Acid fog is just like acid rain. When sulfur dioxide is present in the air, it can be captured by water vapors of all sorts, including fog. If this weren’t bad enough, acid fog tends to be much more acidic than acid rain—up to 10 times as acidic! This acid fog, which can linger in the air for hours or even days, can be as bad as walking through clouds of floating vinegar and is very destructive to plant life, as well as building materials ranging from iron to concrete.