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Statewide Emissions Inventory Program


  • Emission Inventories for 2020 will be due April 15, 2021. Please make sure you are registered for SLEIS if your facility is required to submit an inventory!

Purpose and Method

Federal and state laws require the Utah Division of Air Quality to create a comprehensive emissions inventory for point, area, and mobile sources every three years, and annually for some large point sources.

The Statewide inventories summarize emissions for the following criteria pollutants, in tons per year.

Hazardous air pollutant emissions are reported for point sources only.

The Statewide Emissions Inventory is posted every three years on our website.  You can also find this information on EPA’s National Emissions Inventory website, along with data from all other 49 states.

Point Sources

Point sources are stationary, commercial or industrial sources included in the State Implementation Plan (SIP), major sources that emit more than 100 tons/yr. of a criteria pollutant, or New Source Performance Standard (NSPS) sources. The point source annual emission inventory for criteria pollutants is collected under authority of Utah Administrative Code. The inventory information is required to track SIP progress, calculate the operating permit program emission fee, fulfill annual reporting requirements to EPA, and supply information to the general public. Point sources report their emissions through SLEIS.

Area Sources

Area sources are stationary sources that are too small or too numerous to be treated as individual point sources. The area source inventory is determined from local demographic information, state energy and agricultural statistical data, specific information surveys, and submitted inventories. Source categories range from agricultural dust and outdoor grilling to residential wood combustion, solvent use, and upstream oil and gas facilities. The oil and gas inventory is unique in the area source inventory as rather than using surrogate activity data and generic emission factors, oil and gas companies submit an inventory for their facilities.

Biogenic sources comprise the natural (non-anthropogenic, such as forests, vegetation, and soils) area sources contribution to VOCs and “event” emission sources, such as wildfires, contribute various pollutants to the airshed. Both of these pollution sources are also under the purview of area sources.

Note: The area source inventory remains in development and experiences significant fluctuations. Frequently one inventory is not readily comparable to another due to changing methods and data sources.

Mobile Sources

The mobile source inventory includes both on-road and non-road sources. Vehicles traveling on paved roads and highways comprise the on-road sector, which includes cars, light-duty trucks, heavy-duty trucks, and motorcycles. Non-road mobile sources include a wide variety of internal combustion engines and vehicles not operating on roads and highways, such as diesel locomotives, aircraft, airport ground support equipment, and eleven groups of motorized vehicles and equipment found in the non-road module of the current EPA emissions model “MOVES”. These groups include recreational, construction, industrial, lawn & garden, agricultural, commercial, logging, underground mining, miscellaneous oil field equipment, miscellaneous railroad equipment, and marine and pleasure craft.

Emissions are calculated in various ways.

Using MOVES, the user builds input tables that contain local data for on- and non-road mobile sources. Some important groups of input data include vehicle populations, vehicle miles traveled, fuel properties, vehicle age distributions and temperature and relative humidity data. For non-road motorized equipment, similar data is collected, including equipment populations, fuels, hours and months of operation, etc.

Aircraft and airport ground support equipment emissions are calculated using the Federal Aviation Administration “EDMS” model, now being replaced by the FAA “Aviation Environmental Design Tool”. Inputs include aircraft types and engines, number of takeoffs and landings, ambient temperatures, location of airport, etc.