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How can I find out how much air pollution is released by a certain process?

EPA prepares the National Emissions Inventory (NEI), a comprehensive and detailed estimate of air emissions of both Criteria and Hazardous air pollutants from all air emissions sources. The NEI is prepared every three years by the USEPA based primarily upon emission estimates and emission model inputs provided by State, Local, and Tribal air agencies for sources in their jurisdictions, and supplemented by data developed by the USEPA. The 2011 NEI was built from emissions data in the Emissions Inventory System (EIS).

EPA also develops and provides information about emission factors.  An emissions factor is a tool used to estimate air pollutant emissions from a normally-operating process or activity (e.g., fuel combustion, chemical production). An emissions factor relates the quantity of pollutants released to the atmosphere from a process to a specific activity associated with generating those emissions. 

For most application purposes, users typically assume that an emissions factor represents the average emissions for all emitting processes of similar design and characteristics (i.e., the emissions factor represents a population average).  The simplest form of an emissions factor is a ratio of the mass of pollutant emitted per unit of activity generating the emissions (e.g., pounds of particulate matter (PM) emitted per ton of coal burned). 

In addition, WebFIRE is EPA’s online emissions factor repository, retrieval, and development tool. The WebFIRE database contains EPA’s recommended emissions factors for criteria and hazardous air pollutants (HAP) for industrial and non industrial processes. In addition, WebFIRE contains the individual data values used to develop the recommended factors and other data submitted to EPA by federal, state, tribal, and local agencies; consultants; and industries. 

For each recommended emissions factor and individual data value, WebFIRE contains descriptive information such as industry and source category type, control device information, the pollutants emitted, and supporting documentation.

For further information or assistance with emissions factors please see the following “Contact Us” page: http://www.epa.gov/ttn/chief/comments.html. You may also send an email directly to: info.chief@epa.gov.

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Topic Information
  • Topic #: 23002-16270
  • Date Created: 9/8/2005
  • Last Modified Since: 8/23/2014
  • Viewed: 3348

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