See Also Glossary of Acronyms

Acute Health Effect: An adverse heath effect that occurs over a relatively short period of time, (e.g., minutes, or hours.)

Adverse Health Effect: A health effect from exposure to air contaminants that may range from relatively mild temporary conditions, such as eye or throat irritation, shortness of breath, or headaches to permanent and serious conditions, such as birth defects, cancer or damage to lungs, nerves, liver, heart, or other organs.

Aerosol: Particles of solid or liquid matter that can remain suspended in the air from a few minutes to many months depending on the particle size and weight.

Agricultural Burning: The intentional use of fire for vegetation management in areas such as agricultural fields, orchards, rangelands, and forests. The regulation of agricultural burning is described in the Agricultural Burning Guidelines, Title 17, California Code of Regulations.

Air Basin: An area of the state, often comprising several counties, which is designated by the Air Resources Board (ARB) based on similar meteorological and geographical conditions, with consideration given to political boundary lines when practical. Using these criteria, the ARB has divided the state into 15 air basins. Santa Barbara County is located in the South Central Air Basin, along with San Luis Obispo and Ventura Counties.

Air District: A political body responsible for managing air quality on a regional or county basis. California is divided into 35 air districts. (See also air pollution control district).

Air Monitoring: Sampling for and measuring of pollutants present in the atmosphere.

Air Pollutant: Any foreign and/or natural substance that is discharged, released, or over propagated into the atmosphere that may result in adverse effects on humans, animal, vegetation and/or materials. Also known as an air contaminant. Examples include but are not limited to, smoke, charred paper, dust, soot, grime, carbon, fumes, gases, odors, particulate matter, acids, or any combination thereof.

Air Pollution: Degradation of air quality resulting from unwanted chemicals or other materials in the air.

Air Pollution Control District (APCD): This is the local agency that has authority to regulate stationary, indirect, and area sources of air pollution and governing air quality issues. The APCD proposes and adopts local air pollution rules, enforces those rules, responds to air pollution related complaints, issues permits to polluting sources, inventories sources of air pollution emissions. 

Air Quality Attainment Plan (AQAP): The comprehensive document, required under the California Clean Air Act (Health and Safety Code Section 40910 et. seq.), which details the programs and control measures to be implemented for the purpose of reducing emissions. Emissions ultimately must be reduced to the extent that measured concentrations of pollutants in the air will not exceed California ambient air quality standards.

Air Quality Index (AQI): The USEPA recently revised its methods of reporting air quality and the associated health effects. The Air Quality Index replaces the Pollutant Standards Index (PSI) previously used to report air quality to the public. The AQI is a measure of air quality based on a percentage of the federal air quality standard. An AQI of 100 means the pollutant level is equal to the federal standard for that pollutant. An AQI below 100 means the air quality is better than the standard, and above 100 can be considered unhealthful. The higher the number, the more air pollution we are breathing. In Santa Barbara County, we report the AQI for ozone, based on the federal 8-hour standard. Ozone is the only pollutant for which we have recently violated a federal air quality standard.

Air Quality Simulation Model: A computer program that simulates the transport, dispersion, and transformation of compounds emitted into the air and can project the relationship between emissions and air quality.

Air Toxics: A generic term referring to a harmful chemical or group of chemicals in the air. Typically, substances that are especially harmful to health, such as those considered under EPA's hazardous air pollutant program or California's AB 1807 toxic air contaminant program, are considered to be air toxics. Technically, any compound that is in the air and has the potential to produce adverse health effects is an air toxic.

Airborne Toxic Control Measure (ATCM): A type of control measure, adopted by the ARB (Health and Safety Code Section 39666 et seq.), which reduces emissions of toxic air contaminants from non-vehicular sources. 

Alternate Fuels: Any fuel used for vehicular sources other than standard gasoline or diesel fuels. These include ethanol, methanol, compressed natural gas, liquid petroleum gas and electricity. Alternative fuels are cleaner burning and help meet ARB's mobile and stationary emission standards.

Ambient Air: The air that is in the troposphere and is subjected to meteorological and climatic change. Often used interchangeably with "outdoor" air.

Ambient Air Quality Standard: Health and welfare based standards established by the state or federal government for clean outdoor air that identify the maximum acceptable average concentrations of air pollutants during a specified period of time.

Ammonia (NH₃): A pungent colorless gaseous compound of nitrogen and hydrogen that is very soluble in water and can easily be condensed into a liquid by cold and pressure. Ammonia reacts with NOx to form ammonium nitrate--a major PM2.5 component in the Western United States.

Anthropogenic Emissions: Emissions related to human activity or devices.

ARB (California Air Resources Board): The State's lead air quality agency, consisting of a nine-member Governor-appointed board. It is responsible for attainment and maintenance of the State and federal air quality standards, and is fully responsible for motor vehicle pollution control. It oversees county and regional air pollution management programs.

Area-Wide Source: Stationary sources of pollution (e.g., water heaters, gas furnaces, fireplaces, and residential wood stoves) that are typically associated with homes and non-industrial sources. The emissions from these sources in themselves don’t emit a significant amount of emissions, but when considered collectively with other similar sources become significant. The CCAA requires districts to include area-wide sources in the development and implementation of the AQAPs.

Atmosphere: The gaseous mass or envelope surrounding the earth. From ground level up, the atmosphere is further subdivided into the troposphere, stratosphere, mesosphere, and the thermosphere. Where air pollutants are emitted into a building not designed specifically as a piece of air pollution control equipment, such emission into the building shall be considered an emission into the atmosphere.

Attainment: Achievement of air quality standards.

Attainment Area: A geographic area which is in compliance with the National and/or California Ambient Air Quality Standards (NAAQS OR CAAQS) for a criteria pollutant under the Federal Clean Air Act or California Clean Air Act.

Attainment Plan: In general, a plan that details the emission reducing control measures and their implementation schedule necessary to attain air quality standards. In particular, the federal Clean Air Act requires attainment plans for nonattainment areas; these plans must meet several requirements, including requirements related to enforceability and adoption deadlines.

Average Daily Emissions: Annual emissions divided by 365 (the number of days in a year).

Best Available Control Measure (BACM): A term used to describe the "best" measures (according to U.S. EPA guidance) for controlling small or dispersed sources of particulate matter and other emissions from sources such as roadway dust, woodstoves, and open burning.

Best Available Control Technology (BACT): The most up-to-date methods, systems, techniques, and production processes available to achieve the greatest feasible emission reductions for given regulated air pollutants and processes. BACT is a requirement of NSR (New Source Review) and PSD (Prevention of Significant Deterioration). BACT as used in federal law under PSD is defined as an emission limitation based on the maximum degree of emissions reductions allowable taking into account energy, environmental & economic impacts and other costs. [(CAA Section 169(3))]. The term BACT as used in state law means, an emission limitation that will achieve the lowest achievable emission rates, which means the most stringent of either the most stringent emission limits contained in the SIP for the class or category of source, (unless it is demonstrated that one limitation is not achievable), or the most stringent emission limit achieved in practice by that class in category of source. "BACT" under state law is more stringent than federal BACT and is equivalent to federal LAER (lowest achievable emission rate) which applies to NSR permit actions.

In Santa Barbara County, for nonattainment pollutants, BACT for any stationary source is the more stringent of either: a) the most effective emission control device, emission limit, or technique which has been achieved in practice for the type of equipment comprising such stationary source; or b) any other emission control device or technique determined after public hearing to be technologically feasible and cost-effective by the Air Pollution Control Officer; or c) the most stringent limitation contained in any State Implementation Plan. For attainment pollutants, BACT is an emission limitation based on the maximum degree of reduction for each pollutant which would be emitted from any new or modified stationary source, which on a case-by-case basis, taking into account energy, environmental, and economic impacts and other costs, is achievable for such source or modification through application of production processes or available methods, systems, and techniques, including fuel cleaning or treatment or innovative fuel combustion techniques for control of such pollutant.

BAR (Bureau of Automotive Repair): An agency of the California Department of Consumer Affairs that manages the implementation of the motor vehicle Inspection and Maintenance Program.

Best Available Mitigation Measures (BAMM): Design or operation measures that are directly related to the particular project, and are intended to reduce the number of vehicle trips.

Best Available Retrofit Control Technology (BARCT): An emission limitation based on the maximum degree of reduction achievable by existing sources, taking into consideration environmental, energy and economic needs.

Biogenic Emissions: Biological sources such as plants and animals that emit air pollutants such as volatile organic compounds. Examples of biogenic sources include animal management operations, and oak and pine tree forests. (See also natural resources).

California Air Resources Board (ARB or CARB): The State's lead air quality agency consisting of an eleven-member board appointed by the Governor and several hundred employees. CARB is responsible for attainment and maintenance of the state and federal air quality standards, and is fully responsible for motor vehicle pollution control. CARB oversees county and regional air pollution management programs.

California Ambient Air Quality Standards (CAAQS): Standards set by the State of California for the maximum levels of air pollutants which can exist in the outdoor air without unacceptable effects on human health or the public welfare. These are more stringent than NAAQS.

California Clean Air Act of 1988 (CCAA): The amendments to the California Health and Safety Code resulting from the passage of Assembly Bill 2595. A California law passed in 1988 which provides the basis for air quality planning and regulation independent of federal regulations. A major element of the Act is the requirement that local APCD’s in violation of state ambient air quality standards must prepare attainment plans which identify air quality problems, causes, trends, and actions to be taken to attain and maintain California's air quality standards by the earliest practicable date.

California Environmental Protection Agency (Cal/EPA): A state government agency established in 1991 for unifying environmental activities related to public health protection in the State of California. There are six boards, departments, and offices under the organization of Cal/EPA including the California Air Resources Board (ARB), California Integrated Waste Management Board (IWMB), State Water Resources Control Board (SWRCB), and its nine Regional Water Quality Control Boards (DTSC), and Office of Environmental Health Hazard Assessment (OEHHA). The Cal/EPA boards, departments, and offices are directly responsible for implementing California environmental laws, or play a cooperative role with other regulatory agencies at regional, local, state and federal levels.

California Environmental Quality Act (CEQA): A California law which sets forth a process for public agencies to make informed decisions on discretionary project approvals. The process aids decision makers to determine whether any environmental impacts are associated with a proposed project. It requires environmental impacts associated with a proposed project to be identified, disclosed, and mitigated to the maximum extent feasible.

Carl Moyer Fund: A multi-million dollar incentive grant program designed to encourage reduction of emissions from heavy-duty engines. The grants cover the additional cost of cleaner technologies for on-road, off-road, marine, locomotive and agricultural pump engines, as well as forklifts and airport ground support equipment.

CFCs (Chlorofluorocarbons): Any of a number of substances consisting of chlorine, fluorine, and carbon. CFCs are used for refrigeration, foam packaging, solvents, and propellants. They have been found to cause depletion of the atmosphere's ozone layer.

Chronic Health Effect: An adverse health effect which occurs over a relatively long period of time (e.g., months or years).

CO (Carbon Monoxide): A colorless, odorless gas resulting from the incomplete combustion of fossil fuels. Over 80% of the CO emitted in urban areas is contributed by motor vehicles. CO interferes with the blood's ability to carry oxygen to the body's tissues and results in numerous adverse health effects. CO is a criteria air pollutant. This is one of the six pollutants for which there is a national ambient standard.

Commute: A home-to-work or work-to-home trip made regularly in connection with employment.

Commute Alternatives: Carpooling, vanpooling, transit, bicycling, and walking as commute modes during peak period, as well as any Alternative Work Hours Program which results in the use of any mode of transportation for commuting outside of the peak periods.

Compliance Efficiency: The percent of emission sources subject to a control measure that are in compliance with its requirements. EPA recommends that compliance efficiency is assumed to be 80 percent unless a District proves otherwise.

Composite Efficiency: The efficiency value which represents the actual effect of a control measure on a source category. Composite efficiency is calculated by finding the product of the control efficiency, percent implementation, the compliance efficiency, and the fraction of the source category affected.

Compressed Natural Gas: An alternative fuel used in motor vehicles; considered one of the cleanest alternative fuels because of low hydrocarbon emissions. However, it does emit a significant quantity of nitrogen oxides.

Compressed Work Schedules: Work schedules that compress the traditional 40 hour weekly work period into fewer than five days by adopting longer work day such as 4/40 (4-ten hour days), and 9/80 (8-nine hour and 1-eight hour days out of every ten work days).

Conformity: Conformity is a process mandated in the federal Clean Air Act to insure that federal actions do not impede attainment of the federal air quality standards. General conformity sets out a process that requires federal agencies to demonstrate that their actions are air quality neutral or beneficial. Transportation conformity sets out a process that requires transportation projects that receive federal funding, approvals or permits to demonstrate that their actions are air quality neutral or beneficial.

Congestion: Traffic conditions on roads, highways, or freeways which do not permit movement at optimal legal speeds.

Congestion Management Program: A state mandated program (Government Code Section 65089a) that requires each county to prepare a plan to relieve congestion and reduce air pollution.

Consumer Products: Products such as detergents, cleaning compounds, polishes, lawn and garden products, personal care products, and automotive specialty products which are part of our everyday lives and, through consumer use, may produce air emissions which contribute to air pollution. 

Contiguous Property: Two or more parcels of land with a common boundary or that are separated solely by a public roadway or other public right-of-way.

Contingency Measure: Contingency measures are statute-required back-up control measures to be implemented in the event of specific conditions. These conditions can include failure to meet interim milestone emission reduction targets or failure to attain the standard by the statutory attainment date. Both state and federal Clean Air Acts require that District plans include contingency measures.

Control Efficiency: The percent of emissions that are controlled (i.e. not emitted) as a result of some control on a polluting device or process.

Control Measure: A strategy to reduce the emissions of air pollution caused by a specific activity or related group of activities. An existing control measure is a measure which is currently being implemented as a rule. A proposed for adoption control measure is a measure that the APCD will be mandated to make into a rule if the plan is approved by the Board. A further study control measure is a measure that has the potential of being proposed for adoption, but warrants further study.

Corporate Average Fuel Economy: The sales-weighted average fuel economy of an automobile manufacturer's annual production; CAFE is also used to refer to the Federal law that mandates that automobile manufacturers meet minimum average fuel economy standards.

Cost-Effective: A cost per unit of emission reduction which is lower than or equivalent to the maximum unit costs of the same emission reduction through the use of demonstrated Best Available Control Technology, calculated in current year dollars.

Cost-Effectiveness: For APCD rulemaking purposes, this is defined as the control method costs (dollars) divided by the emission reductions (tons) expected from the control method.

Criteria Pollutants: Pollutants for which State or National Ambient Air Quality Standards exist. Criteria pollutants include ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, lead, sulfates, hydrogen sulfide, and particulate matter with a diameter of 10 microns or less.

Design Day Value: For ozone, the state defines that a calculated design day is based on three years of data excluding: extreme values, values that result from exceptional events or values attributable to overwhelming transport from an upwind district. Under federal law, the design day for ozone is the fourth highest one-hour concentration experienced at an individual monitoring station during the past three years.

Electric Motor Vehicle: A motor vehicle, which uses a battery-powered electric motor as the basis of its operation. Such vehicles emit virtually no air pollutants. Hybrid electric motor vehicles may operate using both electric and gasoline powered motors. Emissions from hybrid electric motor vehicles are also substantially lower than conventionally powered motor vehicles.

Emission Budget: An emission "ceiling" for future transportation emissions that cannot be exceeded. 

Emission Factor: For stationary sources, the relationship between the amount of pollution produced and the amount of raw material processed or burned. For mobile sources, the relationship between the amount of pollution produced and the number of vehicle miles traveled. By using the emission factor of a pollutant and specific data regarding quantities of materials used by a given source, it is possible to compute emissions for the source. This approach is used in preparing an emissions inventory. EMFAC is the Emission Factor model used by ARB to calculate on-road mobile vehicle emissions. This model is part of ARB’s overall on-road mobile source Mobile Vehicle Emission Inventory (MVEI) model.

Emission Forecasting: Estimating air pollutant emissions in future years using population, economic and control projections.

Emission Inventory: An estimate of the amount of pollutants emitted from mobile and stationary sources into the atmosphere over a specific period such as a day or a year.

Emission Offsets: A rule-making concept whereby approval of a new or modified stationary source of air pollution is conditional on the reduction of emissions from other existing stationary sources of air pollution. These reductions are required in addition to reductions required by BACT.

Emission Reductions: The amount of emissions that will be reduced due to the implementation of a control measure. Emission reductions can be calculated by finding the product of the emissions and the composite efficiency, while accounting for existing control.

Emission Standard: The maximum amount of a pollutant that is allowed to be discharged from a polluting source such as an automobile or smoke stack.

Employment Centers: Locations having a concentration of jobs or employment. Centers may vary in size and density, serving sub-regional or local markets, generally meeting the needs of the immediate population.

Environmental Impact Report (EIR): A document discussing the potential adverse environmental impacts of a project required by the California Environmental Quality Act.

Environmental Protection Agency (EPA): The United States agency charged with setting policy and guidelines, and carrying out legal mandates for the protection of national interests in environmental resources.

Ethanol: A clear liquid derived from biomass (also known as "ethyl alcohol" or "grain alcohol").

Evaporative Emissions: Emissions from evaporating gasoline, which can occur during vehicle refueling, vehicle operation, and even when the vehicle is parked. Evaporative emissions can account for two-thirds of the hydrocarbon emissions from gasoline-fueled vehicles on hot summer days.

Exceedance: Ambient pollutant concentrations measured above the applicable ambient air quality standards.

Exhaust Gas Recirculation (EGR): An emission control method that involves recirculating exhaust gases from an engine back into the intake and combustion chambers. This lowers combustion temperatures and reduces NOx.

Expected Peak Day Concentration (EPDC): A calculated value that represents the concentration expected to occur  at a particular site once per year, on average. The calculation procedure uses measured data collected at the site during a three-year period. Measured concentrations that are higher than the EPDC are excluded from the state area designation process.

Facility: A structure, building, or operation, that has one or more permitted pieces of equipment.

Federal Clean Air Act (FCAA): A federal law passed in 1970 and amended in 1977 and 1990 which forms the basis for the national air pollution control effort. Basic elements of the act include national ambient air quality standards for major air pollutants, air toxics standards, acid rain control measures, and enforcement provisions.

Feasible: Feasibility is most frequently used in the context of "feasible" stationary source control measures. In this context, feasible means Best Available Retrofit Control Technology (see definition, above).

Flexible Fuel Vehicle (FFV): A vehicle capable of operating on any combination of methanol, ethanol, and gasoline.

Fraction Reactive Organic Gases (FROG): The weight fraction of reactive organic gases in emissions of total organic gases from a source.

FIP (Federal Implementation Plan): In the absence of an approved State Implementation Plan (SIP), a plan prepared by the EPA which provides measures that nonattainment areas must take to meet the requirements of the Federal Clean Air Act.

Fugitive Dust: Dust particles which are introduced into the air through certain activities such as soil cultivation, off-road vehicles, or any vehicles operating on open fields or dirt roadways.

Gasoline Tolerant: A term used to describe vehicles that normally operate on methanol but can run on gasoline as well.

Growth Management Plan: 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.

Hazardous Air Pollutant (HAP): 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 USEPA, and emission standards are set accordingly.

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

Health-Based Standard (Primary Standard): A dosage of air pollution scientifically determined to protect against human health effects such as asthma, emphysema, and cancer.

Hybrid Electric Vehicle (HEV): Hybrid electric motor vehicles may operate using both electric and gasoline-powered motors. Emissions from hybrid electric motor vehicles are also substantially lower than conventionally powered motor vehicles. (See also Electric Motor Vehicle).

Hydrocarbon: Any of a large number of compounds containing various combinations of hydrogen and carbon atoms. They may be emitted into the air as a result of fossil fuel combustion, fuel volatilization, and solvent use, and are a major contributor to smog. (Also see VOC.)

Hydrogen Sulfide (H₂S): A colorless, flammable, poisonous compound having a characteristic rotten-egg odor. It is used in industrial processes and may be emitted into the air.

Incentives: Measures designed to encourage certain actions or behavior. These include inducements for the use of carpools, buses and other high-occupancy vehicles in place of single occupant automobile travel. Examples include HOV lanes, preferential parking and financial incentives.

Indirect Source: Any facility, building, structure, or installation, or combination thereof, which generates or attracts mobile source activity that results in emissions of any pollutant (or precursor) for which there is a state ambient air quality standard. Examples of indirect sources include employment sites, shopping centers, sports facilities, housing developments, airports, commercial and industrial development, and parking lots and garages.

Indirect Source Control Program: Rules, regulations, local ordinances and land use controls, and other regulatory strategies of air pollution control districts or local governments used to control or reduce emissions associated with new and existing indirect sources.

Indirect Source Review: A major component of an indirect source control program, which applies to new and modified indirect sources. Strategies for indirect source review include permit programs, review and comment on new and modified indirect source projects through the California Environmental Quality Act (CEQA) process, and coordination of air quality, transportation and land use policies through local government general plans. Indirect source review reduces emissions from new and modified sources through best available mitigation measures and additional offsite mitigation such as offsets and mitigation fees.

Inspection and Maintenance Program: A motor vehicle inspection program implemented by the BAR. It is designed to identify vehicles in need of maintenance and to assure the effectiveness of their emission control systems on a biennial basis. Enacted in 1979 and strengthened in 1990. (Also known as the "Smog Check" program.)

Inversion: A layer of warm air in the atmosphere that prevents the rise of cooling air and traps pollutants beneath it.

Lead: A gray-white metal that is soft, malleable, ductile, and resistant to corrosion. Sources of lead resulting in concentrations in the air include industrial sources and crustal weathering of soils followed by fugitive dust emissions. Health effects from exposure to lead include brain and kidney damage and learning disabilities. Lead is the only substance, which is currently listed as both a criteria air pollutant and a toxic air contaminant.

Lead Agency: The public agency which has the principal responsibility to carry out or approve a project.

Level of Service (LOS): A measure of the congested level on a highway facility or intersection based primarily on the comparison between the facility's capacity and the traffic volume it carries. Increasing levels of congestion are designated along a scale from A to F.

Light-Duty Vehicle (LDV): Any motor vehicle with a gross vehicle weight of 6000 pounds or less.

Liquified Petroleum Gas (LPG): A gaseous byproduct of petroleum refining that is compressed to a liquified form for sales. LPG consists of butane, propane, or a mixture of the two, and of trace amounts of propylene and butylene.

Local Agency: Any public agency other than a state or federal agency.

Low Emission Vehicle (LEV): The LEV standards for passenger cars represent a 70 percent reduction in gasoline-equivalent hydrocarbon and a 50 percent reduction in NOX from ARB’s 1994 standards.

Lowest Achievable Emissions Rate (LAER): Under the Federal Clean Air Act, the rate of emissions that reflects (1) the most stringent emission limitation in the State Implementation Plan of any state for a given source unless the owner or operator demonstrates such limitations are not achievable; or (2) the most stringent emissions limitation achieved in practice, whichever is more stringent.

Maintenance Plan: In general, a plan that details the actions necessary to maintain air quality standards. In particular, the federal Clean Air Act requires maintenance plans for areas that have been redesignated as attainment areas.

Memorandum of Understanding (MOU): The Santa Barbara Association of Governments (SBCAG) is the regional agency responsible for preparing regional transportation plans and programs. Most of these programs require the participation of cities, the county, and other affected local agencies. A number of these programs also have implications to regional air quality plans such as the Clean Air Plan. Because the SBCAG currently works with cities and the county on regional transportation programs, and because of the close interaction between many of these programs and the regional air quality plan, the APCD and SBCAG have entered into a Memorandum of Understanding whereby SBCAG is charged with developing the transportation elements of the plan, especially the transportation control measures. TCMs are essentially measures that seek to reduce the use of the single passenger automobile and are implemented by a number of local agencies such as local cities and the county.

Methanol: A colorless, clear liquid derived from natural gas or coal (also known as "methyl alcohol" or "wood alcohol").

Methyl Tertiary Butyl Ether (MTBE): An ether compound added to gasoline to provide oxygen and enhance complete combustion. MTBE is being fazed out of California's gasoline.

Mitigation: A change or alternative to the proposed project which reduces or eliminates its significant adverse environmental impacts. Mitigation can be in the form of traditional offsets, transportation-based mitigation measures that are directly associated with the project under consideration, or mitigation fees to be used to secure off site mitigation.

Mobile Source: Sources of air pollution such as automobiles, motorcycles, trucks, buses, off-road vehicles, boats and airplanes. (Contrast with stationary sources.)

Model Rule: A generically formatted control measure, prepared as a guide for adoption by regulatory agencies. Model rules have no force of law until they are adopted by a regulatory agency. Historically, model rules were prepared by the California Air Resources Board and given to local Air Pollution Control Districts for their consideration. The model rule process has been replaced by the suggested control measure process.

NAAQS (National Ambient Air Quality Standards): Standards set by the federal EPA for the maximum levels of air pollutants which can exist in the outdoor air without unacceptable effects on human health or the public welfare. There are two types of NAAQS. Primary standards set limits to protect public health and secondary standards set limits to protect public welfare.

Natural Resources: Non-manmade emission sources, including biological and geological sources, wildfires, and windblown dust.

Net Emissions: The actual emissions occurring from a new or modified project after actual on site and off site mitigation, and other effective mitigation has been applied, as determined by the Air Pollution Control Officer.

Nitrogen Oxides (Oxides of Nitrogen, NOx): A general term pertaining to compounds of nitric acid (NO), nitrogen dioxide (NO2 ), and other oxides of nitrogen. Nitrogen oxides are typically created during combustion processes, and are major contributors to smog formation and acid deposition. NO 2 is a criteria air pollutant, and may result in numerous adverse health effects; it absorbs blue light, resulting in a brownish-red cast to the atmosphere and reduced visibility.

Nonattainment Area: A geographic area identified by the EPA and/or ARB as not meeting either NAAQS or CAAQS standards for a given pollutant.

NSR (New Source Review): A program used in development of permits for new or modified industrial facilities which are in a nonattainment area, and which emit nonattainment criteria air pollutants. The two major requirements of NSR are Best Available Control Technology and Emission Offset.

Opacity: The amount of light obscured by particle pollution in the atmosphere. Opacity is used as an indicator of changes in performance of particulate control systems.

Outer Continental Shelf: The area of the Pacific Ocean extending twenty-five miles out to sea from the State Tidelands (which extends three miles from the coastline).

Oxygenate: Any oxygen-rich substance added to gasoline to enhance octane and reduce carbon monoxide emissions. 

Ozone: A strong smelling, pale blue, reactive toxic chemical gas consisting of three oxygen atoms. It is a product of the photochemical process involving the sun's energy. Ozone exists in the upper atmosphere ozone layer as well as at the earth's surface. Ozone at the earth's surface causes numerous adverse health effects and is a criteria air pollutant. It is a major component of smog. 

Ozone Precursors: Chemicals such as hydrocarbons and oxides of nitrogen, occurring either naturally or as a result of human activities, which contribute to the formation of ozone, a major component of smog.

Park & Ride: A program that permits a patron to drive a vehicle to a transit station, park in the area provided for that purpose and ride the transit system to his or her destination.

Peak Period/Peak Hour Demand: The time of most intensive use of a service or facility. In terms of travel, generally there is a morning and an afternoon peak on streets and highways.

Permit: Written permission and authorization from a government agency that allows for the construction and/or operation of an emission generating facility or its equipment within certain specified limits or conditions.

Photochemical: Of, relating to, or resulting from the chemical action of radiant energy, especially sunlight.

Planning Inventory: Emissions inventory from which pollution from natural sources (e.g., seeps, vegetation) are excluded because they are currently not regulated by implementation of APCD rules.

PM (Particulate Matter): Any material, except pure water, that exists in the solid or liquid state in the atmosphere, such as soot, dust, smoke, fumes, and aerosols. The size of particulate matter can vary from coarse, wind-blown dust particles to fine particle combustion products. 

PM10 (Particulate Matter less than 10 microns): A major air pollutant consisting of tiny solid or liquid particles of soot, dust, smoke, fumes, and aerosols. The size of the particles (10 microns or smaller, about 0.0004 inches or less) allows them to easily enter the air sacs in the lungs where they may be deposited, resulting in adverse health effects. PM10 also causes visibility reduction and is a criteria air pollutant.

PM2.5 (Particulate Matter less than 2.5 microns): A major air pollutant consisting of tiny solid or liquid particles, generally soot and aerosols. The size of the particles (2.5 microns or smaller, about 0.0001 inches or less) allows them to easily enter the air sacs deep in the lungs where they may cause adverse health effects, as noted in several recent studies. PM2.5 also causes visibility reduction, but is not considered a criteria air pollutant at this time.

Population Exposure Index: A measurement of overall population exposure to ambient pollutant levels based an average per capita exposure and the severity of the exceedance.

Precursor: Any directly emitted pollutant that, when released into the atmosphere, forms or causes to be formed or contributes to the formation of a secondary pollutant for which an ambient air quality standard has been adopted, or whose presence in the atmosphere will contribute to the violation of one or more ambient air quality standards.

PSD (Prevention of Significant Deterioration): A program used in development of permits for new or modified industrial facilities in an area that is already in attainment. The intent is to prevent an attainment area from becoming a non-attainment area. This program, like NSR, can require BACT and, if an AAQS is projected to be exceeded, Emission Offsets.

Pseudocyclic Oil Well: A cyclic well is an oil well where steam is periodically injected into the well reservoir to stimulate production, but where the well is unaffected by steam injection occurring in adjacent wells. A pseudocyclic oil well is also periodically steam injected, however, it is affected by steam injection occurring in adjacent wells.

Public Transportation : Transportation service by bus, rail para-transit, airplane, and ship offered by an operator on a regular basis to the general public.

Public Workshop: A workshop held by a public agency for the purpose of informing the public and obtaining its input on the development of a regulatory action or control measure by that agency.

Reactive Organic Compound (ROC): See reactive organic gases.

Reactive Organic Gases (ROG): A reactive chemical gas, composed of hydrocarbons, that react with nitrogen oxides and contribute to the formation of ozone. Also known as Volative Organic Compounds (see VOC), or as Non-Methane Organic Compounds (NMOCs). The APCD considers all volatile compounds containing carbon except the following to be reactive: ethane, methane, carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, ammonium carbonates, methyl chloroform (TCA), methylene chloride (dichloromethane), CFC-11, CFC-12, HCFC-22, FC-23, CFC-113, CFC-114, CFC-115, HCFC-123, HCFC-134a, HCFC-141b, HCFC-142b.

Reactivity: A measure of the tendency of a hydrocarbon species to react with nitrogen oxides to form atmospheric ozone.

Reasonable Further Progress: Annual incremental reductions in emissions of the relevant air pollutant and its precursors required to ensure attainment of the applicable air quality standard by the applicable date.

Reasonably Available Control Measures (RACM): A broadly defined term referring to technologies and other measures that can be used to control pollution. They include Reasonably Available Control Technology and other measures. In the case of PM10, RACM refers to approaches for controlling small or dispersed source categories such as road dust, woodstoves, and open burning.

Reasonably Available Control Technology (RACT): Process changes and/or devices to minimize air pollution from mobile and stationary sources that are cost-effective and readily available.

Reformulated Gasoline: A gasoline whose composition is changed to reduce exhaust emissions.

Regional Haze: The haze produced by a multitude of sources and activities, which emit fine particles and their precursors across a broad geographic area. National regulations require states to develop plans to reduce the regional haze that impairs visibility in national parks and wilderness areas.

Retrofit: Modification of a polluting device to make it less polluting.

Ridesharing: A cooperative effort of two or more people to travel together. Examples are carpools, vanpools, buspools, trains, and public transit.

ROP Plan: The 1993 Rate-of-Progress Plan. The 1993 ROP Plan demonstrated that by 1996 existing and proposed control measures reduced emissions of reactive organic gases (ROG) to a level 15% below the 1990 baseline inventory.

Santa Barbara Channel: The area of the Pacific Ocean between Santa Barbara County's southern coast and the Channel Islands.

Santa Maria Basin: An area of undersea oil reserves off the western coast of Santa Barbara County.

Secondary Pollutants: Pollutants not emitted directly, but formed in the atmosphere through chemical reactions or transformation of other pollutants (i.e., ozone).

Single Occupant Vehicle (SOV): A motor vehicle occupied by one employee for commute purposes, including motorcycles.

Smog: A combination of smoke, ozone, hydrocarbons, nitrogen oxides, and other chemically reactive compounds which, under certain conditions of weather and sunlight, may result in a murky brown haze that causes adverse health effects. The primary source of smog in California is motor vehicles.

Smog Check: A vehicle inspection and maintenance exam. Smog Check Program: (See Inspection and Maintenance Program.)

Smoke: A form of air pollution consisting primarily of particulate matter (i.e., particles). Other components of smoke include gaseous air pollutants such as hydrocarbons, oxides of nitrogen, and carbon monoxide. Sources of smoke may include fossil fuel combustion, agricultural burning, and other combustion processes.

Solvent : A substance that dissolves another to form a solution.

Source: Something that produces air pollution emissions. Sources can be stationary or mobile, and anthropogenic or natural.

South Coast: The area of Santa Barbara County south of the ridge of the Santa Ynez Mountains and adjacent tidelands.

SO2 (Sulfur Dioxide): A strong smelling, colorless gas that is formed by the combustion of fossil fuels. Power plants, which may use coal or oil high in sulfur content, can be major sources of SO2. SO2 and other sulfur oxides contribute to the problem of acid deposition. SO2 is a criteria pollutant. 

State Implementation Plan (SIP): A comprehensive plan prepared by each state, mandated by the federal Clean Air Act, which describes the existing air quality conditions and measures which will be taken to attain and maintain national ambient air quality standards.

State Tidelands: The area of the Pacific Ocean within three miles of the shores of Santa Barbara County. 

Stationary Source: A non-mobile structure, building, facility, equipment installation or operation. Examples include oil production facilities, industrial coating operations, a rock crushing facility, and factories that use large amounts of solvents. A stationary source is classified as having a common production process, located on one or more adjacent properties, and is under the same or common ownership, operation, or control. (Contrast with mobile sources.)

Stationary Source Control Measures: A control measure designed to limit the kind and amount of pollutants emitted from stationary sources.

Suggested Control Measure (SCM): A document upon which air pollution control rules and regulations can be based. The California Air resources Board issues SCMs to provide guidance to districts in their consideration and development of rules and regulations. However, approval by the ARB of an SCM does not obligate the local districts to develop particular regulations for sources addressed by the SCM. Local districts have the latitude to develop regulations that are stringent, more stringent, or less stringent than SCMs. The stringency of regulations that are developed by the local districts is usually based on the extent to which emissions reductions are needed to achieve compliance with the ambient air quality standards, in that district's area of jurisdiction, as well as other local considerations. The districts also consider the costs for achieving the emission reductions.

Telecommuting: Working at a location other than the conventional office. This place may be the home, or an office other than the employee's primary office. Telecommuting employees can communicate with their offices by telephone.

Total Organic Gases (TOG): Reactive organic gases plus non-reactive organic gases.

Toxic Air Contaminant: An air pollutant, identified in regulation by the ARB, which may cause or contribute to an increase in deaths or in serious illness, or which may pose a present or potential hazard to human health. TACs are considered under a different regulatory process (California Health and Safety Code Section 39650 et seq.) than pollutants subject to CAAQS. Health effects due to TACs may occur at extremely low levels, and it is typically difficult to identify levels of exposure which do not produce adverse health effects.

Transitional Low Emission Vehicle (TLEV): TLEV vehicle standards will be 50 percent less hydrocarbon emissions than 1993 model-year conventional gasoline vehicles. 

Transport: The act of emissions from one source being carried by wind to other locations.

Transportation Control Measure (TCM): Any strategy to reduce vehicle trips, vehicle use, vehicle miles traveled, vehicle idling, or traffic congestion for the purpose of reducing motor vehicle emissions. TCMs can include encouraging the use of carpools and mass transit. TCM’s include both Transportation Demand Management and Transportation System Management measures.

Transportation Demand Management (TDM): The implementation of measures which encourage people to change their mode of travel, or not to make a trip at all, (e. g., ridesharing, pricing incentives, parking management and telecommuting.)

Transportation System Management (TSM): The implementation of measures which improve the efficiency of transportation infrastructure.

Trip: A single or one direction vehicle movement.

UAM (Urban Airshed Model): The three-dimensional photochemical grid model used to simulate ozone formation. Used to project episodic ozone concentrations. (See also air quality simulation model.)

Ultra Low Emission Vehicle (ULEV): ULEV standards would lower gasoline-equivalent hydrocarbon emissions by 85 percent, carbon monoxide by 50 percent, and NOX emissions by 50 percent, from 1993 levels.

United States Environmental Protection Agency (USEPA): The federal agency charged with setting policy and guidelines, and carrying out legal mandates for the protection of national interests in environmental resources.

Vanpool: A van used routinely by six or more employees to commute together. The three basic types of vanpools are owner-operated, employer-sponsored, and vendor-operated.

Vapor Recovery Systems: Mechanical systems that collect and recover chemical vapors resulting from transfer of gasoline from operations such as tank-to-truck systems at refineries, tanker-to-pipeline systems at offshore oil operations, and jump-to-vehicle systems at gasoline stations.

Vehicle Miles Traveled (VMT): Number of miles traveled by a given vehicle in a specified time period. This number is sometimes estimated for the entire fleet of on road vehicles.

Violation: A number of measured exceedances of an applicable ambient air quality standard.

Visibility: The distance that atmospheric conditions allow a person to see at a given time and location. Visibility reduction from air pollution is often due to the presence of sulfur and nitrogen oxides, as well as particulate matter.

Volatile Organic Compound (VOC): This term is generally used similarly to the term "reactive organic gases" but excludes substances that the federal government does not consider to be reactive, or that are considered to have negligible photochemical reactivity. VOCs are hydrocarbon compounds that exist in the ambient air and contribute to the formation of smog and/or may themselves be toxic. VOCs often have an odor, and some examples include gasoline, alcohol, and the solvents used in paints.

Zero Emission Vehicle (ZEV): A vehicle which will maintain zero emissions throughout its lifetime.