You can have an 'uncertain' feeling to a map without the over-done fog.
You can get the same feeling through atmosphere and ambience - the lightmap, ambient sounds, lighting, statics etc.
I have to say it, but using fog is a very DICE way of going about things. I don't want to sound harsh, but I love this map. I respect mappers - mapping is something I haven't managed to get hold of myself. After playing a fair few rounds I just think this map could use a revision.