Search Frequent Questions

Filter By:

Active filters:

Remove all filters

Displaying 1 - 15 of 23 results

  • 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:

  • 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:

  • Redoing calculations if RMP*Comp is updated

    Will RMP*Comp be updated? If so, would I have to redo calculations I might already have made with an earlier version? No, you do not have to redo your work if you have already completed your consequence analyses. RMP*Comp is based on the EPA's Offsite Consequence Analysis Guidance (OCA Guidance)…

    • Last published:

  • Different distances to toxic endpoints with different versions of RMP*Comp

    I've noticed that for certain chemicals, RMP*Comp gives substantially different distances to the toxic endpoint than previous versions. Why? In the current version of RMP*Comp, we have incorporated new chemical-specific distance tables for ammonia, chlorine, and sulfur dioxide. The generic tables are still used for other chemicals (you can see…

    • Last published:

  • Distance to endpoint calculations used by RMP*Comp

    Does RMP*Comp perform some math or modelling in order to arrive at an endpoint distance, or is it simply interpolating from the tables in the EPA's Offsite Consequence Analysis Guidance (OCA Guidance)? RMP*Comp follows the procedures set out in the OCA Guidance . This means that for some scenarios, the…

    • Last published:

  • 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:

  • 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:

  • 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:

  • 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:

  • 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:

  • 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:

  • How often are the NEI data updated and how frequently are the data published?

    The full NEI is created for every third inventory year (e.g., 2008, 2011, 2014, and 2017). The data for each version has been updated two times each for the 2008, 2011, and 2014 NEI cycles. For the 2017 NEI and beyond, the EPA is trying to publish only a single…

    • Last published:

  • 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:

  • RMP*Comp and emergency response

    Can I use RMP*Comp for emergency response? No. It's a planning tool. Many other tools are available for response, including ALOHA . You can learn more by reading CAMEO tools for RMP .

    • Last published:

  • Minimum and Maximum Distance to Endpoint

    The Chemical Accident Prevention Provisions require the completion of a worst-case release scenario analysis (40 CFR §68.25). This analysis includes estimating the greatest distance to endpoint as defined by the parameters in §68.22. Is there a required minimum or maximum distance for the distance to endpoint in the worst case…

    • Last published: