Driving in fog is not something to take lightly. As in most cases speed is a major factor. Fog creates an optical illusion that your body usually perceives as driving slowly. Be sure to check your speed & use proper lights. High beams are not appropriate. You simply see more fog. Look to the side to guide you especially since fog creates a glow when lights hit it. As in other instances increase your following distance & avoid overreaction. If fog gets too heavy find a safe place to pull over & use four-way flashers.