I've driven through some bad ass fog in my life, especially when living around the water. Once had to stand on the front bumper to see an overhead road sign on I 95 in Maryland. I turn on all of my outside lights and go slow.

Several years ago while traveling to Florida when Florida was having all the wild fires, we ran into very heavy smoke going down 301 in northern Florida. The weird thing was that the smoke was coming from fires 40 miles to the east of where we where. Smoke to me is as bad if not worse than fog. In smoke, even the a/c systems don't function well and soon or later you smell like smoke and your eyes get funky.