6. Chronic Obstructive Pulmonary Disease (COPD)
This disease affects the lungs and this makes it difficult for the patient to breath effectively. This is mainly caused by tobacco use as well as second-hand smoke. In 2012, it is estimated that over 3.28 million lives were lost worldwide. This is a serious disease because it causes about 5.8% of all deaths in the world. It is therefore important to quit smoking to avoid this disease.