In an embodiment, a method determines one or more sources of carbon monoxide (CO) in a smart-home environment that includes a plurality of smart devices that have at least measurement and communication capabilities. The method includes measuring a level of CO in the smart-home environment to generate a CO measurement, and providing the CO measurement and one or more current characteristics of the smart-home environment, from one or more of the smart devices to an analyzing device. The method further includes evaluating, by the analyzing device and with the CO measurement and the current characteristics of the smart-home environment, a set of CO correlation scenarios that attribute generation of CO to a corresponding one of a set of specific sources, and selecting one or more of the specific sources as the most likely source of the CO, by aggregating results of the correlation scenarios.