EPA’s AP-42 development methodology: Converting or rerating current AP-42 datasets

Authors: MOORE, THOMAS - Oklahoma State University; BUSER, MICHAEL - Oklahoma State University; Whitelock, Derek; HAMILTON, DOUG - Oklahoma State University; Wanjura, John

Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 7/27/2015
Publication Date: 7/27/2015
Citation: Moore, T.W., Buser, M.D., Whitelock, D.P., Hamilton, D.W., Wanjura, J.D. 2015. EPA’s AP-42 development methodology: Converting or rerating current AP-42 datasets. ASABE Annual International Meeting. Paper no. 15290967.

Interpretive Summary: The U.S. Environmental Protection Agency recently published new methods for updating the Compilation of Air Pollution Emission Factors (AP-42). Regulatory agencies use emission factors to develop facility construction and operating permits. The new method instructs that new data be rated according to an Individual Test Rating (ITR) process and that the data quality ratings of the current AP-42 emission factors be directly converted to the new ITR system. In this study, data gathered from a cotton ginning industry-supported project was used to evaluate the effects of converting the current AP-42 dataset ratings versus rating them according to the ITR process. When directing converted, all of the current AP-42 emission factors were rejected from the emission factor dataset due to low ITRs. When rated according to the ITR process, many of the current AP-42 emission factors then had much higher ITRs and were then included in emission factor determination. To prevent the loss of data, we propose that all current AP-42 emissions datasets should be rerated using the new ITR system. Better, more representative emission factors will ensure that the U.S. ginning industry is more equitably regulated in the future.

Technical Abstract: In August 2013, the U.S. Environmental Protection Agency’s (EPA) published their new methodology for updating the Compilation of Air Pollution Emission Factors (AP-42). The “Recommended Procedures for Development of Emissions Factors and Use of the WebFIRE Database” instructs that the ratings of the current AP-42 datasets be directly converted to the new Individual Test Rating (ITR) system. This study used PM10 data gathered from a cotton ginning industry-supported project initiated in 2008 to evaluate the implications of converting the current AP-42 dataset ratings versus rerating them using the ITR process. This study used the methods contained in “Recommended Procedures for Development of Emissions Factors and Use of the WebFIRE Database” to develop two sets of emission factors for 17 cotton ginning systems: one using converted and the other using rerated AP-42 datasets. Due to their low ITRs, no converted, current AP-42 datasets were retained for emission factor averages. When rerated with the ITR process, the new ratings ranged from 29-91 (out of a possible 100), allowing many datasets to be included in emission factor averages. To prevent the loss of data, we propose that all current AP-42 emissions datasets should be rerated using the new ITR system.