Garage door openers and methods of operating garage doors to reduce the risk of carbon monoxide poisoning. Such a garage door opener includes a motor unit configured to raise and lower an overhead garage door of a garage functionally coupled thereto, and an carbon monoxide (CO) detector that detects and measures a concentration of carbon monoxide gas in the garage. The CO detector directly delivers a signal to the motor unit in response to the detected concentration of carbon monoxide gas exceeding a predetermined CO threshold level for at predetermined duration, so that the garage door opener raises the overhead garage door with the motor unit.