# Create CEM file for 2022?

**URL:** <https://forum.cmascenter.org/t/create-cem-file-for-2022/3243>\
**Category:** SMOKE\
**Created:** [May 13, 2022, 10:57pm UTC](https://forum.cmascenter.org/t/create-cem-file-for-2022/3243 "2022-05-13T22:57:47Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![asmontgomery](https://avatars.discourse-cdn.com/v4/letter/a/898d66/32.png) [@asmontgomery](https://forum.cmascenter.org/u/asmontgomery)\
**Post date:** [May 13, 2022, 10:57pm UTC](https://forum.cmascenter.org/t/create-cem-file-for-2022/3243/1 "2022-05-13T22:57:47Z")

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Hello,

I was wondering if it was possible to convert the first quarter of CEM data from the EPA air data mart into the proper FF10 format. (IE: it’s 2022, and I would like to run some January-February 2022 PTEGU files). If so, is there some documentation for how to create the HOUR\_UNIT\* files from the air data mart data? I have emailed the EPA contact line, and they said they were not sure how to convert the air data mart data into the SMOKE input format.

Thank you!  
Anastasia

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**Author:** ![asmontgomery](https://avatars.discourse-cdn.com/v4/letter/a/898d66/32.png) [@asmontgomery](https://forum.cmascenter.org/u/asmontgomery)\
**Post date:** [May 19, 2022, 12:05am UTC](https://forum.cmascenter.org/t/create-cem-file-for-2022/3243/2 "2022-05-19T00:05:27Z")

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Ok so I figured it out. The EPA uploads cem files quarterly (according to the help desk?), which you can access via FTP: [https://gaftp.epa.gov/DMDnLoad/emissions/hourly/monthly/2022/](https://gaftp.epa.gov/DMDnLoad/emissions/hourly/monthly/2022/)

I made a script to batch download the zip files, unzip them, and save the file names.

Then I formatted the HOUR\_UNIT files to match this: [8.2.7.&nbsp;PTHOUR: Point source hour-specific emissions](https://www.cmascenter.org/smoke/documentation/4.5/html/ch08s02s07.html)  
which just means rearranging the columns of the files from the FTP, formatting the dates, and concattenating all the files within a specific month. I used the PTINV file in the SMOKE/input/ptegu directory to guide me to make sure the IDs were matching up. It’s kinda tricky reading through the user guide to get this, but ends up being straightforward I think?

One negative is that I could not find metadata in the files to help navigate the files across the FTP and the SMOKE platform so that I can really confirm how these are all connected. Like, the EPA files use ‘ORISPL\_CODE’ to match on to the ‘ORISID’, ‘UNITID’ to match ‘BLRID’, etc., etc. (at least, from matching unique datasets across the PTINV, an HOUR\_UNIT\*, and these FTP files, that’s what I have back-engineered to understand?). So I’m working off my matching and assumptions, but it seems to work. Also, I am not sure if I need to further clean the data but that will be my next step to compare my 2021 CEM files to my 2022 CEM files.