At ~3:03 PM, Westmoreland 911 dispatched Station 20 (Murrysville VFC) for a Carbon Monoxide (CO) Alarm at a home on Remaley Road. Station 20 responded with Engine 20 (4 firefighters). Westmoreland 911 also dispatched Station 610 (Murrysville Medic One) to support Station 20. Medic 612 was first on scene, and found that the home's occupant evacuated the structure. Engine 20 arrived, the senior firefighter established the command, and the Engine 20 firefighters entered the structure using 4-Gas Meters to survey the home for carbon monoxide. The firefighters found no traces of CO in the structure, and upon investigation found that the basement CO Detector had given a false alarm since it was past its service life. Command 20 declared the structure safe for reentry, and recommended that the home owner purchase a new CO Detector for the home's basement. Command 20 returned Engine 20 and Medic 612 to service and station.