Search Frequent Questions

Displaying 1 - 15 of 16 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

• 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…

  • 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

• 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

• The regulations at 80.1427(a)(7)(iii) say that 2008 biodiesel RINS + 2009 biodiesel RINs cannot exceed 20% of the 2010 RVO. Does this mean that 80% of the 2010 biomass-based diesel RVO has to come from 2010 RINs?

  See More Frequent Questions about Fuels Registration, Reporting, and Compliance Help . The 20% rollover cap under RFS2 is the same as the rollover cap under the RFS1 program. However, the rollover cap only places a limit on previous year RINs that were NOT used for compliance in 2008 or…

  • Last published: July 24, 2024

• 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

• 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.

  • Last published: May 1, 2024

• Under section 80.1405, the standard for biomass based diesel (BBD) is calculated via a fraction, the numerator of which is equal to the RFV for BBD in compliance year i times 1.5. For 2010 only, would you agree that, using the example of the calculation f

  See More Frequent Questions about Fuels Registration, Reporting, and Compliance Help . The percentage standard for biomass-based diesel in years 2011 and beyond will be based upon the volumes specified in CAA 211(o)(2)(B)(i)(IV), unless some portion of that volume is waived per CAA 211(o)(7)(E). For 2010, the numerator of the…

  • Last published: July 23, 2024

• Where can I obtain the hourly data from Continuous Emissions Monitors (CEMs)?

  The CEM emissions data are available from the EPA Clean Air Markets Program Data website.

  • Last published: August 15, 2024

• What are the units of NEI emissions data?

  NEI emissions values represent total annual emissions for the inventory reporting year. Criteria air pollutants and precursors (CAPs) are reported in short tons per year , and hazardous air pollutants (HAPs) are reported in lbs per year .

  • Last published: January 7, 2025

• What is the definition of VOC?

  There is a regulatory definition of VOC. It is found in 40 CFR 51.100. CFR - code of federal regulations. The definition relates to the intent and requirements of the Clean Air Act. Excerpt from “Volatile Organic Compounds” Definition per 40 CFR Part 51.100(s): " Volatile organic compounds (VOC) means…

  • Last published: March 18, 2024

• How can I get more detailed information? What measurements/sensors are used to measure emissions?

  Access the latest NEI data set . Under 'Sector Summaries - Criteria and Hazardous Air Pollutants by 60 EIS emission sectors', > choose National > for Pollutant, choose PM10 Primary and/ or PM2.5-PRI > Sector, choose all sectors >Submit Query to see results at bottom of page. Open the results…

  • Last published: March 18, 2024

• What does "NEC" stand for in the emissions sectors?

  NEC means “not elsewhere classified” and includes SCCs that are not assigned to any of the other specific industrial process sectors. If you look at the SCC code table available at the SCC web site and filter on the Sector name that includes “NEC”, you can see the type of…

  • Last published: March 18, 2024