Carbon monoxide is an odorless, colorless gas that can cause serious illness and death. Any device that burns fuel produces carbon monoxide or CO. The effects of CO exposure vary from person to person depending on the concentration and length of exposure. At lower levels, CO exposure symptoms include headaches, dizziness, and nausea. At higher levels of exposure, CO can kill you before you are aware it is in your home because it’s impossible to see, smell or taste the toxic fumes.