An automatic smoke/carbon monoxide evacuation system for a building having at least one existing ventilation fan and at least one ventilation passageway to outside the building is provided. The system includes a microprocessor and a smoke/carbon monoxide sensor coupled to the microprocessor and configured to detect presence of smoke/carbon monoxide and send a trigger signal to the microprocessor in response to detecting smoke/carbon monoxide. A power switch is coupled to the existing ventilation fan and is configured to automatically connect the existing ventilation fan to a power source in response to the trigger signal, so that the ventilation fan rotates at a high speed to ventilate the detected smoke/carbon monoxide via the existing ventilation passageway. An alarm device is further communicably coupled to the microprocessor and is configured to issue an alarm in response to the trigger signal.