Therefore, you must have a very solid evidence in support of a verdict of prohibition. It was not possible to include among what Allah has forbidden a substance that was not known, saying that when this will be available, it shall be forbidden. Instead, Islam lays down certain principles which should be applied at all times. I agree with you that tobacco is a harm causing substance. It has been proven beyond any shred of doubt that the smoking of tobacco is very harmful indeed.
Tobacco smoke contains more than four thousand substances, most of which are harmful.
Hence, it is not surprising that tobacco is the major cause of lung cancer. Moreover, smoking causes many types of cancer including cancer of the lips, the gums, the larynx and the bladder, and, in women cancer of the uterus. It also causes chronic bronchitis and emphysema, as well as coronary heart disease. Its effects, as you say, are not limited to the smoker. Passive smoking, or the inhaling of tobacco smoke from other people's cigarettes, is also hazardous and causes the same list of diseases.