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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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  • 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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  • Where can I go to learn more?

    PitWatch.org is the online home of the Berkeley Pit Public Education Committee. This volunteer committee educates residents, students, and the public about the environmental management of the Berkeley Pit.  Information includes the geology, hydrology, current events, and ongoing academic research associated with the Berkeley Pit. This committee frequently shares their…

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  • How can I get involved?

    EPA encourages the public to review our Community Involvement Plan (pdf) (66pp, 6MB) that lays out our specific community involvement activities, and how to become involved at the Site. You can also contact our Community Involvement Coordinator, Mackenzie Meter ( [email protected] ), for site updates and to be added to…

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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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  • 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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