2003 model year motorcycles are shown in Table 2.1-2. Aprilia,
Ducati, Piaggio, and Triumph are large international companies that, with the exception of
Triumph, have large market shares in Europe. Victory Motorcycle is a division of Polaris
Industries, a large U.S. leisure craft producer. The remainder are small U.S.-based
manufacturers or importers.
Table 2.1-2
2003 Motorcycle Manufacturers Excluding the Largest SixA
American Ironhorse
Aprilia
Big Dog Motorcycles
Big Mike's Choppers
Carafree Custom Cycles
Classic Motorcycles & Sidecars
Classic Motorcycles, Inc.
DC Imports
Ducati
Focus Inc.
Force Chopper Design
Indian
Iron Eagle Motorcycles
KTM
Minneapolis Custom Cycles
Moto America
Muz Motorrad
Panzer
Piaggio
Pro-One Performance
Ridley Motorcycle Co.
Roadstertec
Swift Motor Sports
Triumph
Vengeance Motorcycles
Victory Motorcycle
Westward Ind.,Ltd.
BMW, Kawasaki, Harley-Davidson, Honda, Suzuki, Yamaha.
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With the exception of Harley-Davidson/Buell, all the major manufacturers produce at least a
portion of their on-road motorcycles for the U.S. market outside of the U.S. BMW, Suzuki, and
Yamaha manufacture all on-road motorcycles destined for the U.S. market outside of the U.S.
Sixty-five percent of Honda's on-road motorcycles produced for the U.S. market are
manufactured outside the U.S., in either Italy or Japan. Sixty-one percent of Kawasaki's on-road
motorcycles destined for the U.S. market are produced in Japan.
2.2 - Sales and Fleet Size
Motorcycle sales are sensitive to economic cycles due to the recreational nature of
motorcycle ownership. While certainly some are used as basic transportation, in general they are
purchased by consumers who already own one or more cars, and the motorcycle is used for
recreation on evenings or weekends. All available data suggest that recreational uses dominate.
Data from the Federal Highway Administration's last two Nationwide Personal Transportation
surveys indicate that motorcycles were used for only 0.2 percent of the total number of journey-
to-work vehicle trips. RTI International concludes that motorcycle owners are only one-fifth as
likely to use their vehicle for commuting as owners of passenger cars or light trucks.2 In much
of the nation the motorcycle is not a practical means of transportation for one third of the year or
more. Sales were high in the late 1970's and early 1980's, but as the economy neared its
downturn that started around 1987-1988 sales clearly began to drop. Sales bottomed out with
that downturn in 1992, then as the economy boomed in the 1990's sales once again began to take
off, with retail dollars in 1998 approaching triple the retail dollars often years before. Historical
sales and retail dollars are shown in Table 2.2-1. Data for 2000 indicate that the trend
continued, with the retail sales of highway motorcycles up by more than 20 percent relative to
1999. The unit sales of highway motorcycles in calendar year 2000 was approximately 437,000
(including dual-sport motorcycles).11 The current fleet of highway motorcycles is
approximately 4.3 million units.
11 Dealernews. Vol. 37, No. 2, Feb. 2001, p. 158. Available in Docket A-2000-02 for review.
2O
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Table 2.2-1
On-Highway Motorcycle Retail Sales: 1982-2002"
Year
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
Units
(thousands)
577
490
394
311
260
242
230
228
217
203
206
226
245
335
465
470
565
605
605
605
Dollars
(millions)
5758
4789
3935
3132
2556
2213
1931
1773
1563
1333
1157
1148
1072
1304
1401
1375
1580
1111
1542
1463
3 Source: Motorcycle Industry Council,
2002 Motorcycle Statistical Annual.
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2.3 - Usage
Highway motorcycles are primarily for use on public roads and typically fall into one of
four categories: cruiser, touring, sport bike, or standard. A cruiser motorcycle is designed for
relatively short distances and is the most commonly purchased on-road motorcycle in the U.S. A
touring motorcycle is designed for long distance travel and extra load capacity. A sport bike is
designed for performance and uses racing technology, and finally a standard motorcycle is a
basic model. Each of these categories of motorcycles also differs in appearance and styling. For
instance, a cruiser motorcycle has a heavier appearance, a custom paint job, full-view engines,
and swept-back handlebars. A touring bike is built for rider comfort and includes saddlebags. In
contrast, a sportbike is more aerodynamic in appearance, and has low handle bars and high
performance tires.
The highway motorcycle category also includes motorcycles termed "dual-use" or "dual-
sport," meaning that their designs incorporate features that enable them to be competent both on
and off road. Dual-sport motorcycles generally can be described as street-legal dirt bikes,
because they often bear a closer resemblance in terms of design features and engines to true off-
road motorcycles than to highway cruisers, touring, or sport bikes.
2.4 - Current Trends
Analyzing production and sales numbers based on type of motorcycle and engine
displacement reveals that heavyweight motorcycles have become particularly popular in recent
years. In 2000, 72 percent of all on-road motorcycles produced for the U.S. market were
heavyweight motorcycles (651 cc or greater displacement). Just five years prior, heavyweight
motorcycles made up 67 percent of total production for the U.S. market. Until relatively
recently, Harley-Davidson was the only significant manufacturer of American heavyweight
cruiser and touring motorcycles. In 2000, Harley-Davidson/Buell was still the largest producer
of heavy weight on-road motorcycles (it produced 34 percent of all heavyweight motorcycles).
Of the 190 engine families certified in 2002 by manufacturers for sale in the U.S., 162 fall in
the Class III category (above 279cc), representing more than 90 percent of projected sales. More
than three-quarters of projected 2003 highway motorcycle sales are above 700cc. The average
displacement of all 2003 certified engine families is about 940cc, and the average displacement
of certified Class III engine families is above lOOOcc. The sales-weighted average displacement
of 2003 highway motorcycles is about 1 lOOcc. Class I and II motorcycles, which make up about
five percent of projected 2003 sales and only 29 out of 190 certified 2003 engine families,
consist mostly of scooters, with a few dual-sport bikes and entry-level sportbikes and cruisers.
According to the Motorcycle Industry Council (MIC), in 1998 there were about 5.4 million
highway motorcycles in use in the United States (565,000 of these were dual-sport).3 Total sales
in 1998 of highway motorcycles was estimated to be about 411,000, or about 72 percent of
motorcycle sales. About 13,000 of these were dual-sport motorcycles. Recent figures for the
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2000 calendar year show that retail sales approached 438,000 highway motorcycles, about
19,000 of which were dual-sport bikes.4
In the second half of the 1990's, motorcycle production at Harley-Davidson fell short of
meeting the rapidly growing demand for their motorcycles. The result has been the entry of at
least ten new companies into the heavyweight motorcycle market in the last several years. These
companies include two that ceased producing on-road motorcycles more than 50 years ago,
Excelsior Henderson Motorcycles and Indian Motorcycles. Polaris began manufacturing Victory
motorcycles in 1998. American Eagle Motorcycle Company began commercial production in
1996. Other competitors include companies that custom-build heavyweight motorcycles from
mostly non-proprietary components, including Titan, Big Dog, Pure Steel, American Ironhorse,
and Ultra.
A number of these companies have not been successful in the heavyweight motorcycle
market. American Quantum, Excelsior-Henderson, and Titan have filed for bankruptcy. One
possible explanation for the difficulty that smaller companies have had in profiting from
insufficient production of heavy weight motorcycle is that Harley increased its production by
more than expected. Harley-Davidson reports a 17.5 percent increase in production from 1998
to 1999. MIC projects that Harley-Davidson increased production by 15.4 percent between 1999
and 2000.
2.5 - Customer Concerns
2.5.1 - Performance
Adequate performance is clearly an important attribute for highway motorcycles. In
particular, buyers of sport or super-sport motorcycles are generally seeking performance that is
high or even extreme, sometimes rivaling the performance of exclusive racing motorcycles. In
the touring and cruiser segments of the market this kind of outrageous performance is generally
not sought after; these bikes have attributes (such as riding style and position) that make high
performance a less important design factor. For example, touring motorcycles are designed for
long-term riding comfort and luggage carrying capacity, and cruisers are often more focused on a
retro look, sound, and feel that allows them to be noticed cruising down Main Street, not
sprinting down the freeway.
2.5.2 - Cost
Motorcycles can range in price from around $1500 - $2000 for inexpensive entry-level or
dual-sport machines and mopeds and scooters to over $50,000 for elite custom machines.
According to Motorcycle Industry Council data the average amount spent by consumers on a
new motorcycle in 2001 can be estimated at just over $10,100.5 As with other recreational
vehicles, highway motorcycles are generally discretionary purchases. Significant cost increases
could therefore result in decreased sales of these motorcycles if the increased costs cause
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consumers to take their discretionary income elsewhere and into other recreational opportunities.
2.5.3 - Consumer Modifications
Many motorcycle owners personalize their motorcycles in a variety of ways. This is one of
the aspects of motorcycle ownership that is appealing to a large number of motorcycle owners,
and they take their freedom to customize their bikes very seriously. However, there are some
forms of customization that are not legal under the provisions of Clean Air Act section 203 (a),
which states that it is illegal:
"for any person to remove or render inoperative any device or element of design
installed on or in a motor vehicle or motor vehicle engine in compliance with
regulations under this title ... after such sale and delivery to the ultimate purchaser..."
In other words, owners of motor vehicles cannot legally make modifications that cause the
emissions to exceed the applicable emissions standards, and they cannot remove or disable
emission-control devices installed by the manufacturer.
We use the term "tampering" to refer specifically to actions that are illegal under Clean Air
Act section 203; the term, and the prohibition, do not apply generally to the wide range of
actions that a motorcycle enthusiast can do to personalize their vehicle, but only to actions that
remove or disable emission control devices or cause the emissions to exceed the standards. We
know, from anecdotal reports and from some data collected from in-use motorcycles, that a
portion of the motorcycle riding population has removed, replaced, or modified the original
equipment on their motorcycles. This customization can include changes that can be detrimental
(or, in some cases, possibly beneficial) to the motorcycle's emission levels. The NPRM sought
comments and data that could better help us understand the nature of the issue, such that our
proposal could be made with the best understanding possible of current consumer practices. We
did not intend to suggest that we would be revising the existing tampering restrictions to prohibit
many of the things that motorcycle owners are now doing legally.
The emissions standards do not change this "tampering" prohibition, which has been in
place for more than 20 years. Owners would still be free generally to customize their
motorcycles in any way, as long as they do not disable emission controls or cause the motorcycle
to exceed the emission standards. They would also be free, as they are now, to perform routine
maintenance on their motorcycles to restore or maintain the motorcycle engine and related
components in their original condition and configuration.
2.5.4 - Safety
The nature of motorcycling makes riders particularly aware of the many safety issues that
confront them. Many riders that submitted comments to us following the publication of the
NPRM in August of 2002 questioned whether catalytic converters could be implemented on
motorcycles without increasing the risk of harm to the rider and/or passenger. The primary
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concern is regarding the close proximity of the riders to hot exhaust pipes and the catalytic
converter. Protecting the rider from the excessive heat is a concern for both riders and
manufacturers. The current use of catalytic converters on a number of motorcycles (accounting
for tens of thousands in the current fleet) already indicates that these issues are not
insurmountable on a variety of motorcycle styles and engine sizes. A number of approaches to
shielding the rider from the heat of the catalytic converter are possible, such as exterior pipe
covers, shielded foot rests, and similar components. Some manufacturers have found that
placing the converter on the underside of the engine can keep it adequately distant from the rider.
Others may use double-pipe systems that reduce overall heat loss while remaining cooler on the
exterior. Based on the significant lead time that would be allowed for meeting these standards, as
well as on the two years of prior experience in California before meeting the requirements
federally, we believe that these issues can be satisfactorily resolved for the proportion of
motorcycles for which catalytic converters will be required.
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Chapter 2 References
1. "Industry Profile: Highway Motorcycles," RTI International, Contract No. 68-D-99-024,
June, 2003. Available in Docket A-2000-02.
2. "Industry Profile: Highway Motorcycles," RTI International, Contract No. 68-D-99-024,
June, 2003. Available in Docket A-2000-02.
3. Motorcycle Industry Council, "2000 Motorcycle Statistical Annual." Available in Docket
A-2000-02.
4. DealerNews, volume 37, no. 2, February 2001. Available in Docket A-2000-02.
5. Motorcycle Industry Council, "2002 Motorcycle Statistical Annual." Available in Docket
A-2000-02.
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CHAPTER 3: Technology
This chapter describes the current state of spark-ignition technology for engines and
permeation evaporative emission technology as well as the emission control technologies
expected to be available for motorcycle manufacturers. Chapter 4 presents the technical analysis
of the feasibility of the standards.
3.1 - Introduction to Spark-Ignition Engine Technology
The two most common types of engines are gasoline-fueled engines and diesel-fueled
engines. These engines have very different combustion mechanisms. Gasoline-fueled engines
initiate combustion using spark plugs, while diesel fueled engines initiate combustion by
compressing the fuel and air to high pressures. Thus these two types of engines are often more
generally referred to as "spark-ignition" and "compression-ignition" (or SI and CI) engines, and
include similar engines that used other fuels. SI engines include engines fueled with LPG and
CNG. SI engines may also be four-stroke or two-stroke which refers to the number of piston
strokes per combustion cycle. Motorcycle engines are primarily spark-ignition, four-stroke
engines. As of today EPA is aware of one CI motorcycle family; there are no SI motorcycle
families certified on alternative fuels,
3.1.1 - Basics of Spark-Ignition Four-Stroke Engines
Four-stroke engines are used in many different applications. Virtually all highway
motorcycles, automobiles, and many trucks are powered by four-stroke SI engines. Four-stroke
engines are also common in off-road motorcycles, all-terrain vehicles (ATVs), boats, airplanes,
and numerous nonroad applications such as lawn mowers, lawn and garden tractors, and
generators, to name just a few.
A "four-stroke" engine gets it's name from the fact that the piston makes four passes or
strokes in the cylinder to complete an entire cycle. The strokes are intake, compression, power,
and exhaust. Two of the strokes are downward (intake & power) and two of the strokes are
upward (compression & exhaust). Valves in the combustion chamber open and close to route
gases into and out of the combustion chamber or create compression.
The first step of the cycle is for an intake valve in the combustion chamber to open during
the "intake" stroke allowing a mixture of air and fuel to be drawn into the cylinder while an
exhaust valve is closed and the piston moves down the cylinder. The piston moves from top
dead center (TDC) or the highest piston position to bottom dead center (BDC) or lowest piston
position. This creates a vacuum or suction in the cylinder, which draws air and fuel past the
open intake valve into the combustion chamber.
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The intake valve then closes and the momentum of the crankshaft causes the piston to move
back up the cylinder from BDC to TDC, compressing the air and fuel mixture. This is the
"compression" stroke. As the piston nears TDC, at the very end of the compression stroke, the
air and fuel mixture is ignited by a spark from a spark plug and begins to burn. As the air and
fuel mixture burns, increasing temperature and pressure cause the piston to move back down the
cylinder, transmitting power to the crankshaft. This is referred to as the "power" stroke. The
last stroke in the four-stroke cycle is the "exhaust" stroke. At the bottom of the power stroke, an
exhaust valve opens in the combustion chamber and as the piston moves back up the cylinder,
the burnt gases are pushed out through the exhaust valve to the exhaust manifold, and the cycle
is complete.
3.1.2 - Basics of Spark-ignition Two-stroke Engines
Two-stroke SI engines are not generally used for highway motorcycles above 50 cc, but are
used in many highway motorcycles below 50 cc. They have been more widely used in nonroad
applications, especially for recreational vehicles, such as snowmobiles, off-highway motorcycles
and AT Vs. The basic operating principle of the charge scavenged two-stroke engine (traditional
two-stroke) is well understood; in two-strokes the engine performs the operations of intake,
compression, expansion and exhaust, which the four-stroke engine requires four strokes to
accomplish. Two-stroke engines have much higher emission rates than four-stroke engines. We
expect that as a result of this rule, almost all new highway motorcycles will use four-stroke
engines. However, the emission control systems discussed below are generally applicable to
both two-stroke and four-stroke engines, if any manufacturers choose to continue to use two-
stroke engines.
Another difference between two- and four-stroke engines is how the engines are lubricated.
Four-stroke engines use the crankcase as a sump for lubricating oil. Oil is distributed throughout
the engine by a pump through a series of small channels. Because the crankcase in a two-stroke
engine serves as the pump for the scavenging process, it is not possible to use it as an oil sump as
is the case for four-stroke engines. Otherwise, gasoline would mix with the oil and dilute it.
Instead, lubrication for two-stroke engines is provided by mixing specially-formulated two-
stroke oil with the incoming charge of air and fuel mixture. The oil is either mixed with the
gasoline in the fuel tank, or metered into the gasoline as it is consumed, using a small metering
pump. As the gasoline/oil mixture passes through the carburetor, it is atomized into fine droplets
and mixed with air. The gasoline quickly vaporizes, while the less volatile oil forms a fine mist
of fine droplets. Some of these droplets contact the crankshaft, piston pin, and cylinder walls,
providing lubrication. Most of the oil droplets, however, pass out of the crankcase and into the
cylinder with the rest of the incoming charge.
In a two-stroke engine, combustion occurs in every revolution of the crankshaft. Two-
stroke engines eliminate the intake and exhaust strokes, leaving only compression and power
strokes. This is due to the fact that two-stroke engines do not use intake and exhaust valves.
Instead, they have openings, referred to as "ports," in the sides of the cylinder walls. There are
typically three ports in the cylinder; an intake port that brings the air-fuel mixture into the
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crankcase; a transfer port that channels the air and fuel mixture from the crankcase to the
combustion chamber; and an exhaust port that allows burned gases to leave the cylinder and flow
into the exhaust manifold. Two-stroke engines route incoming air and fuel mixture first into the
crankcase, then into the cylinder via the transfer port. This is fundamentally different from a
four-stroke engine which delivers the air and fuel mixture directly to the combustion chamber.
With a two-stroke engine, as the piston approaches the bottom of the power stroke, it
uncovers exhaust ports in the wall of the cylinder. The high pressure burned combustion gases
blow into the exhaust manifold. At the same time, downward piston movement compresses the
fresh air and fuel mixture charge in the crankcase. As the piston gets closer to the bottom of the
power stroke, the transfer ports are uncovered, and fresh mixture of air and fuel are forced into
the cylinder while the exhaust ports are still open. Exhaust gas is "scavenged" or forced into the
exhaust by the pressure of the incoming charge of fresh air and fuel. In the process, however,
some mixing between the exhaust gas and the fresh charge of air and fuel takes place, so that
some of the fresh charge is also emitted in the exhaust. Losing part of the fuel out of the exhaust
during scavenging causes the very high hydrocarbon emission characteristics of two-stroke
engines.
At this point, the power, exhaust, and transfer events have been completed. When the piston
begins to move up, its bottom edge uncovers the intake port. Vacuum draws fresh air and fuel
into the crankcase. As the piston continues upward, the transfer port and exhaust ports are
closed. Compression begins as soon as the exhaust port is blocked. When the piston nears TDC,
the spark plug fires and the cycle begins again.
3.1.3 - Engine Calibration
For most current SI engines, after moving from two-stroke to four-stroke technology, the
two primary variables that manufacturers can control to reduce emissions are the air and fuel
mixture (henceforth referred to as air-fuel ratio) and the spark timing. For highway
motorcycles, these two variables are currently the most common methods for controlling exhaust
emissions.
3.1.3.1 - Air-fuel ratio
The calibration of the air-fuel mixture affects power, fuel consumption (referred to as Brake
Specific Fuel Consumption (BSFC)), and emissions for SI engines. The effects of changing the
air-fuel mixture are shown in Figure 3-1.l Traditionally, in most SI applications, manufacturers
have calibrated their fuel systems for rich operation for two main advantages. First, by running
the engine rich, manufacturers can reduce the risk of lean misfire due to imperfect mixing of the
fuel and air and variations in the air-fuel mixture from cylinder to cylinder. Second, by making
extra fuel available for combustion, it is possible to get more power from the engine. At the
same time, since a rich mixture lacks sufficient oxygen for full combustion, it results in increased
fuel consumption rates and higher HC and CO emissions. As can be seen from the figure, the
best fuel consumption rates occur when the engine is running lean.
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With the use of more advanced fuel systems, manufacturers would be able to improve
control of the air-fuel mixture in the cylinder. This improved control allows for leaner operation
without increasing the risk of lean misfire. This reduces HC and CO emissions and fuel
consumption. Leaner air-fuel mixtures, however, increase NOx emissions due to the higher
temperatures and increased supply of oxygen.
Figure 3-1: Effects of Air-fuel Ratio on Power, Fuel Consumption, and Emissions
I
CL
O
LL
OT
CO
Lean
Stoichiometric
Rich
Power
BSFC
I
I
'co
co
LU
O
LU
Lean
Stoichiometric
Rich
NOx
I
0.7 0.8 0.9 1.0 1.1 1.2
Fuel/Air Equivalence Ratio
1.3
0.7 0.8 0.9 1.0 1.1
Fuel/Air Equivalence Ratio
1.2
1.3
3.1.3.2 - Spark-timing:
For each engine speed and air-fuel mixture, there is an optimum spark-timing that results in
peak torque. If the spark is advanced to an earlier point in the cycle, more combustion occurs
during the compression stroke. If the spark is retarded to a later point in the cycle, peak cylinder
pressure is decreased because too much combustion occurs later in the expansion stroke when it
generates little torque on the crankshaft. Timing retard may be used as a strategy for reducing
NOx emissions, because it suppresses peak cylinder temperatures that lead to high NOx levels.
Timing retard also results in higher exhaust gas temperatures, because less mechanical work is
extracted from the available energy. This may have the benefit of warming catalyst material to
more quickly reach the temperatures needed to operate effectively during light-load operation.2
Some automotive engine designs rely on timing retard at start-up to reduce cold-start emissions.
Advancing the spark-timing at higher speeds gives the fuel more time to burn. Retarding
the spark timing at lower speeds and loads avoids misfire. With a mechanically controlled
engine, a fly-weight or manifold vacuum system adjusts the timing. Mechanical controls,
however, limit the manufacturer to a single timing curve when calibrating the engine. This
means that the timing is not completely optimized for most modes of operation.
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3.1.3.3 - Fuel Metering
Fuel injection has proven to be an effective and durable strategy for improving performance,
controlling emissions and reducing fuel consumption from highway gasoline engines.
Comparable upgrades are also available for gaseous fuels. This section describes a variety of
technologies available to improve fuel metering.
Throttle-body gasoline injection: A throttle-body system uses the same intake manifold as a
carbureted engine. However, the throttle body replaces the carburetor. By injecting the fuel
into the intake air stream, the fuel is better atomized than if it were drawn through with a venturi.
This results in better mixing and more efficient combustion. In addition, the fuel can be more
precisely metered to achieve benefits for fuel economy, performance, and emission control.
Throttle-body designs have the drawback of potentially large cylinder-to-cylinder
variations. Like a carburetor, TBI injects the fuel into the intake air at a single location upstream
of all the cylinders. Because the air-fuel mixture travels different routes to each cylinder, the
amount of fuel that reaches each cylinder will vary. Manufacturers account for this variation in
their design and may make compromises such as injecting extra fuel to ensure that the cylinder
with the leanest mixture will not misfire. These compromises affect emissions and fuel
consumption.
Multi-port gasoline injection: As the name suggests, multi-port fuel injection means that a
fuel injector is placed at each of the intake ports. A quantity of fuel is injected each time the
intake valve opens for each cylinder. This allows manufacturers to more precisely control the
amount of fuel injected for each combustion event. This control increases the manufacturer's
ability to optimize the air-fuel ratio for emissions, performance, and fuel consumption. Because
of these benefits, multi-port injection is has been widely used in automotive applications for over
15 years.
Sequential injection has further improved these systems by more carefully timing the
injection event with the intake valve opening. This improves fuel atomization and air-fuel
mixing, which further improves performance and control of emissions.
Direct injection: Direct Injection (DI) systems are very similar to multi-port injection
systems, since both are electronically controlled systems that inject fuel directly into the
cylinder. The main difference is that DI systems more fully atomize (i.e., break-down into very
small droplets) the fuel, which can greatly improve combustion efficiency resulting in improved
power and reduced emissions. For 2-stroke engines, only air is pumped into the cylinder, rather
than air and fuel. Finely atomized fuel is then injected into the combustion chamber once all of
the ports are closed. This eliminates the short-circuiting of fresh air and fuel into the exhaust
port. The biggest problem with DI is that there is very little time for air to be pumped into the
cylinder and fuel then injected after all of the ports have closed. This is overcome by the use of
numerous engines sensors, a high-speed electronic control module, and software which uses
sophisticated control algorithms.
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DI systems have been in use for the past several years in some small motorcycle, scooter
and marine applications, primarily for personal watercraft (PWC) and outboard engines. There
are numerous variations of DI systems, but two primary approaches that are commercially
available today: high pressure injection and air-assisted injection. There are a number of
companies who have developed high pressure DI systems, but the most successful systems
currently belong to FICHT and Yamaha. The FICHT system uses a special fuel injector that is
able to inject fuel at very high pressure (e.g., over 250 psi). The fuel injector itself is essentially
a piston that is operated by an electromagnet. Fuel enters the injector at low pressure from an
electric fuel pump and is forced out of the injector nozzle at high pressure when the piston
hammers down on the fuel. The Yamaha system uses a high pressure fuel pump to generate the
high fuel pressure. The other DI approach that is most common in various engine applications is
the air-assisted injection system which has been developed by Orbital. The Orbital system uses
pressurized air to help inject the fuel into the combustion chamber. The system uses a small
single cylinder reciprocating air compressor to assist in the injection of the fuel. All three
systems are currently used in some marine applications by companies such as Kawasaki, Polaris,
Sea-Doo, and Yamaha. The Orbital system is also currently used on some small motorcycle and
scooter applications by Aprilla.
3.1.4 - Gaseous Fuels
Engines operating on LPG or natural gas carry compressed fuel that is gaseous at
atmospheric pressure. The technical challenges for gasoline related to an extended time to
vaporize the fuel don't apply to gaseous-fuel engines. Typically, a mixer introduces the fuel into
the intake system. Manufacturers are pursuing new designs to inject the fuel directly into the
intake manifold. This improves control of the air-fuel ratio and the combustion event, similar to
the improvements in gasoline injection technology.
3.2 - Exhaust Emissions and Control Technologies
HC and CO emissions from four-stroke engines are primarily the result of poor in-cylinder
combustion. Higher levels of NOx emissions are the result of leaner air-fuel ratios and the
resulting higher combustion temperatures. Combustion chamber modifications can help reduce
HC emission levels, while using improved air-fuel ratio and spark timing calibrations, as
discussed in sections 3.1.2.1 and 3.1.2.2, can further reduce HC emissions and lower CO
emissions. The conversion from carburetor to EFI will also help reduce HC and CO emissions.
The use of exhaust gas recirculation on can reduce NOx emissions, but is not necessarily needed
for highway motorcycles, due to their relatively low NOx emission levels related to engine
calibrations. The addition of secondary air into the exhaust can significantly reduce HC and CO
emissions. Finally, the use catalytic converters can further reduce all three emissions.
3.2.1 - Combustion chamber design
Unburned fuel can be trapped momentarily in crevice volumes (especially the space
between the piston and cylinder wall) before being released into the exhaust. Reducing crevice
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volumes decreases this amount of unburned fuel, which reduces HC emissions. One way to
reduce crevice volumes is to design pistons with piston rings closer to the top of the piston. HC
may be reduced by 3 to 10 percent by reducing crevice volumes, with negligible effects on NOx
emissions.3
HC emissions also come from lubricating oil that leaks into the combustion chamber. The
heavier hydrocarbons in the oil generally don't burn completely. Oil in the combustion chamber
can also trap gaseous HC from the fuel and prevent it from burning. For engines using catalytic
control, some components in lubricating oil can poison the catalyst and reduce its effectiveness,
which would further increase emissions over time. To reduce oil consumption, manufacturers
can tighten tolerances and improve surface finishes for cylinders and pistons, improve piston
ring design and material, and improve exhaust valve stem seals to prevent excessive leakage of
lubricating oil into the combustion chamber.
3.2.2 - Exhaust gas recirculation
Exhaust gas recirculation (EGR) has been in use in cars and trucks for many years. The
recirculated gas acts as a diluent in the air-fuel mixture, slowing reaction rates and absorbing
heat to reduce combustion temperatures. These lower temperatures can reduce the engine-out
NOx formation rate by as much as 50 percent.4 HC is increased slightly due to lower
temperatures for HC burn-up during the late expansion and exhaust strokes.
Depending on the burn rate of the engine and the amount of recirculated gases, EGR can
reduce fuel consumption. Although EGR slows the burn rate, it can offset this effect with some
benefits for engine efficiency. EGR reduces pumping work since the addition of recirculated gas
increases intake pressure. Because the burned gas temperature is decreased, there is less heat
loss to the exhaust and cylinder walls. In effect, EGR allows more of the chemical energy in the
fuel to be converted to useable work.5
For catalyst systems with high conversion efficiencies, the benefit of using EGR becomes
proportionally smaller. Also, including EGR as a design variable for optimizing the engine adds
significantly to the development time needed to fully calibrate engine models.
The use of EGR may not necessarily be needed for highway motorcycles, due to their
relatively low NOx emission levels related to engine calibrations and packaging constraints.
3.2.3 - Secondary air
Secondary injection of air into exhaust ports or pipes after cold start (e.g., the first 40-60
seconds) when the engine is operating rich, coupled with spark retard, can promote combustion
of unburned HC and CO in the exhaust manifold and increase the warm-up rate of the catalyst.
By means of an electrical or mechanical pump, secondary air is injected into the exhaust system,
preferably in close proximity to the exhaust valve. Together with the oxygen of the secondary
air and the hot exhaust components of HC and CO, oxidation ahead of the catalyst can bring
about an efficient increase in the exhaust temperature which helps the catalyst to heat up quicker
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and also reduces the emissions load into the catalyst. The exothermic reaction that occurs is
dependent on several parameters (secondary air mass, location of secondary air injection, engine
A/F ratio, engine air mass, ignition timing, manifold and headpipe construction, etc.), and
ensuring reproducibility demands detailed individual application for each vehicle or engine
design.
Secondary air injection was first used as an emission control technique in itself without a
catalyst, and still is used for this purpose in many highway motorcycles and some off-highway
motorcycles to meet federal and California emission standards. For motorcycles, air is usually
provided or injected by a system of check valves which uses the normal pressure pulsations in
the exhaust manifold to draw in air from outside, rather than by a pump.
3.2.4 - Catalytic Aftertreatment
Over the last several years, there have been tremendous advances in exhaust aftertreatment
systems. Catalyst manufacturers are progressively moving to palladium (Pd) as the main
precious metal in automotive catalyst applications. Improvements to catalyst thermal stability
and washcoat technologies, the design of higher cell densities, and the use of two-layer washcoat
applications are just some of the advances made in catalyst technology. There are two types of
catalytic converters commonly used: oxidation and three-way. Oxidation catalysts use platinum
and/or palladium to increase the rate of reaction between oxygen in the exhaust and unburned
HC and CO. Ordinarily, this reaction would proceed very slowly at temperatures typical of
engine exhaust. The effectiveness of the catalyst depends on its temperature, on the air-fuel ratio
of the mixture, and on the mix of HC present. Highly reactive species such as formaldehyde and
olefins are oxidized more effectively than less-reactive species. Short-chain paraffins such as
methane, ethane, and propane are among the least reactive HC species, and are difficult to
oxidize. Because they are less reactive, they are also less of a concern as ozone precursors.
Three-way catalysts use a combination of platinum and/or palladium and rhodium. In
addition to promoting oxidation of HC and CO, these metals also promote the reduction of NO to
nitrogen and oxygen. In order for the NO reduction to occur efficiently, an overall rich or
stoichiometric air-fuel ratio is required. The NOx disassociation efficiency drops rapidly as the
ai-fuel ratio becomes leaner than stoichiometric. If the air-fuel ratio can be maintained precisely
at or just rich of stoichiometic, a three-way catalyst can simultaneously oxidize HC and CO and
reduce NOx. The window of air-fuel ratios within which this is possible is very narrow and
there is a trade-off between NOx and HC/CO control even within this window.
There are several issues involved in designing catalytic control systems for the four-stroke
engines covered by this rule. The primary issues are the cost of the system, packaging
constraints, and the durability of the catalyst. This section addresses these issues.
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3.2.4.1 - System cost
Sales volumes of motorcycles are small compared to automotive sales. Manufacturers
therefore have a limited ability to recoup large R&D expenditures for highway motorcycle
engines. For this reason, we believe it is not appropriate to consider highly refined catalyst
systems that are tailored specifically to these applications. The cost of these systems will
decrease substantially when catalysts become commonplace. Chapter 5 describes the estimated
costs for a motorcycle catalyst system.
3.2.4.2 - Packaging constraints
Many motorcycles have space constraints for adding a catalyst because they have been
finely designed over many years with a very compact fit. Automotive catalyst designs typically
have one or two catalyst units upstream of the muffler. This is a viable option for some
motorcycles. However, if there is no available space to add a separate catalyst, it is possible to
build a full catalyst/muffler combination that fits in the same space as the conventional muffler.
With this packaging option, even compact applications should have little or no trouble
integrating a catalyst into the equipment design. The catalyst designs already used on highway
motorcycles clearly demonstrate the viability of this approach. However, unlike automobiles,
there is an active aftermarket for motorcycle accessories which includes exhaust system
components. If an integrated muffler/catalyst approach is used, manufacturers will have to
design them in such a way that removal of the exhaust system for replacement with an
aftermarket component does not inherently result in removal of the catalyst as well. Otherwise,
aftermarket parts will need to include a catalyst.
3.2.4.3 - Two-Stroke Aftertreatment
There are two exhaust aftertreatment technologies that can provide additional emission
reductions from two-stroke engines: thermal oxidation (e.g., secondary air) and oxidation
catalyst. Thermal oxidation reduces HC and CO by promoting further oxidation of these species
in the exhaust. The oxidation usually takes place in the exhaust port or pipe, and may require the
injection of additional air to supply the needed oxygen. If the exhaust temperature can be
maintained at a high enough temperature (e.g., 600 to 700°C) for a long enough period,
substantial reductions in HC and CO can occur. Air injection at low rates into the exhaust
system has been shown to reduce emissions by as much as 77 percent for HC and 64 percent for
CO.12
Like thermal oxidation, the oxidation catalyst is used to promote further oxidation of HC
and CO emissions in the exhaust stream, and it also requires sufficient oxygen for the reaction to
take place. Some of the requirements for a catalytic converter to be used in two-stroke engines
12 White, J.J., Carroll,J.N., Hare, C.T., and Lourenco, J.G. (1991), "Emission Control Strategies for Small
Utility Engines," SAE Paper No. 911807, Society of Automotive Engineers, Warrendale, PA, 1991.
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include high HC conversion efficiency, resistance to thermal damage, resistance to poisoning
from sulfur and phosphorus compounds in lubricating oil, and low light-off temperature.
Application of catalytic converters to two-stroke engines presents a problem, because of the
high concentrations of HC and CO in their exhaust. If combined with sufficient air, these high
pollutant concentrations result in catalyst temperatures that can easily exceed the temperature
limits of the catalyst. Therefore, the application of oxidation catalysts to two-stroke engines may
first require engine modifications to reduce HC and CO and may also require secondary air be
supplied to the exhaust in front of the catalyst.
Researchers of Graz University of Technology and the Industrial Technology Research
Institute (ITRI) in Taiwan have published data on the application of catalytic converters in small
two-stroke moped and motorcycle engines using catalytic converters. The Graz researchers
focused on reducing emissions using catalysts, as well as by improving the thermodynamic
characteristics of the engines, such as gas exchange and fuel handling systems, cylinder and
piston geometry and configurations, and exhaust cooling systems. For HC and CO emissions,
they found that an oxidation catalyst could reduce emissions by 88 to 96 percent. Researchers at
ITRI successfully retrofitted a catalytic converter to a 125 cc two-stroke motorcycle engine, and
demonstrated both effective emissions control and durability.13 The Manufacturers of Emission
Controls Association (MECA)in their publication titled "Emission Control of Two-and Three-
wheel Vehicles," published May 7, 1999, state that catalyst technology has clearly demonstrated
the ability to achieve significant emissions reductions from two-stroke engines. MECA points to
the success of two-stroke moped and motorcycle engines equipped with catalysts that have been
operating for several years in Taiwan, Thailand, Austria, and Switzerland.
3.2.5 - Multiple valves and variable valve timing
Four-stroke engines generally have two valves for each cylinder, one for intake of the air-
fuel mixture and the other for exhaust of the combusted mixture. The duration and lift (distance
the valve head is pushed away from its seat) of valve openings is constant regardless of engine
speed. As engine speed increases, the aerodynamic resistance to pumping air in and out of the
cylinder for intake and exhaust also increases. Automotive engines have started to use two
intake and two exhaust valves to reduce pumping losses and improve their volumetric efficiency
and useful power output. Some highway motorcycles have used multiple valves for years,
especially the high-performance sport motorcycles.
In addition to gains in breathing, 4-valve designs allow the spark plug to be positioned
closer to the center of the combustion chamber, which decreases the distance the flame must
travel inside the chamber. This decreases the likelihood of flame-out conditions in the areas of
the combustion chamber farthest from the spark plug. In addition, the two streams of incoming
13 Hsien, P.H., Hwang, L.K., and Wang, H.W (1992), "Emission Reduction by Retrofitting a 125 cc Two-
Stroke Motorcycle with Catalytic Converter," SAE Paper No. 922175, Society of Automotive Engineers,
Warrendale, PA, 1992.
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gas can be used to achieve greater mixing of air and fuel, further increasing combustion
efficiency and lowering engine-out emissions.
Control of valve timing and lift take full advantage of the 4-valve configuration for even
greater improvement in combustion efficiency. Engines normally use fixed-valve timing and
lift across all engine speeds. If the valve timing is optimized for low-speed torque, it may offer
compromised performance under higher-speed operation. At light engine loads, for example, it
is desirable to close the intake valve early to reduce pumping losses. Variable-valve timing can
enhance both low-speed and high-speed performance with compromise. Variable-valve timing
can allow for increased swirl and intake charge velocity, especially during low-load operating
conditions where this is most problematic. By providing a strong swirl formation in the
combustion chamber, the air-fuel mixture can mix sufficiently, resulting in a faster, more
complete combustion, even under lean air-fuel conditions, thereby reducing emissions.
Variable-valve technology by itself may have somewhat limited effect on reducing
emissions, but combining it with optimized spark plug location and exhaust gas recirculation can
lead to substantial emission reductions.
3.2.6 - Advanced Emission Controls
On February 10, 2000, EPA published new "Tier 2" emission standards for all passenger
vehicles, including sport utility vehicles (SUVs), minivans, vans and pick-up trucks. The new
standards will ensure that exhaust VOC emissions be reduced to less than 0.1 g/mi on average
over the fleet, and that evaporative emissions be reduced by at least 50 percent. Onboard
refueling vapor recovery requirements were also extended to medium-duty passenger vehicles.
By 2020, these standards will reduce VOC emissions from light-duty vehicles by more than 25
percent of the projected baseline inventory. To achieve these reductions, manufacturers will
need to incorporate advanced emission controls, including: larger and improved close-coupled
catalysts, optimized spark timing and fuel control, improved exhaust systems.
To reduce emissions, gasoline-fueled automobile and truck manufacturers have designed
their engines to achieve virtually complete combustion and have installed advanced catalytic
converter systems in the exhaust system. In order for these controls to work well for gasoline-
fueled vehicles, it is necessary to maintain the mixture of air and fuel at a nearly stoichiometric
ratio (that is, just enough air to completely burn the fuel). Poor air-fuel mixture can result in
significantly higher emissions of uncombusted fuel. Current generation automobiles and trucks
are able to maintain stoichiometry by using closed-loop electronic feedback control of the fuel
systems. As part of these systems, technologies have been developed to closely meter the
amount of fuel entering the combustion chamber to promote complete combustion. Sequential
multi-point fuel injection delivers a more precise amount of fuel to each cylinder independently
and at the appropriate time increasing engine efficiency and fuel economy. Electronic throttle
control offers a faster response to engine operational changes than mechanical throttle control
can achieve, but it is currently considered expensive and only used on some higher-price
vehicles. The greatest gains in fuel control can be made through engine calibrations — the
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algorithms contained in the powertrain control module (PCM) software that control the operation
of various engine and emission control components/systems. As microprocessor speed becomes
faster, it is possible to perform quicker calculations and to increase response times for
controlling engine parameters such as fuel rate and spark timing. Other advances in engine
design have also been used to reduce engine-out emissions, including: the reduction of crevice
volumes in the combustion chamber to prevent trapping of unburned fuel; "fast burn"
combustion chamber designs that promote swirl and flame propagation; and multiple valves with
variable-valve timing to reduce pumping losses and improve efficiency. These technologies are
discussed in more detail in the RIA for the Tier 2 FRM.6
As noted above, manufacturers are also using aftertreatment control devices to control
emissions. New three-way catalysts for highway vehicles are so effective that once a TWC
reaches its operating temperature, emissions are virtually undetectable.7 Manufacturers are now
working to improve the durability of the TWC and to reduce light-off time (that is, the amount of
time necessary after starting the engine before the catalyst reaches its operating temperature and
is effectively controlling VOCs, NOx and other pollutants). EPA expects that manufacturers
will be able to design their catalyst systems so that they light off within less than thirty seconds
of engine starting. Other potential exhaust aftertreatment systems that could further reduce cold-
start emissions are thermally insulated catalysts, electrically heated catalysts, and HC adsorbers
(or traps). Each of these technologies, which are discussed below, offer the potential for VOC
reductions in the future. However, there are technological, implementation, and cost issues that
still need to be addressed to incorporate these technologies into automobiles, and these issues are
further magnified when considering their use in lower cost applications such as motorcycles.
For example, the electrical power demands of an electrically heated catalyst system far exceed
the limits of current battery and alternator systems in automobiles, and it may be impractical or
even impossible to add the extra weight and equipment needed for such systems to the limited
space available on a motorcycle. As noted below, it may be necessary in some cases to pair an
electrically heated catalyst with an HC absorber in order to improve emissions, further
complicating the use of these technologies on motorcycles. At this time these advanced
technologies are only used on a limited number of automobiles, in part due to their high cost and
relatively early stage of development. Therefore, at this time it appears that these technologies
would not be a cost-effective means of reducing motorcycle emissions on a nationwide basis.
Thermally insulated catalysts maintain sufficiently high catalyst temperatures by
surrounding the catalyst with an insulating vacuum. Prototypes of this technology have
demonstrated the ability to store heat for more than 12 hours.8 Since ordinary catalysts typically
cool down below their light-off temperature in less than one hour, this technology could reduce
in-use emissions for vehicles that have multiple cold-starts in a single day. However, this
technology would have less impact on emissions from vehicles that have only one or two cold-
starts per day.
Electrically-heated catalysts reduce cold-start emissions by applying an electric current to
the catalyst before the engine is started to get the catalyst up to its operating temperature more
quickly.9 These systems require a modified catalyst, as well as an upgraded battery and charging
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system. These can greatly reduce cold-start emissions, but could require the driver to wait until
the catalyst is heated before the engine would start to achieve optimum performance.
Hydrocarbon adsorbers are designed to trap VOCs while the catalyst is cold and unable to
sufficiently convert them. They accomplish this by utilizing an adsorbing material which holds
onto the VOC molecules. Once the catalyst is warmed up, the trapped VOCs are automatically
released from the adsorption material and are converted by the fully functioning downstream
three-way catalyst. There are three principal methods for incorporating an adsorber into the
exhaust system. The first is to coat the adsorber directly on the catalyst substrate. The
advantage is that there are no changes to the exhaust system required, but the desorption process
cannot be easily controlled and usually occurs before the catalyst has reached light-off
temperature. The second method locates the adsorber in another exhaust pipe parallel with the
main exhaust pipe, but in front of the catalyst and includes a series of valves that route the
exhaust through the adsorber in the first few seconds after cold start, switching exhaust flow
through the catalyst thereafter. Under this system, mechanisms to purge the adsorber are also
required. The third method places the trap at the end of the exhaust system, in another exhaust
pipe parallel to the muffler, because of the low thermal tolerance of adsorber material. Again a
purging mechanism is required to purge the adsorbed VOCs back into the catalyst, but adsorber
overheating is avoided. One manufacturer who incorporates a zeolite hydrocarbon adsorber in
its California SULEV vehicle found that an electrically heated catalyst was necessary after the
adsorber because the zeolite acts as a heat sink and nearly negates the cold start advantage of the
adsorber. This approach has been demonstrated to effectively reduce cold start emissions.
3.3 - Evaporative Emissions
3.3.1 Sources of Evaporative Emissions
Evaporative emissions from motorcycles represents a small but not insignificant part of their
HC emissions. The magnitude of the emissions varies widely depending on the engine design
and application. Evaporative emissions can be grouped into five categories:
DIURNAL: Gasoline evaporation increases as the temperature rises during the day, heating
the fuel tank and venting gasoline vapors.
RUNNING LOSSES: The hot engine and exhaust system can vaporize gasoline when the
engine is running.
HOT SOAK: The engine remains hot for a period of time after the engine is turned off and
gasoline evaporation continues. This problem is most pronounced for carbureted motorcycles.
REFUELING: Gasoline vapors are always present in typical fuel tanks. These vapors are
forced out when the tank is filled with liquid fuel.
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PERMEATION: Gasoline molecules can saturate plastic fuel tanks and rubber hoses,
resulting in a relatively constant rate of emissions as the fuel continues to permeate through these
components.
Among the factors that affect emission rates are: (1) fuel metering (fuel injection or
carburetor); (2) fuel permeation is affected by the material used to construct the fuel lines and
fuel tanks; (3) the proximity of the fuel tank to the exhaust system or other heat sources; (4)
whether the fuel system is sealed and the pressure at which fuel vapors are vented;(5) fuel tank
volume; and (6) where the vehicle is stored when not in-use. Fuel fill level and fuel vapor
pressure are also important, but these are not vehicle design parameters.
3.3.1.1 - Diurnal and Running Loss Emissions
In an open fuel tank, the vapor space is at atmospheric pressure (typically about 14.7 psi),
and contains a mixture of fuel vapor and air. At all temperatures below the fuel's boiling point,
the vapor pressure of the fuel is less than atmospheric pressure. This is also called the partial
pressure of the fuel vapor. The partial pressure of the air is equal to the difference between
atmospheric pressure and the fuel vapor pressure. For example, in an open-vented fuel tank at
60°F, the vapor pressure of typical gasoline would be about 4.5 psi. In this example, the partial
pressure of the air would be about 10.2 psi. Assuming that the vapor mixture behaves as an ideal
gas, then the mole fractions (or volumetric fractions) of fuel vapor and air would be equal to
their respective partial pressures divided by the total pressure; thus, the fuel would be 31 percent
of the mixture (4.5/14.7) and the air would be 69 percent of the mixture (10.2/14.7).
Diurnal emissions occur when the fuel temperature increases, which increases the
equilibrium vapor pressure of the fuel. For example, assume that the fuel in the previous
example was heated to 90°F, where the vapor pressure of that same typical fuel would be about
8.0 psi. To maintain the vapor space at atmospheric pressure, the partial pressure of the air
would need to decrease to 6.7 psi, which means that the vapor mixture must expand in volume.
This forces some of the fuel-air mixture to be vented out of the tank. When the fuel later cools,
the vapor pressure of the fuel decreases, contracting the mixture, and drawing fresh air in
through the vent. When the fuel is heated again, another cycle of diurnal emissions occurs. It is
important to note that this is generally not a rate-limited process. Although the evaporation of
the fuel can be slow, it is generally fast enough to maintain the fuel tank in an essentially
equilibrium state.
Consider a typical fuel use cycle beginning with a full tank. As fuel is used by the engine,
and the liquid fuel volume decreases, air is drawn into the tank to replace the volume of the fuel.
(Note: the decrease in the liquid fuel level could be offset to some degree by increasing fuel
vapor pressure caused by increasing fuel temperature. However, this would be offset by the
decrease in fuel vapor pressure due to weathering.) This would continue while the engine was
running. If the engine was shut off and the tank was left overnight, the vapor pressure of the fuel
would drop as the temperature of the fuel dropped. This would cause a small negative pressure
within the tank that would cause it to fill with more air until the pressure equilibrated. The next
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day, the vapor pressure of the fuel would increase as the temperature of the fuel increased. This
would cause a small positive pressure within the tank that would force a mixture of fuel vapor
and air out. The daily emission rate varies as a function of the diurnal temperature swing the
tank sees, the fuel vapor pressure, the tank volume, and the fuel fill level.
3.3.1.2 - Hot Soak Emissions
Hot soak emissions occur after the engine is turned off, especially during the resulting
temperature rise. For motorcycle engines, the primary source of hot soak emissions is the
evaporation of the fuel left in the carburetor bowl. Other sources can include increased
evaporation of fuel from plastic or rubber fuel lines in the engine compartment.
3.3.1.3 - Refueling Emissions
Refueling emissions occur when the fuel vapors are forced out when the tank is filled with
liquid fuel. At a given temperature, refueling emissions are proportional to the volume of the
fuel dispensed into the tank. Every gallon of fuel put into the tank forces out one-gallon of the
mixture of air and fuel vapors. Thus, refueling emissions are highest when the tank is near
empty. Refueling emissions are also affected by the temperature of the liquid and dispensed
fuels. Vapor shrinkage or vapor growth can occur depending on the temperature difference
between the two fuels involved. Fuel vapor pressure differences are also important.
3.3.1.4 - Permeation
The polymeric material (plastic or rubber) of which many gasoline fuel tanks and fuel hoses
generally are constructed have a chemical composition much like that of gasoline. As a result,
constant exposure of gasoline liquid and vapor to these surfaces allows the material to
continually absorb fuel. The outer surfaces of these materials are exposed to ambient air, so the
gradient drives gasoline molecules to permeate through these fuel-system components and are
emitted directly into the air. Permeation rates are relatively low, but emissions continue at a
nearly constant rate, regardless of how much the vehicle or equipment is used or where it is
stored. Permeation-related emissions can therefore add up to a significant fraction of the total
emissions from gasoline powered vehicles.
3.3.2 Evaporative Emission Controls
This section focuses on emission-control technologies that can be used to reduce permeation
emissions from motorcycle fuel tanks and hoses. Chapter 4 presents more detail on how we
expect manufacturers to use these technologies to meet the emission standards for this rule.
3.3.2.1 Fuel Tanks
Blow molding is widely used for the manufacture of plastic motorcycle fuel tanks.
Typically, blow molding is performed by creating a hollow tube, known as a parison, by pushing
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high-density polyethylene (HDPE) through an extruder with a screw. The parison is then
pinched in a mold and inflated with an inert gas. In automotive applications, non-permeable
plastic fuel tanks are produced by blow molding a layer of ethylene vinyl alcohol (EVOH) or
nylon between two layers of polyethylene. This process is called coextrusion and requires at
least five layers: the barrier layer, adhesive layers on either side of the barrier layer, and HDPE
as the outside layers which make up most of the thickness of the fuel tank walls. However,
multi-layer construction requires additional extruder screws which significantly increases the
cost of the blow molding process.
Multi-layer fuel tanks can also be formed using injection molding. In this method, a low
viscosity polymer is forced into a thin mold to create each side of the fuel tank. The two sides
are then welded together. In typical fuel tank construction, the sides are welded together by
using a hot plate for localized melting and then pressing the sides together. The sides may also
be connected using vibration or sonic welding. To add a barrier layer, a thin sheet of the barrier
material is placed inside the mold prior to injection of the poleythylene. The polyethylene,
which generally has a much lower melting point than the barrier material, bonds with the barrier
material to create a shell with an inner liner. As an alternative, an additional extruder can be
added to inject the barrier layer prior to injecting the HDPE; however, this substantially
increases the cost of the process.
A less expensive alternative to coextrusion is to blend a low permeable resin with the HDPE
and extrude it with a single screw. The trade name typically used for this permeation control
strategy is Selar®. The low permeability resin, typically EVOH or nylon, creates non-
continuous platelets in the HDPE fuel tank which reduce permeation by creating long, tortuous
pathways that the hydrocarbon molecules must navigate to pass through the fuel tank walls.
Although the barrier is not continuous, this strategy can still achieve greater than a 90 percent
reduction in permeation of gasoline. EVOH has much higher permeation resistance to alcohol
than nylon; therefore, it would be the preferred material to use for meeting our standard which is
based on testing with a 10 percent ethanol fuel.
Another type of low permeation technology for fuel tanks would be to treat the surfaces of a
plastic fuel tanks with a barrier layer. Two ways of achieving this are known as fluorination and
sulfonation. The fluorination process causes a chemical reaction where exposed hydrogen atoms
are replaced by larger fluorine atoms which a barrier on surface of the fuel tank. In this process,
fuel tanks are generally processed post production by stacking them in a steel container. The
container is then voided of air and flooded with fluorine gas. By pulling a vacuum in the
container, the fluorine gas is forced into every crevice in the fuel tanks. As a result of this
process, both the inside and outside surfaces of the fuel tank would be treated. As an alternative,
fuel tanks can be fluorinated on-line by exposing the inside surface of the fuel tank to fluorine
during the blow molding process. However, this method may not prove as effective as off-line
fluorination which treats the inside and outside surfaces.
The sulfonation process uses sulfur trioxide to create the barrier by reacting with the
exposed polyethylene to form sulfonic acid groups on the surface. Current practices for
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sulfonation are to place fuel tanks on a small assembly line and expose the inner surfaces to
sulfur trioxide, then rinse with a neutralizing agent. However, this can also be performed off-
line. Either of these processes can be used to reduce gasoline permeation by more than 95
percent.
Fuel tank permeation can also be reduced through the use of alternative materials. For
instance, the majority of motorcycle fuel tanks are made from metal which does not permeate.
Chapter 4 discusses alternative low-permeation polymers which manufacturers may be able to
use to mold plastic tanks.
3.3.2.2 Fuel Hoses
Fuel hoses produced for use in motorcycles are generally extruded nitrile rubber with a
cover for abrasion resistance. Lower permeability fuel hoses produced today for other
applications are generally constructed in one of two ways: either with a low permeability layer or
by using a low permeability rubber blend. By using hose with a low permeation thermoplastic
layer, permeation emissions can be reduced by more than 95 percent. Because the thermoplastic
layer is very thin, on the order of 0.1 to 0.2 mm, the rubber hose retains its flexibility. Three
thermoplastics which have excellent permeation resistance, even with an alcohol-blend fuel, are
ethylene-tetrafluoro-ethylene (ETFE), tetra-fluoro-ethylene, hexa-fluoro-propylene, and
vinyledene fluoride (THV), and Teflon®.
In automotive applications, multilayer plastic tubing, made of fluoropolymers is generally
used. An added benefit of these low permeability lines is that some fluoropolymers can be made
to be conductive and therefore can prevent the buildup of static charges. Although this
technology can achieve more than an order of magnitude lower permeation than barrier hoses, it
is relatively inflexible and may need to be molded in specific shapes for each motorcycle design.
Manufacturers have commented that they would need flexible hose to fit their many designs,
resist vibration, and to simplify the hose connections and fittings.
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Chapter 3 References
1. Heywood, J., "Internal Combustion Engine Fundamentals," McGraw-Hill, Inc., New York,
1988, pp.829-836.
2. Heywood, pp.827-829.
3. Energy and Environmental Analysis, "Benefits and Cost of Potential Tier 2 Emission
Reduction Technologies", Final Report, November 1997, Docket A-2000-01, Document II-A-01.
4. Southwest Research Institute, "Three-Way Catalyst Technology for Off-Road Equipment
Powered by Gasoline and LPG Engines," prepared for CARB, CEP A, and SCAQMD, (SwRI
8778), April 1999, Docket A-2000-01, Document II-A-08.
5. Heywood, pp. 836-839.
6. http://www.epa.gov/otaq/tr2home.htm#Documents. EPA420-R-99-023.
7. McDonald, J., L. Jones, Demonstration of Tier 2 Emission Levels for Heavy Light-Duty
Trucks, SAE 2000-01-1957.
8. Burch, S.D., and J.P. Biel, SULEV and "Off-Cycle" Emissions Benefits of a Vacuum-
Insulated Catalytic Convert, SAE 1999-01-0461.
9. Laing, P.M., Development of an Alternator-Powered Electrically-Heated Catalyst System,
SAE 941042.
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CHAPTER 4: Technological Feasibility
We are finalizing new motorcycle standards under the authority of section 202 of the Clean
Air Act. Sections 202(a) and (b) of the Act provide EPA with the general authority to prescribe
vehicle standards, subject to any specific limitations otherwise included in the Act. Section
202(a)(l) of the Act directs us to establish standards regulating the emission of any air pollutant
from an class or classes of new motor vehicles or engines that, in the Administrator's judgement,
cause or contribute to air pollution which may reasonably be anticipated to endanger public
health or welfare. Section 202(a)(2) directs the Administrator to provide lead time sufficient to
"permit the development and application of the requisite technology, giving appropriate
consideration to the cost of compliance within such period." Section 202(a)(3)(E) directs the
Administrator, in establishing emission standards for highway motorcycles, to "consider the
need to achieve equivalency of emission reductions between motorcycles and other motor
vehicles to the maximum extent practicable."
This chapter presents the technical analyses and information that form the basis of EPA's
belief that the new emission standards are technically achievable accounting for all the above
factors.
4.1 - Exhaust Emission Control from Motorcycles
The emission standards for highway motorcycles are summarized in the Executive
Summary. As discussed in Chapter 3, we believe there are several technologies that can be used
to reduce exhaust emissions from highway motorcycles. This section presents certification
emissions data on a range of emissions levels achieved using different technology options. The
following sections summarize the data and rationale supporting the emission standards for
highway motorcycles.
In the development of the proposal, we considered several regulatory alternatives. These
included: no revision to the standards, harmonization with one of the "tiers" of California
standards (current, 2004 Tier-1, 2008 Tier-2), more stringent standards than those in place in
California, or possibly different implementation timing. We also considered various alternatives
designed to reduce the burden on small manufacturers (these are presented in Chapter 8 on the
Small Business Flexibility Analysis). As required by section 202(a)(3)(E) of the Clean Air Act
(CAA, or "the Act"), we also considered "the need to achieve equivalency of emission
reductions between motorcycles and other motor vehicles to the maximum extent practicable."
After considering comments on the NPRM, we believe the existing standards should be
revised. The existing federal standards were established more than twenty years ago, and it is
clear that emission control technology has advanced a great deal in that time. California has
continued to revise their standards to maintain some contact with current technology, and
manufacturers have generally (but not uniformly) responded by producing motorcycles for sale
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nationwide that meet the more stringent California standards. Thus, in large part the existing
federal standards have been superseded because of the preponderance of manufacturers that have
responded in this way. Those arguing against new emission standards often cite the fact that
motorcycles are typically far cleaner than the existing federal standards require. Although we
agree, we see this fact as a reason for improving emission standards and as evidence that the
current federal standards are out of touch with the reality of today's technology.
We believe it is most appropriate at this time to harmonize with the California exhaust
emission standards, as opposed to other options. For example, the dissimilarities between on-
and off-highway motorcycles do not encourage a one-size-fits-all approach for all motorcycles
(this opinion is supported by a significant number of those who commented on the NPRM). Off-
highway motorcycles are powered predominantly by two-stroke engines, whereas highway
motorcycles are all powered by four-stroke engines as of the 2002 model year. On- and off-
highway motorcycle engines also lie at vastly different ends of the size spectrum. The average
highway motorcycle sold today has a displacement of nearly lOOOcc, whereas almost 90 percent
of off-highway motorcycle engines have an engine displacement of less than 350cc. In addition,
on- and off-highway motorcycles are used in very different ways; finding a set of standards and a
test procedure that adequately represents the typical range of operation for both types would
therefore be extremely challenging. The fact that manufacturers claim that many off-highway
bikes are used solely for competition would create an additional obstacle to technological
harmonization. On-highway motorcycle manufacturers have commented that, to the extent the
standards are revised, harmonization with California, rather than a distinctly different set of
standards, is preferable because it eliminates the possibility of needing two distinct product lines
for California and Federal regulations.1
Delaying implementation of the California standards on a nationwide basis by two years
will provide an opportunity for manufacturers to gain some experience with the technology
needed to meet the new standards. Two years provides time for technology optimization and
cost reduction. Providing a longer delay could potentially provide the option of a further
decrease in the level of the emission standards, given that the technological feasibility of the
California standards has been adequately demonstrated (there are already several motorcycle
models available today that meet the 2008 California standards). However, this would be a
tradeoff against a more timely introduction of the new standards.
We also evaluated whether the federal motorcycle program should incorporate averaging
provisions, as the California program does. Given the desire of most manufacturers to
manufacture a motorcycle for nationwide sale, such a program without averaging would not be
desirable because it would not provide the flexibility needed to meet the California and federal
requirements together and could have at least potentially led to a somewhat less stringent Federal
standard. Therefore, we are providing an averaging program comparable to California's.
In promulgating these standards, EPA has considered the need to achieve equivalency in
emission reduction between motorcycles and other motor vehicles. In most cases the benchmark
technology for spark-ignition engines is found in automobiles. As we have consistently
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indicated, the differences between motorcycles and cars justify different levels of emission
standards. First, motorcycles are typically far less expensive than cars, and we do not believe it
would be appropriate to burden a low-cost transportation alternative with the higher costs of
emission controls that can be justified on more expensive, heavily used motor vehicles. In
addition, cars and light trucks make up a vastly larger proportion of highway vehicles than
motorcycles, which allows for greater economies of scale in the manufacturing process. Cars
and light trucks also represent a far greater percentage of total emissions than highway
motorcycles. The average useful life of a car or light truck is 5 or more times greater than that of
a motorcycle. Emission benefits for the investment are therefore proportionally greater.
Achieving low emission levels on today's cars requires a vast amount of technology, including
high-efficiency catalytic converters (sometimes in multiples) and sophisticated computer
controls. High-efficiency catalytic converters on cars require additional precious metals relative
to the motorcycle catalysts that will be required on some future motorcycles. Additional
precious metals means additional cost, weight, and increased catalyst volume, none of which we
believe are justified for lower cost machines where weight and space limitations can be obstacles
to integrating vehicle emission control technologies. Motorcycles do not have the abundance of
space under the vehicle or under the hood, in locations isolated from the drivers, passengers, and
the elements, that cars and trucks do. Achieving lower average HC+NOx standards would
require more efficient catalysts. This would put upward pressure on CO emission levels and this
could potentially raise heat rejection concerns for the exhaust system. Our final rule carefully
considered these limitations by not requiring large and ultra-sophisticated catalyst technologies,
on-board diagnostic systems, sophisticated evaporative emission controls, and other technologies
that are routinely found on passenger cars today. We believe the standards we are promulgating
are consistent with statutory intent and are appropriate considering factors such as cost, safety,
lead time, noise, and energy. As part of the 2006 technology review and our assessment of the
World Motorcycle Test Cycle, we will review and assess the need for and viability of potential
changes or additions to the exhaust and evaporative emission standards and related provisions as
technology progresses and more information becomes available.
4.1.1 - Class I and II Motorcycles
4.1.1.1 - Class I Motorcycles Above 50cc and Class II Motorcycles
As noted above, we are adopting the current California standards for Class I and Class II
motorcycles. These standards have been in place in California since 1982. The question of
whether or not these standards are technically feasible has been answered in the affirmative,
since 21 of the 22 EPA-certified 2001 model year motorcycle engine families in these classes are
already certified to these standards, all 24 of the 2002 model year engine families meet these
standards, and 22 of 29 2003 model year engine families meet these standards. These 29 model
year 2003 engine families are all powered by four-stroke engines, with a variety of emission
controls applied, including basic engine modifications on almost all engine families, secondary
air injection on three engine families, and catalysts on four engine families.
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Up to one half of the motorcycles in these classes are scooters from European and Asian
manufacturers which tend to be offered at prices significantly lower than the larger Class III
motorcycles, while the remainder is a mix of standard motorcycles, introductory cruisers and
sportbikes, and dual sport motorcycles. The market for these motorcycles is about one-tenth the
size of the Class III market. While it may be technologically feasible for many of these
motorcycles to meet more stringent emission standards, we do not believe it is appropriate at this
time to require additional emission reductions from this segment of the market. Like the case
described below in section 4.1.1.2 for motorcycles under 50cc, manufacturers tend to bring Class
I and II motorcycles to the U.S. that have been designed for the large European and Asian
markets. Standards that are ultimately more stringent than those in Europe and/or Asia could
cause manufacturers to withdraw from the very small U.S. market for these types of motorcycles.
Although a direct comparison is not possible due to differing test procedures, the European HC
standard for motorcycles up to 150cc will be 0.8 g/km starting in 2006. We are adopting an HC
standard of 1.0 g/km.
4.1.1.2 - Class I Motorcycles Under 50cc
As we have described earlier we are applying the current California standard for Class I
motorcycles to motorcycles with displacements of less than 50cc (e.g., most motor scooters).
These motorcycles are currently not subject to regulation by the U.S. EPA or by the State of
California. They are, however, subject to emission standards in Europe and much of the rest of
the world. Historically these motorcycles have been powered by 2-stroke engines, but a trend
appears to be developing that would result in most of these being replaced by 4-stroke engines or
possibly by advanced technology 2-stroke engines, in some cases with catalysts. This trend is
largely due to emission requirements in the European and Asian nations where these types of
two-wheelers are popular forms of transportation.
The 4-stroke engine is capable of meeting our standards. Class I motorcycles above 50cc
are already meeting it, and most of them employ nothing more than a 4-stroke engine. For
example, the existing Class I scooters certify at levels ranging from 0.4 to 0.8 grams per
kilometer HC. All of these achieve the standards with 4-stroke engine designs, and only one
incorporates additional technology (a catalyst). These current engines range from 80 to 15Ice
in displacement, which provides an indication that small 4-stroke scooter engines are capable of
meeting the standards. In a test program conducted by the Japan Automobile Research Institute,
a 49cc 4-stroke achieved average HC emissions of 0.71 g/km, a level that falls well under the 1.0
g/km standard we are adopting.2 The technological feasibility of meeting a 1.0 g/km HC
standard was also supported by MIC if EPA made appropriate revisions to the test cycle and the
useful life, both of which we have adopted in this final rule. The Association of European
Motorcycle Manufacturers (ACEM) confirmed that European manufactures will seek to export
to the U.S. the same motorcycles under 50cc that they develop for the European market, and that
standards in the E.U. are forcing the transition to 2-stroke direct injection and 4-stroke EFI
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technologies in 2002 and 2003.14 ACEM also confirmed the feasibility of meeting the new U.S.
standard and aligned with MIC comments regarding the test cycle and useful life.
In order to meet more stringent standards being implemented worldwide, manufacturers are
developing and implementing a variety of options. Honda, perhaps the largest seller of scooters
in the U.S., has entirely eliminated 2-stroke engines from their scooter product lines as of the
2002 model year. They continue to offer a 50cc model, but with a 4-stroke engine. Both of
Aprilia's 2-stroke 49cc scooters available in the U.S. have incorporated electronic direct
injection technology, which, in the case of one model, enables it to meet the "Euro-2" standards
of 1.2 grams per kilometer HC and 0.3 grams per kilometer NOx, without use of a catalytic
converter.3 Piaggio, while currently selling a 49cc basic 2-stroke scooter in the U.S., expects to
begin production of a direct injection version in 2002, and a 4-stroke 50cc scooter is also in
development. Numerous 49cc models marketed by Piaggio in Europe are available either as a 4-
stroke or a 2-stroke with a catalyst. Piaggio, also an engine manufacturer and seller, is already
offering a 50cc 4-stroke engine to its customers for incorporation into scooters.4
The U.S. represents a very small portion of the market for small motorcycles and scooters.
There are few, if any, manufacturers that develop a small-displacement motorcycle exclusively
for the U.S. market; the domestic sales volumes do not appear large enough at this time to
support an industry of this kind. The Italian company Piaggio (maker of the Vespa scooters), for
example, sold about as many scooters worldwide in 2000 (about 480,000) as the entire volume of
highway motorcycles of all sizes sold in the U.S. in that year. U.S. sales of Vespas in 2000
amounted to about 4800. The largest scooter markets today are in South Asia and Europe, where
millions are sold annually. In Taiwan alone almost 800,000 motorcycles were sold domestically.
More than one third of these were powered by 2-stroke engines. Two- and three-wheelers
constitute a large portion of the transportation sector in Asia, and in some urban areas these
vehicles - many of them powered by 2-stroke engines - can approach 75 percent of the vehicle
population. According to a World Bank report, two-stroke gasoline engine vehicles are
estimated to account for about 60 percent of the total vehicle fleet in South Asia.15
Many nations are now realizing that the popularity of these vehicles and the high density of
these vehicles in urban areas are contributing to severe air quality problems. As a consequence,
some of the larger small motorcycle markets in Asia and India are now placing these vehicles
under fairly strict regulation. It is clear that actions in these nations will move the emission
control technology on small motorcycles, including those under 50cc, in a positive direction.
For example, according to the World Bank report, beginning in 2000 catalytic converters will be
14 ACEM members are: Aprilia, Benelli, BMW, Derbi, Ducati, Honda, Kawasaki, KTM, Malaguti, MV
Augusta, Peugeot, Piaggio, Suzuki, Triumph, Yamaha.
Improving Urban Air Quality in South Asia by Reducing Emissions from Two-Stroke Engine Vehicles.
Masami Kojima, Carter Brandon, and Jitendra Shah. December 2000. Prepared for the World Bank. Available in the
public docket for review, or on the internet at:
http://www.worldbank.org/html/fpd/esmap/publication/airquality.html.
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installed in all new two-stroke engine motorcycles in India, and 2003 standards in Taiwan will
effectively ban new two-strokes with emission standards so stringent that only a four-stroke
engine is capable of meeting them.
Given the emerging international picture regarding emission standards for scooters, we
believe that scooter manufacturers will be producing scooters of less than 50cc displacement that
meet our standards well in advance of the 2006 model year, the first year we will subject this
category of motorcycle to U.S. emission standards.
There are other numerous factors in the international arena that may affect the product
offerings in the less than 50cc market segment. For example, Europe recently changed the laws
regarding insurance and helmet use for under 50cc scooters and mopeds. Previously, the
insurance discounts and lack of helmet requirements in Europe provided two relatively strong
incentives to purchasers to consider a 49cc scooter. Recently, however, the provisions were
changed such that helmets are now required and the insurance costs are comparable to larger
motorcycles. The result was a drop of about 30% in European sales of 49cc scooters in 2001 due
to customers perceiving little benefit from a 49cc scooter relative to a larger displacement
engine.
4.1.2 - Class III Motorcycles
4.1.2.1 - Tier-1 Standards
In the short term, the Tier-1 HC+NOx standard of 1.4 g/km HC+NOx reflects the goal of
achieving emission reductions that could be met with reasonably available control technologies,
primarily involving technologies less costly and complex, and more easily adaptable to the vast
majority of motorcycles, than catalytic converters. As noted earlier, we are adopting this
standard effective with the 2006 model year. Based on current certification data, a number of
existing engine families would already comply with this standard or would need relatively
simple modifications to comply. In other cases, the manufacturers will need to use control
technologies that are available but are not yet used on their particular vehicles (e.g., electronic
fuel injection to replace carburetors, changes to cam lobes/timing, etc.). For the most part,
manufacturers will not need to use advanced technologies such as close-coupled, closed-loop
three way catalysts.
While manufacturers will use various means to meet the Tier-1 standard, there are four
basic types of existing, non-catalyst-based, emission control systems available to manufacturers.
The most important of these is the use of secondary pulse-air injection. Other engine
modifications and systems include more precise fuel control, better fuel atomization and
delivery, and reduced engine-out emission levels from engine changes. These technologies are
used in varying degrees today and are not expected to result in a loss of performance. The
combinations of low-emission technologies ultimately chosen by motorcycle manufacturers are
dependent on the engine-out emission levels of the vehicle, the effectiveness of the prior
emission control system, and individual manufacturer preferences.
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Secondary pulse-air injection, as demonstrated on current motorcycles, is applied using a
passive system (i.e., no air pump involved) that takes advantage of the flow of gases ("pulse") in
the exhaust pipes to draw in fresh air that further combusts unburned hydrocarbons in the
exhaust. Engine modifications include a variety of techniques designed to improve fuel delivery
or atomization; promote "swirl" (horizontal currents) and "tumble" (vertical currents); maintain
tight control on air-to-fuel (A/F) ratios; stabilize combustion (especially in lean A/F mixtures);
optimize valve timing; and retard ignition timing.
4.1.2.1.1 - Secondary Air Injection
Secondary pulse air injection involves the introduction of fresh air into the exhaust pipe
immediately after the gases exist the engine. Secondary pulse-air injection, as demonstrated on
current motorcycles, is applied using a passive system (i.e., no air pump involved) that takes
advantage of the flow of gases ("pulse") in the exhaust pipes to draw in fresh air that further
combusts unburned hydrocarbons in the exhaust. The extra air causes further combustion to
occur, thereby controlling more of the hydrocarbons that escape the combustion chamber. This
type of system is relatively inexpensive and uncomplicated because it does not require an air
pump; air is drawn into the exhaust through a one-way reed valve due to the pulses of negative
pressure inside the exhaust pipe. Secondary pulse-air injection is one of the most effective non-
catalytic emission-control technologies; compared to engines without the system, reductions of
10 to 40 percent for HC are possible with pulse-air injection. Eighty - or about half- of the 162
2003 model year Class III engine families certified for sale in the U.S. employ secondary pulse-
air injection to help meet the current standards. We anticipate that most of the remaining engine
families will use this technique to help meet the Tier 1 and Tier 2 standards. There are 47 2003
engine families that are certified using only engine management techniques (e.g., no use of
catalysts, fuel injection, secondary air injection, or oxygen sensors). The average certification
HC level of these families is 1.17 g/km. By comparing this to the certification results of engine
families that employ secondary air injection as the only means of emission control beyond
engine modifications, we can gain some measure of the effectiveness of secondary air injection.
We find that the currently certified 2003 models which employ secondary air injection have an
average certification level of 0.91 g/km, a reduction of 0.26 g/km (or 22%) relative to those
using only engine modification techniques.
4.1.2.1.2 - Improving Fuel Delivery and Atomization
Improving fuel delivery and atomization primarily involves the replacement of carburetors,
currently used on most motorcycles, with more precise fuel injection systems. There are several
types of fuel injection systems and components manufacturers can choose. The most likely type
of fuel injection manufacturers will choose to help meet the Tier-1 standard is sequential multi-
point fuel injection (SFI).
Unlike conventional multi-point fuel injection systems that deliver fuel continuously or to
paired injectors at the same time, sequential fuel injection can deliver fuel precisely when needed
by each cylinder. With less than optimum fuel injection timing, fuel puddling and intake-
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manifold wall wetting can occur, both of which hinder complete combustion. Use of sequential-
fuel- injection systems help especially in reducing cold start emissions when fuel puddling and
wall wetting are more likely to occur and emissions are highest.
Motorcycle manufacturers are already beginning to use sequential fuel injection (SFI).
Improved emission levels are one benefit of a fuel injection system relative to carburetion, but
other advantages include improved reliability and fuel economy. Of the 151 Class III
motorcycle engine families certified for sale this year, 27 employ SFI systems. These 27 engine
families account for about 30 percent of projected 2001 sales, indicating that these engine
families represent some popular motorcycle models. Indeed, three models that are among the
highest-selling - two from Harley-Davidson and one from Honda - are equipped with SFI. We
anticipate increased applications of this or similar fuel injection systems to achieve the more
precise fuel delivery needed to help meet the Tier-1 and Tier-2 standards. Of the 162 2003
model year Class III motorcycle engine families certified to emission standards, at least 29
employ SFI systems.16 We anticipate increased application of this or similar fuel injection
systems to achieve the more precise fuel delivery needed to help meet the Tier 1 and Tier 2
standards. We analyzed the EPA certification data in the same way as done above with
secondary air injection to estimate the effect of using SFI vehicle on emissions. Again, we
identified the baseline of 47 engine families using the limited technologies and with an average
certification level of 1.17 g/km HC, and compared the emissions of these engines with the
emissions of engines using SFI. What we find is that use of all types of fuel injection can
significantly reduce emissions. If we analyze those engine families that use some form of fuel
injection other than SFI we see an average HC certification level of 1.09 g/km, a modest
reduction of about 7 percent. However, the engines using SFI had significantly lower HC
emissions on average of 0.72 g/km, a reduction of almost 40 percent. While this provides some
indication of what can be achieved with fuel injection techniques (including SFI), it does not
necessarily demonstrate the full potential of this technology. At this point in time it appears that
SFI can get motorcycle certification levels down to about 0.4 - 0.6 g/km HC (certification at
levels in this range can be seen in several current motorcycles that employ no other emission
controls), but in the context of more stringent standards the manufacturers are likely to be able to
accomplish even more with SFI, and further reductions by teaming SFI with additional emission
reduction techniques.
4.1.2.1.3 - Engine Modifications
16 When manufacturers certify to EPA emission standards, they report the fuel delivery system used by each
certified model as carbureted or fuel injected. They also report the emission control technologies used on each model
to meet the emission standards. When reporting the fuel delivery system, they only indicate whether the system is
carbureted or fuel injected, but not the specific type of fuel injection that is installed. When reporting the control
technologies 29 models indicated the use of sequential fuel injection. However, there may be some inconsistencies
in how these technologies are reported, and we believe that there may be models that employ sequential fuel
injection that are shown in our database as being fuel injected, but the manufacturer may not have also specifically
listed sequential fuel injection as a control technology on the motorcycle model. This is why we say "at least" 29
models are currently using sequential fuel injection.
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In addition to the techniques mentioned above, various engine modifications can be made to
improve emission levels. Emission performance can be improved, for example, by reducing
crevice volumes in the combustion chamber. Unburned fuel can be trapped momentarily in
crevice volumes before being subsequently released. Since trapped and re-released fuel can
increase engine-out emissions, the elimination of crevice volumes would be beneficial to
emission performance. To reduce crevice volumes, manufacturers can evaluate the feasibility of
designing engines with pistons that have reduced, top "land heights" (the distance between the
top of the piston and the first ring).
Lubrication oil which leaks into the combustion chamber also has a detrimental effect on
emission performance since the heavier hydrocarbons in oil do not oxidize as readily as those in
gasoline and some components in lubricating oil may tend to foul the catalyst and reduce its
effectiveness. Also, oil in the combustion chamber may trap HC and later release the HC
unburned. To reduce oil consumption, manufacturers can tighten the tolerances and improve the
surface finish on cylinders and pistons, piston ring design and materials, and exhaust valve stem
seals to prevent excessive leakage of lubricating oil into the combustion chamber.
Increasing valve overlap is another engine modification that can help reduce emissions.
This technique helps reduce NOx generation in the combustion chamber by essentially providing
passive exhaust gas recirculation (EGR). When the engine is undergoing its pumping cycle,
small amounts of combusted gases flow past the intake valve at the start of the intake cycle. This
creates what is essentially a passive EGR flow, which is then either drawn back into the cylinder
or into another cylinder through the intake manifold during the intake stroke. These combusted
gases, when combined with the fresh air/fuel mixture in the cylinder, help reduce peak
combustion temperatures and NOx levels. This technique can be effected by making changes to
cam timing and intake manifold design to optimize NOx reduction while minimizing impacts to
HC emissions.
4.1.2.2 - Analysis of EPA Certification Data
Secondary pulse-air injection and engine modifications already play important parts in
reducing emission levels; we expect increased uses of these techniques to help meet the Tier-1
standard. Direct evidence of the extent these technologies can help manufacturers meet the Tier-
1 standard can be found in the EPA on-road motorcycle certification database. This database is
comprised of publicly-available certification emission levels and confidential data (e.g.,
projected sales of each certified engine family) reported by the manufacturers pursuant to
existing requirements. If one thing is clear from the EPA certification data, it is that the vast
majority of motorcycles are certifying at emission levels well below the existing federal HC
standard. The average certification HC level for 2003 Class III motorcycles is 0.93 g/km (the
existing EPA standard is 5.0 g/km). This is due in large part to the fact that manufacturers are
designing one engine family to market in all 50 states; therefore, it is the California requirements
(including the upcoming requirements not yet in effect) that are driving the emission levels down
nationwide. In addition, European nations and others around the world are pursuing lower
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motorcycle emission levels, contributing further to the trend of lower overall emissions from
companies that want to market a worldwide product.
The California ARB reports and discussions with manufacturers revealed that typical NOx
levels range from about 0.5 to 0.7 g/km. Some in-use data collected by the California ARB
indicates an average NOx level for the 109 motorcycles tested of 0.53 g/km. Restricting the data
to 44 1988 and later non-tampered Class III motorcycles results in an average NOx level of 0.5
g/km. Only seven out of these 44 motorcycles had NOx levels that exceeded 0.7 g/km. In
addition, some recent data from 16 1997-1999 Class III motorcycles tested by Environment
Canada found an average NOx level of 0.3 g/km, with a maximum of 0.5 g/km. For the purposes
of our analysis we will use the middle of the range reported by the California ARB, or 0.6 g/km,
which appears somewhat higher than the average based on the additional data. The only
exception is for motorcycles currently equipped with three-way catalysts. In these cases we
assume that the catalyst (or catalysts) are operating at 50 percent efficiency, resulting in
estimated tailpipe NOx emissions of 0.3 g/km.
Of the 162 Class III motorcycle engine families certified for the 2003 model year, 109, or 67
percent, could be certified to HC+NOx levels up to 1.6 g/km today. Although 1.6 g/km would
be in excess of the Tier 1 standard, we believe that the reduction required to get below the
standard of 1.4 g/km HC+NOx is minimal enough such that advanced technologies like high-
efficiency two- or three-way catalysts would not be required. Table 4.1-1 shows the breakdown
of the emission control technologies used by these 109 engine families that could potentially
certify to the Tier-1 standards today. Twenty-six of these, or 24 percent, use 3-way catalysts.
The remaining 84 could be able to certify near the Tier-1 HC+NOx level by using simpler and
less costly engine modifications and secondary air injection. Only 6 of these 84 use a two-way
catalyst.
Table 4.1-1
Breakdown of HC+NOx Estimated Certification Levels by Technology Use
Estimated HC+NOx
Certification Level
0.5-0.7
0.8- 1.0
1.1 - 1.3
1.4- 1.6
Total
No. of
Engine
Families
7
23
45
34
109
No. of Engine Families Using Specified Technology
Engine
Modifications A
7
21
35
27
90
Pulse Air
Injection
4
14
19
22
59
2-way Ox-
Cat.
0
1
1
4
6
3-way
Catalyst
7
9
8
2
26
Includes all forms of fuel injection, electronic control modules, etc. Source: 2001 U.S. EPA Certification
Database
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We also reviewed the limited available model year 2004 California certification data, where
manufacturers are beginning to certify to the Tier 1 standards. Of the 4 engine families certified
with three-way catalysts, 3 had NOx+HC certification levels in the range of 0.32-0.43 g/km, with
an average of 0.54 g/km. The remaining engine families not equipped with three-way catalysts
were in the range of 0.6 -1.4 g/km, with an average NOx+HC levels of 1.1 g/km.
In addition, we are confident that the two years of experience gained by manufacturers in
meeting the new standard in California prior to having to extend compliance nationwide will
help ensure that the new emission control systems are fully developed and fully capable of
meeting the new standards on a nationwide basis.
4.1.2.3 - Tier-2 Standards
In the long term, the Tier-2 HC+NOx standard of 0.8 g/km will ensure that manufacturers
will continue to advance the status of control technologies. The Tier-2 standard will become
effective with the 2010 model year. This standard will present some challenges for
manufacturers; however, several manufacturers are already using some of the technologies that
will be needed to meet this standard. In addition, our implementation time frame gives
manufacturers two years of experience in meeting this standard in California before having to
meet it on a nationwide basis. Several manufacturers already use closed-loop, three-way
catalysts on a number of product lines, and at least two manufacturers are already marketing a
motorcycles that meet this standard. Depending upon assumptions regarding NOx levels, other
manufacturers have products on the market today with emission levels that could meet or almost
meet the Tier-2 standards using two-way catalysts, fuel injection, secondary pulse-air injection,
and other engine modifications. We expect that the significant lead time prior to meeting these
standards on a nationwide basis will allow manufacturers to optimize these and other
technologies to meet the Tier-2 standard.
In addition, the Tier-2 standard is an averaging standard, allowing manufacturers to balance
some motorcycles certified at levels above the standard with others certified to levels below the
standard. Thus, under the program, not every motorcycle must be designed to meet the 0.8 g/km
HC+NOx standard.
To meet the Tier-2 standard for HC+NOx, manufacturers will likely use more advanced
engine modifications and secondary air injection. Specifically, we believe manufacturers will
use computer-controlled secondary pulse-air injection (i.e., the injection valve would be
connected to a computer-controlled solenoid). In addition to these systems, we estimate that
approximately 50 percent of motorcycles will need to use catalytic converter technology to meet
the Tier-2 standards. There are two types of catalytic converters currently in use: two-way
catalysts (which control only HC and CO) and three-way catalysts (which control HC, CO, and
NOx). Under the Tier-2 standard, manufacturers will need to minimize levels of both HC and
NOx. Therefore, to the extent catalysts are used, manufacturers will likely use a three-way
catalyst in addition to engine modifications and computer-controlled, secondary pulse-air
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injection. These types of technologies are used in varying degrees on current models and are not
expected to result in a loss of performance or fuel economy.
4.1.2.4.1 - Improving Fuel Control and Delivery
As discussed previously, improving fuel control and delivery provides emission benefits by
helping to reduce engine-out emissions and minimizing the exhaust variability which the
catalytic converter experiences. One method for improving fuel control is to provide enhanced
feedback to the computer-controlled fuel injection system through the use of heated oxygen
sensors. Heated oxygen sensors (HO2S) are located in the exhaust manifold to monitor the
amount of oxygen in the exhaust stream and provide feedback to the electronic control module
(ECM). These sensors allow the fuel control system to maintain a tighter band around the
stoichiometric A/F ratio than conventional O2 sensors. In this way, HO2S assist vehicles in
achieving precise control of the A/F ratio and thereby enhance the overall emissions
performance of the engine. At least one manufacturer is currently using this technology on
several 2001 - 2003 engine families.
In order to further improve fuel control, some motorcycles with electronic controls may
utilize software algorithms to perform individual cylinder fuel control. While dual oxygen
sensor systems are capable of maintaining A/F ratios within a narrow range, some
manufacturers may desire even more precise control to meet their performance needs. On
typical applications, fuel control is modified whenever the O2S determines that the combined
A/F of all cylinders in the engine or engine bank is "too far" from stoichiometric. The needed
fuel modifications (i.e., inject more or less fuel) are then applied to all cylinders simultaneously.
Although this fuel control method will maintain the "bulk" A/F for the entire engine or engine
bank around stoichiometric, it would not be capable of correcting for individual cylinder A/F
deviations that can result from differences in manufacturing tolerances, wear of injectors, or
other factors.
With individual cylinder fuel control, A/F variation among cylinders will be diminished,
thereby further improving the effectiveness of the emission controls. By modeling the behavior
of the exhaust gases in the exhaust manifold and using software algorithms to predict individual
cylinder A/F, a feedback fuel control system for individual cylinders can be developed. Except
for the replacement of the conventional front O2S with an HO2S sensor and a more powerful
engine control computer, no additional hardware is needed in order to achieve individual
cylinder fuel control. Software changes and the use of mathematical models of exhaust gas
mixing behavior are required to perform this operation.
In order to maintain good driveability, responsive performance, and optimum emission
control, fluctuations of the A/F must remain small under all driving conditions, including
transient operation. Virtually all current fuel systems in automobiles incorporate an adaptive
fuel control system that automatically adjusts the system for component wear, varying
environmental conditions, varying fuel composition, etc., to more closely maintain proper fuel
control under various operating conditions. For some fuel control systems today, this adaptation
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process affects only steady-state operating conditions (i.e., constant or slowly changing throttle
conditions). However, most vehicles are now being introduced with adaptation during
"transient" conditions (e.g., rapidly changing throttle, purging of the evaporative system).
Accurate fuel control during transient driving conditions has traditionally been difficult
because of the inaccuracies in predicting the air and fuel flow under rapidly changing throttle
conditions. Because of air and fuel dynamics (fuel evaporation in the intake manifold and air
flow behavior) and the time delay between the air flow measurement and the injection of the
calculated fuel mass, temporarily lean A/F ratios can occur during transient driving conditions
that can cause engine hesitation, poor driveability and primarily an increase in NOx emissions.
However, by utilizing fuel and air mass modeling, vehicles with adaptive transient fuel control
are more capable of maintaining accurate, precise fuel control under all operating conditions.
Virtually all cars sold in California will incorporate adaptive transient fuel control software;
motorcycles with computer controlled fuel injection can also benefit from this technique at a
relatively low cost.
4.1.2.4.2 - Three-way Catalytic Converters
Three-way catalytic converters traditionally utilize rhodium and platinum as the catalytic
material to control the emissions of all three major pollutants (hydrocarbons (HC), CO, NOx).
Although this type of catalyst is very effective at converting exhaust pollutants, rhodium, which
is primarily used to convert NOx, tends to thermally deteriorate at temperatures significantly
lower than platinum. Recent advances in palladium and tri-metal (i.e., palladium-platinum-
rhodium) catalyst technology, however, have improved both the light-off performance (light-off
is defined as the catalyst bed temperature where pollutant conversion reaches 50% efficiency)
and high temperature durability over previous catalysts. In addition, other refinements to
catalyst technology, such as higher cell density substrates and adding a second layer of catalyst
washcoat to the substrate (dual-layered washcoats), have further improved catalyst performance
from just a few years ago.
Typical cell densities for conventional catalysts used in motorcycles are less than 300 cells
per square inch (cpsi). To meet the Tier-2 standard, we expect manufacturers to use catalysts
with cell densities of 300 to 400 cpsi. If catalyst volume is maintained at the same level (we
assume volumes of up to 60% of engine displacement), using a higher density catalyst
effectively increases the amount of surface area available for reacting with pollutants. Catalyst
manufacturers have been able to increase cell density by using thinner walls between each cell
without increasing thermal mass (and detrimentally affecting catalyst light-off) or sacrificing
durability and performance.
In addition to increasing catalyst volume and cell density, we believe that increased catalyst
loading and improved catalyst washcoats will help manufacturers meet the Tier-2 standard. In
general, increased precious metal loading (up to a certain point) will reduce exhaust emissions
because it increases the opportunities for pollutants to be converted to harmless constituents.
The extent to which precious metal loading is increased will be dependent upon the precious
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metals used and other catalyst design parameters. We believe recent developments in
palladium/rhodium catalysts are very promising since rhodium is very efficient at converting
NOx, and catalyst suppliers have been investigating methods to increase the amount of rhodium
in catalysts for improved NOx conversion.
Double layer technologies allow optimization of each individual precious metal used in the
washcoat. This technology can provide reduction of undesired metal-metal or metal-base oxide
interactions while allowing desirable interactions. Industry studies have shown that durability
and pollutant conversion efficiencies are enhanced with double layer washcoats. These recent
improvements in catalysts can help manufacturers meet the Tier-2 standard at reduced cost
relative to older three-way catalysts.
New washcoat formulations are now thermally stable up to 1050 °C. This is a significant
improvement from conventional washcoats, which are stable only up to about 900 °C. With the
improvements in light-off capability, catalysts may not need to be placed as close to the engine
as previously thought. However, if placement closer to the engine is required for better emission
performance, improved catalysts based on the enhancements described above would be more
capable of surviving the higher temperature environment without deteriorating. The improved
resistance to thermal degradation will allow closer placement to the engines where feasible,
thereby providing more heat to the catalyst and allowing them to become effective quickly.
It is well established that a warmed-up catalyst is very effective at converting exhaust
pollutants. Recent tests on advanced catalyst systems in automobiles have shown that over 90%
of emissions during the Federal Test Procedure (FTP) are now emitted during the first two
minutes of testing after engine start up. Similarly, the highest emissions from a motorcycle
occur shortly after start up. Although improvements in catalyst technology have helped reduce
catalyst light-off times, there are several methods to provide additional heat to the catalyst.
Retarding the ignition spark timing and computer-controlled, secondary air injection have been
shown to increase the heat provided to the catalyst, thereby improving its cold-start
effectiveness.
In addition to using computer-controlled secondary air injection and retarded spark timing
to increase the heat provided to the catalyst, some vehicles may employ warm-up, pre-catalysts
to reduce the size of their main catalytic converters. Palladium-only warm-up catalysts (also
known as "pipe catalysts" or "Hot Tubes") using ceramic or metallic substrates may be added to
further decrease warm-up times and improve emission performance. Although metallic
substrates are usually more expensive than ceramic substrates, some manufacturers and suppliers
believe metallic substrates may require less precious metal loading than ceramic substrates due
to the reduced light-off times they provide.
Improving insulation of the exhaust system is another method of furnishing heat to the
catalyst. Similar to close-coupled catalysts, the principle behind insulating the exhaust system is
to conserve the heat generated in the engine for aiding catalyst warm-up. Through the use of
laminated thin-wall exhaust pipes, less heat will be lost in the exhaust system, enabling quicker
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catalyst light-off. As an added benefit, the use of insulated exhaust pipes will also reduce
exhaust noise. Increasing numbers of manufacturers are expected to utilize air-gap exhaust
manifolds (i.e., manifolds with metal inner and outer walls and an insulating layer of air
sandwiched between them) for further heat conservation.
4.1.2.4.3 -Automotive Technologies
Besides the hardware modifications described above, motorcycle manufacturers may borrow
from other current automobile techniques. These include using engine calibration changes such
as a brief period of substantial ignition retard, increased cold idling speed, and leaner air-fuel
mixtures to quickly provide heat to a catalyst after cold-starts. Only software modifications are
required for an engine which already uses a computer to control the fuel delivery and other
engine systems. For these engines, calibration modifications provide manufacturers with an
inexpensive method to quickly achieve light-off of catalytic converters. When combined with
pre-catalysts, computer-controlled secondary air injection, and the other heat conservation
techniques described above, engine calibration techniques may be very effective at providing the
required heat to the catalyst for achieving the Tier-2 standard. These techniques are currently in
use on most low emission vehicle (LEV) automobiles and may have applications in on-road
motorcycles.
4.1.2.5 - Conclusion
4.1.2.5.1 - Tier-1 Standards
We expect that the Tier-1 standard will be met with reasonably available control
technologies. A number of existing engine families would already comply with this standard or
would need relatively simple modifications to comply. In other cases, the manufacturers will
need to use control technologies that are available but are not yet used on their particular
vehicles (e.g., electronic fuel injection to replace carburetors, secondary pulse air injection,
changes to cam lobes/timing, etc.). For the most part, manufacturers will not need to use
advanced technologies such as close-coupled, closed-loop three way catalysts. The ultimate
combinations of low-emission technologies ultimately chosen by motorcycle manufacturers are
dependent on the engine-out emission levels of the vehicle, the effectiveness of the prior
emission control system, and individual manufacturer preferences.
4.1.2.5.2 - Tier-2 Standards
We expect that the Tier-2 standard will likely require the use of more advanced engine
modifications and secondary air injection. Depending upon assumptions regarding NOx levels,
some manufacturers have products on the market today with emission levels that could meet or
almost meet the Tier-2 standard using two-way catalysts, fuel injection, secondary pulse-air
injection, and other engine modifications. We believe that manufacturers will use computer-
controlled secondary pulse-air injection, in addition to using catalytic converters on some
motorcycles to meet the Tier-2 standards. To the extent catalysts are used, manufacturers will
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likely use a three-way catalyst in addition to engine modifications and computer-controlled,
secondary pulse-air injection. We expect that the significant lead time prior to meeting these
standards on a nationwide basis will allow manufacturers to optimize these and other
technologies to meet the Tier-2 standard.
4.1.3 - Impacts on Noise, Energy, and Safety
As automotive technology demonstrates, achieving low emissions from spark-ignition
engines can correspond with greatly reduced noise levels. Virtually all highway motorcycles are
equipped with sound suppression systems or mufflers. The four-stroke engines used in highway
motorcycles above 50cc are considerably more quiet than the two-stroke engines used by many
of their off-road counterparts. In addition, highway motorcycles are required to meet existing
noise emission standards. The increased use of four-stroke engines in motorcycles below 50cc,
which is expected as a result of this rule, would have the effect of reducing their noise levels.
Adopting new technologies for controlling fuel metering and air-fuel mixing, particularly
the conversion of some carbureted highway motorcycles to advanced fuel injection technologies,
will lead to improvements in fuel consumption.
Many riders have expressed some concerns regarding the close proximity of the riders to hot
exhaust pipes and the catalytic converter. Protecting the rider from the excessive heat is a
concern for both riders and manufacturers. We appreciate and understand the concerns raised by
many motorcyclists regarding the potential safety issues of catalytic converters due to the heat
that the devices can generate. In the NPRM we suggested that current experience with the
installation of catalytic converters on motorcycles - both in the U.S. and worldwide - has
demonstrated that catalytic converters are a safe emission control technology option for
manufacturers. Due to the serious nature of the concerns expressed by riders we have expanded
and improved our assessment of the potential risks of using catalytic converters as an emission
control device on motorcycles. We continue to believe that catalysts can safely be used as a
motorcycle emissions control device.
The additional weight of a catalyst (or even two) does not present a potential safety issue.
Perhaps this would be the case if motorcycle catalysts were comparable to automotive catalysts
in size, weight, and volume, but this is not the case. Motorcycle catalysts do not and will not
have to reach the high efficiency levels of current and projected automotive catalysts, and
consequently their size relative to the displacement of the engine is often smaller. Current
motorcycle catalysts are typically smaller than a 12 ounce can of carbonated drink - perhaps
even half this size or smaller - and weigh no more. Thus, the weight addition caused by a
catalyst will have hardly any effect on the weight of these vehicles. All other things held equal,
the addition of a catalyst to a motorcycle does add some small additional weight to the
motorcycle. But all other things are rarely kept static and without evolution. As demonstrated
by the 2003 Yamaha YZF-R6, it is possible, with the use of advanced materials and
technologies, to add a catalyst and minimize the impact on the overall weight of the exhaust
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system. (Yamaha added a catalyst to the 2003 YZF-R6 while at the same time reducing the total
weight of the exhaust system by more than two pounds.)
There are currently thousands of motorcycles with catalytic converters being ridden in the
U.S. today. These catalyst-equipped motorcycles span the motorcycle categories of cruisers,
touring, sport, standard, and even scooters. In particular, BMW has been using 3-way catalytic
converters on all of their motorcycles since 1991. In recent years the sales of BMW motorcycles
in the U.S. has exceeded 10,000 units per year, and their worldwide sales since 1997 are near
450,000 units. Harley-Davidson has been producing a number of different models with catalytic
converters for the California market since 1995, and company estimates put the total number
sold with catalytic converters since 1995 at around 45,000.17
In addition to BMW and Harley-Davidson, in the last 5 years motorcycle models with
catalytic converters have been sold by Aprilia, Cushman, Ducati, Genuine Scooter, Honda,
Kawasaki, Kwang Yang Motor Co., Malaguti, Milwaukee Motorcycle, Roadstertec, Russian
American Motorbike, Suzuki, Triumph, and Yamaha. Honda models with catalytic converters
include the VTX-1800 and VTX-1300 (cruisers), the Gold Wing GL-1800 (touring), the ST-
1300 (sport touring), and the Interceptor VFR-800 (sport). Kawasaki models include the Ninja
ZX-9R (sport), the ZR-1000 (sport), the Ninja ZX-12R (sport), the ZR-1200 (touring), the VN-
1500 Vulcan (cruiser), and the VN-1600 Vulcan (cruiser). Suzuki models with catalytic
converters include the Burgmaster AN-650 (large scooter). Yamaha motorcycles currently
equipped with catalytic converters include the YZF-R6 (super-sport), the YZF-R1 (sport), and
the FJR-1300 (sport touring).
A conservative estimate based on confidential sales projections made by manufacturers
when they certify their motorcycles to EPA standards, indicates that 80,000 to 100,000 2003
model year motorcycles equipped with catalytic converters could be sold in the U.S. If we
estimate conservatively that there are 150,000 motorcycles on the road today in the U.S. with
catalytic converters,18 and each is driven 2,000-3,000 miles per year, then we can state that over
300 million miles have been ridden on catalyst-equipped motorcycles in the last year. We
believe that twenty percent of the motorcycles sold in the last two years, or 100,000 (or likely
more) currently on the road, ridden for hundreds of millions of miles, can be reasonably argued
to be a significant and substantial in-use demonstration. This total would be far greater if we
included the numerous motorcycles with catalysts being ridden in the several countries that
already have emission standards for motorcycles that manufacturers are meeting by using
catalysts. In these terms it is abundantly clear that there is no shortage of experience with
catalytic converters - both in terms of manufacturers and riders - in the U.S. Worldwide the
17 Jerry Steffy, Harley-Davidson Motor Company, Regulatory Affairs Department. Docket A-2000-2.
18 Sales of catalyst-equipped BMW and Harley-Davidson motorcycles alone since 1995 approach 100,000.
According to BMW Annual Reports their U.S. sales in the last three years have exceeded 13,000 per year. Include
Honda, which has some high-volume products with catalysts such as the Goldwing, and it becomes clear that
150,000 is a conservative estimate.
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experience is several orders of magnitude greater. In fact, substantial factual evidence indicates
that the safety concerns regarding heat generation from catalytic converters are surmountable
(i.e., capable of being overcome). This evidence is not just theoretical or based on engineering
principles and judgement - it is the real-world experience today.
Given the U.S. manufacturer and rider experience with catalytic converters, we believe that
there has been ample opportunity to assess the issue of catalyst safety, not just on a hypothetical
basis but on the basis of actual manufacturing and on-road riding experience. We have already
established that a significant number of manufacturers have engineered, produced, and sold a
large number of motorcycles with catalytic converters. To assess the rider experience and any
potential issues that may have arisen during the hundreds of millions of miles ridden with
catalytic converters in the U.S., we analyzed the database of consumer complaints maintained by
the National Highway Traffic Safety Administration's Office of Defects Investigation. This
database contains all consumer complaints filed since 1995 related to motor vehicles, child
safety devices, and other equipment such as tires. The database is used by NHTSA to assist
them in targeting investigations and potential vehicle recalls.
When the database was obtained by the EPA in February, 2003, it contained over 370,000
entries. About 2,000 records were specific to motorcycles, and 28 of these contained complaints
specifically regarding the exhaust system. Five of these complaints (representing four different
manufacturers) specifically regarded the catalytic converter. Two of these five complaints were
regarding converters that had failed, another two complaints were regarding unusual or strong
odors, and the remaining complaint was regarding a heat shield that fell off. None of the
complaints suggested that heat from the catalytic converter was excessive, improperly managed,
or unsafe. We then expanded our assessment of the database by reviewing the remaining 23
complaints related to exhaust system components. This was done to be sure that we did not
overlook any catalytic converter concerns that may have been improperly categorized or
diagnosed by the consumer filing the complaint. Of these 23, five were regarding issues with the
fuel petcock or fuel check valve, or the oxygen sensors. Seven complaints were regarding a
tailpipe that fell off, was broken, was dented, or somehow failed. An additional four of these
complaints were regarding the following issues: an oil leak; a muffler bracket recall; handling
issues with installation of long aftermarket pipes; and peeling paint.
The remaining seven complaints, which we describe here in greater detail, were specifically
regarding excess heat coming from the exhaust system.
4-18
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No.
1
2
3
4
5
6
7
Make
Kawasaki
Suzuki
Harley-
Davidson
Harley-
Davidson
Harley-
Davidson
BMW
BMW
Model & Year
1988
Z Series
1995
2000
FLHPI
2002
2003
Electraglide
2000
R1200C
2001
K1200RS
Complaint
Passenger on motorcycle received burns on leg from hot mufflers.
Muffler not designed with heat shield, causing burn injury to driver when
motorcycle turned over.
Exhaust manifold reaches temperatures so high that it has an orange glow.
Manufacturer knows of problem, and there isn't a solution. Consumer will
add additional information
Consumer states that when at a stop the exhaust pipe will glow red and
this can cause injuries to the consumer. Dealer notified.
Exhaust system cross over pipe is located too close to seat, causing
driver to be burned while driving, even if properly dressed.
Consumer states exhaust pipes are positioned below foot pegs so that
when you come to a stop and put feet down, it's very likely that pant leg
will at least brush up against pipe. Consumer has ruined clothes because
of this. BMW does not feel this is a problem, they suggested to consumer
that he buy after market exhaust guards, which are expensive.
Exhaust pipes are positioned below foot pegs so that when you come to a
stop and put your foot down you will brush up against hot pipe.
2.
Two of these were regarding burns sustained by riders from a hot muffler (one of which was
sustained in a crash of the motorcycle and not during normal riding conditions). Both of
these complaints were regarding motorcycles known not to be equipped with catalytic
converters; one was produced before catalytic converters were used on motorcycles (a 1988
Kawasaki) and the other by a manufacturer that, to our knowledge, did not utilize catalytic
converters on their motorcycles until the 2003 model year (a 1995 Suzuki). These
complaints demonstrate that the catalytic converter does not introduce a new hazard to
motorcycle riders; the very nature of a motorcycle is that the rider is always in close
proximity to the engine and exhaust system, both of which can generate significant heat and
can cause burns whether or not there is a catalytic converter present.
Another complaint was regarding an exhaust pipe that glowed red at idle (a 2002 Harley-
Davidson). We do not have enough information to determine whether this is a catalyst-
equipped vehicle, but the fact that the complaint originated from an Ohio owner points to
the likelihood of it being a non-catalyst model, because the catalyst-equipped Harley-
Davidsons are in the minority and are generally destined for sale in California. We also do
not know to what extent this motorcycle may have been modified and in what ways
components or tuning characteristics may have been altered or replaced, which could
potentially introduce an operating problem like this one. Clearly a pipe that glows red is not
something that was intentionally engineered by the manufacturer and does not represent a
normal situation, and is more likely due to a defect in the operation of the motorcycle. With
4-19
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respect to this complaint and the following ones regarding Harley-Davidson motorcycles,
Harley-Davidson notes in the Harley-Davidson 2003 Genuine Motor Accessories and
Genuine Motor Parts that tuning characteristics, cam timing, carburetor jetting, overheating,
and other factors can cause discoloration of exhaust pipes. It is entirely possible that these
complaints are a result of some of these factors. In fact, since it occurred at idle when
exhaust gas flow is at its lowest and catalyst efficiency is high this seems even more likely.
3. A 2003 Harley-Davidson generated a complaint regarding cross-over pipes that were
reported to be too close to the seat, burning the rider. This complaint came from a New
York owner, thus, like the Ohio report, may in fact be a motorcycle without a catalytic
converter. In addition, this is the only complaint of this type for this model of motorcycle,
and can not be considered to be indicative of a widespread problem. Again, we do not know
to what extent the owner may have modified the exhaust system or the engine of the
motorcycle, and there are potential modifications and defects unrelated to a catalytic
converter that could increase the heat of the exhaust pipes, particularly near the engine as is
the case with this complaint. Indeed, even if this motorcycle does have a catalytic converter
it would be rearward of the seat concealed in the muffler or elsewhere and would not result
in a complaint of this nature at this location on the motorcycle.
4. A similar complaint came from a 2000 Harley-Davidson owner, who noted that the exhaust
manifold would get so hot that it gave off an orange glow. Like the previous complaint of
hot cross-over pipes, it is highly unlikely that this phenomenon could be explained by the
presence of a catalytic converter, which, if present, would be far rearward of the location
where the exhaust exits the engine. Again, this is more likely the result of a defect or of
some engine changes introduced by the user or mechanic, and not likely related to the
presence of a catalytic converter. Clearly this is not a normal operating characteristic of
Harley-Davidson motorcycles. Exhaust pipe heat is generated when unburned fuel from the
engine is oxidized in the exhaust system in the presence of excess air. This happens
frequently in to a minor degree in all exhaust pipes, but is only significantly if relatively
large amounts of unburned fuel and air are present.
5. Finally, there were two complaints regarding 1200cc BMW motorcycles, one complaint
each regarding the R1200C and the K1200RS. These complaints stated that the exhaust
pipes positioned below the foot pegs can come into contact with the rider's lower leg, thus
potentially burning the lower leg or pants near the foot pegs. Based on the configuration of
the R1200C, it is possible that the catalytic converter is located in the exhaust pipe below
the foot peg, and this is also possibly the configuration of the K1200RS as well. This of
course is a design issue which must be considered in the system, but is not an unresolvable
concern as demonstrated by BMW's suggestion to the user.
We contacted Harley-Davidson and BMW and asked if they were aware of the complaints
filed with NHTSA. We also asked for their own assessment of these complaints. Both
manufacturers responded that they consider these to be isolated cases and not indicative of a
widespread problem or safety issue. BMW noted that the complaints do not appear to be directly
4-20
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related to the catalytic converter, although they are aware of the fact that catalysts can contribute
to overall heat generation. They also stated that a shorter than average person would be more
likely to come into contact with the exhaust pipes, and BMW sells aftermarket protective guards
for customers who might desire some additional protection. Obviously, it is difficult if not
impossible to design a "one-size-fits-all" motorcycle that comfortably and adequately fits people
of all sizes and stature. Harley-Davidson examined their own records and reported only two
instances that might bear some relation to excess heat from catalysts, and neither record
indicated the reporting of any health or safety concerns. They were not able to determine
whether or not the NHTSA complaints involved catalyst-equipped motorcycles. They also
added that they "educate our customers, through warnings in the Owner's Manual, about being
careful not to contact any portion of the motorcycle's exhaust system."
In summary, we do not believe that the data available from NHTSA and described above
demonstrates that a catalytic converter constitutes a significant safety risk. In fact, of the
complaints identified above where heat from the exhaust pipe was reported to be a problem,
there appear to be more involving non-catalyzed systems than there were regarding systems with
catalytic converters. In either case, the complaints represent a tiny minority of the complaints
brought to NHTSA's attention; this would not be the case if there was a generalized problem
with excessive heat from catalyst-equipped motorcycles. The data, however, does demonstrate
that heat management from the exhaust system in general is a packaging and design issue for
manufacturers, and the manufacturers are certainly aware of this need.
We are confident that manufacturers can design and produce motorcycles that respond to
these safety concerns, and information submitted by the manufacturers supports our assessment
that catalytic converters can be safely integrated into motorcycle designs. Every motorcycle
manufacturer who either testified at the public hearing or provided written comments on the
proposed rule has unequivocally stated that they can build motorcycles that will meet the
proposed standards with no negative impact on safety or performance relative to motorcycles
manufactured today. MIC stated in its oral testimony at the public hearing that "With the lead
time that you're providing and with this level of stringency of the standards, there isn't any
technological reason why motorcycles can't be produced that are safe and that have driveability
and performance that is excellent...." Harley-Davidson echoed this view at the hearing as well,
stating that "...the use of cats does raise safety issues for our engineers as they design
motorcycles. However, we have been using cats on many of our motorcycles in California for
several years now and have been able to address any major personal safety issues arising from
the use of cats on bikes." Finally, MECA addressed this issue at the public hearing by noting
that catalyst technology has been applied to over 15 million two- and three-wheelers worldwide
and that, while the safe integration of catalysts is an engineering issue, it has been addressed in a
variety of different ways. There are a number of approaches that manufacturers are using today
to protect the rider from excessive heat. Some motorcycle designs permit the catalyst to be
placed on the underside of the motorcycle where it is unable to contact the rider. Other
manufacturers will use a double-pipe exhaust system to reduce heat loss, allowing the exhaust
gases to remain hot before reaching the catalyst while maintaining lower exterior temperatures.
Some manufacturers are placing the catalyst inside the muffler or close to the manifold in areas
4-21
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where it is unlikely to be contacted by the rider or passenger. Footrests can be shielded and
pipes can be insulated to reduce the exterior transmission of heat. The fact that these approaches
are already being successfully employed, combined with the significant lead time provided for
the Tier 2 standard, leads us to conclude that catalysts can be safely integrated into both current
and future motorcycle designs. It is clearly an engineering issue, but one that can be addressed
in any number of ways to protect the user from the additional heat of the device. There is no
indication from any nation worldwide - some of which are far more dependent on motorcycles as
daily transportation than we are in the U.S. - that the use of catalysts on motorcycles presents a
significant risk to the rider.
4.2 - Permeation Evaporative Emission Control from Motorcycles
The following paragraphs summarize the data and rationale supporting the permeation
emission standards for motorcycles, which are listed in the Executive Summary. As discussed in
Chapter 3, we believe there are several technologies that can be used to reduce permeation
emissions from fuel tanks and hoses to levels below the final standards. This section presents
available emissions data on baseline emissions and on emission reductions achieved through the
application of emission control technology. In addition, this section provides a description of the
test procedures for evaporative emission determination.
4.2.1 Baseline Technology and Emissions
4.2.1.1 Fuel Tanks
Motorcycle fuel tanks are either made of metal or plastic. Because fuel does not permeate
through metal, this discussion focuses on plastic fuel tanks. Plastic fuel tanks are generally
blow-molded or injection-molded using high density polyethylene (HDPE). Data on the
permeation rates of fuel through the walls of polyethylene fuel tanks shows that baseline HDPE
fuel tanks have very high permeation rates compared to those used in automotive applications.
We tested four ATV fuel tanks in our lab for permeation. We also tested three portable marine
fuel tanks and two portable gas cans which are of similar construction. This testing was
performed at 29°C (85°F) with gasoline. Prior to testing, the fuel tanks had been stored with fuel
in them for more than a month to stabilize the permeation rate. The permeation rates are
presented in Table 4.2-1. The average for these ten fuel tanks is 1.32 grams per gallon (of tank
volume) per day. Although these fuel tanks were not specifically produced for use in highway
motorcycles, the same materials and processes are used. Therefore, we believe that this data is
representative of highway motorcycle plastic fuel tanks as well.
4-22
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Table 4.2-1
Permeation Rates for Plastic Fuel Tanks Tested by EPA at 29°C
Tank Capacity
[gallons]
1.3
1.3
1.8
2.1
5.3
6.0
6.0
6.0
6.6
6.6
Permeation Loss
[g/gal/day]
1.66
2.90
1.29
2.28
1.00
0.61
1.19
0.78
0.77
0.75
Tank Type
all terrain vehicle
all terrain vehicle
all terrain vehicle
all terrain vehicle
all terrain vehicle
portable marine
portable marine
portable marine
portable fuel container
portable fuel container
The California Air Resources Board (ARB) investigated permeation rates from portable
fuel containers and lawn & garden equipment fuel tanks. Although this testing was not on
motorcycle fuel tanks, the fuel tanks tested are of similar construction. The ARB data is
compiled in several data reports on their web site and is included in our docket.5'6'7'8'9 Table 4.2-
2 presents a summary of this data which was collected using the ARB test procedures described
in Section 4.2.3. Although the test temperature is cycled from 18 - 41°C rather than held at a
constant temperature, the results would likely be similar if the data were collected at the average
temperature of 29°C used in the EPA testing. The average for these 36 fuel tanks is 1.07 grams
per gallon per day.
4-23
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Table 4.2-2
Permeation Rates for Plastic Fuel Containers Tested by ARE Over a 18-41°C Diurnal
Tank Capacity
[gallons]
1.0
1.0
1.0
1.0
1.0
1.0
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.3
1.4
1.7
2.1
2.1
2.1
2.1
2.5
2.5
3.9
3.9
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
6.6
7.5
Permeation Loss
[g/gal/day]
1.63
1.63
1.51
0.80
0.75
0.75
0.50
0.49
0.51
0.52
0.51
0.51
1.51
1.52
1.27
0.67
1.88
1.95
1.91
1.78
1.46
1.09
0.77
0.88
0.89
0.62
0.99
0.55
0.77
0.64
.39
.46
.41
.47
.09
0.35
Tank Type
portable fuel container
portable fuel container
portable fuel container
portable fuel container
portable fuel container
portable fuel container
portable fuel container
portable fuel container
portable fuel container
portable fuel container
portable fuel container
portable fuel container
portable fuel container
portable fuel container
lawn & garden
lawn & garden
portable fuel container
portable fuel container
portable fuel container
portable fuel container
portable fuel container
portable fuel container
lawn & garden
lawn & garden
portable fuel container
portable fuel container
portable fuel container
lawn & garden
lawn & garden
lawn & garden
portable fuel container
portable fuel container
portable fuel container
portable fuel container
portable fuel container
lawn & garden
It is well known that the rate of permeation is a function of temperature. For most
materials, permeability increases by about a factor of 2 for every 10°C increase in temperature.10
Based on data collected on HDPE samples at four temperatures,11'12 we estimate that the
permeation of gasoline through HDPE increases by about 80 percent for every 10°C increase in
temperature. This relationship is presented in Figure 4.2-1, and the numeric data can be found in
Section 4.2.2.3.
4-24
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Figure 4.2-1: Effect of Temperature on HDPE Permeation
Data on HDPE samples
80% increase in permeation per
10 C increase in temperature
0 10 20 30 40 50 60
degrees Celsius
70
Based on the data from 46 fuel tanks in Tables 4.2-1 and 4.2-2, the average permeation
rate at 29°C is 1.12 grams per gallon per day. However, the standard is based on units of grams
per square meter per day at 28°C. Based on measurements of cut away fuel tanks of this size, we
have found that the wall thickness ranges from 4 to 5 mm. Using an average wall thickness of
4.5 mm and a permeation rate for HDPE of 47 g mm/m2/day at 28°C (Figure 4.2-1) we estimate
that the baseline permeation rate is about 10.4 g/m2/day. Data presented later in this chapter (see
Section 4.2.8.3) shows that the permeation rate of fuel through HDPE is fairly insensitive to the
amount of alcohol in the fuel.
4.2.1.2 Fuel Hoses
Fuel hoses produced for use in motorcycles are generally extruded nitrile rubber with a
cover for abrasion resistance. These hoses are generally designed to meet the requirements
under SAE J3013 for an R7 classification. R7 hose has a maximum permeation rate of 550
g/m2/day at 23°C on ASTM Fuel C (50% toluene, 50% iso-octane). On a fuel containing an
alcohol blend, permeation would likely be higher from these fuel hoses. R7 hose is made
primarily of nitrile rubber (NBR). Based on the data presented in Section 4.2.8.3, permeation
through NBR is about 50 percent higher when tested on Fuel CE10 (10% ethanol) compared to
testing on Fuel C.
4-25
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4.2.2 Permeation Reduction Technologies
4.2.2.1 Fuel Tanks
As discussed in Chapter 3, there are several strategies that can be used to reduce
permeation from plastic fuel tanks. This section presents data collected on five permeation
control strategies: sulfonation, fluorination, non-continuous barrier platelets, coextruded
continuous barrier, and alternative materials.
4.2.2.1.1 Sulfonation
We tested sulfonated, HOPE fuel tanks at 29°C (85°F) with gasoline, E10, and Ml 5.
Prior to testing, the fuel tanks had been stored with gasoline in it for 10-20 weeks to stabilize the
permeation rate. Table 4.2-3 presents the emission results. This data demonstrates more than a
90% reduction in permeation for sulfonated fuel tanks.
Table 4.2-3
Permeation Rates for Sulfonated HDPE Fuel Tanks at 29°C
Test Fuel
gasoline
10%ethanol
15%methanol
6 gallon portable marine tank
g/gal/day g/m2/day
0.06
0.13
0.06
0.67
1.48
0.70
4 gallon ATV tank
g/gal/day g/m2/day
0.09
0.10
0.06
0.73
0.78
0.50
The California Air Resources Board (ARE) collected test data on permeation rates from
sulfonated portable fuel containers using California certification fuel.14 The results show that
sulfonation can be used to achieve significant reductions in permeation from plastic fuel
containers. This data was collected using a diurnal cycle from 18-41°C which is roughly
equivalent to steady-state permeation testing at 30°C. The average emission rate for the 32
sulfonated fuel tanks is 0.35 g/gal/day; however, there was a wide range in variation in the
effectiveness of the sulfonation process for these fuel tanks. Some of the data outliers were
actually higher than baseline emissions. This was likely due to leaks in the fuel tank which
would result in large emission increases due to pressure built up with temperature variation over
the diurnal cycle. Removing these five outliers, the average permeation rate is 0.17 g/gal/day
with a minimum of 0.01 g/gal/day and a maximum of 0.64 g/gal/day.
Variation can occur in the effectiveness of this surface treatment if the sulfonation
process is not properly matched to the plastic and additives used in the fuel tank material. For
instance, if the sulfonater does not know what UV inhibitors or plasticizers are used, they cannot
maximize the effectiveness of their process. In this test program, the sulfonater was not aware of
4-26
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the chemical make up of the fuel tanks. This is the likely reason for the variation in the data
even when the obvious outliers are removed. In support of this theory, the permeation rates were
consistently low for tanks provided by two of the four tank manufacturers. For these 11 fuel
tanks, the average permeation rate was 0.07 which represents more than a 90 percent reduction
from baseline. Earlier data collected by ARB showed consistently high emissions from
sulfonated fuel tanks; however, ARB and the treatment manufacturers agree that this was due to
inexperience with treating fuel tanks and that these issues have since been largely resolved.15
For this reason we do not include the earlier data in this analysis. Table 4.2-4 includes all of the
permeation data, including the outliers.
Table 4.2-4
Permeation Rates for Sulfonated Plastic Fuel
Containers Tested by ARB Over a 18-41°C Diurnal
Tank Capacity
[gallons]
2
2
2
2
2
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
5
5
5
5
5
5
5
Permeation Loss
[g/gal/day]
0.05
0.05
0.05
0.06
0.06
0.06
0.08
0.12
0.14
1.23
1.47
1.87
0.02
0.02
0.48
0.54
1.21
0.03
0.08
0.32
0.38
0.42
0.52
0.64
0.80
0.01
0.04
0.05
0.06
0.11
0.13
0.15
4-27
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ARB also investigated the effect of fuel slosh on the durability of sulfonated surfaces.
Two sets of sulfonated fuel tanks were tested for permeation before and after being rocked with
fuel in them 1.2 million times.16'17 The results of this testing show that more than an 85%
reduction in permeation was possible even after the slosh testing was performed. Table 4.2-5
presents these results which were recorded in units of g/m2/day. The baseline level for Set #1 is
an approximation based on testing of similar fuel tanks, while the baseline level for Set #2 is
based on testing of those tanks.
As with earlier tests performed by ARB, the sulfonater was not aware of the materials
used in the fuel tanks sulfonated for the slosh testing. After the tests were performed, the
sulfonater was able to get some information on the chemical make up of the fuel tanks and how
it might affect the sulfonation process. For example, the UV inhibitor used in some of the fuel
tanks is known as HALS. HALS also has the effect of reducing the effectiveness of the
sulfonation process. Two other UV inhibitors, known as carbon black and adsorber UV, are also
used in similar fuel tank applications. These UV inhibitors cost about the same as HALS, but
have the benefit of not interfering with the sulfonation process. The sulfonater claimed that if
HALS were not used in the fuel tanks, a 97% reduction in permeation would have been seen.18
To confirm this, one manufacturer tested a sulfonated tank similar to those in Set #2 except that
carbon black, rather than HALS, was used as the UV inhibitor. This fuel tank showed a
permeation rate of 0.88 g/m2/day at 40°C19 which was less than half of what the CARB testing
showed on their constant temperature test at 40°C.20 A list of resins and additives that are
compatible with the sulfonation process is included in the docket.21'22
Table 4.2-5
Permeation Rates for Sulfonated Fuel Tanks
with Slosh Testing by ARB Over a 18-41°C Diurnal
Technology Configuration
Set #1 Approximate Baseline
Set #1 Sulfonated
Set #1 Sulfonated & Sloshed
Set #2 Average Baseline
Set #2 Sulfonated
Set #2 Sulfonated & Sloshed
Units
g/mVday
g/mVday
% reduction
g/m2/day
% reduction
g/m2/day
g/m2/day
% reduction
g/m2/day
% reduction
Tankl
10.4
0.73
93%
1.04
90%
12.1
1.57
87%
2.09
83%
Tank 2
10.4
0.82
92%
1.17
89%
12.1
1.67
86%
2.16
82%
Tank3
10.4
1.78
83%
2.49
76%
12.1
1.29
89%
1.70
86%
Average
10.4
1.11
89%
1.57
85%
12.1
1.51
88%
1.98
84%
An in-use durability testing program was also completed for sulfonated HOPE fuel tanks
and bottles.23 The fuel tank had a 25 gallon capacity and was removed from a station wagon that
4-28
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had been in use in southern California for five years (35,000 miles). The fuel tank was made of
HDPE with carbon black used as an additive. After five years, the sulfonation level measured on
the surface of the plastic fuel tank did not change. Tests before and after the aging both showed
a 92 percent reduction in gasoline permeation due to the sulfonation barrier compared to the
permeation rate of a new untreated tank. Testing was also done on 1 gallon bottles made of
HDPE with 3% carbon black. These bottles were shown to retain over a 99 percent barrier after
five years. This study also looked at other properties such as yield strength and mechanical
fatigue and saw no significant deterioration.
One study looked at the effect of alcohol in the fuel on permeation rates from sulfonated
fuel tanks.24 In this study, the fuel tanks were tested with both gasoline and various methanol
blends. No significant increase in permeation due to methanol in the fuel was observed.
4.2.2.1.2 Fluorination
We tested one fluorinated, 6 gallon, HDPE, portable marine fuel tank at 29°C (85°F) with
gasoline. Prior to testing, the fuel tank had been stored with gasoline in it for about 20 weeks to
stabilize the permeation rate. We measured a permeation rate of 0.07 g/gallon/day (0.76
g/m2/day) which represents more than a 90 percent reduction from baseline.
The California Air Resources Board (ARB) collected test data on permeation rates from
fluorinated portable fuel containers using California certification fuel.25'26 The results, presented
in Table 4.2-6, show that fluorination can be used to achieve significant reductions in permeation
from plastic fuel containers. This data was collected using a diurnal cycle from 18-41°C which
is roughly equivalent to steady-state permeation testing at 30°C. Four different levels of
fluorination treatment were tested. The average permeation rate for the 87 fluorinated fuel tanks
is 0.21 g/gal/day which represents about a 75 percent reduction from baseline. However, for the
highest level of fluorination, the average permeation rate was 0.04 g/gal/day which represents a
95 percent reduction from baseline. Earlier data collected by ARB showed consistently high
emissions from fluorinated fuel tanks; however, ARB and the treatment manufacturers agree that
this was due to inexperience with treating fuel tanks and that these issues have since been largely
resolved.27 For this reason we do not include the earlier data in this analysis.
Table 4.2-6
Permeation Rates for Fluorinated Plastic Fuel
Containers Tested by ARB Over a 18-41°C Diurnal
Barrier Treatment*
Tank Capacity
[gallons]
Permeation Loss
[g/gal/day] |
4-29
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Level 3
(average = 0.27 g/gal/day)
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
0.04
0.06
0.25
0.12
0.15
0.17
0.09
0.15
0.12
0.18
0.17
0.14
0.18
0.34
0.41
0.41
0.36
0.41
0.23
0.29
0.31
0.24
0.32
0.16
0.19
0.20
0.11
0.20
0.06
0.06
0.07
0.09
0.10
0.11
0.15
0.23
0.31
0.33
0.24
0.33
0.33
0.51
0.47
0.41
0.45
0.45
0.35
0.37
0.28
0.26
0.35
0.35
0.37
0.28
0.35
0.41
0.47
0.43
0.39
0.47
0.55
4-30
-------
Level 4
(average =0.09 g/gal/day)
Level 5
(average =0.07 g/gal/day)
SPAL
(average =0.04 g/gal/day)
1
1
1
5
5
5
1
1
1
1
1
1
1
1
1
2.5
2.5
2.5
2.5
2.5
5
5
5
5
5
5
0.05
0.05
0.06
0.11
0.11
0.15
0.03
0.04
0.05
0.05
0.07
0.08
0.11
0.11
0.12
0.04
0.04
0.05
0.07
0.07
0.05
0.10
0.11
0.04
0.04
0.04
* designations used in ARB report; shown in order of increasing treatment
All of the data on fluorinated fuel tanks presented above were based on fuel tanks
fluorinated by the same company. Available data from another company that fluorinates fuel
tanks shows a 98 percent reduction in gasoline permeation through a HDPE fuel tank due to
fluorination.28
ARB investigated the effect of fuel slosh on the durability of fluorinated surfaces. Two
sets of three fluorinated fuel tanks were tested for permeation before and after being sloshed with
fuel in them 1.2 million times.29'30 The results of this testing show that an 80% reduction in
permeation was achieved on average even after the slosh testing was performed for Set #1.
However, this data also showed a 99 percent reduction for Set #2. This shows the value of
matching the barrier treatment process to the fuel tank material. Table 4.2-7 presents these
results which were recorded in units of g/m2/day. The baseline level for Set #1 is an
approximation based on testing of similar fuel tanks, while the baseline for Set #2 is based on
testing of those tanks.
4-31
-------
Table 4.2-7
Permeation Rates for Fluorinated Fuel Tanks
with Slosh Testing by ARE Over a 18-41°C Diurnal
Technology Configuration
Set #1 Approximate Baseline
Set #1 Fluorinated
Set #1 Fluorinated & Sloshed
Set #2 Approximate Baseline
Set #2 Fluorinated
Set #2 Fluorinated & Sloshed
Units
g/mVday
g/mVday
% reduction
g/m2/day
% reduction
g/m2/day
g/m2/day
% reduction
g/mVday
% reduction
Tankl
10.4
1.17
89%
2.38
77%
12.1
0.03
>99%
0.07
99%
Tank 2
10.4
1.58
85%
2.86
73%
12.1
0.00
>99%
0.11
99%
Tank3
10.4
0.47
96%
1.13
89%
12.1
0.00
>99%
0.05
>99%
Average
10.4
1.07
90%
2.12
80%
12.1
0.01
>99%
0.01
99%
One study looked at the effect of alcohol in the fuel on permeation rates from fluorinated
fuel tanks.31 In this study, the fuel tanks were tested with both gasoline and various methanol
blends. No significant increase in permeation due to methanol in the fuel was observed.
4.2.2.1.3 Barrier Platelets
We tested portable gas cans molded with low permeation non-continuous barrier platelets
29°C (85°F). Three of the tank types were blended with nylon and tested with gasoline. The
other three tanks represented three different blends with ethylene vinyl alcohol (EVOH) to
optimize permeation control on E10 fuel. Prior to testing, the fuel tanks had been stored with
fuel in it for 10-20 weeks to stabilize the permeation rate. Table 4.2-8 presents the emission
results. This data suggests that EVOH-based Selar® is capable of meeting the permeation
standard on E10.
4-32
-------
Table 4.2-8
Permeation Rates for Plastic Fuel Containers
with Barrier Platelets Tested by EPA at 29°C
Selar® Type*
2% nylon
4% nylon
4% nylon
2% EVOH
4% EVOH
6% EVOH
Fuel Type
Gasoline
Gasoline
Gasoline
E10
E10
E10
Tank Capacity
[gallons]
5
5.3
6.6
6.6
6.6
6.6
Permeation Loss
[g/gal/day] [g/m2/day]
0.34
0.10
0.14
0.23
0.14
0.09
4.0
1.1
1.5
2.8
1.7
1.0
*trade name for barrier platelet technology used in test program
The California Air Resources Board (ARE) collected test data on permeation rates from
portable fuel containers molded with low permeation non-continuous barrier platelets using
California certification fuel. The results show that this technology can be used to achieve
significant reductions in permeation from plastic fuel containers. This data was collected using a
diurnal cycle from 18-41°C which is roughly equivalent to steady-state permeation testing at
30°C. Five different percentages of the barrier material were tested. The average permeation
rate for the 67 fuel tanks is 0.24 g/gal/day; however, there was a wide range in variation in the
effectiveness of the barrier platelets for these fuel tanks. Some of the data outliers were actually
higher than baseline emissions. This was likely due to leaks in the fuel tank which would result
in large emission increases due to pressure built up with temperature variation over the diurnal
cycle. Removing these six outliers, the average permeation rate is 0.15 g/gal/day with a
minimum of 0.04 g/gal/day and a maximum of 0.47 g/gal/day. This represents more than an 85
percent reduction from the average baseline. Table 4.2-9 includes all of the ARB test data,
including the outliers.
Table 4.2-9: Permeation Rates for Plastic Fuel Containers
with Barrier Platelets Tested by ARB Over a 18-41°C Diurnal
Percent Selar®*
4%
(average =0.12 g/gal/day)
Tank Capacity
[gallons]
5.00
5.00
5.00
5.00
5.00
6.00
6.00
Permeation Loss
[g/gal/day]
0.08
0.09
0.13
0.16
0.17
0.08
0.10
4-33
-------
6%
(average =0.16 g/gal/day)
8%
(average =0.32 g/gal/day)
2.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
5.00
5.00
5.00
5.00
5.00
5.00
6.00
6.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
5.00
5.00
6.00
6.00
0.06
0.07
0.10
0.10
0.11
0.11
0.28
0.44
0.45
0.47
0.07
0.07
0.07
0.08
0.12
0.17
0.06
0.07
0.14
0.17
0.21
0.21
0.21
0.65
0.85
0.98
1.66
0.04
0.05
0.07
0.09
0.12
0.16
0.44
0.08
0.10
0.05
0.06
4-34
-------
10%
(average =0.28 g/gal/day)
12%
(average =0.21 g/gal/day)
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
2.00
2.00
2.00
2.00
2.00
2.00
2.00
1.00
1.00
1.00
1.00
1.00
1.00
0.15
0.19
0.19
0.21
0.23
0.26
0.79
0.83
0.88
0.06
0.06
0.07
0.08
0.13
0.14
0.23
0.13
0.14
0.20
0.21
0.23
0.35
*trade name for barrier platelet technology used in test program
The fuel containers tested by ARB used a technology known as Selar® which uses nylon
as the barrier resin. Dupont, who manufacturers Selar®, has recently developed a new resin
(Selar KB®) that uses ethylene vinyl alcohol (EVOH) as the barrier resin. EVOH has much lower
permeation than nylon, especially with alcohol fuel blends (see Section 4.2.2.3). Table 4.2-10
presents permeation rates for HDPE and three Selar KB® blends when tested at 60°C on
xylene.32 Xylene is a component of gasoline and gives a rough indication of the permeation rates
on gasoline. This report also shows a reduction of 99% on naptha and 98% on toluene for 8%
Selar KB®.
Table 4.2-10
Xylene Permeation Results for Selar RB® at 60°C
Composition
100% HDPE
10%RB215/HDPE
10%RB300/HDPE
15%RB421/HDPE
Permeation, g mm/nf/day
285
0.4
3.5
0.8
% Reduction
_
99.9%
98.8%
99.7%
4.2.2.1.4 Coextruded barrier
4-35
-------
One study looks at the permeation rates, using ARB test procedures, through multi-layer
fuel tanks.33 The fuel tanks in this study were 6 layer coextruded plastic tanks with EVOH as the
barrier layer (3% of wall thickness). The outer layers were HDPE and two adhesive layers were
needed to bond the EVOH to the polyethylene. The sixth layer was made of recycled
polyethylene. The two test fuels were a 10 percent ethanol blend (CE10) and a 15 percent
methanol blend (CM15). See Table 4.2-11.
Table 4.2-11
Permeation Results for a Coextruded Fuel Tank Over a 18-41°C Diurnal
Composition
100% HDPE (approximate)
3% EVOH, 10% ethanol (CE10)
3% EVOH, 15% methanol (CM15)
Permeation, g/day
6-8
0.2
0.3
% Reduction
97%
96%
4.2.2.1.5 Alternative Materials
Permeation can also be reduced from fuel tanks by constructing them out of a lower
permeation material than HDPE. For instance, a material that would reduce permeation is the
use of metal fuel tanks because gasoline does not permeate through metal. In addition, there are
grades of plastics other than HDPE that could be molded into fuel tanks. One material that has
been considered by manufacturers is nylon; however, although nylon has excellent permeation
resistance on gasoline, it has poor chemical resistance to alcohol-blended fuels. As shown in
Table 4.2-16, nylon would result in about a 98 percent reduction in permeation compared to
HDPE for gasoline. However, for a 10 percent ethanol blend, this reduction would only be about
40-60 percent depending on the grade of nylon. For a 15 percent methanol blend, the permeation
would actually be several times higher through nylon than HDPE.
Other materials, which have excellent permeation even with alcohol-blended fuels are
acetal copolymers and thermoplastic polyesters. These polymers can be used to form fuel tanks
in the blow-molding, rotational-molding, and injection-molding processes. An example of an
acetal copolymer is known as Celcon® which has excellent chemical resistance to fuel and has
been shown to be durable based on exposure to automotive fuels for 5000 hours at high
temperatures.34 As shown in Table 4.2-16, Celcon® would result in more than a 99 percent
reduction in permeation compared to HDPE for gasoline. On a 10 percent ethanol blend, the use
of Celcon® would result in more than a 95 percent reduction in permeation. Two thermoplastic
polyesters, known as Celanex® and Vandar®, are being considered for fuel tank construction
and are being evaluated for permeation resistance by the manufacturer.
4.2.2.2 Fuel Hoses
Thermoplastic fuel lines for automotive applications are generally built to SAE J2260
specifications.35 Category 1 fuel lines under this specification have permeation rates of less than
4-36
-------
25 g/m2/day at 60°C on CM15 fuel. One thermoplastic used in automotive fuel line construction
is polyvinylidene fluoride (PVDF). Based on the data presented in Section 4.2.2.3, a PDVF fuel
line with a typical wall thickness (1 mm) would have a permeation rate of 0.2 g/m2/day at 23°C
on CM15 fuel. However, manufacturers have expressed concern that this fuel line would not be
flexible enough to use in their applications because they require flexible rubber hose to fit tight
radii and to resist vibration. In addition, using plastic fuel line rather than rubber hose would
require the additional cost of changing hose fittings on the vehicles.
Manufacturers expressed concern about basing the standards on testing with 10% ethanol
fuel. If we were to base the standards on gasoline as a test fuel, then SAE J30 R936 fuel hose
would meet the permeation requirement. This hose is designated for fuel injection systems and
has a maximum permeation rate of 15 g/m2/day on ASTM Fuel C. On a fuel containing an
alcohol blend, permeation would likely be much higher from these fuel hoses. SAE J30
specifically notes that "exposure of this hose to gasoline or diesel fuel which contain high levels,
greater than 5% by volume, of oxygenates, i.e., ethanol, methanol, or MTBE, may result in
significantly higher permeation rates than realized with ASTM Fuel C." R9 hose is made with a
thin low permeation barrier sandwiched between layers of rubber. A typical barrier material
used in this construction is FKM. Based on the data presented in Section 4.2.8.3 for FKM, the
permeation rate is 3-5 times higher on Fuel CE10 than Fuel C. Therefore, a typical R9 hose
meeting 15 g/m2/day at 23°C on Fuel C may actually permeate at a level of 40-50 g/m2/day on
fuel with a 10 percent ethanol blend.
SAE J30 also designates Rl 1 and R12 hose which are intended for use as low permeation
fuel feed and return hose. Rl 1 has thee classes known as A, B, and C. Of these, Rl 1-A has the
lowest permeation specification which is a maximum of 25 g/m2/day at 40°C on CM15 fuel.
Because permeation rates are generally higher on CM15 than CE10 and because they are 2-4
times higher at 40°C than at 23°C, hose designed for this specification would likely meet our
permeation requirement. R12 hose has a permeation requirement of 100 g/m2/day at 60°C on
CM15 fuel. This is roughly equivalent in stringency as the Rl 1-A permeation requirement.
There are lower permeation fuel hoses available today that are manufactured for
automotive applications. These hoses are generally used either as vapor hoses or as short
sections of fuel line to provide flexibility and absorb vibration. One example of such a hose37 is
labeled by General Motors as "construction 6" which is a multilayer hose with an inner layer of
THV sandwiched in inner and outer layers of a rubber known as ECO.19 A hose of this
construction would have less than 8 g/m2/day at 40°C when tested on CE10. In look and
flexibility, this hose is not significantly different than the SAE J30 R7 hose generally used in
motorcycle applications.
Permeation data on several low permeation hose designs were provided to EPA by an
automotive fuel hose manufacturer.38 This hose, which is as flexible as R9 hose, was designed
19 THV = tetrafluoroethylene hexafluoropropylene, ECO = epichlorohydrin/ethylene oxide
4-37
-------
for automotive applications and is available today. Table 4.2-12 presents permeation data on
three hose designs that use THV 800 as the barrier layer. The difference in the three designs is
the material used on the inner layer of the hose. This material does not significantly affect
permeation emissions through the hose but can affect leakage at the plug during testing (or
connector in use) and fuel that passes out of the end of the hose which is known as wicking. The
permeation testing was performed using the ARB 18-41°C diurnal cycle using a fuel with a 10
percent ethanol blend (E10).
Table 4.2-12
Hose Permeation Rates with THV 800 Barrier over ARB Cycle (g/m2/day)
Hose Name
CADBAR9610
CADBAR9710
CADBAR9510
Inner Layer
THV
NBR
FKM
Permeation
0.16
0.17
0.16
Wicking
0.00
0.29
0.01
Leaking
0.02
0.01
0.00
Total
0.18
0.47
0.18
The data presented above shows that there is hose available that can easily meet the hose
permeation standard on E10 fuel. Although hose using THV 800 is available, it is produced for
automobiles that will need to meet the tighter evaporative emission requirements in the
upcoming Tier 2 standards. Hose produced in mass quantities today uses THV 500. This hose is
less expensive and could be used to meet the motorcycle permeation requirements. Table 4.2-13
presents information comparing hose using THV 500 with the hose described above using THV
800 as a barrier layer.39 In addition, this data shows that permeation rates more than double
when tested on CE10 versus Fuel C.
Table 4.2-13
Comparison of Hose Permeation Rates with THV 500 and 800 (g/m2/day)*
Hose Inner
Diameter, mm
6
8
10
THV 500
FuelC
0.5
0.5
0.5
Fuel CE10
1.4
1.4
1.5
THV 800
FuelC
0.2
0.3
0.2
Fuel CE10
0.5
0.5
0.5
Calculated using data from Thwing Albert materials testing (may overstate permeation)
We contracted with an independent testing laboratory to test a section of R9 hose and a
section of automotive vent line hose for permeation.40 These hoses had a six mm inner diameter.
The test lab used the SAE J30 test procedures for R9 hose with both Fuel C and Fuel CE10. We
purchased the R9 hose (which was labeled as such) from a local auto parts store. According to
this testing, the R9 hose is well below the SAE specification of 15 g/m2/day. In fact, it meets this
4-38
-------
limit on Fuel CE10 as well. The automotive vent line showed similar results. This data is
presented in Table 4.2-14.
Table 4.2-14
Test Results on Commercially Available Hose Samples (g/m2/day)
Hose Sample
R9
Automotive vent line
FuelC
10.1
10.9
Fuel CE10
12.1
9.0
Another hose construction that can be used to meet the motorcycle hose permeation
standards is known as F200 which uses Teflon® as a barrier layer. Teflon has a permeation rate
of 0.03-0.05 g-mm/m2/day on 15% methanol fuel. F200 hose is used today to meet SAE J30
Rl 1 and R12 requirements for automotive applications. Table 4.2-15 presents data on
permeation rates for F200 constructions.41
Table 4.2-15
F200 Typical Fuel Permeation
Film Thickness [mils]
2
2
2
2
2
1
1
Hose Diameter [in.]
0.375
0.275
0.275
0.470
0.625
0.625
1.5
Fuel
TF-2
TF-2
M25
CE10
CE10
CE10
CE10
g/m2/day @23°C
0.5
1.5
g/m2/day @40°C
0.7
1
4
3
3
4
4.2.2.3 Material Properties
This section presents data on permeation rates for a wide range of materials that can be
used in fuel tanks and hoses. The data also includes effects of temperature and fuel type on
permeation. Because the data was collected from several sources, there is not complete data on
each of the materials tested in terms of temperature and test fuel. Table 4.2-16 gives an
overview of the fuel systems materials included in the data set. Tables 4.2-17 through 4.2-20
present permeation rates using Fuel C, a 10% ethanol blend (CE10), and a 15% methanol blend
(CE15) for the test temperatures of 23, 40, 50, and 60°C.
4-39
-------
Table 4.2-16
Fuel System Materials
Material Name
Composition
Nylon 12
EVOH
Polyacetal
PBT
PVDF
NBR
HNBR
FVMQ
FKM
FEE
PFA
Carilon
HOPE
LDPE
Celcon
THV
E14659
E14944
ETFE
GFLT
FEP
PTFE
FPA
thermoplastic
ethylene vinyl alcohol, thermoplastic
thermoplastic
polybutylene terephthalate, thermoplastic
polyvinylidene fluoride, fluorothermoplastic
nitrile rubber
hydrogenated nitrile rubber
flourosilicone
fluoroelastomer
fluorothermoplastic
fluorothermoplastic
aliphatic poly-ketone thermoplastic
high density polyethylene
low density polyethylene
acetal copolymer
tetra-fluoro-ethylene, hexa-fluoro-propylene, vinyledene fluoride
fluoropolymer film
fluoropolymer film
ethylene-tetrafluoro-ethylene, fluoroplastic
fluoroelastomer
fluorothermoplastic
polytetrafluoroethylene, fluoroplastic
copolymer of tetrafluoroethylene and perfluoroalkoxy monomer
4-40
-------
Table 4.2-17
Fuel System Material Permeation Rates at 23°C by Fuel Type 42'43'44-45'46'47
Material Name
HOPE
Nylon 12, rigid
EVOH
Polyacetal
PBT
PVDF
NBR (33% ACN)
HNBR (44%ACN)
FVMQ
FKM Viton A200 (66%F)
FKM Viton B70 (66%F)
FKM Viton GLT (65%F)
FKM Viton B200 (68%F)
FKM Viton GF (70%F)
FKM Viton GFLT (67%F)
FKM -2 120
FKM - 5830
Teflon FEP 1000L
Teflon PTFE
Teflon PFA1000LP
Tefzel ETFE 1000LZ
Nylon 12 (GM grade)
Nitrile
Silicone Rubber
Fluorosilicone
FKM
FE 5620Q (65.9% fluorine)
FE 5840Q (70.2% fluorine)
PTFE
ETFE
PFA
THV500
FuelC
g-mm/mVday
35
0.2
-
-
-
-
669
230
455
0.80
0.80
2.60
0.70
0.70
1.80
8
1.1
0.03
-
0.18
0.03
6.0
130
-
-
-
-
-
0.05
0.02
0.01
0.03
Fuel CE10
g-mm/m2/day
_
-
-
-
-
-
1028
553
584
7.5
6.7
14
4.1
1.1
6.5
-
-
0.03
-
0.03
0.05
24
635
-
-
16
7
4
-
-
-
-
CM15
g-mm/m2/day
35
64
10
3.1
0.4
0.2
1188
828
635
36
32
60
12
3.0
14
44
8
0.03
0.05
0.13
0.20
83
1150
6500
635
-
-
-
0.08*
0.04*
0.05*
0.3
* tested on CM20.
4-41
-------
Table 4.2-18
Fuel System Material Permeation Rates at 40°C by Fuel Type 4g-49-50
Material Name
Carilon
EVOH - F101
EVOH - XEP380
HOPE
LDPE
Nylon 12 (L2101F)
Nylon 12 (L2140)
Celcon
Fortran PPSSKX-3 82
Celcon Acetal M90
Celanex PBT 3300 (30% GR)
Nylon 6
Dyneon E14659
Dyneon El 4944
ETFE Aflon COP
m-ETFE
ETFE Aflon LM730 AP
FKM-70 16286
GFLT 19797
Nitrite
FKM
FE 5620Q (65.9% fluorine)
FE 5840Q (70.2% fluorine)
THV-310X
THV-500
THV-610X
FuelC
g-mm/mVday
0.06
<0.0001
O.0001
90
420
2.0
1.8
0.38
-
—
-
-
0.25
0.14
0.24
0.27
0.41
11
13
—
—
-
-
-
0.31
-
Fuel CE10
g-mm/m2/day
1.5
0.013
—
69
350
28
44
2.7
0.12
0.35
3
26
-
-
0.67
-
0.79
35
38
1540
86
40
12
-
-
-
CM15
g-mm/m2/day
13
3.5
5.3
71
330
250
-
-
-
—
-
-
2.1
1.7
1.8
1.6
2.6
—
—
3500
120
180
45
5.0
3.0
2.1
Table 4.2-19
Fuel System Material Permeation Rates at 50°C by Fuel Type 51
Material Name
Carilon
HOPE
Nylon 12 (L2140)
Celcon
ETFE Afcon COP
FKM-70 16286
GFLT 19797
FuelC
g-mm/nf/day
0.2
190
4.9
0.76
-
25
28
Fuel CE10
g-mm/mVday
3.6
150
83
5.8
1.7
79
77
CM15
g-mm/m2/day
—
-
-
-
-
-
4-42
-------
Table 4.2-20
Fuel System Material Permeation Rates at 60°C by Fuel Type 52 53 54 5S
Material Name
Carilon
HOPE
Nylon 12 (L2140)
Celcon
ETFE Afcon COP
FKM-70 16286
GFLT 19797
polyeurethane (bladder)
THV-200
THV-310X
THV-510ESD
THV-500
THV-500 G
THV-610X
ETFE 6235 G
THV-800
FEP
FuelC
g-mm/nf/day
0.55
310
9.5
1.7
-
56
60
285
-
-
6.1
-
4.1
2.4
1.1
1.0
0.2
Fuel CE10
g-mm/mVday
7.5
230
140
11
3.8
170
130
460
54
-
18
11
10
5.4
3.0
2.9
0.4
CM15
g-mm/m2/day
_
-
-
-
-
—
—
-
-
38
35
20
22
9.0
6.5
6.0
1.1
4.2.3 Test Procedures
4.2.3.1 Fuel Tanks
Essentially, two options may be used to test fuel tanks for certification. The first option
is to perform all of the durability tests on a fuel tank and then test the permeation rate. The
second option is to test a fuel tank that has been preconditioned and adjust the results using a
deterioration factor. The deterioration factor would need to be based on testing of that tank or a
similar tank unless you can use good engineering judgment to apply the results of previous
durability testing with a different fuel system. Figure 4.2-2 provides flow charts for these two
options.
4.2.3.1.1 Option 1: full test procedure
Under the first option, the fuel tank is tested both before and after a series of durability
tests. We estimate that this test procedure would take about 49 weeks to complete. Prior to the
first test, the fuel tank must be preconditioned to ensure that the hydrocarbon permeation rate has
stabilized. Under this step, the fuel tank must be filled with a 10 percent ethanol blend (E10),
sealed, and soaked for 20 weeks at a temperature of 28 °C ± 5 °C. Once the permeation rate has
stabilized, the fuel tank is drained and refilled with E10, sealed, and tested for a baseline
permeation rate. The baseline permeation rate from the fuel tank is determined by measuring the
weight difference the fuel tank before and after soaking at a temperature of 28 °C ± 2 °C over a
period of at least 2 weeks.
4-43
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To determine a permeation emission deterioration factor, we are specifying three
durability tests: slosh testing, pressure-vacuum cycling, and ultra-violet (UV) light exposure.
The purpose of these deterioration tests is to help ensure that the technology is durable and the
measured emissions are representative of in-use permeation rates. For slosh testing, the fuel tank
is filled to 40 percent capacity with E10 fuel and rocked for 1 million cycles. The pressure-
vacuum testing contains 10,000 cycles from -0.5 to 2.0 psi. The slosh testing is designed to
assess treatment durability as discussed above. These tests are designed to assess surface
microcracking concerns. These two durability tests are based on a draft recommended SAE
practice.56 The third durability test is intended to assess potential impacts of UV sunlight (0.2
|im - 0.4 |im) on the durability of the surface treatment. Because most of the irradiance from
sunlight in this range is seen in wavelengths above 0.3 |im, we recommend testing with an
average wavelength above 0.3 jim such as the UVA lamp described in SAE J2020.57 In the UV
exposure test, the tank must be exposed to a UV light of at least 24 W/m2 (0.40 W-hr/m2 /min)
on the tank surface for 15 hours per day for 30 days. Alternatively, it can be exposed to direct
natural sunlight for an equivalent period of time in exposure hours. To allow for weekends and
rainy days, these exposure days to not need to be continuous.
The order of the durability tests is optional. However, we require that the fuel tank be
soaked to ensure that the permeation rate is stabilized just prior to the final permeation test. If the
slosh test is run last, the length of the slosh test may be considered as part of this soak period.
Where possible, the deterioration tests may be run concurrently. For example, the fuel tank
could be exposed to UV light during the slosh test. In addition, if a durability test can clearly be
shown to not be appropriate for a given product, manufacturers may petition to have this test
waived. For example, a fuel tank that is only used in vehicles where an outer shell prevents the
tank from being exposed to sunlight may not benefit from UV testing.
After the durability testing, once the permeation rate has stabilized, the fuel tank is
drained and refilled with E10, sealed, and tested for a final permeation rate. The final
permeation rate from the fuel tank is determined using the same measurement method as for the
baseline permeation rate. The final permeation rate would be used for the emission rate from
this fuel tank. The difference between the baseline and final permeation rates would be used to
determine a deterioration factor for use on subsequent testing of similar fuel tanks.
4.2.3.1.2 Option 2: base test with DF
Under the second option, the fuel tank is tested for baseline permeation only, then a
deterioration factor (DF) is applied. We estimate that this test procedure would take about 22
weeks to complete. As with Option 1 baseline testing, the fuel tank must be preconditioned to
ensure that the hydrocarbon permeation rate has stabilized. Under this step, the fuel tank must
be filled with a 10 percent ethanol blend (E10), sealed, and soaked for 20 weeks at a temperature
of 28 °C ± 5 °C. Once the permeation rate has stabilized, the fuel tank is drained and refilled
with E10, sealed, and tested for a baseline permeation rate. The baseline permeation rate from
the fuel tank is determined by measuring the weight difference the fuel tank before and after
soaking at a temperature of 28 °C ± 2 °C over a period of at least 2 weeks.
4-44
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The final permeation rate is then determined by applying a DF to the baseline permeation
rate. The DF, in units of g/m2/day, is added to the baseline permeation rate. This DF must be
determined with testing on a fuel tank in the same emission family.
4.2.3.2 Fuel Hoses
The permeation rate from fuel hoses would be measured at a temperature of 23 °C ± 2 °C
over a period of at least 2 weeks. A longer period may be necessary for an accurate
measurement for hose with low permeation rates. Permeation would be measured through the
weight loss technique described in SAE J30.58 The hose must be preconditioned with a fuel soak
to ensure that the permeation rate has stabilized. Based on times to achieve equilibrium for
permeation measurement described in SAE J226059 for automotive fuel lines, and adjusting for
temperature and test fuel type, we estimate a minimum soak time of 4 weeks. The fuel used for
this testing would be a blend of 90 percent gasoline and ten percent ethanol. This fuel is
consistent with the test fuel used for on-highway evaporative emission testing.
4.2.4 Conclusion
We believe that manufacturers will be able to meet the fuel tank permeation requirements
through several design strategies that include sulfonation, fluorination, barrier platelets, and
coextruded barriers. Our cost analysis, presented in Chapter 5, indicates that sulfonation would
likely be the most attractive technology. However, conversations with manufacturers have
revealed interest in each of these low permeation strategies. We believe the data presented
above supports a final standard which requires about an 85% reduction in permeation, compared
baseline FtDPE fuel tanks, throughout the useful life of the motorcycle.
As discussed above, fuel hose is available today that meets the permeation requirements
for motorcycles. Low permeation hose was generally developed for automotive applications;
however, we believe that this fuel hose can be used in motorcycle applications. Even assuming
that new hose clamps would be required, our analyses in Chapters 5 and 6 show that the low
permeation hose would be inexpensive yet effective.
4.2.5 Impacts on Noise, Energy, and Safety
We would not expect evaporative emission controls to have any impact on noise from a
motorcycle because noise from the fuel system is insignificant.
We anticipate that permeation emission standards will have a positive impact on energy.
By capturing or preventing the loss of fuel through permeation, we estimate that the average
lifetime fuel savings will be 9 gallons for motorcycles which translates to a fuel savings of about
12 million gallons in 2030 when most motorcycles used in the U.S. are expected to have
permeation emission control.
4-45
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We believe that permeation emission standards will have no negative impacts on safety,
and may even have some benefits due to the reduction of fuel vapor around a motorcycle.
4-46
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Figure 4.2-2: Flow Chart of Permeation Certification Test Options
1: Full Test Procedure 2: Base Test with DF*
begin with
new tank
begin with
new tank
preconditioning
28±5C
ElOfuel
20 weeks
preconditioning
28±5C
ElOfuel
20 weeks
permeation test run
gasoline or E10 fuel
28±2C
1
1
1
I
Durability Testing
Pressure Cycling I
10,000x-0.5to 2.0psi !
UV Exposure
24 W/m2
Slosh Testing
1 million cycles
ElOfuel
permeation test run
gasoline or E10 fuel
28±2C
adjust baseline
test result with
DF to determine
certification level
* The deterioration factor (DF) is the
difference between the baseline and
final permeation test runs in the full
test procedure.
** This soak time can be shortened
based on the length of "soak" during
durability testing.
use final permeation
test result for
certification
4-47
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Chapter 4 References
1. See comments on the ANPRM from Harley-Davidson and the Motorcycle Industry Council,
available in the public docket for review.
2. "WMTC 2nd step validation test results in Japan," Japan Automobile Research Institute,
Nov. 29, 2001. Docket A-2000-02.
3. Aprilia website, http://www.apriliausa.com/ridezone/ing/models/scarabeo50dt/moto.htm and
http://www.aprilia.com/portale/eng/caferac_articolo.phtml?id=14. Available in the public
docket for review. Docket A-2000-02.
4. Piaggio Engine Division website, http://www.engines.piaggio.com/.
5. www.arb.ca.gov/msprog/spillcon/reg.htm, Updated March 26, 2001, Copy of linked data
reports available in Docket A-2000-01, Document IV-A-09.
6. "Permeation Rates of Small Off Road Engine High-Density Polyethylene Fuel Tanks (April
2001 Testing), June 8, 2001, California Air Resources Board, Docket A-2000-01, Document IV-
A-101.
7. "Permeation Rates of Small Off Road Engine High-Density Polyethylene Fuel Tanks
(February 2001 Testing), June 8, 2001, California Air Resources Board, Docket A-2000-01,
Document IV-A-100.
8. "Permeation Rates of High-Density Polyethylene Fuel Tanks (June 2001), June 12, 2001,
California Air Resources Board, Docket A-2000-01, Document IV-A-99.
9. Email from Jim Watson, California Air Resources Board, to Phil Carlson, U.S. EPA, "Early
Container Data," August 29, 2002, Docket A-2000-01, Document IV-A-103.
10. Lockhart, M., Nulman, M., Rossi, G., "Estimating Real Time Diurnal Permeation from
Constant Temperature Measurements," SAE Paper 2001-01-0730, 2001, Docket A-2000-01,
Document IV-A-21.
11. Hopf, G., Ries, H., Gray, E., "Development of Multilayer Thermoplastic Fuel Lines with
Improved Barrier Properties," SAE Paper 940165, 1994, Docket A-2000-01, Document IV-A-
22.
12. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of
Polymeric Materials," SAE Paper 2001-01-1999, 2001, Docket A-2000-01, Document IV-A-23.
13. SAE Recommended Practice J30, "Fuel and Oil Hoses,"June 1998, Docket A-2000-01,
Document IV-A-92.
4-48
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14. www.arb.ca.gov/msprog/spillcon/reg.htm, Updated March 26, 2001, Copy of linked data
reports available in Docket A-2000-01, Document IV-A-09.
15. Email from Jim Watson, California Air Resources Board, to Phil Carlson, U.S. EPA,
"Early Container Data," August 29, 2002, Docket A-2000-01, Document IV-A-103.
16. "Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine
Fuel Tanks," California Air Resources Board, June 21, 2002, Docket A-2000-01, Document IV-
A-77.
17. "Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine
Fuel Tanks," California Air Resources Board, March 7, 2003, Docket A-2000-02, Document IV-
A-05.
18. Conversation between Mike Samulski, U.S. EPA and Tom Schmoyer, Sulfo Technologies,
June 17, 2002.
19. "Sulfo Data", E-mail from Tom Schmoyer, Sulfotechnologies to Mike Samulski, U.S.
EPA, March 17, 2003, Docket A-2000-02, Document IV-A-08.
20. "ADDENDUM TO: Durability Testing of Barrier Treated High-Density Polyethylene
Small Off-Road Engine Fuel Tanks," California Air Resources Board, March 27, 2003, Docket
A-2000-02, Document IV-A-07.
21. "Resin and Additives - SO3 Compatible," Email from Tom Schmoyer, Sulfo Technologies
to Mike Samulski and Glenn Passavant, U.S. EPA, June 19, 2002, Docket A-2000-01, Document
IV-A-40.
22. Email from Jim Watson, California Air Resources Board, to Mike Samulski, U.S. EPA,
"Attachment to Resin List," August 30, 2002, Docket A-2000-01, Document IV-A-102.
23. Walles, B., Nulford, L., "Five Year Durability Tests of Plastic Gas Tanks and Bottles with
Sulfonation Barrier," Coalition Technologies, LTD, for Society of Plastics Industry, January 15,
1992, Docket A-2000-01, Document IV-A-76.
24. Kathios, D., Ziff, R., "Permeation of Gasoline and Gasoline-Alcohol Fuel Blends Through
High-Density Polyethylene Fuel Tanks with Different Barrier Technologies," SAE Paper
920164, 1992, Docket A-2000-01, Document II-A-60.
25. www.arb.ca.gov/msprog/spillcon/reg.htm, Updated March 26, 2001, Copy of linked data
reports available in Docket A-2000-01, Document IV-A-09.
26. "Permeation Rates of Blitz Fluorinated High Density Polyethylene Portable Fuel
Containers," California Air Resources Board, April 5, 2002, Docket A-2000-01, Document IV-
A-78.
4-49
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27. Email from Jim Watson, California Air Resources Board, to Phil Carlson, U.S. EPA,
"Early Container Data," August 29, 2002, Docket A-2000-01, Document IV-A-103.
28. www.pensteel.co.uk/light/smp/fluorination.htm. A copy of this site is available in Docket
A-2000-01, Document IV-A-86.
29. "Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine
Fuel Tanks," California Air Resources Board, June 21, 2002, Docket A-2000-01, Document IV-
A-77.
30. "Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine
Fuel Tanks," California Air Resources Board, March 7, 2003, Docket A-2000-02, Document IV-
A-05.
31. Kathios, D., Ziff, R., "Permeation of Gasoline and Gasoline-Alcohol Fuel Blends Through
High-Density Polyethylene Fuel Tanks with Different Barrier Technologies," SAE Paper
920164, 1992, Docket A-2000-01, Document II-A-60.
32. "Selar RB Technical Information," Faxed from David Zang, Dupont, to Mike Samulski,
U.S. EPA on May 14, 2002, Docket A-2000-01, Document IV-A-88.
33. Fead, E., Vengadam, R., Rossi, G., Olejnik, A., Thorn, J., "Speciation of Evaporative
Emissions from Plastic Fuel Tanks," SAE Paper 981376, 1998, Docket A-2000-01, Document
IV-A-89.
34. E-mail from Alan Dubin, Ticona, to Mike Samulski, U.S. EPA, "Fuel Permeation Chart
and Aggressive Fuels Brochure," July 31, 2002, Docket A-2000-01, Document IV-A-97.
35. SAE Recommended Practice J2260, "Nonmetallic Fuel System Tubing with One or More
Layers," 1996, Docket A-2000-01, Document IV-A-18.
36. SAE Recommended Practice J30, "Fuel and Oil Hoses," June 1998, Docket A-2000-01,
Document IV-A-92.
37. "Visit to Dyneon on June 12, 2002," Memorandum from Mike Samulski, U.S. EPA to
Docket A-2000-01, June 17, 2002, Docket A-2000-01, Document IV-E-31.
38. "Meeting with Avon on June 27, 2002," Memorandum from Mike Samulski, U.S. EPA to
Docket A-2000-01, August 6, 2002, Docket A-2000-01, Document IV-E-33.
39. "Meeting with Avon on June 27, 2002," Memorandum from Mike Samulski, U.S. EPA to
Docket A-2000-01, August 6, 2002, Docket A-2000-01, Document IV-E-33.
40. Akron Rubber Development Laboratory, "TEST REPORT; PN# 49503," Prepared for the
U.S. EPA, September 3, 2002, Docket A-2000-01, Document IV-A-106.
4-50
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41. Fuller, R., "Unique Low Permeation Elastomeric Laminates for Fuel Hose; F200
Technology used in Automotive Fuel Hose," Hearing Testimony for Dupont-Dow Elastomers on
NPRM, October 7, 2002, Docket A-2000-02, Document IV-D-66.
42. Hopf, G., Ries, H., Gray, E., "Development of Multilayer Thermoplastic Fuel Lines with
Improved Barrier Properties," SAE Paper 940165, 1994, Docket A-2000-01, Document IV-A-
22.
43. Stahl, W., Stevens, R., "Fuel-Alcohol Permeation Rates of Fluoroelastomers,
Fluoroplastics, and Other Fuel Resistant Materials," SAE Paper 920163, 1992, Docket A-2000-
01, Document IV-A-20.
44. "Visit to Dyneon on June 12, 2002," Memorandum from Mike Samulski, U.S. EPA to
Docket A-2000-01, June 17, 2002, Docket A-2000-01, Document IV-E-31.
45. Goldsberry, D., "Fuel Hose Permeation of Fluoropolymers," SAE Paper 930992, 1993,
Docket A-2000-01, Document IV-A-91.
46. Tuckner, P., Baker, J., "Fuel Permeation Testing Using Gravimetric Methods," SAE Paper
20001-01-1096, 2000, Docket A-2000-01, Document IV-A-96.
47. Fuller, R., "Unique Low Permeation Elastomeric Laminates for Fuel Hose; F200
Technology used in Automotive Fuel Hose," Hearing Testimony for Dupont-Dow Elastomers on
NPRM, October 7, 2002, Docket A-2000-02, Document IV-D-66.
48. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of
Polymeric Materials," SAE Paper 2001-01-1999, 2001, Docket A-2000-01, Document IV-A-23.
49. Duchesne, D., Hull, D., Molnar, A., "THV Fluorothermoplastics in Automotive Fuel
Management Systems," SAE Paper 1999-01-0379, 1999, Docket A-2000-01, Document IV-A-
90.
50. "Meeting with Ticona April 24, 2003," Memorandum from Mike Samulski, U.S. EPA to
Docket A-2000-02, May 1, 2003, Docket A-2000-02, Document IV-E-05.
51. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of
Polymeric Materials," SAE Paper 2001-01-1999, 2001, Docket A-2000-01, Document IV-A-23.
52. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of
Polymeric Materials," SAE Paper 2001-01-1999, 2001, Docket A-2000-01, Document IV-A-23.
53. "Visit to Dyneon on June 12, 2002," Memorandum from Mike Samulski, U.S. EPA to
Docket A-2000-01, June 17, 2002, Docket A-2000-01, Document IV-E-31.
54. Facsimile from Bob Hazekamp, Top Dog Systems, to Mike Samulski, U.S. EPA,
"Permeation of Polyurethane versus THV Materials @ 60°C," January 14, 2002, Docket A-
4-51
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2000-01, Document II-B-30.
55. Duchesne, D., Hull, D., Molnar, A., "THV Fluorothermoplastics in Automotive Fuel
Management Systems," SAE Paper 1999-01-0379, 1999, Docket A-2000-01, Document IV-A-
90.
56. Draft SAE Information Report J1769, "Test Protocol for Evaluation of Long Term
Permeation Barrier Durability on Non-Metallic Fuel Tanks," Docket A-2000-01, Document
IV-A-24.
57. SAE Surface Vehicle Standard J2020, "Accelerated Exposure of Automotive Exterior
Materials Using a Fluorescent UV and Condensation Apparatus," Revised February, 2003,
Docket A-2000-02, Document IV-A-10.
58. SAE Recommended Practice J30, "Fuel and Oil Hoses," June 1998, Docket A-2000-01,
Document IV-A-92.
59. SAE Recommended Practice J2260, "Nonmetallic Fuel System Tubing with One or More
Layers," 1996, Docket A-2000-01, Document IV-A-18.
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CHAPTER 5: Costs of Control
This chapter describes our approach to estimating the cost of complying with emission
standards. We start with a general description of the approach to estimating costs, then provide
estimated costs for the technologies we expect manufacturers to use to meet new standards, and
average per vehicle costs. This analysis is largely divided into discussions of the costs for three
areas of the rulemaking: permeation emission control, Class III motorcycle exhaust emission
control, and <50cc motorcycle exhaust emission control. We have not included costs (or
emission reductions) for exhaust standards for Class I/Class II motorcycles at or above 50 cc,
because most already meet the new standards, and therefore, we do not expect significant
additional costs. Class III motorcycles represent about 90 percent of total motorcycle sales. In
addition to per vehicle costs, we also present total costs and an analysis of the estimated
aggregate cost to society.
5.1 - Methodology
We developed the costs for individual technologies using information provided by ICF,
Incorporated and Arthur D. Little, as cited below. The technology characterization and cost
figures reflect our current best judgment based on engineering analysis, information from
manufacturers, and the published literature. The analysis combines cost figures including
markups to the retail level.
Costs of control include variable costs (for incremental hardware costs, assembly costs,
and associated markups) and fixed costs (for tooling, R&D, and certification). Variable costs are
marked up at a rate of 29 percent to account for the manufacturers' overhead and profit.1 For
technologies sold by a supplier to the engine manufacturers, an additional 29 percent markup is
included for the supplier's overhead and profit. All costs are in 2001 dollars. For fixed costs, we
estimated that R&D and facility costs will be incurred three years prior to production on average
and tooling and certification costs will be incurred one year prior to production. These fixed
costs were then increased seven percent for each year prior to the start of production to reflect
the time value on money. Warranty costs are estimated to be 5 percent of hardware costs on
average. Actual warranty costs may be somewhat higher in the first few years of the program
and lower in the long-term, as any warranty problems that arise are addressed by manufacturers.
Fixed costs are assessed for eight years, after which they are fully amortized and are
therefore no longer part of the cost calculation.20 Manufacturers commented that eight years is
the appropriate time frame for amortization of costs for the motorcycle industry.2 Manufacturers
are expected to meet the Tier 1 and Tier 2 standards using the same technologies, but on fewer
20 Except for Tier 1 certification costs, which are assessed over 4 years, because manufacturers may certify
again for the Tier 2 standards.
5-1
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models for Tier 1. This approach is facilitated by the averaging program, where low emissions
can be achieved on some models while others exceed the standards, as long as the standards are
met on average. It is also facilitated by the lead time provided to manufacturers to meet the
standards which allows them to plan out product development. We believe this approach makes
sense because the manufacturers would not invest in an engine line to meet Tier 1 and then
revise the engine line again to meet Tier 2. It is effectively the same approach as one would take
if there were no Tier 1 standards but the Tier 2 standards were phased in earlier to achieve the
same emissions reductions. For these reasons, we believe it is appropriate to use a fixed cost
recovery period of eight years for both the Tier 1 and Tier 2 standards. Manufacturers will likely
invest in engine lines only once during the course of meeting the Tier 1 and Tier 2 standards.
Those investments continue to provide benefits long-term.
The analysis presents an estimate of costs that would apply in the first year of new
emission standards and the corresponding long-term costs. Long-term costs decrease due to two
principal factors. First, fixed costs are assessed over the first eight years of sales, after which
they are fully amortized and are therefore no longer part of the cost calculation. Second,
manufacturers are expected to learn over time to produce the engines with the new technologies
at a lower cost. Because of relatively low sales volumes, manufacturers are less likely to put in
the extra R&D effort for low-cost manufacturing. As production starts, assemblers and
production engineers will then be expected to find significant improvements in fine-tuning the
designs and production processes. Consistent with analyses from other programs, we reduce
estimated variable costs by 20 percent beginning with the third year of production.3 Based on
comments we received that many of the technologies have already been used on at least some
models and therefore manufacturers already have experience with them, we are not including
additional cost reductions due to learning. We believe it is appropriate to apply one 20 percent
reduction here, given that the industries are facing emission regulations for the first time in many
years and it is reasonable to expect learning to occur with the experience of producing and
improving emission-control technologies.
Even though the analysis does not reflect all the possible technology variations and
options that are available to manufacturers, we believe the projections presented here provide a
cost estimate representative of the different approaches manufacturers may ultimately take. We
expect manufacturers in many cases to find and develop approaches to achieve the emission
standards at a lower cost than we describe in this analysis.
We received several comments on our cost analysis and aspects of the analysis have been
changed for the Final RSD based on these comments. A full discussion of the comments and
subsequent changes is provided in Chapter 5 of the Summary and Analysis of Comments
document for this rule.
5-2
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5.2 Costs for Permeation Evaporative Emission Control
5.2.1 - Technologies and Estimated Costs for Permeation Control
As discussed in earlier chapters, we believe that there are several technologies that could
be used to meet the permeation emission standards. Table 5.2-1 presents our best estimates of
the costs of applying various evaporative emission control technologies to motorcycles using the
average fuel tank size and hose length discussed in Chapter 6.
The cost for including low permeation barrier platelets in blow-molded fuel tanks
(generally known as Selar®) is based on increased material costs. No changes should be
necessary to the blow-molding equipment. We used 10 percent EVOH which is about $3 per
pound and 90 percent HDPE which is about $0.55 per pound. This equates to a price increase of
about $0.30 per pound. Depending on the shape of the fuel tank and the wall thickness,
motorcycle fuel tanks weigh about 1-1.3 pounds per gallon of capacity. Another option would
be to mold the entire fuel tank of a low permeation material such as nylon, an acetal copolymer,
or a thermoplastic polyester. These materials have list prices of about $1-2 per pound4;
therefore, the cost of using these alternative materials would be about 3-7 times higher than
presented below for barrier platelets with 10 percent EVOH.
There are now regulations that require permeation controls on over one million
recreational vehicles (ATVs, off-highway motorcycles, snowmobiles) beginning in 2008. Such
requirements are soon now being consdered for lawn and garden equipment in California as well.
One strategy that fuel tank manufacturers may use to meet these existing recreational vehicle
standards and pending California small engine fuel tank standards would be molding multi-layer
fuel tanks with continuous barriers. Industry experts tell us that a rotomolding machine can
produce about 150,000 units per year. These manufacturers would likely purchase new blow-
molding machines with four or five additional injection screws for the barrier layer, two
adhesion layers, an additional HDPE layer, and potentially a regrind layer. A machine that could
blow-mold multi-layer tanks would cost about 2 million dollars. In addition, tooling costs for
each new tank design would be about $50,000. EPA believes that motorcycle vehicle
manufacturers may have the option of purchasing multi-layer fuel tanks from vendors set up to
manufacture multi-layer fuel tanks for these other applications. If they purchase their tanks from
a vendor, which is more likely, the cost of the rotomolding equipment would be spread over total
production rather than just the motorcycle tanks. For the motorcycle analysis, we considered a
fuel tank with a material composition of 3% EVOH at $3/lb, 4% adhesive layer at $l/lb and the
remainder HDPE. We anticipate that motorcycle manufacturers may only use 10,000 to 15,000
plastic fuel tanks per year (10% of sales x (550,000 to 600,000 units) divided by 5 to 6
manufacturers). Assuming total annual production of 150,000 blow-molded tanks per machine,
with 10 different molds, and an amortization of the capital costs over 8 years, we get a cost per
tank of $2.49. This includes a prorated portion of the new blow-molding machine, the
appropriate mold, and additional materials as described above.
5-2
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Surface treatment costs are based on price quotes from companies that specialize in this
fluorination5 and sulfonation.6 The fluorination costs are a function of the geometry of the fuel
tanks because they are based on how many fuel tanks can be fit in a treatment chamber. The
price sheet referenced for our fluorination prices assumes rectangular shaped containers. For
irregular shaped fuel tanks, the costs would be higher because they would have to be fit into
baskets with volumes larger than the volume of the fuel tanks. Therefore, we consider a void
space equal to about 25 percent of the volume of the fuel tank. For sulfonation, the shape of the
fuel tanks is less of an issue because the treatment process is limited only by the spacing on the
production line which is roughly the same for the range of fuel tank sizes used in recreational
vehicles. These prices do not include the cost of transporting the tanks; we estimated that
shipping, handling and overhead costs would be an additional $0.30-$0.50 per fuel tank
depending on tank size and shape.7
Barrier fuel hose incremental costs estimates are based on costs of existing products used
in marine and automotive applications.8A1° We estimate that the cost increment compared to
non-barrier hose used in most motorcycles today is about $0.60 per foot.11 To be conservative,
we consider the cost of upgrading hose clamps to all applications to account for any stiffness in
barrier hose. We estimate a cost increase of about $0.40 for two clamps.12
Table 5.2-1
Permeation Control Technologies and Incremental Costs*
Technology
barrier platelets (10% EVOH)
coextrusion (3% EVOH, 4% adhesive)
sulfonation treatment
shipping/handling
fluorination treatment
shipping/handling
barrier hose fuel hose
hose clamps
5 gallon tank, 1.5 ft. hose
$2.20
$3.14
$1.20
$0.48
$3.25
$0.48
$1.16
$0.52
* includes a 29% markup for overhead and profit
To determine the total costs per motorcycle we use the scenario that all manufacturers
use sulfonation to reduce permeation from their fuel tanks and use barrier fuel hose. For this
analysis, we consider the cost of shipping fuel tanks to an outside vendor for treatment rather
than using the lower cost of in-house sulfonation. For motorcycles with metal fuel tanks, which
we estimate make up about 90 percent of motorcycle sales,13 we assume that no low permeation
technology would be used on the fuel tank. We estimate the total per vehicle costs would be
$3.36 for motorcycles with plastic fuel tanks and $1.68 for motorcycles with metal fuel tanks.
Weighting the costs across motorcycles with metal and plastic fuel tanks, we get an average cost
5-4
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of $1.85 per motorcycle. These costs do not include the fuel savings associated with a reduction
permeation which is discussed below in section 5.2.2.
5.2.2 - Operating Cost Savings for Permeation Control
Permeation evaporative emissions are essentially fuel that is lost to the atmosphere. Over
the lifetime of a typical motorcycle, this can result in a significant loss in fuel. The anticipated
reduction in evaporative emissions due to the tank and hose permeation standards will result in
significant fuel savings. Table 5.2.-2 presents the value of the fuel savings for control of
permeation emissions. These numbers are calculated using an estimated fuel cost of $1.10 per
gallon and fuel density of 6 Ibs/gallon (for lighter hydrocarbons which evaporate first). The
figures in Table 5.2-2 are based on the per motorcycle emissions described in Chapter 6. Note
that the fuel savings are significantly larger than the costs.
Table 5.2-2
Fuel Savings Per Motorcycle Due to Permeation Control
Evaporative HC reduced [tons/life]
Fuel savings [gallons/life]
Undiscounted savings [$/life @$1.10/gal]
Lifetime fuel savings (NPV, 7%)
motorcycle with
a plastic fuel tank
0.036
12.0
$13.19
$9.20
motorcycle with
a metal fuel tank
0.025
8.1
$8.93
$6.23
aggregate
0.026
8.5
$9.35
$6.52
5.2.3 - Compliance Costs for Permeation Emission Control
We expect that in the early years, manufacturers will perform durability and permeation
testing on their fuel tanks for certification. They will be able to carry over this data in future
years and will be able to carry across this data to other fuel tanks made of similar materials and
using the same permeation control strategy regardless of tank size or shape. For the first year we
estimate durability and certification testing to cost about $15,000 per manufacturer on the
assumption that they will use the same materials and permeation control strategy for all of their
fuel tanks to reduce costs. This cost would not apply to manufacturers who only use metal fuel
tanks. Because manufacturers can design-certify by using hose meeting SAE J30 Rl 1-A or R12,
we do not anticipate that testing costs are likely for hose. However, to be conservative, we
consider an additional $1,000 for hose testing, if a manufacturer wishes to demonstrate that
alternative hoses meet the EPA requirements. In addition, we estimate about $10,000 for
engineering and clerical work. As with other fixed costs, we amortized the cost over 8 years of
engine sales to calculate per unit certification costs shown in Table 5.2-3. These compliance
costs are in addition to the exhaust emission compliance costs discussed in section 5.3.2.
5-5
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Table 5.2-3
Estimated Per Unit Certification Costs (with plastic tanks)
units/year
certification costs
Highway Motorcycles
10,000
$0.33
25,000
$0.13
5.3 - Exhaust Emission Control for Class III Highway Motorcycles
Costs estimated for Class III highway motorcycles were developed in cooperation with
ICF Incorporated and Arthur D. Little - Acurex Environmental. The analysis was built upon an
analysis completed by the California Air Resources Board (ARB) when they proposed new
emission standards in October of 1998. The ARB standards, finalized in 1999 and applicable
only to Class III motorcycles (280 cc and greater), will occur in two phases. A Tier 1 standard
of 1.4 g/km HC+NOx will apply to Class III motorcycles for the 2004 through 2007 model
years, and a Tier 2 standard of 0.8 g/km HC+NOx will apply to Class III motorcycles for the
2008 and later model years. These new standards may be met on a corporate-average basis. Our
analysis, while following the general methodology used by the ARB, incorporates some changes
to the methodology as well as some component cost estimates that differ from those used by the
ARB.14
The ARB Staff Report estimated costs for two displacement ranges for Class III
motorcycles: 280 to 699 cc and 700 cc and greater. Currently the smaller range is subject to an
HC standard of 1.0 g/km in California, while the larger displacement range is subject to an HC
standard of 1.4 g/km in California. In order to simplify the calculations, two specific engine
displacements were used to compare with the ARB displacement categories. The ARB Staff
Report indicates that the sales-weighted average for the 280cc to 699cc class was 600cc and the
sales weighted average for the greater than 700cc category was 1200cc. EPA certification data
shows that the national averages for the two displacement categories are 593cc and 1260cc, thus
demonstrating that the ARB analysis is reasonably representative of the national market. These
sales weighted averages were used in developing the cost estimates. The costs include a mark-up
to the retail level.
The analysis for Class III motorcycles combines the fixed costs and individual
technology costs into a total estimated cost package. The composite analysis weights the costs
by the projected percentage of use of the technologies both in the baseline and control scenarios
to project industry-wide average per vehicle costs. The full analysis for Class III is followed by
an analysis of costs for motorcycles under 50cc in Section 5.4.
5.3.1 - Research and Development Costs
Rather than estimate the R&D associated with applying technologies on an individual
technology-by-technology basis, for the Final Rule we have estimated a per manufacturer cost
5-6
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for R&D and then spread those costs over eight years of average production per manufacturer.
We have changed our approach to R&D costs, based in part on comments submitted by MIC,
and our engineering judgment.15 We would not expect manufacturers to develop each emission
control system component separately with multiple staff years devoted to each component.
Manufacturers have experience with the technologies being considered and these technologies
are already being used on some models. We would expect that for each engine line there would
be a systems approach where emissions controls would be developed in combination and then
optimized for each model.
Since the technologies are well known and have been applied to at least some models, we
would expect that an average of 4 staff years per engine line would be more than a sufficient
amount of development time. Manufacturers typically have about 8 engine lines, according to
MIC, which would mean that each manufacturer would spend a total of about 32 engineering
staff years (about $3.8 million, at $120,000 per staff year) to meet the standards. We have also
included $175,000 per line for equipment-related R&D costs. This would cover the costs of
prototype hardware and test vehicles. We believe that these are conservatively high estimates
given the state of technology today, with about 49 percent of sales already equipped with fuel
injection and 46 percent of sales equipped with secondary air systems. Models already equipped
with technologies such as fuel injection or pulse air would require much less work than more
basic models. With regard to catalysts, catalysts systems are highly developed and have already
been used on some motorcycles. We would expect some additional R&D for system
optimization and would also expect R&D efforts to focus on durable system designs that
discourage accidental removal and tampering.
We also expect manufacturers to modify products in an orderly manner over time.
Models that are modified later will benefit from the R&D experience from earlier models. We
believe this approach is likely both because several years of lead-time is provided for the Tier 2
standards and due to the averaging approach for the standards. Averaging allows manufacturers
to balance emissions across their Class III product line. Averaging also allows Tier 1 and Tier 2
to be met using the same technological approaches, but on fewer models for Tier 1. We have
assigned 25 percent of the total R&D to Tier 1 and 75 percent to Tier 2, based on the fact that
more technology changes will be need for Tier 1 than Tier 2, as shown in section 5.3.3, below.
Also, manufacturers are expected to take advantage of averaging and make significant
modifications only once during the course of implementing the Tier 1 and Tier 2 standards.
To determine an average per vehicle cost for R&D, we used estimated annual sales per
manufacturer, an 8 year recovery period, and a rate of return of 7 percent. R&D costs are
projected to be incurred 3 years prior to production, and increased 7 percent for each year prior
to the start of production to reflect the time value on money. MIC estimates 2001 sales of on-
highway motorcycles (including dual sport models) to be about 575,000 units, and they estimate
that about 91 percent of all motorcycles are sold by the six large manufacturers.21 These
21 "Statistical Annual 2002", Motorcycle Industry Council, pp.7-8.
5-7
-------
estimates are consistent with estimated sales projection data for the 2003 model year from our
certification database submitted by manufacturers on a confidential business information basis.
Based on the certification data, we have estimated that Class III annual sales are about 528,000
and we are using this to calculate a per manufacturer sales estimate for large manufacturers. For
our analysis, we have used an updated per manufacturer sales estimate of 80,000 units per
manufacturer (528,000*0.91/6). We did not attempt to include any potential future changes in
unit sales or number of engine lines per manufacturer in the analysis. The results on the analysis
are shown in the table below.
Table 5.3-1
Average Per Vehicle R&D Costs
R&D cost per manufacturer
Annual sales per manufacturer
Years to recover
Per unit R&D costs
$5. 24 million
80,000
8
$13
The above analysis presents an average R&D cost using average numbers of engine lines
and average annual sales estimates. Manufacturers with lower than average sales per engine line
may experience proportionately higher per unit R&D costs while those with higher than average
sales per engine line would experience lower per unit costs. It should be noted that because the
California standards were adopted in 1998 and EPA standards lag the California standards by
two years, much of the R&D would take place before EPA standards have to be met. Therefore,
those costs could be attributed to California's action rather than new EPA standards. We believe
that this argument is strong for costs incurred prior to our proposal. We would not necessarily
assign costs to standards where those costs were incurred prior to the standards being proposed
or the costs were incurred for some other reason or some other benefit ensued. We understand
that according to MIC, it is the stated business practice of their member companies to amortize
future costs over 50 state production for models sold nationwide. This seems reasonable to us
provided the benefits of such R&D are enjoyed by all riders. Now that we have finalized
standards, manufacturers will incorporate the EPA standards into their product plans along with
California standards. We have revised our approach to R&D costs for the final analysis to take
this into account.
5.3.2 - Technologies and Estimated Costs for Class III Exhaust Emission Control
Highway motorcycles are currently powered mostly by carbureted four-stroke engines.
However, even in the absence of new regulation, the penetration of fuel-injected models is
increasing, most likely due to the improvements in reliability, performance, and fuel economy
that fuel injection can offer. EPA's motorcycle certification database for model years 2001
through 2003 indicates that the most prevalent emission controls used to meet the current
standards are engine modifications and mechanically-controlled secondary air injection. To an
5-S
-------
increasingly greater extent manufacturers are now incorporating fuel injection and catalytic
converters on some 2001 through 2003 models. Table 5.3-9 shows the increased use of these
technologies in the 2003 model year relative to the 2001 model year, based on EPA certification
data. For example, catalyst usage increased from 13 to 21 percent, and fuel injection usage
increased from 37 to 48 percent, for the larger Class III motorcycles.
While manufacturers will use various means to meet the future standards, there are four
basic types of existing emission control technologies on which we have based our cost analysis;
engine modifications, electronic fuel injection, pulse air systems, and catalytic converters with
oxygen (O2) sensors. These technologies are being used to varying degrees already and we
would expect manufacturers to increase the use of these approaches to meet future standards. In
general, we would expect emissions control strategies to include more precise fuel control, better
fuel atomization and delivery, reduced engine-out emission levels from engine changes, and
increased use of catalysts.
We have included the costs for increased use of engine modifications to meet the Tier 1
standards. We would expect this approach to be used on essentially all engine models. Engine
modifications include changes such as improved cylinder honing for better oil control, modified
cam profiles to provide increased valve overlap (providing internal exhaust gas recirculation),
and piston modifications to improve ring land height, tumble and squish for reduced
hydrocarbon emissions and better combustion. As shown in Table 5.3-1, we have estimated the
per unit cost of engine modifications to be in the $6 to $8 range.
Table 5.3-1
Engine Modification Costs
Engine Size
600cc
1200cc
Variable Costs
mproved Pistons
Number Required
Hardware costs
Markup @ 29%
Warranty Markup @ 5%
Total Component Costs
$2
2
$4
$1
$0
$5.16
$3
2
$6
$2
$0
$7.74
Fixed Costs
Tooling Costs
Jnits/yr.
fears to recover
Fixed cost/unit
Total Costs ($)
$30,000
10,000
8
$0.54
$5.70
$35,000
10,000
8
$0.63
$8.37
The combinations of low-emission technologies ultimately chosen by motorcycle
manufacturers are dependent on the engine-out emission levels of the vehicle, the effectiveness
of the prior emission control system, and individual manufacturer preferences. We believe
5-9
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manufacturers will increase their use of electronic fuel injection in order to achieve better fuel
delivery control. We project that the use of electronic fuel injection will increase to meet the
Tier-1 and Tier-2 standards, with an accompanying decline in the use of carburetion. Tables 5.3-
2 and 5.4-3 provide estimates of the costs of carburetor systems and electronic fuel injection
systems. To project the incremental costs of going to electronic fuel injection we have
subtracted the costs of the carburetor systems. We have estimated the incremental costs of
electronic fuel control to be in the range of $183 and $191.
Table 5.3-2
Carburetor Costs
Engine Size
Carburetor
Number Required
hardware Cost to Manufacturer
^abor @ $28 per hour
^abor overhead @ 40%
Markup @ 29%
Total Component Costs
600cc
$60
2
$120
$1
$1
$35
$157
1200cc
$60
2
$120
$1
$1
$35
$157
5-10
-------
Table 5.3-3
Electronic Fuel Injection Costs
Engine Size
600cc
1200cc
Variable Costs
njectors (each)
Number Required
3ressure Regulator
ntake Manifold
Throttle Body /Position Sensor
niel Pump
iCM
\ir Intake Temperature Sensor
Vlanifold Air Pressure Sensor
njection Timing Sensor
Wiring/Related Hardware
hardware Cost to Manufacturer
^abor @ $28 per hour
^abor overhead @ 40%
Markup @ 29%
Warranty Markup @ 5%
Total Component Costs
$12
2
$10
$30
$35
$20
$100
$5
$10
$5
$10
$249
$4
$2
$72
$12
$339
$15
2
$10
$30
$35
$20
$100
$5
$10
$5
$10
$255
$4
$2
$74
$13
$348
Fixed Cost
Fooling Costs
Jnits/yr.
^ears to recover
Fixed cost/unit
Total Costs (^
$10,000
10,000
8
$0.18
$340
$12,000
10,000
8
$0.22
$348
We are also projecting the increased use of pulse air systems and catalyst systems for
both the Tier 1 and Tier 2 standards. We have estimated the cost of both a mechanical and an
electronically controlled pulse air system and have projected the use of the electronic system for
motorcycles equipped with electronic fuel control systems. We have added a $10 cost to the
pulse air valve costs shown in Table 5.3-4 to cover the costs of upgraded materials that may be
needed to handle the additional heat created by using secondary air. The total cost for secondary
air systems are $22 for mechanical systems and $27 for electronic systems. Catalyst cost and
oxygen sensor cost estimates are provided in Tables 5.3-5 through 5.3-7. For catalysts, we
expect an increase in use both for Tier 1 and Tier 2. While we do not expect catalysts to be used
on all models, they will likely remain a key tool for emissions control. We are also projecting
the increased use of oxygen sensors and have tied the increase in their use to the use of catalysts.
It seems reasonable to expect manufacturers to use oxygen sensors with catalysts to ensure
stoichiometric engine operation to optimize catalyst and engine performance.
5-11
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Table 5.3-4
Pulse Air Valve Costs
Engine Size
Pulse Air Valve Type
600cc
Mechanical
Electronic
1200cc
Mechanical
Electronic
Variable Costs
-'ulse Air
^abor @ $28 per hour
^abor overhead @ 40%
Vlarkup @ 29%
Warranty Markup @ 5%
Total Component Costs
$8
$1
$0
$3
$0
$12
$12
$1
$0
$4
$1
$17
$8
$1
$0
$3
$0
$12
$12
$1
$0
$4
$1
$17
Fixed Costs
Fooling Costs
Jnits/yr.
^ears to recover
Fixed cost/unit
Total Costs f$1
$8,000
10,000
8
$0.14
$12
$8,000
10,000
8
$0.14
$17
$10,000
10,000
8
$0.18
$12
$10,000
10,000
8
$0.18
$17
Table 5.3-5
Catalyst Costs to Manufacturer
Emission Level
Catalyst Volume (L)
Vletallic Substrate
Washcoat
3recious Metals
:an (18 gauge 304 SS)
TOTAL MAT. COST
LABOR
.abor Overhead @ 40%
supplier Markup @ 29%
Manufacturer Price
0.30
$8.80
$0.54
$5.65
$1.09
$16.08
$11.20
$4.48
$9.21
$40.98
0.60
$11.60
$1.09
$11.30
$1.52
$25.51
$11.20
$4.48
$11.94
$53.13
5-12
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Table 5.3-6
Catalyst Costs
Engine Size
600cc
1200cc
Variable Costs
Dxidation Catalyst
^abor @ $28 per hour
^abor overhead @ 40%
3EM markup @ 29%
Warranty Markup @ 5%
Total Component Costs
$41
$1
$1
$12
$2
$57
$53
$1
$1
$16
$3
$74
Fixed Costs
Tooling Costs
Jnits/yr.
fears to recover
Fixed cost/unit
Total Costs ($)
$10,000
10,000
8
$0.18
$58
$10,000
10,000
8
$0.18
$74
Table 5.3-7
Oxygen Sensor Costs
Engine Size
600cc
1200cc
Variable Costs
Dxygen Sensors
Number Required
Hardware costs
Markup @ 29%
Warranty Markup @ 5%
Total Component Costs
$10
2
$20
$6
$1
$27
$10
2
$20
$6
$1
$27
Fixed Costs
Fooling Costs
Jnits/yr.
fears to recover
Fixed cost/unit
Total Costs ($)
$5,000
10,000
8
$0.09
$27
$5,000
10,000
8
$0.09
$27
5.3.2 - Compliance Costs for Class III Exhaust Emission Control
We estimate highway motorcycle chassis-based certification to cost about $25,000 per
engine line, including $10,000 for engineering and clerical work and $15,000 for durability and
certification testing. Although carry-over of data from Tier 1 to Tier 2 is likely, we have
included certification costs for both Tier 1 and Tier 2. As discussed above in section 5.3.1, each
large manufacturer on average has 8 engine lines, for a total per manufacturer cost for
certification of $200,000 per manufacturer. As with other fixed costs, we amortized the Tier 2
5-13
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certification cost over 8 years of engine sales to calculate per unit certification costs shown in
Table 5.3-8. Tier 1 certification costs are amortized over 4 years. We are not projecting
increased facility costs because manufacturers currently are required to certify and therefore
have adequate test facilities. In addition, because California standards are schedule to be
implemented two years earlier than the EPA standards would be, we would expect actual average
certification costs to be much lower than those estimated here. It is likely that data from the
California program would be used by manufacturers for EPA certification. Also, the analysis
presents an average certification cost using average numbers of engine lines and average annual
sales estimates.
Manufacturers with lower than average annual sales may experience proportionately
higher per unit certification costs. For example, if sales were only 10,000 units per year for Tier
1 (the cut-off point for reduced certification burden), certification-related costs would be about
still be about $0.80 $1.60 since these manufacturers have only one or two engine families which
will incur this cost. If a manufacturer was very small (<3,000 total sales and one engine family)
then unit costs could be kept to about $2.00 by spreading Tier 1 costs over more years. As a
frame of reference, there are about 40 manufacturers. About 80 percent of these qualify for the
reduced certification burden provisions (<10,000 units) and have only one or two families. Most
of these (about 60%) are quite small (<3000 units) And only one family and at this point do not
have to meet Tier 2 .
Table 5.3-8
Estimated Per Unit Costs
Cost per Manufacturer
Years to recover
total units/year
certification costs per unit
Tier 1
$200,000
4
80,000
$0.79
Tier 2
$200,000
8
80,000
$0.45
5.3.3 - Total Costs for Class III Exhaust Emission Control
The analysis below combines the costs estimated above into a total composite or average
cost per vehicle. The composite analysis weights the costs by projecting the percentage of their
use, both in the baseline and control scenario, to project industry-wide average per vehicle costs.
Baseline estimates were made based on the sales weighted current usage rate indicated by our
certification database. The weighting between the two engine displacement ranges is also based
on projected sales information submitted by manufacturers at time of certification. The table
below presents the baseline technology usage for the most recent three model years for which we
have data (2001, 2002, and 2003). The analysis uses the 2003 as the technology baseline, but the
2001 and 2002 penetration of the various technologies is presented to illustrate the progress that
5-14
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already appears to be underway in implementation of technologies such as engine modifications,
fuel injection, and catalyst-based systems. For example, almost half of the larger motorcycles
(where most U.S. sales are) are fuel-injected as of the most recent model year, a trend that we
expect to continue as manufacturers implement designs intended to meet the upcoming
California and European standards, both of which are large motorcycle markets.
For electronic fuel injection, we are attributing half the cost to emissions control and the
other half to improved performance. We believe this is appropriate because the technology
provides substantial benefits in performance and reliability in addition to improved emissions.
Discounting the cost by one-half also helps account for the current trend toward increased use of
electronic fuel injection in the absence of more stringent federal emissions standards (i.e., to
some degree the trend would have continued anyway).
A summary of the estimated near-term and long-term per unit average incremental costs
for highway motorcycles is provided in Tables 5.3-9 and 5.3-10. Long-term costs do not include
fixed costs, which are retired, and include cost reductions due to the learning curve. It is
important to note that these cost estimates are average costs and are based on both the current
state of technology and projections of technology needed to meet standards. Our average cost
estimates consider, for example, that almost half of current production is already equipped with
fuel injection and about 20 percent of production is equipped with catalysts. To estimate average
per unit costs, the costs associated with the increased use of emission control technologies due to
the new standards are spread over all units produced. Costs for individual models would be
higher or lower than the average depending on the changes manufacturers decide to make for
their various models. Models already equipped with fuel injection, pulse air, and a catalyst are
likely to have low incremental costs compared to models that are not currently equipped with
these technologies. The averaging program for the standards provides manufacturers with
flexibility in determining what technologies to use on their various models.
5-15
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Table 5.3-9. Estimated Average Costs For Motorcycles (Tier 1)
600 cc (17%)
1200 cc (83%)
R&D
engine modifications
electronic fuel injection*
mechanical pulse air valve
electronic pulse air valve
catalyst
O2 sensors
Compliance
total
R&D
engine modifications
electronic fuel injection*
mechanical pulse air valve
electronic pulse air valve
catalyst
O2 sensors
Compliance
total
Near Term Composite Incremental Cost
Long Term Composite Incremental Cost
Cost
$13
$6
$92
$22
$27
$58
$27
$1
--
$13
$8
$96
$22
$27
$74
$27
$1
--
--
--
Baseline Usage Rate
2001
0%
60%
20%
53%
0%
10%
0%
0%
--
0%
54%
37%
39%
0%
13%
5%
0%
--
--
--
2002
0%
66%
23%
48%
0%
15%
1%
0%
--
0%
53%
47%
37%
0%
20%
5%
0%
--
--
--
2003
0%
66%
54%
69%
0%
16%
0%
0%
0%
53%
48%
40%
0%
21%
5%
0%
Tierl
Control
Usage Rate
25%
100%
54%
60%
40%
15%
15%
100%
--
25%
100%
50%
50%
50%
25%
25%
100%
--
--
--
Incremental Cost
$3
$2
$0
($2)
$11
$0
$4
$1
$18
$3
$4
$2
$2
$14
$3
$5
$1
$33
$30
$21
: The electronic fuel injection costs have been discounted by 50 % to reflect the portion of the cost attributed to emissions control.
5-16
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Table 5.3-10
Estimated Average Costs For Motorcycles (Tier 2)
600 cc (17%)
1200 cc (83%)
R&D
engine modifications
electronic fuel injection*
mechanical pulse air valve
electronic pulse air valve
catalyst
O2 sensors
Compliance
total
R&D
engine modifications
electronic fuel injection*
mechanical pulse air valve
electronic pulse air valve
catalyst
O2 sensors
Compliance
total
Near Term Composite Incremental Cost
Long Term Composite Incremental Cost
Cost
$13
$6
$92
$22
$27
$58
$27
$0.45
$13
$8
$96
$12
$17
$74
$27
$0.45
--
--
Tier 1 Usage Rate
25%
100%
54%
60%
40%
16%
15%
0%
25%
100%
50%
50%
50%
25%
25%
0%
--
--
Tier 2 Control Usage Rate
100%
100%
60%
40%
60%
50%
50%
100%
100%
100%
60%
40%
60%
50%
50%
100%
--
--
Incremental Cost
$10
$0
$5
($4)
$5
$20
$10
$0.45
$46
$10
$0
$9
($2)
$3
$19
$7
$0.45
$46
$46
$28
* The electronic fuel injection costs have been discounted by 50 % to reflect the portion of the cost attributed to emissions control.
5-17
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5.3.3 - Costs for Small Manufacturers not Subject to Tier 2 Standards
Based on certification records, we identified 18 small Class 3 motorcycle manufacturers
that would not have to meet the Tier 2 standards at this time. These manufacturers would also
benefit from longer lead time and other small business flexibilities. We believe, based on
conversations with manufacturers and an examination of certification data, that these motorcycle
manufacturers will take a much different approach to meeting Tier 1 standards than large
manufacturers. Several Class 3 models are currently certified near or below the Tier 1 standards
(see Chapter 6) with no electronic fuel injection or catalysts. These small manufacturers are
expected to be able to meet the Tier 1 standards through engine modifications and calibration
changes alone. As indicated by the certification data and the emissions levels, some of the
engines have already been modified for emissions control and would likely meet the Tier 1
standard with little or no additional work. Also, it is important to note that several small
motorcycle manufacturers purchase engines from engine manufacturers, such as S&S Cycle,
who conduct the R&D necessary for their engines to meet the standards. This means that the
R&D costs are spread over many more units than a single vehicle manufacturer would sell.
These vehicle manufacturers would be expected to continue to purchase such engines, install
them in their bikes, and then certify them, as they do now.
We identified that 12 of the 18 small motorcycle manufacturers purchase engines from
separate engine manufacturers, such as S&S Cycle. There are 6 small manufacturers that do not
identify a separate engine manufacturer and may make their own engines. Of these six
manufacturers, only one manufacturer has certification HC levels above 0.7 g/km. This indicates
that the small manufacturers will be able to meet the Tier 1 standards with relatively modest
additional changes to their motorcycle engines and costs are likely to be minimal given the lead
time provided to small companies for optimization. Additional lead-time allows manufacturers
to consider emissions standards during the course of improving their products over time. It is
also worth noting that these standards apply in California two model years before they apply in
the rest of the US. Overall, we do not see a basis for expecting the Tier 1 standards to cause
small manufacturers to be significantly adversely affected or to leave the market.
We have conducted a cost analysis for small manufacturers. The results of the analysis
are provided in the table below. Taking the approach used for large manufacturers, described
above, we have estimated one staff year of development per small manufacturer, $43,750 (one-
fourth the large manufacturer cost) for prototype hardware, and $25,000 for certification. These
R&D costs are the same as that projected for the large manufacturers for Tier 1. The R&D
estimate is conservatively high considering the current state of technology and emissions
performance noted above. The estimated tooling and variable costs for engine modifications are
from the draft RSD and have not changed for the final RSD. Fixed costs are projected to be
recovered over 8 years of average sales of 1,000 units per year. This estimate of average annual
sales is based on current sales for small manufacturers. For purposes of estimating R&D costs,
engine manufacturers are considered the primary manufacturer rather than the vehicle
manufacturer. As shown in the table, small manufacturers may experience higher per unit fixed
costs but these are off-set by lower per unit variable costs associated with technology. The
5-18
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overall per unit cost estimate is somewhat higher for small manufacturers for Tier 1 ($50
compared to $30 for large manufacturers) but is less than the estimated large manufacturer costs
for Tier 1 and Tier 2 combined.
Variable costs
R&D
Tooling
Certification
total
Cost per manufacturer
n/a
$163,750
$35,000
$25,000
per unit cost
$8
$31
$6
$5
$50
As described above, the per unit fixed costs estimated in the table are dependent on the
sales per year for the manufacturer. As described above, we used average sales of 1,000 units
per year in our analysis. Manufacturers with lower annual sales may experience proportionally
higher than average per unit fixed costs, while manufacturers with higher than average sales may
experience lower than average fixed costs. For example, a manufacturer with annual sales of
200 units would be estimated to have per unit R&D costs of about $150 (assuming also that the
manufacturer incurred an overall R&D cost of $163,750), whereas a manufacturer with sales of
3,000 would be estimated to have a per unit R&D cost of about $10. The median annual sales
for small manufacturers making their own engines is about 550 units per year. Using this
number in the above analysis of costs would result in an R&D estimate of $57 and an overall
cost of $84 per unit. However, the R&D costs per unit will also depend on how much work will
be involved in meeting the new standards for a particular manufacturer. Several motorcycles
currently certified by small volume manufacturers have emissions certification levels that
indicate they can meet the standards with little additional work, if any. In these cases, the
estimated R&D costs described above would likely be overstated. Also, manufacturers with
relatively high emissions engines may choose to switch engines rather than invest in reducing
emissions from their current product. By providing additional lead-time, we believe we are
giving manufacturers time to seek out the best overall option for their product.
5.4 - Exhaust Emission Control for Highway Motorcycles Under 50cc
We are establishing standards that are in line with standards already established in the
countries and regions that represent the major scooter markets in the world, and which produce
millions of scooters. The US scooter market is tiny in comparison to these markets. In costing
out changes in technology, it is therefore reasonable to project that the research and development
and tooling necessary to meet standards will occur in response to the standards in other
countries, rather than EPA standards. US standards would ensure that clean scooters developed
for major markets also are the ones brought into the US market rather than traditional 2-strokes.
It is also reasonable to expect that the fixed costs of research and development and tooling are
5-19
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spread over the worldwide unit sales for those scooters. Therefore, we would expect those costs
to be very small on a per unit basis.
To establish cost estimates for under 50 cc motorcycles, we first looked at the detailed
cost analysis performed for our Small SI Engine Phase 2 Standards rulemaking, in which the cost
for converting from 2-stroke to 4-stroke was estimated to be about $14 per unit for a small
engine (about 25 cc). 16 The unit basis for this analysis was 90,000 units. EPA's estimate was
supported in comments received from one small SI engine manufacturer that estimated a cost of
about $15 for production less than 1 million units and another that estimated a unit cost of about
$10.
We also searched available literature and found a report prepared for the World Bank that
estimated the difference in cost between a 2-stroke to a 4-stroke 50 cc scooter to be about $60
per unit.17 We believe the difference in the two cost estimates can be accounted for in the
difference in engine displacement and manufacturer mark-up. The $60 estimate appears to be
reasonable for a baseline 4-stroke engine. We are assuming that the cost represents a long-term
stabilized cost rather than the initial cost of production. To the extent the $60 estimate reflects
costs of initial production, the long-term costs may be somewhat lower due to the learning curve
effect. Also, to the extent that some manufacturers currently may have initial costs that are
somewhat higher than $60, we believe that costs reductions are likely to take place prior to 2006,
due to the learning curve effect and a substantial increase in production in response to the world
markets. Costs are likely to be stabilized by 2006.
In addition to the cost of the scooter, manufacturers will also incur costs for certification.
Our estimate of average certification costs is $1.52 per vehicle based on average U.S. sales per
engine family of 4,300 units. We have used the same methodology and costs for certification
used for motorcycles above 50 cc (see section 5.2.2.2 - Compliance Costs) because the
requirements are the same. We have established average sales per vehicle line using U.S. sales
information provided by the Motorcycle Industry Council for motorcycles under 50cc.
The average cost for motorcycles under 50 cc must account for the fact that some
scooters are already equipped with 4-stroke engines and that portion of the market is likely to
remain 4-stroke prior to 2006. For those, the costs for meeting the standards would essentially
be the cost of certification. Based on current our estimated sales split between two and four-
strokes in the less than 50 cc market, we are projecting that 4-strokes will account for about 30
percent of sales prior to 2006.22 Sales weighting the estimated cost for a 2-stroke of $61.52 and
the estimated cost for the 4-stroke of $1.52 (for certification) results in an estimated average cost
for motorcycles under 50cc of about $44.
22 The approximate sales split is based on available information from MIC, discussions with industry, and
the number of 4-stroke 50 cc models currently offered in the US by non MIC manufacturers and importers.
5-20
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Switching from conventional 2-stroke engines to 4-stroke engines results in a fuel
economy savings of at least 30 percent. We have estimated a net present value per vehicle
lifetime savings of about $8, using the factors provided in the table below.18
Table 5.4-1
Estimate Per vehicle Lifetime Fuel Use and Cost
Annual Miles (miles/year)
Average Life (years)
Fuel consumption (miles per gallon)
Fuel cost ($/gal pre-tax)
Discounted Lifetime Fuel Consumption
Discounted Lifetime Fuel Cost
2-stroke
650
6
70
$1.10
43.45 gallons
$47.80
4-stroke
650
6
91
$1.10
36.43 gallons
$40.07
5.5 - Highway Motorcycle Aggregate Costs
The above analyses developed incremental per vehicle cost estimates for highway
motorcycles. Using these per vehicle costs and projections of future annual sales, we have
estimated total aggregate annual costs for the highway motorcycle standards. To estimate future
sales for Class III motorcycles, we started with 2002 sales of 534,000 units and projected out
using a nominal annual growth rate of 1 percent.19 For motorcycles below 50cc, we estimated
2002 sales of about 30,000 units and also applied a compound growth rate of 1 percent.20
Aggregate fuel savings for the motorcycles less than 50cc, has also been estimated based on the
usage and fraction of the fleet converted to 4-stroke engines.21 Fuel savings has also been
estimated for permeation evaporative emissions control. Note this analysis does not include
costs for Class I motorcycles > 50cc or Class II motorcycles as we believe essentially all meet
the Tier 1 standard for 2006. For simplicity, we have included the small volume manufacturer
motorcycle sales and costs for Tier 2 in this calculation, even though these manufacturers are not
now covered by Tier 2 requirements (small volume manufacturers are only about 1.3 percent of
Class III sales). Table 5.5-1 presents the results of this analysis. As shown in the table, annual
aggregate costs increase from about $18 million in 2006 to about $42 million in 2010 when the
program is fully phased in. Costs are projected to then decline somewhat to about $33 million as
fixed costs are retired, after which costs are projected to gradually increase over time due to
growth in vehicle sales.
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Table 5.5-1
Annual Aggregate Costs for Highway Motorcycles
Calendar
Year
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
Total Cost,
Excluding Fuel Savings
flVTillirms Srt
17.9
18.1
16.4
16.5
41.7
42.1
38.4
38.7
37.3
37.6
37.9
38.3
33.3
33.7
34.0
34.4
34.7
35.1
35.5
35.8
36.2
36.6
37.0
37.4
37.7
Fuel Savings
flVTillirms Srt
0.02
0.07
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.1
4.6
5.2
5.7
6.3
6.8
7.2
7.5
7.8
8.1
8.3
8.6
8.8
9.0
9.3
9.5
5-22
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Chapter 5 References
1. "Update of EPA's Motor Vehicle Emission Control Equipment Retail Price Equivalent (RPE)
Calculation Formula," Jack Faucett Associates, Report No. JACKFAU-85-322-3, September
1985, Docket A-2000-01, Document II-A-54.
2. Comments from Motorcycle Industry Council (MIC), January 7, 2003, Docket A-2000-02,
Docket item #
3. For further information on learning curves, see Chapter 5 of the Economic Impact, from
Regulatory Impact Analysis - Control of Air Pollution from New Motor Vehicles Emissions
Standards and Gasoline Sulfur Control Requirements, EPA420-R-99-023, December 1999. A
copy of this document is included in Air Docket A-2000-01, at Document No. II-A-83. The
interested reader should also refer to previous final rules for Tier 2 highway vehicles (65 FR
6698, February 10, 2000), marine diesel engines (64 FR 73300, December 29, 1999), nonroad
diesel engines (63 FR 56968, October 23, 1998), and highway diesel engines (62 FR 54694,
October 21, 1997).
4. "Plastic News," Resin Pricing for May 5, 2003, www.plasticnews.com, Docket A-2000-02.
5. "Information on Costs and Effectiveness of Fluorination Received from Fluoroseal,"
Memorandum from Mike Samulski to Docket A-2000-1, March 27, 2002, Docket A-2000-01,
Document IV-B-03.
6. "Visit to Sulfo Technologies LLC on April 18, 2002," Memorandum from Mike Samulski,
U.S. EPA to Docket A-2000-01, April 22, 2002, Document IV-B-07.
7. "Shipping Costs," Memorandum from Glenn Passavant, U.S. EPA to Docket A-2000-01,
March 27, 2002, Document IV-B-01.
8. Trident Marine Hose, "Retail Price List 2001," Docket A-2000-01, Document No. IV-A-15.
9. Denbow, R., Browning, L., Coleman, D., "Report Submitted for WA 2-9, Evaluation of the
Costs and Capabilities of Vehicle Evaporative Emission Control Technologies," ICF, ARCADIS
Geraghty & Miller, March 22, 1999, Docket A-2000-01, Document IV-B-05.
10. "Meeting with Avon on June 27, 2002," Memorandum from Mike Samulski, U.S. EPA to
Docket A-2000-01, August 6, 2002, Docket A-2000-01, Document IV-E-33.
11. Denbow, R., Browning, L., Coleman, D., "Report Submitted for WA 2-9, Evaluation of the
Costs and Capabilities of Vehicle Evaporative Emission Control Technologies," ICF, ARCADIS
Geraghty & Miller, March 22, 1999, Docket A-2000-01, Document No. IV-B-05.
12. Denbow, R., Browning, L., Coleman, D., "Report Submitted for WA 2-9, Evaluation of the
Costs and Capabilities of Vehicle Evaporative Emission Control Technologies," ICF, ARCADIS
5-23
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Geraghty & Miller, March 22, 1999, Docket A-2000-01, Document No. IV-B-05.
13. "Use of Plastic Fuel Tanks in Highway Motorcycles," Memorandum from Roberts French
to Docket A-2000-02, June 5, 2003, Docket A-2000-02.
14. Arthur D. Little-Acurex Environmental. Memorandum from Lou Browning to Chris
Lieske: On-Road Motorcycle Draft Final Cost Comparisons, June 22, 2001, Docket A-2000-01,
Document II-G-145.
15. "Meeting with Motorcycle Industry Council," Memorandum from Roberts French, U.S.
EPA to Docket A-2000-02, July 14, 2003. See also Chapter 5 of Summary and Analysis of
Comments.
16. EPA Final Regulatory Impact Analysis, Phase 2 Final Rule: New Nonroad Handheld
Spark-Ignition Engines At or Below 19 Kilowatts, March 2000, EPA420-R-00-004
17. "Air Pollution from Motor Vehicles, Standards and Technology for Controlling Emissions",
Asif Faiz, Christopher S. Weaver, Michael Walsh, The World Bank, Washington DC,
November 1996, Docket A-2000-01, Document IV-A-29.
18. "Spreadsheet for Modeling the Emissions Inventories from On-Highway Motorcycles
<50cc under the Proposed Rule", Memorandum from Phil Carlson to Docket A-2000-01, April
12, 2002, Docket A-2000-01, Document IV-B-09.
19. 2002 Sales by engine size provided by Motorcycle Industry Council, Docket A-2000-01,
Document IV-A-21.
20. The Motorcycle Industry Council provided 2001 sales estimates for member companies of
17,166 for scooters below 50 cc. We were unable to find statistics for non-MIC companies
which make up a sizable share of the market. To attempt to account for sales for these non-MIC
companies we asked several companies for their estimate of the overall 50cc scooter market and
have based our final sales estimates on the information they provided.
21. "Spreadsheet for Modeling the Emissions Inventories from On-Highway Motorcycles
<50cc under the Proposed Rule", Memorandum from Phil Carlson to Docket A-2000-01, April
12, 2002, Docket A-2000-01, Document IV-B-09.
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CHAPTER 6: Emissions Inventory
6.1 - General Methodology
The following chapter presents our analysis of the emission impact of exhaust and
permeation standards for highway motorcycles. We first present an overview of the
methodology used to generate the emissions inventories, followed by a discussion of the specific
information used in generating the permeation and exhaust emission inventories. Emissions
from a typical motorcycle are also presented. This analysis does not monetize the emission
reductions or health benefits.
6.1.1 - Highway Motorcycle Exhaust Emissions
The modeling of highway motorcycle >50cc emissions is typically done with our
MOBILE model. However, the inputs for motorcycles >50cc used in the MOBILE model have
not been updated in many years. In developing the proposal for highway motorcycles, we came
across new information on current emission levels, revised scrappage estimates, and revised
mileage accumulation rates for such vehicles. Because of this new information, we developed a
spreadsheet for modeling the effect of the standards for highway motorcycles >50cc that
incorporates this new information. In addition, a similar spreadsheet was developed for modeling
the effect of the standards for highway motorcycles <50cc (currently unregulated). A copy of
both spreadsheets developed for modeling the effect of the standards on highway motorcycles
has been placed in the docket for this rulemaking.1'2
6.1.2 - Highway Motorcycle Evaporative Emissions
Evaporative emissions refer to hydrocarbons released into the atmosphere when gasoline,
or other volatile fuels, evaporate from a vehicle. For this analysis, we model three types of
evaporative emissions:
- permeation: These emissions are due to fuel that works its way through the material
used in the fuel system. Permeation is most common through plastic fuel tanks and
rubber hoses.
- diurnal: These emissions are due to temperature changes throughout the day. As the
day gets warmer, the fuel heats up and begins to evaporate.
- refueling: These emissions are the vapors displaced from the fuel tank when fuel is
dispensed into the tank.
Because evaporative emissions are dependent on ambient temperatures and fuel
properties which vary through the nation and through the year, we divided the nation into six
6-1
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regions and modeled each region individually for each day of the year. The daily temperatures
by region are based on a report which summarizes a survey of dispensed fuel and ambient
temperatures in the United States.3 Because of this temperature effect, the evaporative emission
calculations were performed using spreadsheet models rather than by using MOBILE. Copies of
the spreadsheets developed for modeling marine evaporative emissions are included in the
docket.4 The calculations in these spreadsheets are described below.
6.1.2.1 - Permeation Emissions
For our permeation emissions modeling, we used the emission data presented in Chapter
4 to determine the mass of hydrocarbons permeated through plastic fuel tanks and rubber fuel
hoses on motorcycles. There is no permeation through metal fuel tanks. Because permeation is
very sensitive to pressure, we used Arrhenius' relationship5 to adjust the emission factors by
temperature:
P(T) = P0 x EXP(-a / T) (Eq. 6-1)
where:
T = absolute temperature
P(T) = permeation rate at T
P0 and a are constants
We determined the constants by relating the equation to the known properties of
materials used in fuel tanks and hoses (presented in Chapter 4). Based on data presented in
Chapter 4, permeation increases by about 80 percent with each 10°C increase in temperature for
high density polyethylene (HDPE). We do not have similar data for nitrile rubber used in hoses;
however, in general, permeation doubles with every 10°C increase in temperature.6 In addition,
we have data on the effect of temperature on permeation through FKM which is a
fluoroelastomer commonly used as a permeation barrier in hoses. This data, presented in
Chapter 4, supports using the general relationship, in our modeling, of doubling permeation
through hoses for every 10°C increase in temperature.
6.1.2.2 - Diurnal Emissions
For diurnal emission estimates, we used the Wade equations7'8'9 to calculate grams of
hydrocarbons emitted per day per volume of fuel tank capacity. The Wade equations are well
established and are used in both the MOBILE and draft NONROAD models with an adjustment
based on empirical data. These calculations are a function of vapor space, fuel vapor pressure,
and daily temperature variation and are as follows:
Vapor space (ft3) = ((1.15 - tank fill) x tank size) / 7.841 (Eq. 6-2)
where:
6-2
-------
tank fill = fuel in tank/fuel tank capacity™
tank size = fuel tank capacity in gallons
T! (°F) = (Tmax - T.J x 0.922 + Tmin (Eq. 6-3)
where:
Tmax = maximum diurnal temperature (°F) of the fuel
Tmin = minimum diurnal temperature (°F) of the fuel
V100 (psi) = 1.0223 x RVP + [(0.0357 X RVP)/(1-0.0368 x RVP)] (Eq. 6-4)
where:
V100 = true vapor pressure at 100°F
RVP = Reid Vapor Pressure of the fuel
E100 (%) = 66.401-12.718 x V100 +1.3067 x (V100)2 - 0.077934 x (V100)3
+ 0.0018407 x (V100)4 (Eq. 6-5)
D^ (%) = E100 + [(262 / (0.1667 * E100 + 560) - 0.0113] x (100 - T^) (Eq. 6-6a)
Dmax (%) = E100 + [(262 / (0.1667 * E100 + 560) - 0.113] x (100 - T\) (Eq. 6-6b)
where:
Dmin/max= distillation percent at the max/min temperatures in the fuel tank
E100 = percent of fuel evaporated at 100°F from equation 6-5
P! (psi) = 14.697 - 0.53089 x D^ + 0.0077215 x D^2 - 0.000055631 x D^3
+ 0.0000001769 x D^4 (Eq. 6-7a)
PF (psi) = 14.697 - 0.53089 x Dmax + 0.0077215 x Dmax2 - 0.000055631 x Dmax3
+ 0.0000001769 x Dmax4 (Eq. 6-7b)
Density (Ib/gal) = 6.386 - 0.0186 x RVP (Eq. 6-8)
MW (Mb mole) = (73.23 - 1.274 x RVP) + [0.5 x( T^ + Tj) - 60] x 0.059 (Eq. 6-9)
Diurnal emissions (grams) = vapor space x 454 x density x [520 / (690 - 4 x MW)]
x 0.5 x [Pj / (14.7 - PT) + PF / (14.7 - PF)]
x [(14.7 - Pj) / (T^ + 460) - (14.7 - PF) / (Tx + 460)] (Eq. 6-10)
where:
We use 50% fill for our calculations.
6-3
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MW = molecular weight of hydrocarbons from equation 6-9
PI/F = initial and final pressures from equation 6-7
We use these same equations in our modeling of evaporative emissions from on-highway
vehicles. EPA uses a correction factor of 0.78 to the Wade model for automotive diurnal
emission modeling based on empirical data collected on automobiles.10 This correction factor
seems reasonable based on data we collected on exposed fuel tanks vented through a hose. This
test data is presented in Table 6.1.2-1 compared to calculated theoretical results.
Although the testing was performed on fuel tanks that are larger than motorcycle fuel
tanks, we believe that it is appropriate to use these correction factors. We do not believe that
fuel tank size will significantly affect the results because the diurnal emissions are a function of
vapor space and temperature. The test measurements were normalized using fuel capacity,
thereby removing the effect of vapor space on the recorded results. If the thermal inertia of the
fuel in the larger tanks were to affect the temperature range seen by the fuel during testing, it
would have the effect of reducing the measured results. Therefore, using these correction factors
for motorcycles would, if anything, underestimate the diurnal emission inventory.
Table 6.1.2-1
Baseline Diurnal Evaporative Emission Results (varied temperature)
Diurnal
Temperature
72-96F
72-96F
74-91F
71-86F
77-88F
Tank Size
[gallons]
17
30
30
30
30
Evaporative HC
[g/gallon/day]*
1.4
1.5
1.1
0.9
0.7
Wade HC
[g/gallon/day]*
2.3
2.3
1.3
1.0
0.9
ratio of measured grams
to Wade estimate
0.60
0.65
0.85
0.86
0.75
* based on total capacity of the fuel tank in gallons
6.1.2.3 - Refueling Emissions
We used the MOBILE model to estimate the amount of fuel consumed by motorcycles.
To estimate refueling emissions, we used an empirical equation to calculate grams of vapor
displaced during refueling events. This equation was developed based on testing of 22 highway
vehicles under various refueling scenarios and in the emission benefits calculations for our
onboard refueling vapor recovery rulemaking for cars and trucks.11 These calculations are a
function of fuel vapor pressure, ambient temperature, and dispensed fuel temperature. The
refueling vapor generation equation is as follows:
Refueling vapor (g/gal) = EXP(-1.2798 - 0.0049 x (Td - Tt) + 0.0203 x Td
6-4
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+ 0.1315xRVP) (Eq. 6-10)
where:
Td = dispensed fuel temperature (°F)
Tt = fuel temperature in tank (°F)
RVP = Reid Vapor Pressure of the fuel (psi)
For the fuel temperature in the tank, we used average ambient temperature for a surrogate
for fuel temperature because we did not have data relating fuel tank temperature during refueling
events to ambient temperature. We believe that this is a reasonable assumption because exhaust
systems are not generally near the fuel tanks in motorcycles; therefore, the fuel temperature is
not likely heated significantly during operation. Title 40, Section 80.27 of the Code of Federal
Regulations specifies the maximum allowable fuel vapor pressure allowed for each state in the
U.S. for each month of the year. We used these limits as an estimate of fuel vapor pressure in
our calculations.
6.2 - Effect of Emission Controls by Engine/Vehicle Type
The remainder of this chapter discusses the inventory results for highway motorcycles
exhaust and evaporative emissions. Also, this section provides more details inputs and
methodologies used for the motorcycle inventory calculations.
6.2.1 - Exhaust Emissions
As noted above, we projected the annual tons of exhaust HC and NOx, from on-highway
motorcycles using one spreadsheet for on-highway motorcycles <50cc and a second spreadsheet
for on-highway motorcycles >50cc. Both of the spreadsheets are based on the MOBILE model
and incorporate new information on current emission levels, updated scrappage rates, and
updated mileage accumulation rates for on-highway motorcycles. This section describes inputs
to the calculations that are specific to on-highway motorcycles then presents the resulting
emissions inventories. These results are for the nation as a whole and include baseline and
control inventory projections. It should be noted that the analysis presented below for
motorcycles >50cc focuses on Class III motorcycles only. Consistent with the cost analysis
presented in Chapter 5, we have not assumed any emission reductions for Class I/Class II
motorcycles at or above 50 cc, because most already meet the new standards. (Class I and II
motorcycles currently represent only about five percent of sales of motorcycles >50cc.)
6.2.1.1 - Inputs for the Inventory Calculations
Several usage inputs are specific to the calculations for on-highway motorcycles exhaust
emissions. These inputs are annual use, average operating life, and population. Based on data
received from an industry trade group, we developed annual usage rates (i.e., mileage
accumulation rates), and average operating life estimates for on-highway motorcycles.12'13 The
average operating lifetimes were estimated to be 6.0 years for on-highway motorcycles <50cc
and 12.5 years for on-highway motorcycles >50cc. Due to limited information on motorcycles
6-5
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<50cc, an average mileage accumulation rate of 650 miles/year was used for each year of
operation (based on survey information provided by the industry trade group). The annual
mileage accumulation rates for motorcycles >50cc used in the analysis (based on the results of a
motorcycle user survey provided by the industry trade group) are contained in Table 6.2.1-1.
The average mileage accumulation rate over the lifetime of a typical motorcycle >50cc is
estimated to be 2,907 miles/year.
Table 6.2.1-1
Mileage Accumulation Rates for On-highway Motorcycles >50cc
Age (yrs)
1
2
3
4
5
6
7
8
9
10
11+
Annual Mileage
3,308
3,320
3,751
3,330
1,920
2,884
3,021
3,475
4,131
3,977
2,032
Source: Motorcycle Industry Council User Survey
In order to generate emission inventories for on-highway motorcycles, the spreadsheets
developed for this analysis calculate a fleet-average emission factor (in grams per mile) and
multiply the result by the total vehicle miles traveled (VMT) estimate for the appropriate portion
of the highway motorcycle fleet (i.e., <50cc and >50cc) in a given year. The on-highway
motorcycle fleet VMT estimates used for this analysis are summarized in Table 6.2.1-2. The on-
highway motorcycle >50cc fleet VMT estimates were developed for our recent rulemaking for
model year 2007 and later heavy-duty engines and vehicles standards.14 The 2001 VMT estimate
for on-highway motorcycles <50cc was calculated based on the estimated 2001 population of on-
highway motorcycles <50cc multiplied by the average mileage accumulation rate of 650
miles/year. VMT estimates for future year on-highway motorcycles <50cc were grown at the
same rate as on-highway motorcycles >50cc.
6-6
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Table 6.2.1-2
On-Highway Motorcycle Fleet VMT in Specific Calendar Year (Millions of Miles)
Category
On-Highway
Motorcycles
<50cc
On-Highway
Motorcycles
>50cc
2000
75
11,469
2005
88
13,466
2010
102
15,562
2020
130
19,885
2030
158
24,208
The current fleet of on-highway motorcycles <50cc is powered mostly by two-stroke
engines. Beginning in 2002, a number of new vehicles (estimated to be about 30% of the new
sales) are being powered by four-stroke engines. The baseline (i.e., pre-control) emission factors
for two-strokes used in the spreadsheet analysis for on-highway motorcycles <50cc are based
primarily on the results of testing uncontrolled two-stroke mopeds.15 (Because the emission
factors for baseline two-stroke mopeds are the average of over one hundred vehicles of different
ages, the emission levels are used to represent a fleet average level; no deterioration is added to
the average levels cited in the report.) The baseline four-strokes now being introduced are
assumed to have emission factors at the levels described below for Tier 1 vehicles. (As noted in
Chapter 4, the Tier 1 standards are expected to result in the conversion of two-strokes to four-
strokes. We believe that existing four-stroke designs would meet the Tier 1 standards.) The HC
and CO emission factors for Tier 1 on-highway motorcycles <50cc are based on the HC and CO
standards factoring in the effect of deterioration under certification conditions. The estimated
emission factors also assume that manufacturers will include a compliance margin (estimated to
be 20 percent) when certifying. (For NOx, where we do not have a mandatory standard, we have
assumed that four-strokes emit at the level of uncontrolled small 4-stroke motorcycles taken
from a separate report.16) The deterioration factors for Tier 1 on-highway motorcycles <50cc are
based on the data for the smallest motorcycles used in the MOBILE model. Table 6.2.1 .-3
contains the emission factors and deterioration rates for on-highway motorcycles <50cc used in
the spreadsheet analysis.
6-7
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Table 6.2.1-3
Zero-Mile Level Emission Factors and Deterioration Rates
for On-Highway Motorcycles <50cc
Control Category
Baseline (Pre-control)
- two- strokes
Baseline (Pre-control)
- four-strokes
Tier 1
THC
ZML,
g/mi
9.66
1.27
1.27
DR,
g/mi/lOkmi
0
1.31
1.31
CO
ZML,
g/mi
16.1
15.5
15.5
DR,
g/mi/ 10k mi
0
2.53
2.53
NOx
ZML,
g/mi
0.10
0.32
0.32
DR,
g/mi/ 10k mi
0
0
0
The baseline (i.e., Tier 0) emission factors used in the spreadsheet analysis for on-
highway motorcycles >50cc are based on the average certification levels of current (i.e., model
year 2003) on-highway motorcycles >50cc. The baseline deterioration rates were taken from the
MOBILES model. In order to estimate the control HC+NOx zero-mile level emission level for
Tier 1 on-highway motorcycles, we took the Tier 1 HC+NOx standard of 2.26 grams per mile
(g/mi) and multiplied it by 0.67, which is the ratio of the baseline zero-mile HC level based on
certification data compared to the baseline (i.e., Tier 0) HC standard. (We do not currently have
a NOx standard for on-highway motorcycles >50cc.) Because we are including an HC+NOx
standard for Class III on-highway motorcycles, we have assumed that the Tier 1 HC/NOx split
will remain the same as the baseline HC/NOx split. Because we do not currently regulate NOx
for on-highway motorcycles >50cc, we based the HC/NOx split on current on-highway
motorcycle >50cc certification data from the California Air Resources Board which does have a
NOx standard. For the Tier 1 deterioration rates, we applied a factor of 0.67, which is the ratio
of the pre-control HC zero-mile level compared to the estimate Tier 1 HC zero-mile level. For
Tier 1 on-highway motorcycles >50cc, the NOx deterioration rate was assumed to be zero (i.e.,
no deterioration in NOx emissions). (The MOBILE model currently estimates no deterioration
in NOx emissions for on-highway motorcycles.) To estimate the emission factors and
deterioration rates for Tier 2 on-highway motorcycles >50cc, the Tier 1 emission factors and
deterioration rates were multiplied by a factor of 0.57, which is the ratio of the Tier 1 to Tier 2
HC+NOx standards. Table 6.2.1 -4 presents the emission factors and deterioration rates used in
the spreadsheet analysis for on-highway motorcycles >50cc. (Because we are not changing the
CO standard for on-highway motorcycles >50cc, the CO emission factors and deterioration rates
are the same for baseline and control cases.)
6-8
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Table 6.2.1-4
Zero-Mile Level Emission Factors and Deterioration Rates
for On-Highway Motorcycles >50cc
Control Category
Baseline (Tier 0)
Tier 1
Tier 2
THC
ZML,
g/mi
1.42
1.01
0.57
DR,
g/mi/lOkmi
0.70
0.50
0.28
CO
ZML,
g/mi
17.4
17.4
17.4
DR,
g/mi/ 10k mi
2.46
2.46
2.46
NOx
ZML,
g/mi
0.70
0.52
0.30
DR,
g/mi/ 10k mi
0
0
0
The Tier 1 standards for on-highway motorcycles are scheduled to take effect in 2006.
The Tier 2 standards for on-highway motorcycles >50cc are scheduled to take effect in 2010.
(The Tier 2 standards apply only to Class III motorcycles. Class I and II motorcycles have Tier
1 standards only that are different than the standard presented for Class III. As noted earlier, we
have not assumed any emission reductions for Class I/Class II motorcycles at or above 50 cc,
because most already meet the new standards.)
Another piece of information needed to develop the fleet average gram per mile emission
factors is information on the scrappage/survival rates of on-highway motorcycles. For our
spreadsheet analyses, we used scrappage/survival rate information provided in an industry trade
group survey.17'18 Table 6.2.1-5 presents the scrappage/survival rate information used in the
spreadsheet models for on-highway motorcycles.
6-9
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Table 6.2.1-5
Scrappage/Survival Rates for On-highway Motorcycles
Age
1
2
3
4
5
6
7
8
9
10
11
12
13
Fraction Surviving
<50cc
0.94
0.88
0.79
0.71
0.60
0.50
0.36
0.28
0.23
0.13
0.08
0.05
-
>50cc
0.99
0.97
0.96
0.94
0.91
0.88
0.82
0.75
0.71
0.66
0.60
0.55
0.45
Age
14
15
16
17
18
19
20
21
22
23
24
25
-
Fraction Surviving
<50cc
-
-
-
-
-
-
-
-
-
-
-
-
-
>50cc
0.40
0.34
0.29
0.25
0.18
0.12
0.09
0.06
0.04
0.03
0.01
0
-
Source: Motorcycle Industry Council
One final adjustment included in the spreadsheets, is an adjustment to account for
temperature effects on emissions. In order to account for these impacts, the MOBILES model
was run at ambient temperature conditions of 75°F and at typical summertime temperature
ambient conditions. The MOBILES outputs (in grams per mile) were compared for the two runs.
The results showed that HC emissions decreased by 1 percent under summertime conditions and
NOx emissions decreased by approximately 8 percent. These adjustments were applied to the
emission factors in the spreadsheets.
6.2.1.2 - Reductions Due to the Standards
We anticipate that the exhaust standards for on-highway motorcycles will result in a 50
percent reduction in both exhaust HC and NOx inventories by the year 2020. Tables 6.2.1-6 and
6.2.1.-7 present our projected exhaust HC and NOx emission inventories for on-highway
6-10
-------
motorcycles (combining both <50cc and >50cc vehicles) and the anticipated emission reductions
from the standards.
Table 6.2.1-6
Projected Exhaust HC Inventories and Reductions for On-Highway Motorcycles
(short tons)
Calendar Year
2000
2005
2010
2020
2030
Baseline
34,000
39,000
45,000
58,000
70,000
Control
34,000
39,000
41,000
28,000
28,000
Reduction
0
0
4,000
29,000
43,000
% Reduction
0%
0%
10%
51%
60%
Table 6.2.1-7
Projected Exhaust NOx Inventories and Reductions for On-Highway Motorcycles
(short tons)
Calendar Year
2000
2005
2010
2020
2030
Baseline
8,000
10,000
11,000
14,000
17,000
Control
8,000
10,000
10,000
7,000
7,000
Reduction
0
0
1,000
7,000
10,000
% Reduction
0%
0%
12%
50%
57%
6.2.1.3 - Per Equipment Emissions from On-highway Motorcycles
The following section describes the development of the emission estimates on a per piece
of equipment basis over the average lifetime of a typical on-highway motorcycle. The emission
estimates were developed to estimate the cost per ton of the standards as presented in Chapter 7.
In order to estimate the emissions from an on-highway motorcycle, information on the
emission level of the vehicle, the annual usage rate of the vehicle, and the lifetime of the vehicle
are needed. The values used to predict the per piece of equipment emissions for this analysis and
the methodology for determining the values are described below.
6-11
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The information necessary to calculate the emission levels of a piece of equipment over
the lifetime of a typical on-highway motorcycle were presented in Table 6.2.1-3 and Table 6.2.1-
4. A brand new on-highway motorcycle emits at the zero-mile level presented in the tables. As
the on-highway motorcycle ages, the emission levels increase based on the pollutant-specific
deterioration rate. Deterioration continues throughout the lifetime of the vehicle and the amount
of deterioration is directly proportional to the number of miles accumulated on the on-highway
motorcycle.
As described earlier in this section, the annual usage rate for an on-highway motorcycle
<50cc is estimated to be 650 miles per year and the average lifetime is estimated to be 6.0 years.
For on-highway motorcycles >50cc, the annual usage rate is estimated to be 2,907 miles per year
and the average lifetime is estimated to be 12.5 years.
Using the information described above, we calculated the lifetime HC or HC+NOx
emissions from typical on-highway motorcycles for both current (i.e., pre-control for <50cc and
Tier 0 for >50cc) vehicles and vehicles meeting the standards. Table 6.2.1-8 presents the
lifetime HC or HC+NOx emissions for typical on-highway motorcycles on both an undiscounted
and discounted basis (using a discount rate of 7 percent). Table 6.2.1-9 presents the
corresponding lifetime HC or HC+NOx emission reductions for the standards. HC estimates are
shown for on-highway motorcycles <50cc because we are not including a NOx standard.
HC+NOx estimates are shown for on-highway motorcycles >50cc because we are using a
combined HC+NOx standard. (As noted earlier, the analysis for >50cc motorcycles is based on
a Class III motorcycle. We are not projecting any emission reductions from the standards for
Class I/Class II motorcycles >50 cc, because most already meet the new standards.)
Table 6.2.1-8
Lifetime Emissions from a Typical On-highway motorcycle (short tons)
Control Level
Current (Pre-control for <50cc)
Current (Tier 0 for >50cc)
Tier 1
Tier 2
<50cc Motorcycles
Exhaust HC
Undiscounted
0.031
-
0.007
-
Discounted
0.026
-
0.006
-
>50cc Motorcycles
Exhaust HC+NOx
Undiscounted
-
0.141
0.100
0.057
Discounted
-
0.093
0.066
0.038
6-12
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Table 6.2.1-9
Lifetime Emission Reductions from a Typical On-highway motorcycle (short tons)
Control Increment
Current (Pre-control) to Tier 1
Current (Tier 0) to Tier 1
Tier 1 to Tier 2
<50cc Motorcycles
Exhaust HC
Undiscounted
0.024
-
-
Discounted
0.020
-
-
>50cc Motorcycles
Exhaust HC+NOx
Undiscounted
-
0.041
0.043
Discounted
-
0.027
0.029
6.2.2 - Evaporative Emissions
We projected the annual tons of hydrocarbons evaporated into the atmosphere from
motorcycles using the methodology discussed above in Section 6.1.2. These evaporative
emissions include permeation, diurnal, and refueling emissions. Although the standards do not
specifically require the control of diurnal and refueling emissions, we model them here for
comparison. This section presents our baseline and controlled national inventory projections for
evaporative emissions.
6.2.2.1 - Inputs for the Inventory Calculations
Several usage inputs are needed to calculate evaporative emissions from motorcycles.
These inputs are fuel tank sizes, population, and distribution throughout the nation. We used an
average fuel tank size of 5 gallons and average hose length of 1.5 feet for motorcycles. We
assumed that the national fuel tank distribution would be a function of the engine distribution.
We estimate that about 10% of motorcycle fuel tanks are plastic, while the remaining fuel tanks
are metal.19 Table 6.2.2-1 presents the vehicle distribution by region based on statistics collected
by the Motorcycle Industry Council.20 The total population for 1998 was estimated to be about
5.4 million on-highway motorcycles.
6-13
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Table 6.2.2-1
Motorcycle Population Distribution by Region
Region
Northeast
Southeast
Southwest
Midwest
West
Northwest
Total
Population
2,413,600
952,800
486,100
527,400
767,100
227,000
5,374,000
Fraction of Total
45%
18%
9%
10%
14%
4%
100%
6.2.2.2 Permeation Emissions Inventory and Reductions
Based on the data presented in Chapter 4, we developed the emission factors presented in
Table 6.2.2-2. For the purposes of this modeling, fuel tank permeation rates are expressed in
terms of g/gallon/day because the defining characteristic of the fuel tanks in our model is tank
fuel capacity. The standard requires that the fuel tanks meet an 85 percent reduction in
permeation throughout its useful life. For this modeling, we assume that manufacturers will
strive to achieve a 95 percent reductions from new tanks and that 85 percent in-use control will
be achieved over the the life of an average tank. Hose permeation rates are based on g/m2/day.
We believe that hoses designed to meet the 15 g/m2/day standard on 10 percent ethanol fuel will
permeate at least 50 percent less when gasoline is used. Therefore, we model permeation from
this hose to be about half of the permeation from fuel hose designed to meet 15 g/m2/day on
gasoline.x To show the effect of temperature on permeation rates, we present emission rates at
three temperatures.
Table 6.2.2-2
Fuel Tank and Hose Permeation Emission Factors
Material
Polyethylene fuel tanks
New barrier treated HDPE fuel tank
Aged barrier treated HDPE fuel tank
Metal fuel tanks
SAE R7 fuel hose
SAE R9 barrier fuel hose
Alcohol resistant barrier fuel hose
23°C (73°F)
0.78 g/gal/day
0.04 g/gal/day
0.11 g/gal/day
0 g/gal/day
550 g/m2/day
15 g/m2/day
7.5 g/m2/day
29°C (85°F)
1.12 g/gal/day
0.06 g/gal/day
0.1 7 g/gal/day
0 g/gal/day
873 g/m2/day
24 g/m2/day
12 g/m2/day
40°C (104°F)
2.08 g/gal/day
0.10 g/gal/day
0.31 g/gal/day
0 g/gal/day
1800g/m2/day
49 g/m2/day
25 g/m2/day
x This is appropriate because the baseline emissions are modeled based on the use of gasoline as a fuel. If
we were to consider that a fraction of the fuel contains oxygenates, both the baseline and control emission inventory
projections would increase.
6-14
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Using the population and temperature distributions discussed above, we calculated
baseline and controlled permeation emission inventories for motorcycles. Tables 6.2.2-3 and
6.2.2-4 present our projected permeation reductions from fuel tanks and hoses.
Table 6.2.2-3
Projected Fuel Tank Permeation Emissions from Motorcycles [short tons]
Vehicle
2005
2010
2015
2020
2030
Baseline
711
822
936
1,051
1,279
Controlled
711
649
445
231
137
Reduction
0
173
491
820
1,142
Table 6.2.2-4
Projected Fuel Hose Permeation Emissions from Motorcycles [short tons]
Vehicle
2005
2010
2015
2020
2030
Baseline
13,526
15,631
17,802
19,973
24,315
Controlled
13,526
12,183
7,812
2,950
422
Reduction
0
3,448
9,989
17,023
23,893
6.2.2.3 Per Motorcycle Permeation Emissions
In developing the cost per ton estimates in Chapter 7, we need to know the lifetime
emissions per motorcycle. We determine annual per motorcycle evaporative emissions by
dividing the total annual evaporative emissions by the motorcycle population. Per motorcycle
emission reductions are based on the modeling described above. Table 6.2.2-5 presents these
results with and without the consideration of a 7 percent per year discount on the value of
emission reductions. The figures presented here weight the fuel tank emissions between
motorcycles with metal (90%) and with plastic tanks (10%). If only motorcycles with plastic
fuel tanks were considered, the per motorcycle tank permeation would be ten times higher than
presented below.
6-15
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Table 6.2.2-5
Typical Lifetime Permeation Emissions Per Motorcycle (short tons)
Tank*
Hose
Total
Baseline
Undiscounted
0.0013
0.0249
0.0262
Discounted
0.0009
0.0174
0.0183
Control
Undiscounted
0.0001
0.0003
0.0005
Discounted
0.0001
0.0002
0.0003
Reduction
Undiscounted
0.0012
0.0246
0.0258
Discounted
0.0008
0.0172
0.0180
* Would be ten times higher if only motorcycles with plastic tanks were considered.
6.2.2.4 Other Evaporative Emissions
We calculated diurnal and refueling vapor loss emissions using the general inputs in
section 6.2.2.1 and the methodology described in sections 6.1.2.2 and 6.2.1.3. Although we are
not regulating these emissions, we present the inventory projections for comparison. Table
6.2.2-6 presents the baseline diurnal emission factors for the certification test conditions and a
typical summer day with low vapor pressure fuel and a fill level of 50%. (This comparison is for
illustrative purposes; as discussed above, we modeled daily temperature for 365 days over 6
regions of the U.S.) Decreasing temperature and fuel RVP and increasing fill level all have the
effect of reducing the diurnal emission factor. Table 6.2.2-7 presents our diurnal emission
projections.
Table 6.2.2-6
Diurnal Emission Factors for Test Conditions and Typical Summer Day
Evaporative Control
baseline
72-96°F, 9 RVP* Fuel, 40% fill
1.6 g/gallon/day
60-84°F, 8 RVP* Fuel, 50% fill
0.65 g/gallon/day
* Reid Vapor Pressure
Table 6.2.2-7
Projected Diurnal Emissions from Motorcycles
Calendar Year
2000
2005
2010
2020
2030
HC [Short Tons]
5,332
6,248
7,221
9,227
11,233
To calculate the refueling vapor displacement emissions from motorcycles, we needed to
know the amount of fuel added to the fuel tank per year. Therefore, we used the VMT estimates
6-16
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in 6.2.1-2 coupled with a fuel consumption rate of 50 miles per gallon to determine the amount
of fuel consumed by motorcycles. We then used the amount of fuel consumed as the amount of
fuel added to the tank. Table 6.2.2-8 contains the estimated refueling emission inventories for
motorcycles.
Table 6.2.2-8
Projected Refueling Emissions from Motorcycles
Calendar Year
2000
2005
2010
2020
2030
HC [Short Tons]
1,036
1,216
1,406
1,601
2,186
6-17
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Chapter 6 References
1. "Spreadsheet for Modeling the Emission Inventories from On-Highway Motorcycles >50cc
under the Final Rule," EPA memo from Phil Carlson to Docket A-2000-02, June 26, 2003.
2. "Spreadsheet for Modeling the Emission Inventories from On-Highway Motorcycles <50cc
under the Final Rule," EPA memo from Phil Carlson to Docket A-2000-02, June 27, 2003.
3. API Publication No. 4278, "Summary and Analysis of Data from Gasoline Temperature
Survey Conducted at Service Stations by American Petroleum Institute," Prepared by Radian
Corporation for American Petroleum Institute, November 11, 1976, Docket A-2000-01,
Document II-A-16.
4. "Evaporative Emission Calculations for Highway Motorcycles," EPA memo from Mike
Samulski to Docket A-2000-02, August 1, 2002.
5. Nulman, M., Olejnik, A., Samus, M., Fead, E., Rossi, G., "Fuel Permeation Performance of
Polymeric Materials," SAE Paper 2001-01-1999, 2001, Docket A-2000-01, Document IV-A-23.
6. Lockhart, M., Nulman, M, Rossi, G., "Estimating Real Time Diurnal Permeation from
Constant Temperature Measurements," SAE Paper 2001-01-0730, 2001, Docket A-2000-01,
Document IV-A-21.
7. D. T. Wade, "Factors Influencing Vehicle Evaporative Emissions," SAE Paper 670126,
1967, Docket A-2000-01, Document II-A-59.
8. Wade et. al., "Mathematical Expressions Relating Evaporative Emissions from Motor
Vehicles without Evaporative Loss-Control Devices to Gasoline Volatility," SAE Paper 72070,
1972, Docket A-2000-01, Document II-A-58.
9. S. Raghuma Reddy, "Prediction of Fuel Vapor Generation from a Vehicle Fuel Tank as a
Function of Fuel RVP and Temperature," SAE Paper 892089, 1989, Docket A-2000-01,
Document II-A-61.
10. S. Raghuma Reddy, "Prediction of Fuel Vapor Generation from a Vehicle Fuel Tank as a
Function of Fuel RVP and Temperature," SAE Paper 892089, 1989, Docket A-2000-01,
Document II-A-61.
11. "Final Regulatory Impact Analysis: Refueling Emission Regulations for Light Duty
Vehicles and Trucks and Heavy Duty Vehicles," U.S. EPA, January 1994, Docket A-2000-01,
Document II-A-79.
12. "Information on On-Highway Motorcycle Mileage Accumulation Rates and Survival
Fractions Supplied by the Motorcycle Industry Council," EPA memo from Phil Carlson to
Docket A-2000-01, September 12, 2001, Docket A-2000-01, Document II-B-22.
6-18
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13. "Additional Information on Mileage Accumulation, Survival Fraction, and Sales Supplied
by the Motorcycle Industry Council for On-Highway Motorcycles <50cc," EPA memo from Phil
Carlson to Docket A-2000-01, April 12, 2002, Document IV-B-11.
14. "Procedures for Developing Base Year and Future Year Mass and Modeling Inventories for
the Heavy-Duty Engine and Vehicle Standards and Highway Diesel Fuel Rulemaking," U.S.
Environmental Protection Agency, April 2000. Pages VI-2 and VI-15, Docket A-2000-01,
Document II-A-76.
15. "Air Pollution from Motor Vehicles, Standards and Technologies for Controlling
Emissions," prepared by Asif Faiz, Christopher Weaver, and Michael Walsh for the World Bank,
1996, Docket A-2000-01, Document IV-A-29.
16. "Exhaust Pollution Abatement Technologies and the Requirements for a world-wide
Motorcycle Emissions Test Cycle," Rudolf Rijkeboer and Cornells Havenith.
17. "Information on On-Highway Motorcycle Mileage Accumulation Rates and Survival
Fractions Supplied by the Motorcycle Industry Council," EPA memo from Phil Carlson to
Docket A-2000-01, September 12, 2001, Docket A-2000-01, Document II-B-22.
18. "Additional Information on Mileage Accumulation, Survival Fraction, and Sales Supplied
by the Motorcycle Industry Council for On-Highway Motorcycles <50cc," EPA memo from Phil
Carlson to Docket A-2000-01, April 12, 2002, Document IV-B-11.
19. "Use of Plastic Fuel Tanks in Highway Motorcycles," Memorandum from Roberts French
to Docket A-2000-02, June 5, 2003, Docket A-2000-02.
20. "2000 Motorcycle Statistical Annual," Motorcycle Industry Council, Docket A-2000-01,
Document II-D-03.
6-19
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CHAPTER 7 Cost Per Ton
7.1 - Cost Per Ton for Exhaust and Permeation Control
7.1.1 - Introduction
This chapter presents our estimate of the cost per ton of control for the emission
standards contained in this program. The analysis relies on the costs estimates presented in
Chapter 5 and the estimated lifetime emissions reductions using the information presented in
Chapter 6. Cost per ton estimates are presented for motorcycles less than 50 cc and for Class 3
motorcycles. We noted in Chapters 5 and 6, we are not expecting significant costs or emissions
reductions for Class 1 and 2 motorcycles above 50cc from the new exhaust standards. Therefore,
we have not calculated cost per ton estimates for these classes for the exhaust standards. The
chapter also presents a summary of the cost per ton values of other recent EPA mobile source
rulemakings for comparison purposes. Finally, this chapter presents the estimated costs and
emission reductions as incurred over the first twenty years after the standards are implemented.
In calculating net present values that were used in our cost-per-ton estimates, we used a
discount rate of 7 percent, consistent with the 7 percent rate reflected in the cost-per-ton analyses
for other recent mobile source programs. OMB Circular A-94 requires us to generate benefit and
cost estimates reflecting a 7 percent rate. Using the 7 percent rate allows us to make direct
comparisons of cost-per-ton estimates with estimates for other, recently adopted, mobile source
programs.
However, we consider that the cost and cost-per-ton estimates for future proposed mobile
source programs could reflect a 3 percent rate. The 3 percent rate is in the 2 to 3 percent range
recommended by the Science Advisory Board's Environmental Economics Advisory Committee
for use in EPA social benefit-cost analyses, a recommendation incorporated in EPA's new
Guidelines for Preparing Economic Analyses (November 2000). Therefore, we have also
calculated the overall cost-effectiveness of today's rule based on a 3 percent rate to facilitate
comparison of the cost-per-ton of this rule with future proposed rules which might use the 3
percent rate. The results using both a 3 percent and 7 percent discount rate are provided in this
Chapter.
7.1.2 - Permeation Evaporative Emission Control for Motorcycles
This section provides our estimate of the cost per ton of evaporative emissions reduced
from motorcycles. The analysis relies on the per motorcycle costs estimated in Chapter 5 and the
estimated lifetime emissions reductions (tons) presented in Chapter 6. All costs and emission
reductions are discounted to the year of sale of the motorcycles at a rate of 7 percent. Table
7.1.2-1 presents the cost per ton with and without consideration of the significant fuel savings
that will result from evaporative emission control assuming a 7 percent discount rate. The cost
7-1
-------
per ton results assuming a 3 percent discount rate are presented in Table 7.1.2-2. As shown in
these tables, the fuel savings more than offset the cost of this evaporative emission control
technology.
Table 7.1.2.-1
Estimated Cost Per Ton of Evaporative HC Reduced
(7 percent discount rate)
tank permeation
hose permeation
aggregate
Average
Cost Per
Motor-
cycle
$0.17*
$1.68
$1.85
Lifetime Fuel
Savings Per
Motorcycle
(NPV)
$0.30
$6.23
$6.52
Lifetime
Reductions
PerMC
(NPV tons)
0.001
0.017
0.018
Discounted Per MC
Cost Per Ton without
Fuel Savings
($/ton)
$205
$98
$103
Discounted Per MC
Cost Per Ton with
Fuel Savings
($/ton)
($158)
($265)
($260)
* $1.68 for plastic fuel tanks (10% of sales) and $0 for metal fuel tanks (90% of sales)
Table 7.1.2.-2
Estimated Cost Per Ton of Evaporative HC Reduced
(3 percent discount rate)
tank permeation
hose permeation
aggregate
Average
Cost Per
Motor-
cycle
$0.17*
$1.68
$1.85
Lifetime Fuel
Savings Per
Motorcycle
(NPV)
$0.36
$7.57
$7.93
Lifetime
Reductions
PerMC
(NPV tons)
0.001
0.021
0.022
Discounted Per MC
Cost Per Ton without
Fuel Savings
($/ton)
$169
$80
$84
Discounted Per MC
Cost Per Ton with
Fuel Savings
($/ton)
($194)
($238)
($279)
* $1.68 for plastic fuel tanks and $0 for metal fuel tanks
7.1.3 - Exhaust Emission Control for Motorcycles
This section provides our estimate of the cost per ton of emissions reduced for on-
highway motorcycles. For on-highway motorcycles <50 cc, we have calculated cost per ton on
the basis of HC only because we are only finalizing an HC standard. For Class 3 on-highway
motorcycles, we have calculated cost per ton on the basis of HC plus NOx because we are
finalizing HC plus NOx standards. The analysis relies on the per vehicle costs estimated in
Chapter 5 and the estimated net present value of the per vehicle lifetime emissions reductions
(tons) presented in Chapter 6.
Table 7.1.3.-1 presents the cost per ton estimates for the standards for on-highway
motorcycles <50cc. As described in Chapter 5, we expect a decrease in operating costs (i.e.,
decreased fuel costs) as manufacturers convert from 2-stroke to 4-stroke designs to meet the
7-2
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standards. Therefore, Table 7.1.3-1 presents cost per ton estimates both without and with the
fuel savings included for both a 7 percent and 3 percent discount rate.
Table 7.1.3.-1
Estimated On-Highway Motorcycle <50cc Cost Per Ton of HC Reduced
Discount
Rate
7%
3%
Cost per
Vehicle
(NPV)
$43.50
$43.50
Lifetime
Fuel Savings
(NPV)
$7.70
$8.50
Lifetime
Reductions
(NPV, tons)
0.020
0.022
Discounted Per Vehicle
Cost Per Ton without
Fuel Savings
($/ton)
$2,130
$1,950
Discounted Per Vehicle
Cost Per Ton with Fuel
Savings
($/ton)
$1,750
$1,570
As described in Chapter 5, the estimated per vehicle costs for on-highway motorcycles
>50cc change over time, with reduced costs in the long term. We have estimated both a near-
term and long-term cost per ton for both the Tier 1 and Tier 2 standards, with the Tier 2
estimates incremental to Tier 1. The results of the analysis are presented in Table 7.1.3.-2
assuming a 7 percent discount rate. The cost per ton results assuming a 3 percent discount rate
as presented in Table 7.1.3.-3.
Table 7.1.3.-2
Estimated Class 3 On-Highway Motorcycle Cost Per Ton of HC+NOx Reduced
(7 percent discount rate)
Standard
Tier 1 - Near-term
Tier 1 - Long-term
Tier 2 - Near-term
Tier 2 - Long-term
Cost per Vehicle
(NPV)
$30
$21
$45
$28
Lifetime Reductions
(NPV tons)
0.026
0.029
Discounted Per Vehicle Cost Per Ton
($/ton)
$1,150
$800
$1,550
$960
-------
Table 7.1.3.-3
Estimated Class 3 On-Highway Motorcycle Cost Per Ton of HC+NOx Reduced
(3 percent discount rate)
Standard
Tier 1 - Near-term
Tier 1 - Long-term
Tier 2 - Near-term
Tier 2 - Long-term
Cost per Vehicle
(NPV)
$30
$21
$45
$28
Lifetime Reductions
(NPV tons)
0.033
0.036
Discounted Per Vehicle Cost Per Ton
($/ton)
$920
$640
$1,240
$770
7.2 - Cost Per Ton for Other Mobile Source Control Programs
Because the primary purpose of cost-effectiveness is to compare our program to
alternative programs, we made a comparison between the cost per ton values presented in this
chapter and the cost-effectiveness of other programs. Table 7.2-1 summarizes the cost
effectiveness (with a 7 percent discount rate) of several recent EPA actions for controlled
emissions from mobile sources.
Table 7.2-1
Cost-effectiveness of Previously Implemented
Mobile Source Programs (Costs Adjusted to 2001 Dollars)1
Program
Tier 2 vehicle/gasoline sulfur
2007 Highway HD diesel
2004 Highway HD diesel
Off-highway diesel engine
Tier 1 vehicle
NLEV
Marine SI engines
On-board diagnostics
Marine CI engines
mon
1,437-2,423
1,563-2,002
227 - 444
456 - 724
2,202 - 2,993
2,069
1,255 - 1,979
2,480
26- 189
By comparing the cost per ton values presented in earlier in this chapter to those in Table
7.2-1, we can see that the cost effectiveness of the standards for this rulemaking are in or below
the range of these other programs. It is true that some previous programs have been more cost
efficient than the motorcycle program. However, it should be expected that the next generation
of standards will be more expensive than the last, because the least costly means for reducing
emissions is generally pursued first.
7-4
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The primary advantage of making comparisons to previously implemented programs is
that their cost-effectiveness values were based on a rigorous analysis and are generally accepted
as representative of the efficiency with which those programs reduce emissions. Unfortunately,
previously implemented programs can be poor comparisons because they may not be
representative of the cost-effectiveness of potential future programs. Therefore, in evaluating the
cost-effectiveness of our program, we also considered whether our proposal is cost-effective in
comparison with potential future means of controlling emissions. In the context of the Agency's
rulemaking which would have revised the ozone and PM NAAQS, the Agency compiled a list of
additional known technologies that could be considered in devising new emission reductions
strategies.2 Through this broad review, over 50 technologies were identified that could reduce
NOx, VOC, or PM. The cost-effectiveness of these technologies averaged approximately
$5,000/ton for VOC, $13,000/ton for NOx, and $40,000/ton for PM. Although a $10,000/ton
limit was actually used in the air quality analysis presented in the NAAQS revisions rule, these
values clearly indicate that, not only are future emission control strategies likely to be more
expensive (less cost-effective) than past strategies, but the cost-effectiveness of our program falls
within the range of potential future strategies.
In summary, given the array of controls that will have to be implemented to make
progress toward attaining and maintaining the NAAQS, we believe that the weight of the
evidence from alternative means of providing substantial NOx + HC emission reductions
indicates that our program is cost-effective. This is true from the perspective of other mobile
source control programs or from the perspective of other stationary source technologies that
might be considered.
7.3 - 20-Year Cost and Benefit Analysis
The following section presents the year-by-year cost and emission benefits associated
with the standards for the 20-year period after implementation of the standards.
Table 7.3-1 presents the year-by-year cost and emission benefits for the permeatiom
controls. (The numbers presented in Table 7.3-1 are not discounted.) For the permeation
standards, where we expect a reduction in fuel consumption due to the standards, the fuel
savings are presented separately. The overall cost, incorporating the impact of the fuel savings is
also presented.
7-5
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Table 7.3-1
Cost and Emission Benefits of the Permeation Emission Requirements
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
HC+NOx*
Benefits (tons)
1,154
2,362
3,621
4,918
6,259
7,637
9,049
10,480
11,956
13,431
14,916
16,408
17,843
19,023
19,833
20,593
21,333
22,018
22,695
23,328
Cost w/o
Fuel Savings
$1,102,991
$1,132,327
$1,161,664
$1,191,911
$1,222,158
$1,252,404
$1,282,651
$1,312,897
$1,270,569
$1,300,830
$1,331,090
$1,361,351
$1,391,611
$1,421,872
$1,452,133
$1,482,393
$1,512,654
$1,542,915
$1,573,161
$1,603,408
Fuel Savings
$418,932
$857,231
$1,314,526
$1,785,089
$2,271,922
$2,772,072
$3,284,794
$3,804,321
$4,339,891
$4,875,284
$5,414,423
$5,956,206
$6,477,017
$6,905,439
$7,199,253
$7,475,201
$7,744,052
$7,992,590
$8,238,364
$8,468,105
Cost w/
Fuel Savings
$684,059
$275,096
($152,862)
($593,178)
($1,049,764)
($1,519,668)
($2,002,143)
($2,491,424)
($3,069,322)
($3,574,454)
($4,083,333)
($4,594,855)
($5,085,406)
($5,483,567)
($5,747,120)
($5,992,808)
($6,231,398)
($6,449,675)
($6,665,203)
($6,864,697)
* - Permeation benefits are HC only.
Table 7.3-2 presents the sum of the costs and emission benefits over the twenty year
period after the permeation requirements will take effect, on both a non-discounted basis and a
discounted basis (assuming a seven percent discount rate). The annualized cost and emission
benefits for the twenty-year period (assuming the seven percent discount rate) are also presented.
7-6
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Table 7.3-2
Annualized Cost and Emission Benefits for the
Period 2008-2027 due to the Permeation Standards
Undiscounted
20-year Value
Discounted
20-year Value
Annualized Value
Evaporative HC
Benefits
(short tons)
269,000
121,000
11,400
Cost w/o Fuel
Savings
(Million $)
$26.9
$14.6
$1.4
Fuel Savings
(Million $)
$97.6
$44.0
$4.2
Cost w/
Fuel Savings
(Million $)
($70.7)
($29.4)
($2.8)
Table 7.3.-3 presents the year-by-year cost and emission benefits for the on-highway
motorcycle exhaust requirements. (The numbers presented in Table 7.3-3 are not discounted and
include the benefits and savings for all on-highway motorcycles, including those <50cc and
those >50cc.)
7-7
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Table 7.3-3
Cost and Emission Benefits of the On-Highway Motorcycle Exhaust Emission Standards
Year
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
HC+NOx
Benefits (tons)
495
1,593
2,990
4,384
5,869
8,483
11,549
14,805
17,834
21,378
24,222
27,290
30,671
33,982
36,243
38,430
40,454
42,331
44,043
45,646
Cost w/o
Fuel Savings
$17,910,738
$18,068,493
$15,276,796
$15,408,213
$40,574,886
$40,910,636
$37,134,822
$37,436,171
$36,027,234
$36,334,641
$36,645,121
$36,958,706
$31,988,827
$32,308,715
$32,631,803
$32,958,121
$33,287,702
$33,620,579
$33,956,785
$34,296,353
Fuel Savings
$24,176
$67,997
$106,724
$141,465
$171,344
$197,498
$217,751
$235,520
$251,815
$263,984
$274,101
$282,971
$289,553
$296,134
$302,715
$309,296
$315,877
$322,458
$329,039
$335,620
Cost w/
Fuel Savings
$17,886,562
$18,000,496
$15,170,073
$15,266,747
$40,403,541
$40,713,138
$36,917,071
$37,200,652
$35,775,419
$36,070,656
$36,371,020
$36,675,735
$31,699,275
$32,012,582
$32,329,088
$32,648,825
$32,971,825
$33,298,121
$33,627,746
$33,960,733
Table 7.3-4 presents the sum of the costs and emission benefits over the twenty year
period after the exhaust requirements for on-highway motorcycles take effect, on both a non-
discounted basis and a discounted basis (assuming a seven percent discount rate). The
annualized cost and emission benefits for the twenty-year period (assuming the seven percent
discount rate) are also presented.
-------
Table 7.3-4
Annualized Cost and Emission Benefits for the Period 2006-2025
due to the On-Highway Motorcycle Exhaust Emission Standards
Undiscounted
20-year Value
Discounted
20-year Value
Annualized Value
HC+NOx
Benefits
(short tons)
453,000
191,000
18,100
Cost w/o Fuel
Savings
(Million $)
$633.4.
$339.5
$32.0
Fuel Savings
(Million $)
$4.7
$2.3
$0.2
Cost w/
Fuel Savings
(Million $)
$629.0
$337.2
$31.8
Table 7.3-5 presents the aggregate year-by-year cost and emission benefits for the
combination of the permeation and exhaust emission standards. (The numbers presented in
Table 7.3-5 are not discounted.)
7-9
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Table 7.3-5
Cost and Emission Benefits of the Requirements
for the Permeation and Exhaust Emission Standards
Year
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
HC+NOx
Benefits (tons)
495
1,593
4,144
6,746
9,490
13,401
17,808
22,442
26,883
31,858
36,178
40,721
45,587
50,390
54,086
57,453
60,287
62,924
65,376
67,664
69,843
71,825
Cost w/o
Fuel Savings
$17,910,738
$18,068,493
$16,379,787
$16,540,540
$41,736,550
$42,102,547
$38,356,980
$38,688,575
$37,309,885
$37,647,538
$37,915,690
$38,259,536
$33,319,917
$33,670,066
$34,023,414
$34,379,993
$34,739,835
$35,102,972
$35,469,439
$35,839,268
$36,212,477
$36,589,117
Fuel Savings
$24,176
$67,997
$525,656
$998,696
$1,485,871
$1,982,587
$2,489,673
$3,007,591
$3,536,610
$4,068,305
$4,613,993
$5,158,256
$5,703,976
$6,252,340
$6,779,732
$7,214,735
$7,515,130
$7,797,659
$8,073,091
$8,328,210
$8,580,565
$8,816,887
Cost w/
Fuel Savings
$17,886,562
$18,000,496
$15,854,131
$15,541,844
$40,250,679
$40,119,960
$35,867,307
$35,680,984
$33,773,276
$33,579,232
$33,301,697
$33,101,280
$27,615,942
$27,417,727
$27,243,682
$27,165,257
$27,224,705
$27,305,313
$27,396,347
$27,511,057
$27,631,912
$27,772,230
Table 7.3-6 presents the sum of the costs and emission benefits over the twenty-two year
period after all of the requirements take effect, on both a non-discounted basis and a discounted
basis (assuming a seven percent discount rate). The annualized cost and emission benefits for
the twenty-two year period (assuming the seven percent discount rate) are also presented. (A
twenty-two period is used in this aggregate analysis to cover the first twenty years of each of
standards which begins in 2006 for exhaust emissions and concludes in 2008 for the permeation
requirements.)
7-10
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Table 7.3-6
Annualized Cost and Emission Benefits for the Period 2006-2027
due to the Exhaust and Permeation Standards
Undiscounted
22-year Value
Discounted
22-year Value
Annualized Value
HC+NOx
Benefits
(short tons)
817,000
321,000
29,000
Cost w/o Fuel
Savings
(Million $)
$730.3
$369.7
$33.4
Fuel Savings
(Million $)
$103.0
$40.9
$3.7
Cost w/
Fuel Savings
(Million $)
$627.2
$328.7
$29.7
7-11
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Chapter 7 References
1. Gross Domestic Product Implicit Price Deflator, U. S. Department of Commerce, Bureau of
Economic Analysis, http://www.stls.frb.org/fred/data/gdp/gdpdef, April 12, 2002, Docket A-
2000-01, Document IV-A-31.
2. "Regulatory Impact Analyses for the Particulate Matter and Ozone National Ambient Air
Quality Standards and Regional Haze Rule," Appendix B, "Summary of control measures in the
PM, regional haze, and ozone partial attainment analyses," Innovative Strategies and Economics
Group, Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency,
Research Triangle Park, NC, July 17, 1997, Docket A-2000-01, Document II-A-77.
7-12
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CHAPTER 8: Small Business Flexibility Analysis
This section presents our Small Business Flexibility Analysis (SBFA) which evaluates
the impacts of the rule on small businesses. Prior to issuing the proposal, we analyzed the
potential impacts of our program on small businesses. As a part of this analysis, we convened a
Small Business Advocacy Review (SB AR) Panel, in accordance with the Regulatory Flexibility
Act (RFA) as amended by the Small Business Regulatory Enforcement Fairness Act of 1996
(SBREFA), 5 USC 601 et seq. Through the Panel process, we gathered advice and
recommendations from small entity representatives (SERs) who would be affected by our
rulemaking. The final report of the Panel has been placed in the rulemaking record.
8.1 - Requirements of the Regulatory Flexibility Act
The Regulatory Flexibility Act was amended by SBREFA to ensure that concerns
regarding small entities are adequately considered during the development of new regulations
that may affect them. Although we are not required by the Clean Air Act (CAA or the Act) to
provide special treatment to small businesses, the Regulatory Flexibility Act requires that we
carefully consider the economic impacts that our proposed rules will have on small entities. In
general, the Regulatory Flexibility Act calls for determining, to the extent feasible, a rule's
economic impact on small entities, exploring regulatory options for reducing any significant
economic impact on a substantial number of such small entities, and explaining the ultimate
choice of regulatory approach.
When proposing rules subject to notice and comment under the CAA, we are generally
required under the Regulatory Flexibility Act to conduct an Initial Regulatory Flexibility
Analysis (IRFA), unless we certify that the requirements of a regulation will not cause a
significant impact on a substantial number of small entities. Although we are not required to
conduct a Final Regulatory Flexibility Analysis (FRFA), EPA has decided to prepare an
assessment of the impacts of the final rule on small entities. This SBFA would meet the
requirements of a FRF A, were we required to prepare one.
In accordance with section 609(b) of the Regulatory Flexibility Act, we conducted
outreach to affected small entities and convened an SB AR Panel before conducting the IRFA for
the proposal. Through the SBAR Panel we obtained advice and recommendations of
representatives of small entities that would potentially be subject to the rulemaking
requirements. A summary of the recommendations of the SBAR Panel and small entities is
presented in the Final Panel Report {Final Report of the Small Business Advocacy Review Panel
on Control of Emissions from Nonroad Large Spark Ignition Engines, Recreational Engines
(Marine and Land-based), and Highway Motorcycles, July 17, 2001). An IRFA was prepared, in
accordance with section 603 of the Regulatory Flexibility Act. The IRFA can be found in
Chapter 8 of the Draft Regulatory Support Document for the Notice of Proposed Rulemaking
(NPRM).
3-1
-------
We proposed the majority of the Panel recommendations, and took comments on this and
other issues. Since highway motorcycles have had to meet emission standards for more than
twenty years, EPA has good information on the number of companies that manufacture or
market highway motorcycles for the U.S. market in each model year. In addition to the largest
six manufacturers (BMW, Harley-Davidson, Honda, Kawasaki, Suzuki, Yamaha), we find as
many as several dozen more companies that have operated in the U.S. market in the last couple
of model years. Most of these are U.S. companies that are either manufacturing or importing
motorcycles, although a few are U.S. affiliates of larger companies in Europe or Asia. Some of
the U.S. manufacturers employ only a few people and produce only a handful of custom
motorcycles per year, while others may employ several hundred and produce up to several
thousand motorcycles per year. These new emission standards impose no new development or
certification costs for any company producing compliant engines for the California market. In
fact, implementing the California standards with a two-year delay also allows manufacturers to
streamline their production to further reduce the cost of compliance. The estimated hardware
costs are less than one percent of the cost of producing a highway motorcycle, so none of these
companies should have a compliance burden greater than one percent of revenues. We expect
that a small number of companies affected by EPA emission standards will not already be
certifying products in California. For these companies, the modest effort associated with
applying established technology will add compliance costs representing between 1 and 3 percent
of revenues. The flexible approach we are adopting to limit testing, reporting, and
recordkeeping burden prevents excessive costs for all these companies. Thus, EPA has
determined that this final rule will not have a significant impact on a substantial number of small
entities. However, we have included several provisions designed to reduce the burden on small
entities. A full description of the regulatory flexibilities that are being offered to small entities to
minimize their burden is located in Section 8.6, "Steps Taken to Minimize the Economic Impact
on Small Entities."
Although this final rule will not have a significant impact on a substantial number of
small entities, we have prepared this Small Business Flexibility Analysis that examines the
impact of the rule on small entities, along with regulatory alternatives that could reduce that
impact. This analysis would meet the requirements for a Final Regulatory Flexibility Analysis
(FRFA) has that analysis been required. The key elements of an SBFA are:
the need for, and objectives of, the rule;
the significant issues raised by public comments, a summary of the Agency's assessment
of those issues, and a statement of any changes made to the rule as a result of those
comments;
the types and number of affected small entities to which this rule will apply;
the projected reporting, record keeping, and other compliance requirements of the
regulation, including the classes of small entities that would be affected and the type of
professional skills necessary for the preparation of the report or record; and,
the steps taken to minimize the economic impacts of the regulation on small entities,
consistent with the stated objectives of the applicable statutes.
8-2
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8.2 - Need For and Objectives of the Rule
Emission standards have been in place for motorcycles since 1978. These cover exhaust
HC and CO and crankcase emissions. Prior to this rule, there were no standards controlling NOx
from highway motorcycles. The current standards do not apply to motorcycles with engines less
than 50 cubic centimeters displacement. Under CAA section 202 (a)(3)(E), EPA is required to
"consider the need to achieve equivalency of emission reductions between motorcycles and other
vehicles to the maximum extent practicable." Light-duty vehicles, light-duty trucks and engines
used in heavy-duty vehicles have each gone through several generations of emission standards
since 1978, and indeed each of these categories is facing tough new standards in the next few
years. With these developments and the recent promulgation of emission standards for off-road
motorcycles, this was an appropriate time for EPA to reconsider the existing standards.
On December 7, 2000, EPA issued an Advance Notice of Proposed Rulemaking
(ANPRM), and then issued a Notice of Proposed Rulemaking (NPRM) on September 14, 2001.
This final rule contains new standards and related requirements for on-highway motorcycles.
8.3 - Issues Raised by the Public Comments
The SB AR Panel considered a range of options to assist small motorcycle manufacturers
and provide regulatory flexibilities to help in decreasing the burden on small manufacturers. In
the NPRM, we took comment on many of the options suggested by the Panel and SERs during
the SBREFA process. The SBREFA Final Panel Report details all of the comments and
regulatory alternatives suggested by SERs. The regulatory alternatives recommended by the
Panel are located in Section 9 of the Report. While the SBREFA process included many types
vehicles, there were specific recommendations aimed at highway motorcycles. The Panel-
recommended alternatives for motorcycle manufacturers qualifying as small manufacturers that
we proposed in the NPRM are listed below.
(1) Delay of Proposed Standards
As laid out in the Final Panel Report, we proposed a delay of the proposed
standards- Tier 1 in 2008 and no Tier 2; we also pledged to participate with the
California Air Resources Board in a 2006 technology review.
(2) Broader Engine Families
We proposed to leave the existing provisions that currently allow broader engine
families unchanged.
(3) Exemption from production line testing
There is no production line testing (PLT) currently, and we did not propose PLT
in the NPRM although we were considering it at the time we met with the SERs.
(4) Averaging, banking, and trading
We proposed an averaging program to enhance compliance and we requested
comment on banking and trading programs to supplement this flexibility.
(5) Hardship provisions
-------
We proposed hardship provisions, not only for small manufacturers, but for all
manufacturers as recommended by the Panel.
(6) Reduced Cert Data Submittal and Testing Requirements
These already exist for manufacturers with fewer than 10,000 unit sales per year.
The Panel recommended no changes to this and we did not propose any changes.
We received comments on the above Panel-recommended proposals in relation to small
as well as large manufacturers. Of these, we are finalizing a delay in the standards, an emissions
averaging program, and hardship provisions for all manufacturers. We are not finalizing PLT
and we are finalizing no changes to the current reduced certification data submittal/testing
requirements for manufacturers with fewer than 10,000 yearly unit sales. Lastly, we will not be
changing the current provisions that allow for broader engine families.
We also received a number of other comments during the public comment process
relating to small businesses. These comments were mainly focused on the following six subject
areas: 1) the impact on the broader motorcycle industry, especially small/independent and
aftermarket shops and the assertion that EPA did not fulfill its SBREFA obligations with regard
to these shops ; 2) the customer rejection of products; 3) fewer options for customers and lower
sales; 4) an increase in the cost of ownership and the inability to service motorcycles; 5) the
reduction/elimination of competition from aftermarket and specialty shops, elimination of
aftermarket supplies and services, and consumers will be forced to purchase only manufacturer-
offered products; 6) the Barcia Act/H.R. 5433. A detailed summary of all of the comments that
we received regarding the NPRM can be found in the Final Summary and Analysis of Comments
located in the public docket for this rulemaking.
8.4 - Description of Affected Entities
Small entities include small businesses, small organizations, and small governmental
jurisdictions. For the purposes of assessing the impacts of the proposed rule on small entities, a
small entity is defined as: (1) a small business that meets the definition for business based on the
Small Business Administration's (SBA) size standards (see Table 11-1); (2) a small
governmental jurisdiction that is a government of a city, county, town, school district or special
district with a population of less than 50,000; and (3) a small organization that is any not-for-
profit enterprise which is independently owned and operated and is not dominant in its field.
Table 8.4-1 provides an overview of the primary SBA small business categories potentially
affected by this regulation.
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Table 8.4-1
Primary SBA Small Business Categories Potentially Affected by this Regulation
Industry
Motorcycle manufacturers
NAICS3 Codes
336991
Defined by SBA as a
Small Business If:b
<500 employees
NOTES:
a. North American Industry Classification System
b. According to SBA's regulations (13 CFR 121), businesses with no more than the listed number of employees or
dollars in annual receipts are considered "small entities" for purposes of a regulatory flexibility analysis.
Of the numerous manufacturers supplying the U.S. highway motorcycle market, Honda,
Harley Davidson, Yamaha, Kawasaki, Suzuki, and BMW are the largest, accounting for 95
percent or more of the total U.S. sales. All of these companies except Harley-Davidson and
BMW also manufacture off-road motorcycles and ATVs for the U.S. market. Harley-Davidson
is the only company manufacturing highway motorcycles exclusively in the U.S. for the U.S.
market.
Since highway motorcycles have had to meet emission standards for over twenty years,
EPA has good information on the number of companies that manufacture or market highway
motorcycles for the U.S. market in each model year. In addition to the big six manufacturers
noted above, EPA finds as many as several dozen more companies that have operated in the U.S.
market in the last couple of model years. Most of these are U.S. companies that are either
manufacturing or importing motorcycles, although a few are U.S. affiliates of larger companies
in Europe or Asia. Some of the U.S. manufacturers employ only a few people and produce only
a handful of custom motorcycles per year, while others may employ several hundred and
produce up to several thousand motorcycles per year.
8.5 - Projected Reporting, Recordkeeping, and Other Compliance
Requirements of the Regulation
For any emission control program, we must be sure that the regulated engines will meet
the standards. Historically, EPA programs have included provisions placing manufacturers
responsible for providing these assurances. This final rule includes testing, reporting, and record
keeping requirements. Testing requirements for some manufacturers include certification
(including deterioration factor testing), and production-line testing. Reporting requirements
include test data and technical data on the engines including defect reporting. Manufacturers
keep records of this information. Because EPA has regulated motorcycle emissions for almost
25 years, these are generally not new compliance requirements for motorcycle manufacturers,
but those that have been in place for many years. The only noteworthy change here is the
addition of permeation evaporative emission control requirements for fuel lines and fuel tanks.
While essentially all motorcycles will be affected by the fuel line requirements, only about ten
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percent of motorcycles use fuel tanks which are constructed of material which is not inherently
low in permeation. We have designed these programs to involve the absolute minimum of testing
and certification reporting requirements.
8.6 - Steps to Minimize Significant Economic Impacts on Small Entities
While the highway motorcycle market is dominated by large companies, there are a large
number of small businesses manufacturing motorcycles. The provisions discussed below will
reduce the economic burden on small businesses, allowing harmonization with California
requirements in a phased, but timely manner. We have developed our special compliance
provisions partly in response to the technology, timing, and scope of the requirements that apply
to the small businesses in California's program. The flexibilities described below will be
available for small entities with U.S. highway motorcycle annual sales of fewer than 3,000 units
per model year (combined Class I, II, and III motorcycles) and fewer than 500 employees
worldwide. These provisions are appropriate because of the significant research and
development resources may be necessary to meet the emission standards and related
requirements. These provisions will reduce the burden while ensuring the vast majority of the
program is implemented to ensure timely emission reductions. Many small highway motorcycle
manufacturers market unique "classic" and "custom" motorcycles, often with a "retro"
appearance, that tends to make the addition of new technologies a uniquely resource-intensive
prospect.
8.61 Delay of Implementation Timing of the Standards
We are delaying compliance with the Tier 1 standard of 1.4 g/km HC+NOx until the
2008 model year for small manufacturers, and at this time, we are not requiring these
manufacturers to meet the Tier 2 standard. The existing California regulations do not require
small manufacturers to comply with the Tier 2 standard of 0.8 g/km HC+NOx. The California
Air Resources Board (ARE) found that the Tier 2 standard represents a significant technological
challenge and is a potentially infeasible limit for these small manufacturers. As noted above,
many of these manufacturers market specialty products with a "retro" simplicity and style that
may not easily lend itself to the addition of advanced technologies like catalysts and electronic
fuel injection. However, the California ARB has acknowledged that, in the course of their
progress review planned for 2006, they will revisit their small-manufacturer provisions. We plan
to participate with the ARB and others in the 2006 progress review. Following our review of
these provisions, as appropriate, we may decide to propose to make changes to the emission
standards and related requirements through notice and comment rulemaking, including the
applicability of Tier 2 to small businesses. The hardship provisions described above could be
used to provide a small manufacturer with yet additional lead time if justified.
8.6.2 Broader Engine Families
Small businesses have met EPA certification requirements since 1978. Nonetheless,
certifying motorcycles to revised emission standards has cost and lead time implications.
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Relaxing the criteria for what constitutes an engine or vehicle family could potentially allow
small businesses to put all of their models into one vehicle or engine family (or more) for
certification purposes. Manufacturers would then certify their engines using the "worst case"
configuration within the family. This is currently allowed under the existing regulations for
small-volume highway motorcycle manufacturers. These provisions remain in place without
revision.
8.6.3 Averaging, Banking, and Trading
An emission-credit program allows a manufacturer to produce and sell engines and
vehicles that exceed the applicable emission standards, as long as the excess emissions are offset
by the production of engines and vehicles emitting at levels below the standards. The sales-
weighted average of a manufacturer's total production for a given model year must meet the
standards. An emission-credit program typically also allows a manufacturer to bank credits for
use in future model years. The emission-credit program we are implementing for all highway
motorcycle manufacturers includes emissions averaging within the three classes of motorcycles
and allows for averaging between the Classes I and II and averaging between Class III and
Classes I/II with the restriction that credits can flow only out of Class III into Classes I and II,
and not the opposite. The banking program is limited to the Class III Tier 2 requirements; these
do not involve small motorcycle manufacturers at this time. Some credit programs allow
manufacturers to buy and sell credits (trade) between and among themselves. We are not
implementing such a provision at this time, but such flexibility could be made available to all
small manufacturers as part of the upcoming technology review.
8.6.4 Reduced Certification Data Submittal and Testing Requirements
Current regulations allow significant flexibility for certification by manufacturers
projecting sales below 10,000 units of combined Class I, II, and III motorcycles. For example, a
qualifying manufacturer must submit an application for certification with a statement that their
vehicles have been tested and, on the basis of the tests, conform to the applicable emission
standards. The manufacturer retains adequate emission test data, for example, but need not
submit it. Qualifying manufacturers also need not complete the detailed durability testing
required in the regulations. We are incorporating no changes to these existing provisions.
8.6.5 Hardship Provisions
We proposed two types of hardship provisions, one of which was intended specifically
for small businesses and the other intended for all manufacturers. The first type of hardship
provision allows a small volume motorcycle manufacturer to petition for up to three years
additional lead time if the manufacturer can demonstrate that it has taken all possible steps to
comply with the standards but the burden of compliance would have a significant impact on the
company's solvency. The second type of hardship provision allows a company to apply for
hardship relief if circumstances outside of the company's control cause a failure to comply, and
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the failure to sell the noncompliant product would have a major impact on the company's
solvency.
In general, we do not expect that manufacturers will need to use these hardship
provisions. However, having such provisions available gives us the flexibility to
administratively deal with a unexpected situations that may arise as companies work toward
compliance with the regulations. Thus, we are adopting these hardship provisions as proposed.
8.7 - Conclusion
EPA has conducted a substantial outreach program designed to gather information as to
the effect of this final rulemaking on small entities. This process included a SBAR Panel, which
sought advice and recommendations from potentially affected small entities regarding ways to
minimize their compliance burden. We published both an ANPRM and a NPRM which
requested comments from potentially affected entities, as well as other interested parties in the
public at large. From the information that we have gathered during this process, we have found
that there are 42 manufacturers that certified motorcycles in the year 2003. Of these, 30
manufacturers are small by the SBREFA definition given in section 8.4. However, certification
emission data indicates that essentially all of these 30 manufacturers are currently meeting the
Tier 1 exhaust emission standard. Given small costs of complying with the permeation
evaporative emission requirements and the lead time and other flexibilities that are being
finalized in this rulemaking, these manufacturers will not be significantly affected by the rule.
Therefore, we have determined that this final rulemaking will not have a significant economic
impact on a substantial number of small entities.
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