Carbon monoxide (CO) is a respiratory poison that is produced during fires with insufficient oxygen supply. It is one of the most dangerous components of smoke gases and a primary cause of smoke inhalation fatalities in fires. Hazardous concentrations of carbon monoxide can also occur with faulty heating systems, gas boilers, improper operation of fireplaces, or in suicides involving CO. The book presents the properties and dangers of carbon monoxide, measurement techniques, medical aspects, operational tactics, and typical case examples.