Unfortunately, I didn't get as far as I hoped I would. Nevertheless this is the mod as of now.
I hope you like the bit that's finished, and I am open for suggestions.

EDIT:
GitHub project is now online:
https://github.com/egomaxisum/egos-air-filtering-mod

Hey d4rksh4de!

I'm working on a mod based on your Idea, unfortunately I have very little time these days, so I'll probably only upload the first version on Sunday!
I hope, you can wait that long.

egomaxisum

Too bad.
But thank you, you saved me a lot of time trying!

Hey Plysken!

I've actually had exactly the same idea you did and I've been working on it for a few days. I just found this thread now and I was wondering if any progress has been made?

If someone else has a better overview of the code could you please tell me where to find the file that specifies ...