I REFER to the opinions aired about the deaths of three students who died napping in a car recently. Everyone was quick to point out that the cause of death was due to inhalation of carbon monoxide. The conclusion was arrived before any investigation was conducted. This is also the conclusion persistently reported in all cases of deaths inside a stationary vehicle over the past decades. This is a dangerous misconception.
Here I wish to point out that the conclusion could be wrong. We must dispel the fallacy that carbon monoxide poisoning is the only cause of death napping in cars. Death from carbon monoxide would happen if the exhaust gas is routed into the car via a hose as in the cases of suicides. Otherwise leaks from the exhaust system would dissipate freely into the atmosphere rather than find their way into the car.
I worked in an industrial gas company for nearly 30 years. Death napping in cars is most often the result of asphyxiation. Atmospheric air contains 21% oxygen. When we breathe our body uses up approximately 5% of the oxygen. The air we exhale contains approximately 16% oxygen. When a car is moving the oxygen content in the car is replenished with external air forced into the car.
For a stationary car the oxygen content would gradually drop as a result of human respiration. No external air would get into the car if the windows are fully wound up. When the oxygen level drops to 19% occupants in the car would start to yawn. This is a reaction of the body trying to get more oxygen. When the oxygen level drops to 16%, people would become unconscious. If the victim was discovered at this moment, he could be saved. When the oxygen level drops to 10% and below, death would occur. Hence if you need to take a nap in your car, I would advise you to roll down the window an inch or more to prevent asphyxiation. Do the same when you are caught in a traffic jam.
Furthermore it is easy to identify death due to carbon monoxide. In spite of asphyxiation, cyanosis (turning blue) does not occur; the skin of the victim is pink or pale and the lips bright red.
Wong Soo Kan
Petaling Jaya
