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Voluntary Diesel Retrofit Program
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Glossary

(Terms with the ? symbol are linked to this glossary)

Aftertreatment device Engine pollutant emissions are generally reduced by engine modifications, fuel specifications or exhaust gas aftertreatment. An aftertreatment device is a component used to reduce engine pollutant emissions downstream of the combustion chamber. Catalytic converters and particulate traps are examples of aftertreatment devices.

Alternative Fuel An alternative fuel is any fuel other than gasoline and diesel fuels, such as methanol, ethanol, compressed natural gas, and other gaseous fuels. Generally, alternative fuels burn more cleanly and result in less air pollution.

Catalytic Converter A catalytic converter consists of a metal housing filled with a hard material which is covered with a catalytic compound. The presence of the catalytic converter in the engine exhaust system breaks down the chemicals in the exhaust and reduces harmful pollutant emissions.

Certified Certification means, with respect to new highway and nonroad engines, obtaining a certificate of conformity for an engine family that complies with the highway or nonroad engine emission standards and requirements.

CMAQ Congestive Mitigation and Air Quality Improvement Program.  CMAQ was introduced in the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA). It is set up to provide Federal funding to help fulfill Clean Air Act mandates in areas that do not meet ambient air quality standards or may have trouble meeting those standards (nonattainment or maintenance areas).

Conformity (Rule) The conformity rule requires that transportation plans, programs, and projects conform to state air quality implementation plans (SIPs) and establishes the criteria and procedures to determine if plans comply. Conformity to a SIP means that transportation activities will not produce new air quality violations, worsen existing violations, or delay timely attainment of the national ambient air quality standards.

CO Carbon monoxide (CO) is a colorless, odorless and poisonous gas produced by the burning of fuels. Automobiles are the primary source of CO pollution. When CO enters the bloodstream, it reduces the delivery of oxygen to the body's organs and tissues. Health threats are most serious for those who suffer from cardiovascular disease, particularly those with angina or peripheral vascular disease. Exposure to elevated CO levels can cause impairment of visual perception, manual dexterity, learning ability and performance of complex tasks.

77% of the nationwide CO emissions are from transportation sources. The largest emissions contribution comes from highway motor vehicles. Thus, the focus of CO monitoring has been in urban areas where the main source of CO is motor vehicle exhaust. Other major CO sources are wood-burning stoves, incinerators and industrial sources.

Diesel Engine An engine that operates on diesel fuel and principally relies on compression-ignition for engine operation. The non-use of a throttle during normal operation is indicative of a diesel engine.

Engine Family Each group of engines with similar emission characteristics is defined as a separate engine family. Vehicles or engines in an engine family are expected to have similar emission characteristics. A permanent label is affixed to the engine which list the engine family designation as well as other important information

Environmental Justice The goal of environmental justice is to ensure that all people, regardless of race, national origin or income, are protected from the adverse impacts of environmental hazards and to ensure that one group is not disproportionately affected. To be classified as an environmental justice community, residents must be a minority and/or low income group; excluded from the environmental policy setting and/or decision-making process; subject to a disproportionate impact from one or more environmental hazards; and experience a disparate implementation of environmental regulations, requirements, practices and activities in their communities. Environmental justice is about real people facing real problems and designing practical solutions to address challenging environmental issues. The environmental justice movement advocates programs that promote environmental protection within the context of sustainable development. Utilizing various methods, including traditional knowledge about the eco-system and community mobilization, the environmental justice community has become a formidable force in protection of both the urban and rural environments.

ETV ETV is the abbreviation for EPA's Environmental Technology Verification Program which was established to carefully examine and judge the efficacy of a technology. The goal of ETV is to verify the environmental performance characteristics of commercial-ready technology through the evaluation of objective and quality assured data, so that potential purchasers and permitters are provided with an independent and credible assessment of what they are buying and permitting. For more information on ETV see http://www.epa.gov/etv/centers/center5.html.

HC An exhaust and evaporative pollutant of hydrogen and carbon atoms resulting from unburned fuel. HC contributes to the formation of ozone which is responsible for the choking, coughing, and stinging eyes associated with smog. Ozone damages lung tissue, aggravates respiratory disease, and makes people more susceptible to respiratory infections. Children are especially vulnerable to ozone's harmful effects, as are adults with existing disease.

Highway Engine Any engine which is designed to transport people or property on a street or highway.

Low Sulfur Fuel Current EPA regulations specify that diesel test fuel contain 300 - 500 ppm sulfur for highway engines and 300 - 4000 ppm sulfur for nonroad engines. Significant reductions from these current sulfur levels are necessary in order for many retrofit technologies to provide meaningful, lasting emissions reductions. The manufacturers of these retrofit technologies will specify the maximum allowable sulfur level for effective operation of its products. In addition to enabling a wide array of emissions control technologies, the use of low sulfur alone reduces emissions of particulate matter. Sulfate, a major constituent of particulate matter, is produced as a byproduct of burning diesel fuel containing sulfur. Reducing the sulfur content of fuel in turn reduces sulfate byproducts of combustion and therefore particulate matter emissions. The retrofit program will verify particulate matter reductions from the use of low sulfur alone. For the purposes of the diesel retrofit program diesel fuel must contain less than 50 ppm sulfur to be considered a low sulfur fuel.

Marine Engine An engine that is installed or intended to be installed on a marine vessel. This definition does not include portable auxiliary engines for which the fueling, cooling and exhaust systems are not integral parts of the vessel.

Model Year The manufacturer's annual new model production period which includes January 1 of the calendar year, ends no later than December 31 of the calendar year, and does not begin earlier than January 2 of the previous calendar year. Where a manufacturer has no annual new model production period, model year means calendar year.

National Ambient Air Quality Standards (NAAQS) The Clean Air Act, which was last amended in 1990, requires EPA to set National Ambient Air Quality Standards for pollutants considered harmful to public health and the environment. The Clean Air Act established two types of national air quality standards. Primary standards set limits to protect public health, including the health of "sensitive" populations such as asthmatics, children, and the elderly. Secondary standards set limits to protect public welfare, including protection against decreased visibility, damage to animals, crops, vegetation, and buildings.

The EPA Office of Air Quality Planning and Standards (OAQPS) has set National Ambient Air Quality Standards for six principal pollutants, which are called "criteria" pollutants. The standards can be viewed on the OAQPS Web site.

NESCAUM "NESCAUM" is the acronym for the Northeast States for Coordinated Air Use Management, an interstate association of air quality control divisions in the Northeast states. The eight member states are comprised of the six New England States, as well as New York and New Jersey. NESCAUM's purpose is to exchange technical information, and to promote cooperation and coordination of technical and policy issues regarding air quality control among the member states. To accomplish this, NESCAUM sponsors air quality training programs, participates in national debates, assists in exchange of information, and promotes research initiatives.

Nonattainment area A locality where air pollution levels persistently exceed National Ambient Air Quality Standards. Designating an area as nonattainment is a formal rulemaking process and EPA normally takes this action only after air quality standards have been exceeded for several consecutive years.

Nonroad Engine Although nonroad engines can be self-propelled, their primary function is to perform a particular task. Examples of nonroad engines include garden tractors, lawnmowers, bulldozers and cranes. More information.

NOx Oxides of nitrogen (NOx) are a family of reactive gaseous compounds that contribute to air pollution in both urban and rural environments. NOx emissions are produced during the combustion of fuels at high temperatures. The primary sources of atmospheric NOx include highway sources (such as light-duty and heavy-duty vehicles), nonroad sources (such as construction and agricultural equipment, and locomotives) and stationary sources (such as power plants and industrial boilers). NOx can irritate the lungs, cause bronchitis and pneumonia, and lower resistance to respiratory infections. Nitrogen oxides are an important precursor both to ozone and acid rain, and may affect both terrestrial and aquatic ecosystems.

Oxidation Catalyst A type of catalyst (catalytic converter) which chemically converts HC (hydrocarbons) and CO (carbon monoxide) to water vapor and carbon dioxide.

Ozone Ozone (O3) is a photochemical oxidant and the major component of smog. While O3 in the upper atmosphere shields the earth from harmful ultraviolet radiation that comes from the sun, high concentrations of O3 at ground level are a major health and environmental concern. O3 is not emitted directly into the air but is formed through complex chemical reactions between emissions of volatile organic compounds (VOC) and oxides of nitrogen (NOx) in the presence of sunlight. These reactions are stimulated by sunlight and temperature so that peak O3 levels occur typically during the warmer times of the year. Both VOCs and NOx are emitted by transportation and industrial sources such as autos, chemical manufacturing, dry cleaners and paint shops.

O3 causes health problems because it damages lung tissue, reduces lung function and sensitizes the lungs to other irritants. Scientific evidence indicates that ambient levels of O3 not only affect people with impaired respiratory systems, such as asthmatics, but healthy adults and children as well. Exposure to O3 for several hours at relatively low concentrations has been found to significantly reduce lung function and induce respiratory inflammation in normal, healthy people during exercise. This decrease in lung function generally is accompanied by symptoms including chest pain, coughing, sneezing and pulmonary congestion.

Particulate Trap/Filter An aftertreatment device which filters or traps diesel particulate matter from engine exhaust until the trap becomes loaded to the point that a regeneration cycle is implemented to burn off the trapped particulate matter.

PM Particulate matter (PM) includes dust, dirt, soot, smoke and liquid droplets directly emitted into the air by sources such as factories, power plants, cars, engines, construction activity, fires and natural windblown dust. Particles formed in the atmosphere by condensation or the transformation of emitted gases are also considered particulate matter.

Based on studies of human populations exposed to high concentrations of particles (sometimes in the presence of SO2) and laboratory studies of animals and humans, the health effects associated with exposure to PM are serious. They include effects on breathing and respiratory symptoms, aggravation of existing respiratory and cardiovascular disease, alterations in the body's defense systems against foreign materials, damage to lung tissue, as well as premature death. The major subgroups of the population that appear to be most sensitive to the effects of particulate matter include individuals with chronic obstructive pulmonary or cardiovascular disease or influenza, asthmatics, the elderly and children. Particulate matter also soils and damages materials, and is a major cause of impaired visibility in the United States.

Retrofit An engine "retrofit" includes (but is not limited to) any of these activities:

-addition of new/better pollution control aftertreatment equipment to certified engines
- upgrading a certified engine to a cleaner certified configuration
- upgrading an uncertified engine to a cleaner "certified-like" configuration
- conversion of any engine to a cleaner fuel
- early replacement of older engines with newer (presumably cleaner) engines (in lieu of regular expected rebuilding)
- use of cleaner fuel and/or emission reducing fuel additive (w/o engine conversion)

Retrofit Manufacturer Any party engaged in the manufacturing, producing or assembling engine pollution control equipment, upgrade kits, replacement engines, or clean fuel or fuel additives designed to be used by participants in the Voluntary Diesel Retrofit Program.

State Implementation Plan (SIP) State Implementation Plan (SIP) is a written plan that describes a State's strategy for achieving and maintaining the National Ambient Air Quality Standards. Section 110 of the Clean Air Act requires that states developair quality plans for areas that do not meet national air standards outlining how they will reduce pollution. SIPs assure that programs designed to achieve emission reductions are implemented.

SIP Credit The permanent, measurable emission benefits that are accounted for in a State Implementation Plan.

Upgrade Kit An upgrade kit consists of a set of later model year engine components, such as fuel injectors, piston assemblies, ring sets, liners and camshafts, and engine calibrations that would be installed on an older version of the engine. The purpose of an upgrade kit is to make the older version of the engine closer, or perhaps identical to, a newer or current version of the engine. This will result in making the upgraded engine cleaner.

Verified Retrofit Technology List This is a list that EPA prepares of Heavy Duty Diesel (HDD) emission control technologies that are suitable for use with HDD engines. If a control technology appears on EPA's list, the manufacturer’s emission reduction claims have been confirmed through EPA’s Environmental Technology Verification Program. For more information on ETV see http://www.epa.gov/etv/centers/center5.html.

Voluntary Mobile Source Emission Reduction Policy (VMEP) VMEP is a policy that allows States to obtain SIP credits for voluntary emission reduction activities. The policy also encourages investment in innovative emission reduction programs and actions. More information




Abbreviations

CRT Continuously Regenerating Technology
CEM Catalytic Exhaust Muffler
FHWA Federal highway Administration
FTP Federal Test Procedure
MERCS Mobile Source Emission Reduction Credits
NAAQS National Ambient Air Quality Standards
NEJAC National Environmental Justice Advisory Council
OAR Office of Air and Radiation
OCHP Office of Children's Health Protection
OTAQ Office of Transportation and Air Quality
SCR Selective Catalytic Reduction
SCRT Selective Catalytic Reduction and Continuously Regenerating Technology
TRAQ Transportation Air Quality Center
VEMP Voluntary Mobile Source Emission Reduction Programs
Key Topics: Overview
Perspectives: Air Quality Planners
Perspectives: Fleet Owner
Perspectives: Retrofit Maker
Diesel Emissions
Diesel Timeline
Economic Incentives
Emissions Trading
Retrofit Workshop
NESCAUM Report

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