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  • 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 .

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  • 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…

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  • 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…

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  • 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…

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  • Tier2 Submit validation error due to incorrect CAS number

    What do I do if I get a validation error in Tier2 Submit due to an incorrect Chemical Abstracts Service (CAS) number? Your CAS number should be typed exactly as it appears on the substance's SDS. Review your safety data sheet (SDS) to see if the CAS number was typed…

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  • How do I download the data from the “Data Summaries” tab on the NEI data pages?

    On these pages after you run a query, there should be icons that at the top of the data table generated by your query. These icons look like this: COPY CSV EXCEL PDF PRINT If these icons do not appear, it is because Adobe Flash is being blocked by your…

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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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  • Completing Tier II Forms When Information Has Not Changed

    Pursuant to 40 CFR 370.42(c) and (r) , an owner or operator submitting federal Emergency Planning and Community Right-to-Know Act (EPCRA) Tier II inventory information must indicate if the facility or chemical information is identical to that submitted last year. If the facility or chemical information is the same as…

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  • What facilities are required to report to the NEI?

    The emissions reporting thresholds are in the Air Emissions Reporting Rule (AERR), 40 CFR Part 51, Subpart A, Appendix A, Table 1 , which require state/local air agencies to report emissions as point sources for facilities that meet or exceed these emissions thresholds. The AERR requires states/locals to report to…

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  • Why do the PM2.5 emissions for the electric utilities source category jump up between 1998 and 1999?

    The estimation method for PM emissions from fuel combustion sources was enhanced beginning with the 1999 National Emissions Inventory. Prior to 1999, the emissions measurement data methodology only included the filterable portion (which means the solid particle matter at elevated stack temperatures). Beginning with the 1999 NEI, both the filterable…

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  • How do I reset my password for the Emissions Inventory System?

    Instructions for resetting your password are available in the Emissions Inventory System (EIS) User’s Manual and How To’s section on “How Do I Update My Password?” Follow the instructions to reset your password.

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  • Where can I get maps and/or emissions of facility emissions data?

    The EPA provides emissions maps in two ways. First, each of the last three NEI years have a “Facility Mapping” tab available on the main NEI page for that inventory year (for example, see the 2020 NEI page). With this tool, maps can be created for one state at a…

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