Why the climate control of Hyundai Tucson occasionally involves recycling air in the cabin

The point is that the Hyundai Tucson climate control system is fitted with an air quality sensor-it is installed in front of the radiators and reacts to changes in atmospheric composition. For example, if you drive a truck with smoky fumes, it sends a signal at which the system automatically includes recycling. As soon as the air quality improves, climate control goes back to the previous regime.