For police officers spending long hours in buses during Korea’s summer heat, relief may soon come not from stronger air conditioning but from a nearly transparent film on the windows. Hyundai Motor Group said Wednesday it has applied its Nano Cooling Film to two Universe buses operated by the 1st Mobile Unit of the Seoul Metropolitan Police Agency. The buses serve as mobile offices and living spaces for officers responding to demonstrations and other public safety duties, making heat inside the vehicles a persistent concern during hot weather. Because dark window tinting is difficult to use on police buses for operational and regulatory reasons, officers can be particularly exposed to high temperatures while carrying out their duties. Nano Cooling Film is designed to reflect solar heat while also radiating infrared heat from inside a vehicle to the outside, according to Hyundai Motor Group. The three-layer material includes two layers that reflect near-infrared wavelengths from sunlight and another layer that releases mid-infrared wavelengths from inside the vehicle. Hyundai Motor Group