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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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  • 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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  • What is a farm for purposes of the SPCC Rule?

    In the December 2006 amendments to the SPCC Rule, EPA defined a farm as "a facility on a tract of land devoted to the production of crops or raising of animals, including fish, which produced and sold, or normally would have produced and sold, 1,000 or more of agricultural products…

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  • Examples of an agent of a Professional Engineer

    Except as provided in 40 CFR §112.6 for qualified facilities, a Professional Engineer (PE) or an agent of the PE must visit and examine the facility before the PE certifies an SPCC Plan (40 CFR §112.3(d)). What are some examples of an agent of a PE? An agent of a…

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  • What is considered bulk oil storage capacity?

    The revised rule recognizes that oil is sometimes stored in bulk and sometimes used operationally. A bulk storage container is any container storing oil at a facility. Bulk oil storage containers may include, but are not limited to tanks, containers, drums, and mobile or portable totes. Operational use includes oil-filled…

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  • Mobile fuel tanker as a facility

    Is a non-transportation related mobile fuel tanker with more than 55 gallons located near a 55 gallon drum storage area considered a facility? Perhaps. "Facility" is defined in Part 112 to mean "any mobile or fixed, onshore or offshore building, structure, installation, equipment, pipe, or pipeline (other than a vessel…

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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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  • 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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  • 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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  • 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 a field-constructed container?

    What are the types of containers or equipment containing oil reservoirs that would be considered field-constructed containers and thus subject to the brittle fracture evaluation of 40 CFR §112.7(i)? As found in the Preamble language provided on page 47112 of the July 17, 2002 SPCC final rule, EPA provides a…

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  • What is oil-filled operational equipment?

    Oil-filled operational equipment is equipment that includes an oil storage container (or multiple containers and associated piping intrinsic to the operation of the equipment) in which the oil is present solely to support the function of the apparatus or the device. It is not considered a bulk storage container, and…

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  • Are biogenic emissions included in the emissions trends Tier 1 data?

    No, the biogenic emissions are not included in the emissions trends Tier 1 data. If needed, users can add the biogenic data either as a separate Tier, or specify its inclusion in the “Miscellaneous” Tier 1 group.

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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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