Carbon monoxide is a colorless, odorless gas, present in engine exhaust. When breathed, it bonds to the blood much more readily than oxygen. Once it has bonded with the blood, it remains for a long period of time. It can take your body up to several days to remove carbon monoxide from the blood. As a result, the blood becomes less and less able to absorb oxygen and deliver it throughout the body.
Because of the blood's strong preference for carbon monoxide over oxygen and this strong, high duration bond, carbon monoxide can accumulate in the blood very slowly over long periods of time. This means it is very dangerous, even when present in very minute quantities.
A person's susceptibility to carbon monoxide poisoning increases with altitude.
Detecting Carbon Monoxide Poisoning
Because carbon monoxide is present in engine exhaust, smelling exhaust inside the airplane is a good indication that carbon monoxide is also inside the airplane. However, because it is dangerous in such low quantities, it may be difficult or impossible for a person to detect. For this reason, it is recommended that a carbon monoxide detector be installed in the airplane. Detectors are cheap and may provide the only indication of exposure to this deadly gas.
Symptoms of carbon monoxide poisoning include headache, blurred vision, dizziness, drowsiness, and muscle weakness.
Muscular weakness is one of the more common symptoms of carbon monoxide poisoning. If the poisoning continues, it leads to vomiting, convulsions, coma, and death.
Dealing with Carbon Monoxide in the Cabin
A common cabin heater design involves running outside air through a heat exchanger and then into the cabin. The heat exchanger uses hot exhaust from the engine to warm the outside air. The system is designed so that the exhaust gasses always remain completely separate from the air moving into the cabin. If exhaust is smelled inside the cabin, the heater might be leaking exhaust gasses. Shut off the cabin heater and open available fresh air vents and windows. Utilize any established procedures or checklists available for your airplane concerning smoke or fumes in the cockpit. If necessary, declare an emergency, land, and seek medical care.