Attached Link: http://www.buckrogers.demon.co.uk/3d/fog.zip

This is its readme file:-

Its zip file contains these files:-
 fog256.obj        fog, with 256 planes
 fog128.obj        fog, with 128 planes
 fog64.obj         fog, with 64 planes
 fog32.obj         fog, with 32 planes

  Hereinunder, for c:Poser' read whatever folder your Poser is in.  Folder' means `directory', for those who remember times before Windows 95.
  In folder and file names, don't ignore case of letters.

  Each fog is a cube from {0,0,0} to {1,1,1}, composed of some number of parallel planes. Each plane is one big polygon, at right angles to the z axis.
  The texture mapping of each plane is the full range {0,0} to {1,1}.
  The object may not be visible if you look at it exactly along the xy plane.
  Instructions:-
  Import one of the fog--.obj files so it becomes a prop.
  Set its maximum and minimum transparency to 99%, or less if needed. How foggy the view of an object is, depends on how many of the planes of fog.obj are between the object and the camera.
  Set its color and its highlight color to white for ordinary fog, or say red=128, blue=green=255 for underwater effect.
  Position and xscale and yscale and zscale fog.obj to enclose the objects in the scene and the  camera being used. The top of fog--.obj should be not far above the top of the scene.
  yrotate fog.obj so its z axis is as far as possible towards the camera.
  To change the denseness of the fog, change its zscale value or its transparency values.
  Warning: it will add a fair bit to Poser render times.