Emission Inventory

The Santa Barbara County Air Pollution Control District maintains an air pollution emission inventory for the County. The air pollutants tracked by this inventory are known as criteria pollutants, which are pollutants with state and federal ambient air quality standards that were developed using health-based criteria. Criteria pollutants include: reactive organic compounds (ROC), nitrogen oxides (NOx), carbon monoxide (CO), sulfur oxides (SOx), and particular matter (PM10 and PM2.5). The emission inventory is compiled through a collaborative effort by the District and the California Air Resources Board (CARB) and is broken down into specified source categories:

Stationary sources that are subject to District permitting requirements and can typically be pinpointed on a map. These sources can range in size from an individual generator to larger facilities such as a wastewater treatment plant or an oil & gas processing facility. Emissions from stationary sources are estimated by the District.

Area sources are typically small, geographically dispersed processes that generally are not subject to District permitting requirements. For example, natural gas combustion in homes is considered an area source, and emissions from area sources are estimated jointly by the District and CARB.

Mobile sources are subdivided into two categories, On-Road Motor Vehicles and Other Mobile Sources. On-Road Motor Vehicles consist of passenger cars, motorcycles, trucks, and buses and Other Mobile Sources consist of ships, planes, trains, and off-road equipment. Emissions from mobile sources are estimated by CARB.

Natural Sources consist of biogenic sources (e.g., organic compounds emitted by plants), geogenic sources (e.g., natural oil & gas seeps), and wildfires. Emissions from natural sources are estimated by CARB. The inventories presented below are “planning emissions inventories,” which do not include the emissions from natural sources since they are not regulated nor controlled through implementation of emission control measures.

Emission Inventory Trends 2000-2019

The District’s emission inventory accounts for pollutants emitted from all emission sources (excluding natural sources) from two geographical regions: Santa Barbara County and the Outer Continental Shelf. The historical emission trends show that the District’s emissions have generally decreased over time, largely due to the implementation of District emission control measures and the effect of cleaner automobiles.

2017 Emission Inventory Summary 

Reactive organic compounds (ROCs) contribute to the formation of ground level smog and can be formed through the use and evaporation of paints and solvents or through various combustion processes.

Oxides of nitrogen (NOx) consists mainly of nitric oxide (NO) and nitrogen dioxide (NO2), and they contribute to the formation of ground-level ozone. Common sources of these compounds include any equipment that combusts fuels, such as emergency generators, processing facilities, and mobile sources (cars, trucks, buses, ships, and off-road equipment).

Ozone, a primary component of smog, forms through a complex photochemical reaction involving ROC, NOx, and the presence of heat and sunlight. Exposure to ozone can cause respiratory health effects such as coughing, shortness of breath and reduced lung function, and can aggravate asthma and other respiratory illnesses.

Sulfur oxides (typically SO2), can be emitted into the atmosphere from the burning of fossil fuels by power plants and industrial facilities as well as transportation fuels. SOx can harm the respiratory system and can react with other compounds to form particulate matter pollution.

PM10 is particulate matter less than 10 microns in diameter and PM2.5 is particulate matter less than 2.5 microns in diameter. Suspended particles less than 10 microns in diameter (about one-fifth of the diameter of a human hair) can bypass the body’s protective mechanisms, and be inhaled into the airway and lungs and can cause respiratory and cardiovascular illnesses. PM2.5 pollution is a subset of PM10 and can cause more serious respiratory and cardiovascular health issues.

Additional Emissions Inventory Resources

For more information regarding the District’s emissions inventory, please contact Alex Economou by phone at (805) 961-8894 or by email at [email protected].