Carbon monoxide with the chemical formula of (CO) is a odorless, colorless gas. It is toxic to hemoglobic animals including humans, by binding to the hemoglobin themselves, forming a compound that cannot transfer oxygen around the body. As a result, you can die from carbon dioxide poisoning.

Carbon monoxide is formed when there's insufficient oxygen to support the combustion of a fuel(which contains carbon e.g. butane):

C4H10 + 6 O2 -> 5 H2O + 3 CO2 + CO

Carbon monoxide readily combines with oxygen with a catalyst of platinum present in the following reaction:

2CO + O^2 --Pt> CO^2