Fog question

hi, i'm wondering how i can make my sp map have dust that sits around in certain areas. In city 17, the part where you're under the highway and the manhacks ambush you from the sky, there is a cloud of fog up above you. i've also noticed clouds of fog outside certain areas at the top of the citadel. Does anyone know what i'm talking about?

func_dustcloud creates plain blobs of color that don't look as clean

any suggestions?
thanks.

Use env_smokevolume or func_smokevolume or whatever it's called. I
don't remember the entity name, but look through the list - it's a
brush entity. You'll
probably need to tweak the settings, but it does the job well.