Jump to main content.

Basic Information

Under the Clean Air Act, EPA establishes air quality standards to protect public health, including the health of "sensitive" populations such as people with asthma, children, and older adults. EPA also sets limits to protect public welfare. This includes protecting ecosystems, including plants and animals, from harm, as well as protecting against decreased visibility and damage to crops, vegetation, and buildings. View more information regarding the national standards for these pollutants.

EPA has set national air quality standards for six common air pollutants (also called the criteria pollutants):

Four of these pollutants (CO, Pb, NO2, and SO2) are emitted directly from a variety of sources. Ozone is not directly emitted, but is formed when oxides of nitrogen (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight. PM can be directly emitted, or it can be formed when emissions of NOx, sulfur oxides (SOx), ammonia, organic compounds, and other gases react in the atmosphere.

To achieve these standards, EPA has in place regulatory and voluntary programs to reduce the amount of air pollutants emitted from a wide range of emission sources. To keep track of these emissions, the EPA maintains the National Emission Inventory (NEI), the national database of air pollutant emissions information. EPA conducts a comprehensive emissions inventory every three years. EPA also modifies the NEI at least annually to correct and augment its inventory data. Developing and updating the inventory is time-consuming, and EPA is working to reduce the amount of time it takes. While the data provided in this site are several years old, they do reflect the most recent inventory. For additional technical information about the NEI, visit the National Emission Inventory website.

Emissions Data Source

This site is linked directly to AirQuest, a data warehouse that stores summary-level emissions and other air quality-related data. AirQuest obtains the emissions data for this site from the National Emissions Inventory mentioned previously.

This site groups emissions into 12 major source sectors. The table below provides more detail about which sources are included in each sector. For a more detailed description of these sectors, see the latest NEI report.

12 Major Source Sectors Detailed Category Names
Fertilizer & Livestock Livestock Waste
Fertilizer Application
Electricity Generation Fuel Combustion - Electric Utilities
Fossil Fuel Combustion Fuel Combustion - Industrial Boilers, Internal Combutions Engines
Fuel Combustion - Commercial/Institutional
Fuel Combustion - Residential Fossil
Residential Wood Combustion Fuel Combustion - Residential Fireplaces
Fuel Combustion - Residential Woodstoves
Waste Disposal Waste Disposal
Waste Disposal - Open Burning
Fires Wildfires
Prescribed Fires
Agricultural Field Burning
Logging Slash Burning
Industrial Processes Industrial Process - NEC
Commercial Cooking
Industrial Process - Metals
Industrial Process - Chemical Manufacturing
Industrial Process - Storage & Transfer
Industrial Process - Petroleum Refineries
Industrial Process - Oil & Gas Production
Industrial Process - Pulp & Paper
Industrial Process - Cement Manufacturing
On Road Vehicles On-Road Vehicles - Gasoline
On-Road Vehicles - Diesel
Non Road Equipment Non-Road Equipment - Gasoline
Non-Road Equipment - Diesel
Planes, Trains, & Ships
Road Dust Unpaved Roads
Paved Roads
Solvent Use Solvent - Non-industrial
Surface Coating - Industrial
Degreasing
Surface Coating - Architectural
Graphic Arts
Solvent - Not Classified Elsewhere
Dry Cleaning
Miscellaneous Agriculture - Crop Tilling & Livestock Dust
Construction
Gas Stations
Bulk Gasoline Terminals
Other Miscellaneous Sources

 

Local Navigation

Jump to main content.