# PM25 OUTPUT ERROR about CMAQ5.3.3-ISAM

**URL:** <https://forum.cmascenter.org/t/pm25-output-error-about-cmaq5-3-3-isam/6159>\
**Category:** CMAQ\
**Created:** [March 8, 2026, 2:34pm UTC](https://forum.cmascenter.org/t/pm25-output-error-about-cmaq5-3-3-isam/6159 "2026-03-08T14:34:02Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![lizadams](https://avatars.discourse-cdn.com/v4/letter/l/49beb7/32.png) [@lizadams](https://forum.cmascenter.org/u/lizadams)\
**Post date:** [March 17, 2026, 9:15pm UTC](https://forum.cmascenter.org/t/pm25-output-error-about-cmaq5-3-3-isam/6159/2 "2026-03-17T21:15:08Z")

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Please see this prior issue.

> [@Only Simulating Primary Particulate Matter (PPM) with CMAQ](https://forum.cmascenter.org/t/only-simulating-primary-particulate-matter-ppm-with-cmaq/3626/2):
>
> Dear Alpha\_Su, Thanks for your question. While quantifying the contribution of primary vs. secondary species to total PM is a highly valuable result, it can be a bit tricky to process it from CMAQ output. For some time, CMAQ has employed various chemical and mass transfer schemes to process aerosols that sort of blur the lines between primary and secondary – this is of course happening in the real atmosphere as well. As you point out, APOC and APOM are nominally ‘primary organic aerosol’, but …

This is the total for CMAQv5.4+, which is likely different that the version that you are using.  
!! Total PM Aggregates  
ATOTIJ\_ONR ,ug m-3 ,ASO4I\_ONR[1]+ANO3I\_ONR[1]+ANH4I\_ONR[1]+ANAI\_ONR[1]+ACLI\_ONR[1]   
+AECI\_ONR[1]+AOTHRI\_ONR[1] \   
+ASO4J\_ONR[1]+ANO3J\_ONR[1]+ANH4J\_ONR[1]+ANAJ\_ONR[1]+ACLJ\_ONR[1]   
+AECJ\_ONR[1]+AOMIJ\_ONR[0]+AOTHRJ\_ONR[1]+AFEJ\_ONR[1]+ASIJ\_ONR[1]   
+ATIJ\_ONR[1]+ACAJ\_ONR[1]+AMGJ\_ONR[1]+AMNJ\_ONR[1]+AALJ\_ONR[1]+AKJ\_ONR[1] here ONR is the tagged species

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