Cigarette smokers are at danger of more than nicotine when they smoke. Tobacco smoke contains many different chemicals including benzene, formaldehyde, styrene, and carbon monoxide, all toxic chemicals with known effects. Nicotine is broken down by the body to an even more addictive and long lasting substance cotinine.

But what about the filters? The filters are usually made from cellulose acetate, and studies have shown that smokers commonly ingest and/or inhale some of these fibres. This happens because small fragments of cellulose acetate become separated from the filter at the end face. The cut surface of the filter of nearly all cigarettes has these fragments. This means that if you smoke a filter cigarette you are likely to have small fragments of plastic-like material in your tubes and lungs.

Dont let this be an excuse to go back to smoking unfiltered cigarettes. Cigarette smoke damages your heart as well as your lungs. Carbon monoxide and nicotine are the two chemicals in cigarette smoke that probably have the most effect on the heart. Carbon monoxide attaches to red blood cells, so that in smokers up to half the blood can be carrying carbon monoxide rather than oxygen.

Nicotine stimulates the body to produce adrenaline which makes the heart beat faster and raises blood pressure, forcing the heart to work harder. Other parts of the smoke appear to damage the lining of the coronary arteries and this leads to the build up of fatty material in the arteries.

Many smokers have switched to low tar cigarettes. It is the tar that causes cancer, but low tar cigarettes don't necessarily have less carbon monoxide and nicotine, so may be no less harmful for the heart. (This doesn't mean that you should go back to higher tar cigarettes, but it does mean that you can't believe that your health will be fine because you are smoking low tar cigarettes.)

My father's last words before he died of a heart attack were "I'm dying for a cigarette." He had no idea how true that was.