The California emission inventory contains information on the following air pollution sources:

• Stationary sources - approximately 13,000 individual facilities defined as point sources. Point sources are fixed pollution sources such as electric power plants and refineries.
• Area-wide sources - approximately 80 source categories. An area-wide source category is made up of sources of pollution mainly linked to human activity. Examples of these sources include consumer products and architectural coatings used in a region 
• Mobile sources - all on-road vehicles such as automobiles and trucks; off-road vehicles such as trains, ships, aircraft; and farm equipment

The principal agencies contributing data to the stationary and area-wide source inventory are the CARB and the California air pollution control and air quality management districts. The CARB, the California Department of Transportation (Caltrans), and regional transportation agencies are the principal agencies involved in developing the mobile source inventory. Information represented in the California
emission inventory is a snap-shot of a variety of dynamic and variable processes. As such, the emission inventory can only represent an estimate of what is actually occurring. In summer 2011, a new NOx monitoring station was installed at the TRPA offices in Stateline, Nevada. Data from 2013 and 2014 for this site are now available.