Hey ArtistArtorias,
Take a look at our Documentation on Atmosphere Fog, as I believe this is what you are looking for.
Atmospheric Fog
https://docs.unrealengine.com/latest/INT/Engine/Actors/FogEffects/AtmosphericFog/index.html
Once you find the right values for this actor placed in your scene, the Atmospheric Fog can add a great degree of realism to your scene.
Cheers,