While driving in thick fog, are you always obliged to exercise special caution?

Yes, this is an obligation arising from the regulations. According to Art. 30 para. 1 of the Road Traffic Act, in conditions of reduced visibility caused by fog or other reasons, the driver must exercise special caution. As can be seen in the video, the dense fog drastically limits visibility, which requires a significant reduction in speed and readiness to react immediately to hazards.