1. It is also mandatory to use lighting when there are weather or environmental conditions that significantly reduce visibility, such as in the case of fog, heavy rain, snow, clouds of smoke or dust or any other analogous circumstance (article 43 of the articulated text).
2. In the cases referred to in the previous section, the front fog lights or the short or long-range headlights must be used.
The front fog lamp can be used alone or simultaneously with the short-range headlights or even with the long-range full beam headlights.
The front fog lamp can only be used in such cases or in sections of narrow roads with many curves, meaning that, having a roadway of 6.50 metres wide or less, are marked with signs indicating a succession of nearby curves among themselves, regulated in article 149.
The rear fog lamp should only be switched on when the weather or environmental conditions are particularly unfavourable, such as in heavy fog, heavy rain, heavy snow or heavy clouds of dust or smoke.
3. Driving without lights in situations with no or reduced visibility will be considered a serious infringement, as foreseen in article 65.4.e) of the articulated text.
We must keep in mind that although we are driving during the day, there are sometimes atmospheric factors that significantly reduce visibility, so we must use the corresponding lighting both to see and to be seen by the rest of users.
When there are fog banks, many drivers think that dipped headlights are enough or when it is cloudy but it is daylight, there are drivers who do not think that turning on the fog lights is necessary and they do not realise that their car is no longer visible to other road users at certain distances, avoidable by using fog lights.