The **low beam light**, also known as the dipped beam, is essential for ensuring safety in conditions of reduced visibility. It is mandatory to use it in various situations, and one of the most important is during the day in case of **dense fog**.

- Fog significantly reduces visibility, making it necessary to use lights that allow you to see and be seen by other drivers. The low beam light is suitable for these conditions because it does not dazzle other drivers and improves road visibility.

- Additionally, low beam lights must be used in other situations such as driving through tunnels or temporary lanes due to roadworks or accidents, but fog is one of the most critical conditions that require their immediate use.

Therefore, in case of dense fog, it is essential to turn on the low beam lights to improve road safety.