Where:
On any road, particularly in areas prone to fog, smoke, dust, or mist, such as valleys, coastal regions, or routes near industrial or agricultural zones.
These signs are often placed before sections of road where visibility can suddenly decrease.

Purpose:
To warn that visibility ahead may be limited due to fog, smoke, dust, or other atmospheric conditions, which could make it difficult to see road markings, obstacles, or other vehicles.
Reduced visibility increases the risk of accidents, especially if drivers are travelling too fast or following too closely.

Action:
Reduce your speed immediately and drive at a pace that allows you to stop safely within the distance you can see ahead.
Switch on your headlights (on dim) and, if visibility is very poor, use fog lights if your vehicle is equipped with them.
Avoid overtaking unless absolutely necessary, as other vehicles may be hidden in the fog or smoke.
Maintain a greater following distance from the vehicle in front to allow more reaction time.
Be alert for slow-moving or stationary vehicles, pedestrians, and animals that may appear suddenly.
If the visibility becomes dangerously low, pull over safely to the side of the road and switch on your hazard lights until conditions improve.