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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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  • Do settlement communications, such as past “agreements in principle,” impact the implementation of the final Consent Decrees?

    The parties are bound by the terms of the various final, publicly available consent decrees. These consent decrees were made available for public comment before they were finalized and entered by the Court. Past settlement communications and documents created in the course of settlement discussions have been incorporated (or not)…

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  • What is the Confidentiality Order?

    The Confidentiality Order (Order) is a court order entered by the Federal District Court for the District of Montana (Court) on August 8, 2002, and amended by the Court on December 31, 2003, that applies to Superfund settlement negotiations in the Clark Fork River Basin, including the following sites: Silver…

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  • How does EPA ensure that the potentially responsible parties complete their work?

    All cleanup activities performed by the PRPs are subject to enforcement instruments (i.e., consent decrees or administrative orders) that provide for EPA approval of all deliverables and oversight of all work performed by the PRPs.

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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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  • Why is the Confidentiality Order important?

    The Confidentiality Order (Order) has been, and continues to be, effective in assisting the parties in reaching settlements under the framework established by the Court in US v. ARCO and still pending in court – six consent decrees to date have been entered since the Order was issued. There are…

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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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  • 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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  • 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://ofmpub.epa.gov/sccwebservices/sccsearch/ .

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  • Why were the consent decree negotiations under a confidentiality order?

    The confidentiality order was issued by the federal district court in 2002 to encourage and facilitate settlement negotiations. The court determined that the confidentially order was appropriate to ensure that the parties were afforded the opportunity to engage in frank, open discussion so that litigation could be settled promptly and…

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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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