Answer. Combustion in limited supply of, oxygen produces CO is air due to incomplete burning. Being colorless and odourless, its presence cannot be noticed easily and readily. When inhaled, it binds with the hemoglobin most strongly than that of oxygen. Thus, hindering the supply of oxygen in body. Exposure to higher concentration of CO causes headache and fatigue. If inhaled for a longer time it results in breathing difficulties and ultimately death. To avoid incomplete combustion burning is prefered in open air. In open air complete combustion takes place that produces CO2 instead of CO.