Search Frequent Questions

Displaying 1 - 15 of 44 results

• 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.

  • Last published: March 18, 2024

• 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

• How Can I Reduce the Time Needed to Run the Nonroad Emission Factor Post-Processing Scripts?

  See More Frequent Questions about MOVES and Related Models . Very long run times are not unusual for Nonroad emission factor post-processing scripts, particularly with a large output database. To reduce script run time, we recommend doing the following: Reduce the size of your output database by choosing just the…

  • Last published: July 10, 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

• How can residents communicate with EPA about activities at the Norwood Landfill site?

  This EPA website ( www.epa.gov/norwood ) is dedicated to the investigations in the Norwood community. We encourage you to use the site and submit any questions you might have through the form that appears on the website. We also welcome any feedback you might have on the webpage.

  • Last published: March 12, 2024

• Where can residents get the most accurate and up-to-date information on the Norwood Landfill site?

  The www.epa.gov/norwood website is the site with the most accurate and up-to-date information regarding EPA’s investigations in the Norwood community.

  • Last published: March 11, 2024

• 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.

  • Last published: May 1, 2024

• 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…

  • Last published: May 1, 2024

• 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…

  • Last published: May 28, 2024

• How Do I get Carbon Dioxide Equivalent (CO2e) Results for Nonroad Equipment?

  See More Frequent Questions about MOVES and Related Models . CO2e is simply the combination of the pollutants that contribute to climate change adjusted using their global warming potential. This can be done manually summing the mass of the pollutants multiplied by their global warming potential factors. These are the…

  • Last published: July 11, 2024

• How Do I Get Emission Factors or Inventory Totals for Nonroad Equipment Aggregated by the Various Categories used by MOVES?

  See More Frequent Questions about MOVES and Related Models . We have included a set of post-processing scripts that take the results of a Nonroad run and generate other output options. These scripts are all available in the MOVES graphical user interface in the Post Processing pull-down menu under “Run…

  • Last published: August 2, 2024

• 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.

  • Last published: August 15, 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