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  • How does PM2.5 relate to PM species such as EC, OC, SO4, NO3, PMFINE, and DIESEL-PM25?

    Primary PM2.5 estimates are speciated into the five PM species in the NEI: elemental (black) carbon (EC), organic carbon (OC), nitrate (NO3), sulfate (SO4), and the remainder of PM25-PRI (PMFINE). Diesel engine PM25-PRI and PM10 emissions are also labeled as DIESEL-PM25 and DIESEL-PM10 for mobile source diesel engines. For all…

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  • Where can I find older NEI data (prior to 2008)?

    The raw data and summaries that are still available (dating back to 1990) can be obtained from the web page https://www.epa.gov/air-emissions-inventories/pollutant-emissions-summary-files-earlier-neis . Starting with 2001 data, a more limited selection of summary files are available.

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  • Where can I download hourly emissions data from continuous monitoring?

    Hourly emissions data files are available from the Clean Air Markets Division of EPA, collected as part of 40 CFR Part 75. The download location has changed in February, 2023. The new location is https://campd.epa.gov/data/bulk-data-files . Once on this new site, use the menu (at the left) and the Keyword…

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  • Can MOVES Report Output in Terms of Fuel Consumption?

    See More Frequent Questions about MOVES and Related Models . Although gallons of fuel consumed are not reported by MOVES, the factors used to convert total energy consumption (a MOVES reporting option) to gallons of fuel are contained in the FuelSubtype table (energy content, reported in kilojoules per gram of…

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  • How Can I Determine the Effect of Speed on Vehicle Emissions?

    See More Frequent Questions about MOVES and Related Models . MOVES can be run in either “Inventory” or “Emission Rates” mode. With Emission Rates, MOVES reports emission rates for the 16 average speed bins used by MOVES for each hour of the day and additional emission rate output that may…

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  • How do the different parts of particulate matter (PM) fit together?

    The various parts of PM in the NEI are related as follows. PM10-FIL > PM25-FIL because PM10-FIL includes PM25-FIL PM25-PRI = PM25-FIL + PM-CON This equation only applies at the process level. Because some sources only can report PM2.5 (due to test method differences), this equation does not apply to…

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  • How do I use MOVES at Project Scale?

    See More Frequent Questions about MOVES and Related Models . The MOVES model can estimate emissions at national, county or project scale. Project scale is useful for estimating an individual transportation project like an intersection or transit project, but it requires detailed inputs that describing the vehicle population and activity…

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  • Can I use MOVES to Model Emissions from Vehicles in other Countries?

    See More Frequent Questions about MOVES and Related Models . The MOVES model was designed specifically to model the emissions from vehicles and equipment designed to meet emission standards in the United States. There are considerable challenges to adapting the MOVES framework to other nations, primarily around the need for…

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  • How complete are the data in the National Emissions Inventory?

    While the goal of the National Emissions Inventory (NEI) program is to include all emissions data, there are always challenges meeting this goal. The answer about completeness of coverage of sources depends on the emissions sector and pollutant. In general, the criteria air pollutants and precursors (CAPs) are expected to…

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  • Where is more information available about emissions estimation methods used by the EPA?

    For criteria air pollutants and precursors as well as for hazardous air pollutants, the methods are described in the technical support document (TSD) for the latest National Emissions Inventory (NEI) available from the main NEI page . For greenhouse gas emissions, you can find greenhouse gas inventory methods from the…

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  • Can I get access to the Emissions Inventory System if I am not a data provider to EPA?

    The Emission Inventory System (EIS) is a secured database for EPA and State/Local and Tribal Air Agencies only. The EIS is used to develop the National Emission Inventory (NEI). While you cannot have access to EIS, you can have access to the current and past NEIs through EPA’s NEI website…

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  • What is the cause of the large decrease in electric utility emissions, particularly sulfur dioxide, starting in 1995?

    SO2 emissions reductions from utilities during this time are primarily attributed to the impacts of the acid rain program. As described on EPA’s Acid Rain Program web page, Phase 1 of this program began in 1995 and affected 263 units at 110 most coal-burning electric utility plants in 21 eastern…

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  • What sources make up the Tier 1 categories used in the emissions trends?

    Tier 1 categories are assigned by source classification codes (SCCs) that are the most specific processes available in the NEI. The latest SCC list with the Tier 1 assignments can be downloaded from the EPA SCC website in Comma Separate Values (CSV) format.

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  • Does MOVES Incorporate Anticipated Improvements in VOC Emission Factors Resulting from Improved Fuel Economy?

    See More Frequent Questions about MOVES and Related Models . Changes in fuel consumption affect VOC emissions by reducing refueling vapor losses and spillage. Other emissions (such as sulfates) are also affected by fuel consumption. MOVES incorporates changes due to fuel economy requirements that were finalized as of the date…

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