A utility vehicle, cab ventilation system which includes a fan and a main filter located in the cab roof section with an upstream pre-filter mounted on the exterior of the cab roof. The pre-filter rotates about an axis parallel to air flow and centrifugally forces matter outward, effectively reducing material build up and frequency of service to the main filter within the roof section. The pre-filter can be built into a new cab ventilation system or provided in a module, for adding to existing cab ventilation systems.