Adding fog systems for effect

I did this a little earlier in the process, before adding coloured lights, however i forgot to mention it and thought it was important so came back to it.
These are a series of images showing how i added fog particles into the scene, and the difference they made to the scene. The fog acts as a ray of light coming from the window behind, once the texture for the sky has been put in place.
I created the fog using a volume primitive and using 'CubeFog', changing the scale of the cube, and the density of the fog to suit the specific shot.