Final answer:
If equipped with fog lamps, a bus may activate them when visibility is reduced to 300 feet or less, enhancing safety during poor atmospheric conditions.
Step-by-step explanation:
If a bus is equipped with fog lamps, they may be activated when atmospheric conditions reduce visibility to 300 feet or less. This is to ensure that the bus is visible to other road users and that the driver has adequate visibility to navigate the road. Activating fog lamps under such conditions can significantly improve safety for both the bus passengers and other vehicles on the road.