# Aermod dispersion modelling

**URL:** <https://forum.cmascenter.org/t/aermod-dispersion-modelling/3702>\
**Category:** AERMOD\
**Created:** [November 10, 2022, 10:16am UTC](https://forum.cmascenter.org/t/aermod-dispersion-modelling/3702 "2022-11-10T10:16:23Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![ievalaganovska](https://avatars.discourse-cdn.com/v4/letter/i/e9bcb4/32.png) [@ievalaganovska](https://forum.cmascenter.org/u/ievalaganovska)\
**Post date:** [November 10, 2022, 10:16am UTC](https://forum.cmascenter.org/t/aermod-dispersion-modelling/3702/1 "2022-11-10T10:16:23Z")

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Question for air pollution modelers, who use AERMOD VIEW.

I am modelling air pollution for a pig farm. Pig farm ventilation systems operate differently each month, so I have to implement those changes throughout the year. I don’t see the way how to do that because only variations I can use, are now being applied for “emission rate”. F.e., if I apply variation 0,7 for certain source, it will reduce emission rate (from 1 g/s to 0,7 g/s) not gas exit flow rate (from 1 m3/s to 0,7 m3/s). Lower ventilation power contributes to higher emissions, but AERMOD does the opposite now.

The question is whether it is possible to apply variations to the parameter “gas exit flow rate”?

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**Author:** ![foley.kristen](https://avatars.discourse-cdn.com/v4/letter/f/d9b06d/32.png) [@foley.kristen](https://forum.cmascenter.org/u/foley.kristen)\
**Post date:** [November 15, 2022, 6:49pm UTC](https://forum.cmascenter.org/t/aermod-dispersion-modelling/3702/2 "2022-11-15T18:49:27Z")

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Greetings, In case you are unable to connect with other AERMOD users on this forum you may want to reach out to the contacts on this EPA Contact Us page:

> **[Contact Us about Air Quality Models | US EPA](https://www.epa.gov/scram/forms/contact-us-about-air-quality-models)**
>
> The contact us form for the Air Quality Models topic at EPA.