Science & Technology
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What sources make up the Sectors or Tiers used in the emissions data summaries?
Tier 1 and Sector 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 and Sector 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 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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Why do mobile source NOx emissions jump higher between 2001 and 2002 on the emissions trends?
The emissions model used for mobile sources changed from MOBILE6.2 to MOVES 2010 in December 2009. This change included a notable increase in NOx emissions. The EPA adjusted data back to 2002 to reflect the change in models. The higher emissions in 2002 are because of this method change and…
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Emission Trends - FAQ
Emissions Trends frequently asked questions
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2020 National Emissions Inventory (NEI) Resources for State, Local, Tribal Agencies
Submittal and preparation documents for state, local, tribal agencies for all data categories of the 2020 National Emissions Inventory
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Emissions Science Improvements: Temporal and Spatial Allocations
Plans for new and improved temporal and spatial approaches for the National Emissions Inventory.
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Website Not Working - FAQ
Website Not Working FAQs
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The point source maps are not working on the NEI data tab. What do I do?
The point source maps use a web service provided by Envirofacts. Please report your problem to the Envirofacts “Contact Us” page here.
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RFC 18001 – Anthraquinone – Supplemental Information
RFC 18001 – Anthraquinone – Supplemental Information demonstrating that National Toxicology Program Technical Report 494 should not be the basis for provisional screening values presented in Appendix A of “Provisional Peer-Reviewed Toxicity Values
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Stakeholders Opposition to Denka’s Request for Reconsideration of EPA’s Toxicological Review of Chloroprene
Submittal by the Louisiana Environmental Action Network concerning a request for reconsideration.
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May 26, 2005 RFC: Approval of Air Credits and State Implementation Plan Amendments that Violate EPA's Data Quality Guidelines
Submitted on behalf of the National Paint and Coatings Association and Sherwin-Williams
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December 21, 2005 EPA response to RFC: Approval of Air Credits and State Implementation Plan Amendments that Violate EPA's Data Quality Guidelines
EPA response to the Request for Correction (RFC)
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October 11, 2005 RFC: Risk Assessment for Metan Sodium
Submitted on behalf of the Metam Sodium Alliance
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September 5, 2006 EPA response to RFC: Guidelines for Carcinogen Risk Assessment, Basing Hazard Categorization on Results of Animal Studies
EPA response to the Request for Correction (RFC)
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October 12, 2006 EPA response to RFC: Risk Assessment for Metan Sodium
EPA response to the Request for Correction (RFC)
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EPA Response to RFC 23002 - Toxic Substances Control Act (TSCA) Risk Evaluation for 1,4-Dioxane
This page contains the Agency's response to RFC 23002 - Toxic Substances Control Act (TSCA) Risk Evaluation for 1,4-Dioxane
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EPA response to information quality alert - issued Dec. 16, 2019
RFC 19004 EPA response to information quality alert concerning atrazine
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Performance-Based Measurement System (PBMS) & Flexible Approach
Performance-Based Measurement System (PBMS) & Flexible Approach, Frequent Questions
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How do the different parts of particulate matter (PM) fit together?
The various parts of PM in the National Emissions Inventory (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…