Tobacco contains at least three substances that can cause problems: tar, carbon monoxide and nicotine.
Tar is a black sticky substance that settles on the flagella of the mucous membrane, which goes from the nose to the lungs. This causes the flagella not to remove dust and dirt very well anymore. Tar can lead to bronchitis, pulmonary emphysema, lung cancer and cancer of the throat, oesophagus or larynx.
Carbon monoxide originates from the combustion of vegetable material. It is a colourless and scentless gas. It causes the blood not to transport oxygen as well anymore, which causes the heart and also other body parts to get too little oxygen.
Carbon monoxide damages the walls of blood vessels so that fat and calcium can settle more easily. Carbon monoxide leads to a reduced condition, arteriosclerosis, heart complaints (Angina pectoris, heart infarct), cerebral infarction and brain haemorrhage.
Nicotine stimulates the nervous system, which brings up the heartbeat and contracts the (small) blood vessels. This causes higher blood pressure. Nicotine leads to addiction and hypertension.