Tobacco smoke contains more than 4000 components. Some of these are nicotine, carbon monoxide, ammonia, benzene, nitrobenzene, phenol, 2,4,dimethylphenol, acet-aldehyde, hydrogen cyanide, toluene and O-cresol. Most studies have been done on nicotine and various gases, in particular, carbon monoxide (CO).
Although the effects of the many constituents of smoke are not understood, the effect of nicotine is well documented.
Cigarette smoke is divided into two phases:
• A tar phase: defined as the material that is trapped when the smoke stream is passed through the Cambridge glass-fiber filter that retains 99.9% of all particulate material with a size >0.1 mm.
• A gas phase: the material that passes through the filter.
A. Nicotine
Nicotine stimulates the adrenal glands to put out excessive adrenaline and noradrenaline. The higher the nicotine concentration inhaled, the greater the outpouring of adre¬naline. If someone puts a gun to your head, you need all the adrenaline and noradrenaline that your adrenals and nerves can produce to enable you to fight or run. So adrenaline is great stuff, but it has many harmful effects. The heart rate and blood pressure increase, which means more work for the heart. The heart muscle will also require a bigger supply of oxygen. The platelets become sticky and may clump onto the surface of atheromatous plaques in one of your coronary arteries and a heart attack can occur.

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