Emission Inventory

A broad quantitative listing of air pollutant precursor emissions within a certain area or region. Man-made (anthropogenic) emissions are divided into four general categories, stationary, area-wide, on-road motor vehicles, and other mobile sources. Each of these broad categories are further subdivided into more descriptive subcategories defined by more specific emission processes. Emission inventories updates are part of the overall requirement for plan revisions. Emission trends and forecasts are good indicators of progress towards cleaner air. Current estimates of the various regional planning inventories are located below.

Point Sources

Stationary Sources

This category of the emissions is comprised of individual industrial, manufacturing, and commercial facilities called "point sources." Broken down further to subcategories such as fuel combustion (e.g., space and water heating), waste disposal (e.g., landfills and composting), cleaning and surface coatings (e.g., auto refinishing and furniture coatings), petroleum production and marketing (e.g., bulk gasoline storage and transfer) to name a few.

​Area-Wide Sources

This category includes combined emissions data from processes and sources that are individually small, widespread and not well-defined "point sources." Area-wide subcategories include solvent evaporation (e.g., consumer products and architectural coatings) and miscellaneous processes (e.g., residential fuel combustion and farming operations). Emissions from these sources are calculated from product sales, population and employment data, and other information for a wide range of activities.

​Mobile Sources

On-Road Motor Vehicles

Emissions from on-road motor vehicles are a major source of the emissions and are estimated by the California Air Resources Board (CARB). The on-road motor vehicles inventory category consists of passenger cars, trucks, buses, and motorcycles.  

Other Mobile Sources

Other mobile sources includes aircraft, trains, ships, off-road vehicles and equipment used for construction, farming, commercial, industrial, and recreational activities.