What should a driver do if they encounter heavy fog?

When encountering heavy fog, reducing speed and using low-beam headlights is the most effective and safest approach. Heavy fog significantly decreases visibility, making it difficult to see other vehicles, traffic signals, and obstacles. By reducing speed, a driver can ensure they have adequate reaction time to respond to unexpected situations that may arise in low visibility conditions.

Using low-beam headlights is crucial as they provide adequate illumination closer to the roadway without causing the light to reflect off the fog, which can reduce visibility even further. High-beam headlights can create a glare when the light reflects off the fog, leading to a dangerous situation where visibility is actually worsened.

Although waiting for the fog to clear by pulling over is a potential action, it may not always be practical or safe, especially if the fog persists for an extended period. In many cases, it's better to proceed cautiously while adhering to safe driving practices. Hence, adjusting speed and properly using headlights are key actions to take in such conditions.