Firstly, the incomplete combustion engine result in carbon monoxide (CO), soot and crude oil. CO is colorless, odorless, lighter than air and highly poisonous. In the human body, it can causes the blood cannot receive oxygen for breathing. Red blood cells pick up CO quicker than they pick up oxygen. If there is a lot of CO in the air, the body may replace oxygen in blood with CO. This blocks oxygen from getting into the body, which can damage tissues and result in death. CO can also combine with proteins in tissues, destroying the tissues and causing injury and death.