Glossary
A
A subset of air basin, the term denotes a geographical area that shares the same air because of topography, meteorology and climate.
An authorization to emit, during a specified year, up to one ton of carbon dioxide equivalent.
Pursuant to Assembly Bill 1811, ARB with the California Energy Commission, developed a joint plan to spend $25 million for the purposes of incentivizing biofuels and high-efficiency, low-emitting vehicle technology. The funds were for developing specific measures to reduce air pollution and greenhouse gas emissions from fuels and mobile sources. AB 1811 required the funds to be encumbered by June 30, 2007, and expended by June 30, 2009.
Fuels such as methanol, ethanol, natural gas and liquid petroleum gas that are cleaner burning and help to meet ARB's mobile and stationary emission standards. These fuels may be used in place of less clean fuels for powering motor vehicles. For more information, visit our alternative fuels website.
The air occurring at a particular time and place outside of structures. Often used interchangeably with "outdoor air." (See also air.)
Health- and welfare-based standards for outdoor air which identify the maximum acceptable average concentrations of air pollutants during a specified period of time. (See also CAAQS and NAAQS and Criteria Air Pollutant.) For more information, visit our ambient air quality standards website.
A non-profit organization that provides a forum for producers, consumers and representatives of government and industry to write laboratory test standards for materials, products, systems and services. ASTM publishes standard test methods, specifications, practices, guides, classifications and terminology. For more information, visit our ASTM website.
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.
A biochemical process in which bacteria break down biodegradable organic material, such as manure, in an oxygen-free environment. Temperature, moisture, nutrient content and pH, can be controlled through the use of an airtight chamber (digester). The break-down of the organic material results in biogas, a mixture of methane (CH4), carbon dioxide (CO2) and trace amounts of other gases.
Those sources for which a methodology is used to estimate emissions. This can include area-wide, mobile and natural sources and also groups of stationary sources (such as dry cleaners and gas stations). The California Clean Air Act requires air districts to include area sources in the development and implementation of the AQMP. In the California emission inventory all sources that are not reported as individual point sources are included as area sources. The federal air toxics program defines a source that emits less than 10 tons-per-year of a single hazardous air pollutant (HAP) or 25 tons-per-year of all HAPs as an area source. For more information, visit our area-wide source methodologies website.
Sources of pollution where the emissions are spread over a wide area, such as consumer products, fireplaces, road dust and farming operations. Area-wide sources do not include mobile sources or stationary sources.
A type of hydrocarbon, such as benzene or toluene. Some aromatics are toxic.
A mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled. The U.S. EPA has banned or severely restricted its use in manufacturing and construction and the ARB has imposed limits on the amount of asbestos in serpentine rock that is used for surfacing applications.
A chronic inflammatory disorder of the lungs characterized by wheezing, breathlessness, chest tightness and cough.
The gaseous mass or envelope of air surrounding the Earth. From ground-level up, the atmosphere is further subdivided into the troposphere, stratosphere, mesosphere and the thermosphere.
A geographical area identified to have air quality as good as, or better than, the national and/or California ambient air quality standards (NAAQS/CAAQS). An area may be an attainment area for one pollutant and a nonattainment area for others.
A pre-construction permit issued by an air district.