1. Carbon monoxide is a chemical produced from the incomplete burning of natural gas or other products containing carbon.

   Carbon monoxide poisoning is an illness caused by exposure to too much carbon monoxide — a colorless, odorless and tasteless gas. Too much carbon monoxide in the air you breathe can greatly diminish your ability to absorb oxygen, leading to serious tissue damage.
2. 
   

CO is poisonous because it blocks the ability of the blood to absorb oxygen. It is called the “silent killer” because it is colorless and has no smell. CO results from the burning of all fossil fuels – not just gas and it is given off most when things smolder rather than burn fiercely. CO is poisonous because it combines with hemoglobin in red blood cells, about 240 times more tightly than oxygen. Hemoglobin is the substance that carries oxygen from the lungs to all organs of the body. The compound formed, called carboxyhaemoglobin, and effectively reduces the ability of the blood to transfer oxygen. CO arises from the partial combustion of carbon bearing compounds and so it is when a barbecue is smoldering, for example, that the
danger is greatest.

Carbon monoxide is toxic because it reduces the capacity of bloody to carry oxygen. The carbon monoxide molecules permanently bind onto the haemoglobin of the red blood cells, thus meaning that the red blood cells are unable to carry oxygen. Because the red blood cells are unable to carry oxygen, our body cells don't receive oxygen. This means that they are unable to respire and thus simple bodily functions such as digestion, excretion and even the pumping of the heart are unable to continue. However, the main cause of death is due to the brain not receiving oxygen.