Fuels such as methanol, ethanol, natural gas and liquid propane gas that are cleaner burning and help to meet ARB's mobile and stationary emission standards.

A county agency with authority to regulate stationary, indirect and area sources of air pollution (e.g., power plants, highway construction and housing developments) within a given county, and governed by a district air pollution control board composed of the elected county supervisors. (Compare AQMD).

Health- and welfare-based standards for clean outdoor air that identify the maximum acceptable average concentrations of air pollutants during a specified period of time.

An adverse health effect that occurs over a relatively short period of time (e.g., minutes or hours).

Particles of solid or liquid matter that can remain suspended in air for long periods of time because of extremely small size and light weight.

Amounts of foreign and/or natural substances occurring in the atmosphere that may result in adverse effects on humans, animals, vegetation and/or materials.

A mathematical relationship between emissions and air quality that simulates the transport, dispersion and transformation of compounds emitted into the air.

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 the 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 [..]

The air at a particular time and place outside of structures. Often used interchangeably with outdoor air.

A group of counties or portions of counties, or an individual county specified in law with authority to regulate stationary, indirect and area sources of air pollution within the region and governed by a regional air pollution control board composed mostly of elected officials from within the region. (Compare APCD).