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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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  • Accidental releases from non-covered processes

    Should the owner or operator include accidental releases from processes containing listed substances below the threshold quantity in the five-year accident history required under the hazard assessment provisions of 40 CFR Part 68, Subpart B, and in the incident investigation requirements under 40 CFR Part 68, Subparts C and D…

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  • Do I have to report accidents that resulted in medical treatment?

    I had a release where several people were treated at the hospital and released; they attributed their symptoms to exposure. We do not believe that their symptoms were in fact the result of exposure to the released substance. Do we have to report these as offsite impacts? Yes, you should…

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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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  • 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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  • 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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  • What is the definition of "offsite property damage?"

    I am working on the five-year accident history portion of the hazard assessment under the RMP. Section 68.42(a) tells me to include "all accidental releases from covered processes that resulted in deaths, injuries, or significant property damage on site, or known offsite deaths, injuries, evacuations, sheltering in place, property damage…

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  • When does the accident history's five-year period begin?

    The hazard assessment requirements under 40 CFR Part 68, Subpart B include provision of a five-year accident history, as specified at §68.42. When does the five-year period to be reported in the accident history begin? The five-year accident history must include information on all accidental releases from covered processes meeting…

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  • What is the definition of injury?

    Under the hazard assessment requirements of 40 CFR Part 68, Subpart B, an owner or operator must document a five-year accident history including all accidental releases from covered processes that resulted in deaths, injuries, or significant property damage on site, or known offsite deaths, injuries, evacuations, sheltering in place, property…

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  • Do Program Level 1 processes need to do five-year accident histories?

    What is the relationship between the accident history criteria for Program 1 and the five-year accident history? If my process is eligible for Program 1, do I still need to do a five-year accident history? The five-year accident history is an information collection requirement that is designed to provide data…

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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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  • Is there any volume cap when using previously-retired 2008 or 2009 biodiesel RINs to satisfy an obligated party?s 2010 Biomass Based Diesel RVO? Can 2008 or 2009 biodiesel RINs that were previously-retired in 2009 also be used to satisfy Advanced Biofuel

    See More Frequent Questions about Fuels Registration, Reporting, and Compliance Help . 2008 and 2009 biodiesel and renewable diesel RINs (that is, RFS1 RINs with a D code of 2 and RR code of 15 or 17) used for compliance purposes in 2009 can also be used to reduce the…

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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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