If you are driving in a heavy fog, which lights should you use?

When driving in heavy fog, using low beam headlights is the most effective option. Low beam headlights provide sufficient illumination for the road immediately in front of you without causing glare that can reflect off the fog and impair visibility. High beam headlights are not suitable in foggy conditions because the light from them tends to scatter, creating a blinding effect that limits the driver's ability to see further ahead and may also affect other drivers.

Parking lights are designed to indicate that a vehicle is stationary and provide minimal illumination, making them inadequate for navigating through fog. Flashing hazard lights are intended to alert other drivers to a stopped or slow-moving vehicle but do not enhance visibility on the road ahead.

Using low beam headlights helps maintain better visibility and safety by ensuring both the driver and surrounding vehicles can see and be seen effectively in challenging weather conditions such as heavy fog.