Creating Fog in Autodesk Maya

https://docs.arnoldrenderer.com/display/A5AFMUG/Fog

Related to atmospheric volume

https://docs.arnoldrenderer.com/display/A5AFMUG/Atmosphere+Volume

Found in the Arnold render settings.

This atmospheric shader node simulates the effect of light scattering, which causes more distant objects to appear lower in contrast, especially in outdoor environments.

Fog Attributes 
Color 
Distance 
Height 
Ground Normal 
Ground Point 
0.020 
5.000 
0.000 
0.000

The defaultFog node can be selected from the outliner (Show Dag Objects Only must be disabled).

Outline r 
C,' defauItLightSet 
C,' defauItObjectSet 
defauItArnoIdDispIayDr 
defauItArnoIdDriver 
defauItArnoIdFiIter 
defauItArnoIdRenderO' 
defauItCoIorMgtGIobaI