Carbon monoxide pollution may cause loss of consciousness or death in the exposed individual. For such an event to occur, the likely minimum percentage saturation level of carboxyhemoglobin in human blood would be:

Carbon monoxide is a colourless, odourless gas. 

Key Points

• Cars, trucks, and other machinery that burns fossil fuels are the main emitters of CO in the outdoor air. 
• Carboxyhemoglobin (COHb ) forms after a mixture of carbon monoxide gets mixed with haemoglobin in blood cells. 
• At a COHb level of about 10%, carbon monoxide is likely to cause headaches. 
• At a COHb level of about 40%, carbon monoxide starts to cause coma and collapse and at 50–60% the poisonings are often lethal. 

Thus, Carbon monoxide pollution may cause loss of consciousness or death in the exposed individual. For such an event to occur, the likely minimum percentage saturation level of carboxyhemoglobin in human blood would be 60%. 

Additional Information

•  It has an affinity for haemoglobin that is 200 times greater than that of oxygen.