FOGGY FUBAR

Fog doesn't cause crashes, going too fast through the fog does! Smoke covering the road doesn't cause crashes, going too fast through the smoke does. Dark of night doesn't cause crashes, going too fast through the dark does.
Are you getting the point?
If visibility is 150 feet and it takes 300 feet to stop, then you are overdriving your eyeballs.
Slow down, Skippy!
Whether the visibility is limited due to fog, smoke, headlight range, curves, dips, rises in the road or whatever else, it is up to you to know how far down the road you can see and how long it will take you to stop. The latter should never exceed the former.
Oh, you may get away with it a thousand times and never end up like those in the image above, but your luck just may run out and then you and possibly many others are completely screwed.
If you speed through the fog hoping that a pileup is not blocking the way, you are a damn fool. Most of the folks in this picture obviously took that chance and they ended up regretting their mistake (or worse). Some were going slowly enough to stop in time, but then along came still more rocket scientists going too fast and wham!
Sometimes, one can do everything perfectly and still end up smushed.
The bottom line is try to avoid traveling in low-visibility conditions and if you do find yourself in that situation, keep the speed down, stay to the right and have good insurance.