What is Carbon Monoxide? It is an invisible, odorless, colorless gas created when fuels, such as gasoline, wood, charcoal, coal, natural gas, propane, oil, kerosene and methane burn incompletely. It’s a silent killer. The only safe way to know if carbon monoxide is present is to install carbon monoxide alarms on every level of your home. For frequently asked questions please click on the link.