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Posted: 06/03/2014

On May 16, 2014 the Environmental Protection Agency (EPA) released a new version (14134) of AERMOD and AERMOD’s meteorological pre-processor AERMET. The summary of the bug fixes and enhancements to AERMOD and AERMET can be found in the model change bulletin available on EPA’s Support Center for Regulatory Air Quality Models (SCRAM) website.

In response to these updates, Iowa DNR has reprocessed all of the 2005-2009 meteorological datasets using the new version of AERMET.

Sensitivity tests were conducted using the new version of AERMOD and the new meteorological data set. The results of these tests indicate that the changes to AERMOD will have little effect on the model results, and the changes to AERMET will have only a slightly larger impact. As a result of implementing the new versions of AERMOD and AERMET, there should be an average change in maximum modeled concentration of less than 1 percent. Of all the source types and averaging periods analyzed, approximately 99 percent resulted in maximum concentrations within 5 percent of the previous versions.

The new meteorological data can be differentiated from the previous versions by the letter “F” appended to the end of the file names. Applicants should begin using the new meteorological data immediately. The data can be found on the Department’s meteorological data webpage.

If you have any questions please contact Alyssa Fizel at (515)-725-9566 or

This list serve article is intended for consultants, industries, environmental groups, general public, and other entities regulated under the Clean Air Act. It was written by the DNR Air Quality Bureau to share regulatory news, program updates and technical guidance.