Carbon monoxide is an invisible, odorless, colorless gas created from incomplete combustion.
Heating and cooking equipment are possible sources of carbon monoxide, as are vehicles running in an attached garage. You can protect yourself by ensuring that heating equipment and furnaces are properly maintained and operated according to manufacturers recommendations. You should also never let your vehicle, or lawn and garden equipment run in an attached garage. The symptoms vary greatly from person to person, depending on age and general health, the concentration of exposure, and the length of exposure. High concentrations are dangerous for even brief periods .