Emission Sources

Emission Sources in California

California's diverse landscape, industries, and population contribute to various sources of air pollution. CARB, in cooperation with local Air Quality Management Districts and Air Pollution Control Districts, categorizes emission sources into six major sectors:

Stationary Point

Stationary point sources are most often individual facilities that have specific locations. These sources are typically permitted by Air Districts.

Examples: power plants, oil refineries, manufacturing facilities, food processing plants

Stationary Aggregated

Stationary aggregated sources groups sources based off similarity

Examples: gasoline stations, dry cleaners, agricultural pumps, small engines and generators

For more information on how we estimate stationary aggregated emissions, visit Index of Methodologies by Major Category.

Areawide

Areawide sources do not have have a specific location and are spread over large areas.

Examples: consumer products, paved and unpaved roads, fugitive windblown dust

For more information on how we estimate areawide emissions, visit Index of Methodologies by Major Category.

On-Road Mobile Sources

On-road mobile sources are vehicles that typically operate on roadways.

Examples: passenger cars, light and heavy-duty trucks, motorcycles, buses, motor homes

For more information on the on-road emission inventory, visit the EMFAC page.

Off-Road Mobile Sources

Off-road mobile sources are vehicles and equipment that operate off roadways.

Examples: aircraft, trains, ships, boats, construction equipment, farm machinery, airport ground support equipment

For more information on CARB off-road inventory, visit the OFFROAD page.

Natural Sources

Emissions that are not a result of human activity.

Examples: vegetation, petroleum seeps, wildfires

For more information on CARB off-road models, visit the Natural Source Methodologies page.