Frequent Questions

Section 5 and 6 basis of estimate codes for emission factors: E1 vs E2

On Sections 5 and 6 of the TRI Form R, facilities must indicate the principal method used to determine the amount of releases and other waste management activities.  What is the difference between the two basis of estimate codes for emissions factors, E1 and E2?

The E1 code indicates that the estimate is based on published emission factors, such as those relating release quantity to through-put or equipment type (e.g., air emission factors).  These emission factors are generated from data published by trade associations and other organizations, and take into account averages for a type of activity for specific process / equipment/ sector(s) to achieve a general emissions factor.  AP-42 emission factors would fit mostly likely under E1.

The E2 code indicates that the estimate is based on site-specific emission factors, such as those relating release quantity to through-put or equipment type (e.g., air emission factors).  These emission factors are developed specifically for a situation or process on site and take into account the actual field conditions at the location, rather than an average across the industry.

Additional information about emissions factors is available in AP-42, Compilation of Air Pollutant Emission Factors.  AP-42 is available at the following URL:

www.epa.gov/ttn/chief/ap42

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