# New species add (GAS phase)

**URL:** <https://forum.cmascenter.org/t/new-species-add-gas-phase/3433>\
**Category:** CMAQ\
**Created:** [July 19, 2022, 9:14pm UTC](https://forum.cmascenter.org/t/new-species-add-gas-phase/3433 "2022-07-19T21:14:04Z")\
**Posts on this page:** 1\
**Showing post:** 2

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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:** [July 19, 2022, 9:32pm UTC](https://forum.cmascenter.org/t/new-species-add-gas-phase/3433/2 "2022-07-19T21:32:57Z")

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In general, adding a new gas phase species likely will entail also modifying the chemical mechanism in CMAQ, unless you want to add an inert tracer species.

For more background on adding a chemically reactive species, please see [this tutorial](https://github.com/USEPA/CMAQ/blob/main/DOCS/Users_Guide/Tutorials/CMAQ_UG_tutorial_chemicalmechanism.md).

For more background on adding an inert tracer species, please see [this tutorial](https://github.com/USEPA/CMAQ/blob/main/DOCS/Users_Guide/Tutorials/CMAQ_UG_tutorial_tracers.md).

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