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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 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 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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  • 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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  • What changes did EPA finalize to the SPCC Rule in December 2006?

    The revised rule modifies requirements for facilities with smaller oil storage capacity and specific types of oil-filled operating equipment. If a facility has 10,000 gallons or less in aggregate aboveground oil storage capacity and the facility meets the oil discharge history criteria, then an owner/operator of a facility may prepare…

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  • SPCC change in ownership

    If there is a change in ownership at a facility, can the facility operate under the same SPCC Plan without the certification from a professional engineer (PE)? If no change in procedures has been made, it may still be feasible to operate under the existing SPCC Plan. The information in…

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  • Liability of oil retailers at SPCC regulated farm

    If a farm is out of compliance of Spill Prevention, Control, and Countermeasure (SPCC) regulations and is checked by EPA and/or has a spill, is the retailer that filled the tank liable? No, EPA considers the oil tank owner responsible for lack of compliance.

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  • How are emissions trends compiled?

    For criteria air pollutants and precursors, the emissions trends are based on the triennial National Emissions Inventory data, with some interim year data included for non-triennial years. The methods and interim-year approaches are described on the “Development of Data” tab included with the data provided on the Air Pollutant Emissions…

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  • What does an annual emissions value in the NEI represent (one year or multiple years)?

    The NEI provides total annual emissions for a single year.

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  • How do I determine what SCCs have changed between inventory years?

    These are available in the EIS (Reporting Code table) or public website: https://sor-scc-api.epa.gov/sccwebservices/sccsearch/ Filter on “last inventory year” to remove SCCs no longer active. If this column has a date in it, then the SCC has been retired as of that date. The “last updated date” (column J) indicates when…

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  • What is included in the emissions “Tiers”?

    The Tiers are assigned by a Source Classification Code (SCC), which has the most detail about the emissions processes that generate the emissions. The full list of SCCs, their associated Tiers, and the SCC descriptions is available online at https://sor-scc-api.epa.gov/sccwebservices/sccsearch/ .

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  • Where are the NAICS/ SIC and SCC codes changes that have been implemented for the 2017NEI?

    Please refer to the NEI webpage for 2017 documentation , and follow the link for Appendix 2 - 2017 NEI Plan Code Changes. That Excel file describes anticipated changes for the SCCs and NAICS and includes a helpful read me. I'll just note in the next NEI/EIS email that SCC…

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  • Are the GHGs in the National Emissions Inventory Complete?

    No, the 2020 National Emissions Inventory (NEI) does not comprehensively capture all sources and sinks of greenhouse gases (GHGs) in the United States. For this information, users should review the EPA’s annual Inventory of U.S. Greenhouse Gas Emissions and Sinks . However, the NEI does report GHG emissions for select…

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  • PE certifying a technical amendment

    Except as provided in 40 CFR §112.6 for qualified facilities, a Professional Engineer (PE) must certify all technical amendments to an existing SPCC Plan (§112.5(c)). When certifying a technical change to an existing SPCC Plan, does the PE have to inspect and certify the entire Plan or only the amended…

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