Lights in daytime fog

You must always use lights if visibility is less than 100 metres (by law).

Your lights won't help you to see in foggy conditions, however, they help others to see you, therefore the more light you have, the better.

Use headlamps and fog lamps. Parking or dim-dip lights are as good as useless in daytime fog because they will not penetrate the vapour sufficiently.

If the fog is really thick, use full headlamps and spot-lamps - better still, stop for a cup of tea!