<unk>  is a recreational activity in which a substance, most commonly tobacco, is burnt and the smoke tasted or inhaled. This is primarily done as a form of recreational drug use, as combustion releases the active substances in drugs such as nicotine and makes them available for absorption through the lungs. It can also be done as a part of religious rituals, to induce trances and spiritual enlightenment. The most common method of<unk>  today is through cigarettes, either industrially manufactured or rolled with loose tobacco and a rolling paper. Other forms, though less common, are pipes, cigars, bongs, and hookahs.<unk>  is one of the most common forms of recreational drug use.
Smoking
Sedentary lifestyle
Obesity
Passive smoking
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Old age
Ageing