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The following information covers OTAQ modeling and inventories. Modeling is EPA's method for estimating emissions from on-road vehicles, nonroad sources, and fuels. Inventories are calculations of total emissions of a pollutant for a given area at a defined time and set of conditions.

For further information or assistance regarding this web page, contact:
ASD Information Line, phone: (734) 214-4636 or email: asdinfo@epa.gov

Geared toward the public, Mobile Source Emissions - Past, Present, and Future provides general information on the different air pollutants produced by mobile sources and fuels, and of the various programs that OTAQ has undertaken to control emissions of those pollutants, and the impact those programs have had on emissions. It also links to the AIRData web site which has air pollution data for both toxics and criteria pollutants for the entire United States down to the county level.

MOBILE Model links to information on the MOBILE vehicle emission factor model, which is a software tool for predicting gram per mile emissions of hydrocarbons, carbon monoxide, oxides of nitrogen, carbon dioxide, particulate matter, and toxics from cars, trucks, and motorcycles under various conditions.

NONROAD Model links to information on the NONROAD emission inventory model, which is a software tool for predicting emissions of hydrocarbons, carbon monoxide, oxides of nitrogen, particulate matter, and sulfur dioxides from small and large nonroad vehicles, equipment, and engines.

NMIM, or National Mobile Inventory Model, is a free, desktop computer application developed by EPA to help you develop estimates of current and future emission inventories foron-road motor vehicles and nonroad equipment. NMIM uses current versions of MOBILE6 and NONROAD to calculate emission inventories, based on multiple input scenarios that you oenter into the system. You can use NMIM to calculate national, individual state, or county inventories.

MOVES, or MOtor Vehicle Emission Simulator, is an effort to develop a new set of modeling tools for the estimation of emissions produced by on-road and nonroad mobile sources. Also known as the "New Generation Model," MOVES will encompass all pollutants (including hydrocarbons [HC], Carbon Monoxide [CO], oxides of nitrogen [NOx], particulate matter [PM], air toxics, and greenhouse gases) and all mobile sources at the levels of resolution needed for the diverse applications of the system.

Fuels Models links to information on EPA's heavy-duty diesel fuel analysis program, which seeks to quantify the air pollution emission effects of diesel fuel parameters on various nonroad and highway heavy-duty diesel engines. It also links to the Complex Model and the Simple Model used for the Reformulated Gasoline Program.

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Related Information:

Special Modeling in Support of the Heavy Duty Engine/Vehicle and Highway Diesel Fuel Final Rule

This web page provides support documentation and modeling procedures for the Heavy Duty Engine/Vehicle and Highway Diesel Fuel Final Rule. This page includes, but is not limited to, a modeled estimate for one-hour concentrations of fine particulate matter, ground-level ozone levels in extended time periods, PM emissions as they impact national scale toxics, and diesel fuel requirement.

Special Modeling in Support of the Tier 2/Gasoline Sulfur Final Rule

This web page provides information about special vehicle and engine emission modeling completed in support of the Tier 2/Gasoline Sulfur Final Rulemaking. The modeling analyzed on-highway, light-duty vehicles and trucks (all pollutants), heavy-duty gasoline vehicles (NOx and VOC), heavy-duty vehicles (PM and SOx), nonroad stationary, and other sources. Also, photochemical ozone modeling and toxics modeling are provided.

Emission Inventories
This web site contains the document, "Procedure for Emission Inventory Preparation - Volume IV: Mobile Sources" and several EPA papers that describe the effects of raising speed limits on vehicle emissions.

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Mobile Source Observation Database (MSOD)

CALINE Models (e.g., CALINE3 & CALINE4)

Vehicle Clean Screening
This web page provides information on vehicle clean screening, vehicle profiling, and remote sensing device issues. Clean Screening is the term used to describe methods that states can use to excuse cars from a scheduled Inspection and Maintenance emissions test. Remote sensing is a way to measure pollutant levels in a vehicle's exhaust while the vehicle is traveling down the road.

Mobile Source Present and Future Models Workshop
Ann Arbor, November 5-7, 2002:

A 3-day modeling workshop was held in Ann Arbor, MI, November 5 through 7, 2002. The first day of the workshop (November 5) was devoted to the NONROAD model, the second day to the MOVES model, and the third day to the MOBILE6 model.

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Links to Related EPA Information:

Clearinghouse for Inventories and Emissions Factors (CHIEF)
Emission Factor and Inventory Group, Office of Air Quality Planning and Standards Latest emission factor and inventory information, including AP-42 emission factor documents, inventory training tools, emission estimation software, and emissions modeling tools.

Air Pollution Emissions Overview
Office of Air Quality Planning and Standards Information on what emissions are and where they come from, and on measuring, reporting, and using emissions data.

Links to Related Non-EPA web Sites:

Mobile Source Emission Inventory Program Exit EPA disclaimer
California Environmental Protection Agency, California Air Resources Board
This web site contains information on California's on-road and nonroad mobile source emission factors for California and the motor vehicle activity components such as vehicle-miles-traveled, starts and vehicle population. It includes recent publications, the on-road model software and associated system documentation and commonly requested outputs from this model, known as "model runs."

Travel Model Improvement ProgramExit EPA disclaimer
U.S. Department of Transportation
The Travel Model Improvement Program (TMIP) is a multi-year, multi-agency program to develop new travel demand modeling procedures that accurately and reliably forecast travel for a broad range of modes, policy actions and operational conditions. This web site has been established to assure that practitioners have access to the best transportation planning methods available.

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