California Air Resources Board

Vehicles that can use a combination of fuels such as alcohol fuel and unleaded gasoline.

Air borne solid particles that result from the burning of coal and other solid fuel.

Any active duty military personnel of a foreign country assigned to a California military installation as part of an exchange or joint training agreement authorized or sponsored by the U.S. Department of Defense. Foreign Military Officers are not subject to California direct import vehicle requirements for registration and have the same privileges as out-of-state military personnel.

Fuels such as coal, oil and natural gas; so-called because they are the remains of ancient plant and animal life.

An electrochemical cell that captures the electrical energy of a chemical reaction between fuels such as liquid hydrogen and liquid oxygen and converts it directly and continuously into the energy of a direct electrical current. For more information, see the ARB's fuel cell portal.

A zero-emission vehicle that runs on compressed hydrogen fed into a fuel cell "stack" that produces electricity to power the vehicle.

Dust particles that are introduced into the air through certain activities such as soil cultivation, or vehicles operating on open fields or dirt roadways. This is a subset of fugitive emissions.

Emissions not caught by a capture system; which are often due to equipment leaks, evaporative processes and windblown disturbances.

Solid particles under 1 micron in diameter formed as vapors condense, or as chemical reactions take place.

The California Environmental Quality Act (CEQA) allows public agencies to prepare a plan or other written documentation in lieu of an environmental impact report (i.e., a functional equivalent environmental document) which outlines the environmental analyses as part of any regulatory process. Prior to taking final action on any proposal for which significant environmental issues have been raised, the decision maker will provide a written response to each such issue.

A combustion chamber; an enclosed structure in which fuel is burned to heat air or material.

An engine that uses a compressor to draw in air and compress it. Fuel is then added to the air and combusted in a combustor. Hot combustion gases exiting the engine turn a turbine which also turns the compressor. The engine's power output can be delivered from the compressor or turbine side of the engine.

The evaporative properties of gasoline. Gasoline vapor is a volatile organic compound. (See also Reid Vapor Pressure.)

An increase in the temperature of the Earth's troposphere. Global warming has occurred in the past as a result of natural influences, but the term is most often used to refer to the warming predicted by computer models to occur as a result of increased emissions of greenhouse gases. For more information, go to ARB's climate change website.

The relative warming of a greenhouse gas over a specified period of time as compared to carbon dioxide (GWP of 1). GWP allows for the conversion of different greenhouse gas emissions into the same emissions unit, carbon dioxide equivalents (CO₂E).

A score that ranks each vehicle's CO₂-equivalent value on a scale of 1-10 (10 being the cleanest) relative to all other vehicles. All vehicles manufactured after January 1, 2009, must display this score on the Environmental Performance Label.

The processes and activities involved in the pickup, movement and delivery of goods (agricultural, consumer, industrial products and raw materials) from producers/points of origin to consumers/point of use or delivery. 'Goods movement' relies on a series of transportation, financial and information systems for this to occur, that involves an international, national, state, regional and local networks of producers and suppliers, carriers and representative agents from the private sector, the public sector (federal, state, regional and local governmental agencies) and the general public.

The warming effect of the Earth's atmosphere. Light energy from the sun which passes through the Earth's atmosphere is absorbed by the Earth's surface and re-radiated into the atmosphere as heat energy. The heat energy is then trapped by the atmosphere, creating a situation similar to that which occurs in a car with its windows rolled up. A number of scientists believe that the emission of CO₂ and other gases into the atmosphere may increase the greenhouse effect and contribute to global warming. (Climate Change: see ClimateChange.ca.gov gloss.)

Atmospheric gases such as carbon dioxide, methane, chlorofluorocarbons, nitrous oxide, ozone and water vapor that slow the passage of re-radiated heat through the Earth's atmosphere. (See also ClimateChange.ca.gov gloss.)

Greenhouse Gases, Regulated Emissions and Energy Use in Transportation model used to determine emissions from various vehicle and fuel combinations.

A motor vehicle originally intended by its manufacturer for sale outside of the United States. Such a vehicle does not have the same registration rights a vehicle intended by its manufacturer for sale in the United States.

A plan for a given geographical region containing demographic projections (i.e., housing units, employment and population) through some specified point in time and which provides recommendations for local governments to better manage growth and reduce projected environmental impacts.

An air pollutant listed under section 112 (b) of the Federal Clean Air Act as particularly hazardous to health. Emission sources of hazardous air pollutants are identified by U.S. EPA and emission standards are set accordingly. For more information, visit our Title III website area.

A phenomenon that results in reduced visibility due to the scattering of light caused by aerosols. Haze is caused in large part by man-made air pollutants.

A document that identifies the risks and quantities of possible adverse health effects that may result from exposure to emissions of toxic air contaminants. A health risk assessment cannot predict specific health effects; it only describes the increased possibility of adverse health effects based on the best scientific information available.

A dosage of air pollution scientifically determined to protect against human health effects such as asthma, emphysema and cancer.

This regulation authorizes random roadside smoke opacity testing of heavy-duty diesel trucks and buses. The opacity of exhaust emitted from these engines must not exceed 40 percent (1991 and newer engine model years) or 55 percent (all pre-1991 engines). Gasoline and diesel trucks and buses are also inspected for tampering and for engine certification label compliance.