More than enough reasons to ban smoking immediately

During World War II, the second biggest cause of deaths (after military action) was respiratory diseases. Many people died from emphysema and lung cancer, after suffering from breathing difficulties and coughing up blood. The cause was unclear, although some put it down to environmental factors, e.g. the tarring of roads.

Post-war, a young researcher named Richard Doll studied patients in London with suspected lung cancer to ascertain if there was a common factor in their stories. Patients were asked detailed questions - occupation, family history, background health, diet etc. He then kept close tabs on the patients.