The body's fight to stay healthy in the face of the increased energy that your are expending is major stress. Environmental Factors Very hot or very cold climates can be stressful. Very high altitude may be a stress. Toxins or poisons are a stress. Smoking destroys cells that clean your trachea, bronchi, and lungs.
Smoking causes emphysema and chronic bronchitis, which progress to slow suffocation.
The carbon monoxide from cigarette smoking causes chronic carbon monoxide poisoning. Tobacco use damages the arteries in your body, causing insufficient blood supply to the brain, heart, and vital organs. Cigarette smoking increases the risk of cancer 50 fold. Chewing tobacco or snuff is no safe haven. It also damages your arteries, and it carries the same cancer risk.