An autonomous ventilation system includes a variable-speed exhaust fan, a controller, an exhaust hood, and a spillage sensor. The exhaust fan removes air contaminants from an area. The controller is coupled to the exhaust fan and adjusts the speed of the exhaust fan. The exhaust hood is coupled to the exhaust fan and directs air contaminants to the exhaust fan. The spillage sensor is coupled to the controller, detects changes in an environmental parameter in a spillage zone adjacent to the exhaust hood, and communicates information relating to detected changes in the environmental parameter to the controller. The controller adjusts the speed of the exhaust fan in response to information relating to detected changes in the environmental parameter.