When is it advisable for a commercial driver to use low-beam headlights?

Using low-beam headlights in foggy conditions is advisable because low beams illuminate the road directly in front of the vehicle without creating a large amount of glare that can reflect back off the fog. When high beams are used in fog, the light can reflect off the water droplets in the fog, creating a blinding effect for the driver and reducing visibility. Low beams provide adequate illumination while minimizing this issue, making it safer to navigate through fog.

In contrast, using low beams in bright daylight is generally unnecessary, as their effectiveness is reduced during sunlight. On well-lit highways, drivers can typically rely on ambient lighting from streetlights, while in open fields, where visibility is unobstructed, high beams may be more appropriate for providing maximum illumination.