Render passes with Environment Fog

[Dynast]

I'm wondering how work render passes with Environment Fog,
My scene is an exterior one with fog and when i enable Render Passes in Render Settings, the fog desappear of my viewer and render, my primary environment too.
It replace by black (alpha) area but it's not the same calibration. I also don't see a pass dedicate to Environment Fog.
Am i force to disable render passes to have the correct image i want ?
I think there is something I don't understand.

Thank you for your help

[aoktar]

Please always try to support your questions with some images. Otherwise i have to make a new scene and test it.
I can see the contribution of environment fog in passes. What's your passes which doesn't show fog?