State the main sources and effects of carbon monoxide.

Carbon monoxide is formed by incomplete combustion of fuels in homes, factories and automobiles.

Harmful effects of carbon monoxide :
Carbon monoxide is a highly poisonous gas. If inhaled, it binds with haemoglobin 200 times more strongly than oxygen reducing the blood's ability to carry oxygen by converting haemoglobin into carboxyhaemoglobin. So, even in small quantities, it is fatal and can lead to death.