Carbon monoxide (CO) is an invisible, odorless, tasteless gas produced when fossil fuels do not burn completely or are exposed to heat. These fuels include wood, coal, charcoal, oil, natural gas, gasoline, kerosene, and propane. Common household appliances are often sources of CO. If they are not properly maintained, are improperly ventilated, or malfunction, CO levels can rise quickly. CO is a real danger now that homes are more energy efficient. Airtight homes with added insulation, sealed windows, and other weatherproofing can sometimes trap CO inside. The best way to protect yourself is to install CO alarms in your home.
Information found on First Alert