Search Frequent Questions

Displaying 1 - 15 of 22 results

• 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…

  • Last published: April 17, 2024

• 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…

  • Last published: April 17, 2024

• What if there is a gap in coverage of the GLEJGP?

  EPA has set up national technical assistance centers (TCTACs), including one solely for tribes and tribal nations, that are geared towards communities. There are two in Region 5: one in Minneapolis and one in Chicago. The TCTACs are separate from this RFA ; however, they cover the entire Great Lakes…

  • Last published: September 5, 2024

• 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…

  • Last published: January 7, 2025

• Does EPA have a minimum threshold/definition for the Regional scale program? In other words, what does Regional mean or is it open to applicants to determine at any scale?

  GLNPO wants to be extremely flexible and encourage PRs to think about which regions they could expect to effectively cover when creating their application. There are no additional criteria from EPA on how big or small the Project RFA should be.

  • Last published: September 5, 2024

• 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…

  • Last published: January 7, 2025

• 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…

  • Last published: January 7, 2025

• 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…

  • Last published: March 18, 2024

• 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/ .

  • Last published: March 18, 2024

• 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…

  • Last published: January 7, 2025

• 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.

  • Last published: January 7, 2025

• 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…

  • Last published: January 23, 2025

• 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…

  • Last published: May 31, 2024

• What are EPA’s plans for the 2020 National Emissions Inventory given the atypical situation from COVID-19 that is impacting emissions? What will it be used for?

  The EPA intends to prepare a 2020 National Emissions Inventory in collaboration with state, local, and tribal air agency partners. The Air Emissions Reporting Rule (AERR) requires states and delegated local and tribal agencies to report emissions from stationary sources and provide model inputs for onroad and nonroad sources (except…

  • Last published: August 15, 2024

• Could a regional application, include an entire state?

  Yes, with the caveat that the entire state must fall within the historic bounds of the Great Lakes basin. For example, if the Principal Recipient is proposing a GLEJGP for the state of Illinois, projects may fall in the portion of the state within the Great Lakes basin, but not…

  • Last published: September 5, 2024