Smoking affects the body's blood supply through narrowing the arteries and making them sticky, causing a build up of dangerous fatty deposits.
Smoking also raises blood pressure and makes the heart work harder for the same effect. At the same time, the carbon monoxide in smoke deprives the body of oxygen. This makes the heart work even harder, which can lead to abnormal heart rhythms, chest pain or tightness and poor muscle function.
Blockages in the blood supply around the heart can lead to a heart attack, and blockages to the brain cause strokes. Further, blockages in the blood vessels supplying arms and legs (known as peripheral vascular disease) cause severe pain and may lead to amputation.
Smoking causes over 40% of heart disease in those under 65 years of age. Smokers have up to four times the risk of suffering sudden cardiac death than nonsmokers.
Passive smoking is also associated with an increase in the risk of heart disease.
Smoking causes myeloid leukaemia - a cancer that affects the bone marrow and organs that manufacture blood.