Carbon monoxide
Carbon monoxide (CO) is a colorless, odorless, and tasteless gas that is toxic to humans at higher concentrations. Carbon monoxide can be produced from the partial oxidation of carbon-containing compounds, such as in internal combustion engine; it forms when there is not enough oxygen to produce carbon dioxide (CO2).
Carbon monoxide was allegedly one of the homicidal gases used during the Holocaust. It was allegedly used in gas vans and in some of the Holocaust camps.
Holocaust revisionists have in particular criticized the supposed use of diesel engines to produce carbon monoxide. See Holocaust material evidence: Gas vans and gas chambers using diesel exhaust.
