Ray, pedantic I know, but it's carbon monoxide, CO , that's truly poisonous. Lethal in very small concentrations and odorless, tasteless and invisible, which makes it an insidious killer. Always produced by engine exhausts, along with carbon dioxide, CO2
CARBON MONOXIDE, CO
100ppm [0.01%] in air will give you a headache,
400ppm [0.04%] can prove fatal, and
1.28% will kill you in less than 3 minutes, so this is not a gas to take chances with.
CARBON DIOXIDE, CO2
CO2 is totally harmless unless the concentration in the air rise to a significant percentage. Actually, CO2 is the 'fizz' ingredient in soft drinks. Plain asphyxia, ie lack of oxygen, being its only danger, a very unlikely occurance.
CO in very small concentrations causes all kinds of problems with human physiology and recovery can take months or indeed the damage may prove permanent.
Any engine exhaust or indeed any device such as a gas water-heater requires proper maintenance to prevent combustion products entering the vehicle, for this very reason.
Alan
