You can develop an emissions factor from individual performance test values that you select from the WebFIRE database using the same procedures that EPA follows to develop new or revise existing factors. To begin, retrieve the test data values of interest by entering each of the search criteria below in sequence and clicking on the "Submit Search" button. As you select each search criteria, the drop-down menu for the next criteria shows the available selections based on the entries you provided for the previous criteria. You must specify a selection for each search criteria field.

The data outlier test in the WebFIRE emissions factor calculation procedures requires that the data set you select include at least three data values. This CSV table lists the data sets (grouped by Source Classification Code (SCC), pollutant, control device configuration, and activity) for which the WebFIRE database contains at least three data values. At this time, a user cannot group different SCC and control device configurations when developing user-defined emissions factors.

Note: The EPA does not retain a copy of user-defined emissions factors. In addition, the intended application of a user-defined emissions factor is contingent upon approval of the regulatory authority (state, local, tribal, etc.).

The emissions factor development tool on this page allows users to derive emissions factors for single SCCs and control device configurations. To develop emissions factors that apply to more than one SCC and/or control configuration, users can apply the guidance and calculations contained in the t-Test Evaluation and Emissions Factor Calculation spreadsheets available here to data sets of interest that the user downloads WebFIRE.