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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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  • Can a facility divide a process when assigning program levels?

    My process includes a series of interconnected units, as well as several storage vessels that are co-located. Several sections of the process could qualify for Program 1. Can I divide my process into sections for the purpose of assigning Program levels? No, you cannot subdivide a process for this purpose…

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  • If a stationary source has processes ineligible for Program 1, are all processes ineligible?

    If a stationary source has several processes that are covered under 40 CFR Part 68, and some of those processes have had an accidental release within the past five years (effectively making those processes ineligible for Program 1 status), are the individual processes from which no accidents have occurred also…

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  • If a covered process has an accident, when does it lose eligibility for Program 1 status?

    A process covered under 40 CFR Part 68 is eligible for Program 1 requirements if it meets all of the criteria listed at 40 CFR §68.10(b). Those criteria include a requirement that the process cannot have had an accidental release of a regulated substance that led to offsite death, injury…

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  • Applicability of program levels and prevention program requirements for co-located vessels

    I have a tank with 1,000,000 pounds of toluene diisocyanate (TDI), which is covered under the RMP rule, but not under OSHA PSM. Considered by itself, the TDI would be Program 2 for EPA. The tank, however, is close to equipment that has chlorine above the applicable threshold and is…

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  • Changing from a Program 2 or 3 process to a Program 1 process

    If five years have passed since the last accident involving a covered process, and that process meets the other two requirements identified under 40 CFR §68.10(b) for Program 1 eligibility, could that process become a Program 1 process even if it had previously been identified as a Program 2 or…

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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 do I register renewable gasoline?

    See More Frequent Questions about Fuels Registration, Reporting, and Compliance Help . Manufacturers/importers of renewable gasoline for on-road use are required to register the fuel with the EPA. To register, see: Register or Update a Fuel or Fuel Additive Request under 40 CFR Part 79 . Please indicate “renewable gasoline”…

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  • Where can I find the public list of registered fuels and fuel additives?

    See More Frequent Questions about Fuels Registration, Reporting, and Compliance Help . An online list of fuels and fuel additives registered with EPA is located here: Register or Update a Fuel or Fuel Additive Request under 40 CFR Part 79 .

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  • How do I register renewable diesel?

    See More Frequent Questions about Fuels Registration, Reporting, and Compliance Help . Manufacturers/importers of renewable diesel for on-road use are required to register the fuel with the EPA. To register, see Register or Update a Fuel or Fuel Additive Request under 40 CFR Part 79 . Please indicate “renewable diesel”…

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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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  • Assigning program level 1 if a public receptors is just beyond distance to endpoint

    Our distance to the endpoint for the worst-case release is 0.3 miles. The nearest public receptor is 0.32 miles away. What tools are available to document that the public receptor is beyond the distance to the endpoint so we can qualify for Program 1? The results of any air dispersion…

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