Fog like that on a busy multilane interstate, you don’t know what to do. Keep moving and hit somebody, stop and get hit. I guess you could try to pull over as far right on the emergency lane as possible, exit the vehicle and get behind the guardrail until the fog clears. Not much else you can do.
I have been in one white-out here, in which I could not figure out what to do - luckily I was NOT on a highway, and it soon passed, but I literally could see nothing outside my cr except white everywhere, and it all looked the same. It was very dis-orientating. I imagine thick fog would be similar. BTW, these things (fog) happen in other parts of the country too. One thing that MIGHT help is for everyone to slow down, but not too suddenly (or no one vehicle should slow down too suddenly, unless all do).