Air filters clean debris from the cabin air. Air filters are considered to be "fresh" air filters if they are cleaning exterior air that is entering the cab through the climate control system. Air filters are considered to be "re-circulation" air filters if they are cleaning air that is already in the cab. In general, all cabin climate control systems have the capacity to recirculate air, but not all are designed to have filtration. However, not all cabin climate control systems have the ability to supply filtered fresh air or cabin pressurization. Fresh air filtration and pressurization are more commonly equipped in off road equipment or hazardous environments with higher-end designs to provide a safe working environment for the machine operator.