Atmospheric fog noise Tweet

[PEJ16]

Hi there, I have a little question here.
I'm sure it was answered a millions times before, but nothing seems to apply to me, or maybe I just didn't understand.

I'm trying to have an atmospheric fog in octane, but I'm getting a lot of noise.
I'm not asking for it to be perfect, I can still denoise after, but I'm really having trouble with the police car light's noise.
I've tried pushing the samples of the police car's lights, but then, as expected, My main moon light is noisy.

So here is the original scene:
[img][IMG]https://nsa40.casimages.com/img/2020/12/08/201208123123173771.png[/img][/img]
Here it is with medium in an octane sky
[img][IMG]https://nsa40.casimages.com/img/2020/12/08/201208123100472314.png[/img][/img]
And here it is with a vdb cloud
[img][IMG]https://nsa40.casimages.com/img/2020/12/08/201208122204694235.png[/img][/img]

As I would like to make a short film, time render is very important.
Do any of you know how to get past that ?
Thank you very much.