Volumetric Fog

I am not very familiar with fog, so I could use a little FP help here.
I am trying to make a “sandstorm” type of effect, with lots of dust particles and volumetric fog (fog inside the map, from what I believe). However, I need to be able to turn the fog on and off, as well as determine how visible it is. Is there any way to do this via Lua? If needed, I can get my mapper to put something inside the map if need be.

In jintos module, there was some fog stuff, leme see if i can get a link for you

Fog stuff near the botom, some w/o documentation, some w/