# Do EQUATES PM2.5 estimates include secondary PM2.5?

**URL:** <https://forum.cmascenter.org/t/do-equates-pm2-5-estimates-include-secondary-pm2-5/5217>\
**Category:** EQUATES\
**Created:** [September 13, 2024, 5:52pm UTC](https://forum.cmascenter.org/t/do-equates-pm2-5-estimates-include-secondary-pm2-5/5217 "2024-09-13T17:52:13Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![sarahd](https://avatars.discourse-cdn.com/v4/letter/s/8c91f0/32.png) [@sarahd](https://forum.cmascenter.org/u/sarahd)\
**Post date:** [September 13, 2024, 5:52pm UTC](https://forum.cmascenter.org/t/do-equates-pm2-5-estimates-include-secondary-pm2-5/5217/1 "2024-09-13T17:52:13Z")

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Hi everyone,

I am looking for clarification on whether the EQUATES PM2.5 estimates represent primary PM2.5 or both primary and secondary PM2.5. I am looking specifically at the PM2.5\_AVG variable in the daily average surface concentrations 12US1 file.

Thank you for your help!

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**Author:** ![hogrefe.christian](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@hogrefe.christian](https://forum.cmascenter.org/u/hogrefe.christian)\
**Post date:** [September 13, 2024, 6:11pm UTC](https://forum.cmascenter.org/t/do-equates-pm2-5-estimates-include-secondary-pm2-5/5217/2 "2024-09-13T18:11:16Z")

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Hello @sarahd ,

thanks for your interest in the EQUATES data. The EQUATES CMAQ PM2.5 concentrations represent the effects of both primary emissions and secondary formation in the atmosphere.

Christian

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**Author:** ![sarahd](https://avatars.discourse-cdn.com/v4/letter/s/8c91f0/32.png) [@sarahd](https://forum.cmascenter.org/u/sarahd)\
**Post date:** [September 13, 2024, 6:29pm UTC](https://forum.cmascenter.org/t/do-equates-pm2-5-estimates-include-secondary-pm2-5/5217/3 "2024-09-13T18:29:47Z")

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Thank you Christian!