Carbon monoxide (CO) is a colorless, odorless, tasteless gas by-product of internal combustion engines and is found in exhaust gases. Sufficiently high levels of CO in your bloodstream will lead to oxygen starvation and the onset of symptoms (such as headaches, drowsiness, nausea, or shortness of breath).
Many internal combustion engine airplanes are heated by air that has been warmed by circulating air around the exhaust system using a heater shroud. A defect or leak in the exhaust pipes or muffler can introduce CO into the cockpit.
Pilots often overlook or dismiss the onset of symptoms and don’t connect them with the possibility of exposure to CO. Continued exposure increases risks to pilots, including impaired judgment and decreased ability to control the airplane and, eventually, incapacitation and even death.
Read more in this NTSB Safety Alert and view the video below for a better understanding of the dangers that lurk.