Considering the number of years people have been smoking, whether it's cigarettes, pipes or cigars, it is only recently that we have discovered the extent of the damage that smoking can cause to our health.

In our guide to passive smoking:

Introduction to passive smoking

Smoking, especially heavy smoking can be the cause of a number of serious diseases, many of which we are aware of, such as lung cancer and heart disease and others of which we have been less informed about, for example atherosclerosis or osteoporosis.

Likewise, we have been even more in the dark about the effects that other people's smoking has on our health, or passive smoking, as it is otherwise known. It is only in the last twenty years or so that conclusive evidence proving that the inhalation of other people's smoke may also be a major health hazard has come to light and can no longer be ignored.

Research carried out in the US during the early 1990's estimated that exposure to tobacco smoke or passive smoking was the third leading preventable cause of death. Only active smoking and alcohol abuse preceded it.

In the US, it has been estimated by the EPA (Enviromental Protection Agency) that 3,000 non-smokers die each year from lung cancer, as a result of breathing in other people's tobacco smoke. 800 of those deaths are caused from exposure to secondhand smoke in the home, whilst a staggering 2,200 from exposure in the workplace or in public places.

Non-smokers who are exposed to breathing in tobacco smoke at home have a 25% higher risk of developing lung cancer or heart disease. If this is added to exposure in the workplace and public places, the risk goes up to as high as 60%.

Many children are affected by passive smoking in the home. In the UK almost half of all children are exposed to secondhand smoke indoors, as either one or both parents smoke in front of them. Doctors say that more than 17,000 children a year, who are under the age of 5 years old, are admitted into hospital due to the harmful effects of passive smoking. If parents did not smoke at home, these illnesses and admissions into hospital could have been avoided.

Due to these recent warnings about passive smoking, a number of Governments are implementing or proposing to implement a complete ban on smoking in all indoor public places and in all workplaces, in order to protect the health of non smokers and smokers and to promote and smoke-free and healthy environment for all.

What is passive smoking?

Passive smoking is also known as secondhand or involuntary smoking. It is basically the breathing in and exposure to other people's cigarette smoke, which is also known as secondhand smoke or Environmental tobacco smoke.

Environmental tobacco smoke is one of the biggest sources of indoor air pollution. As well as making your home or your workplace smell bad, it also, more importantly can lead to lung cancer and heart disease in smokers and in non-smokers.

Scientists have ranked indoor air pollution as one of the top five major environmental health risks that affect us today. This statistic is quite worrying as most people spend as much as 90% of their time indoors.

Babies and children are especially at risk and their health, as a child and even as an adult in years to come, is jeopardised if they are exposed to passive smoking at home.

Environmental tobacco smoke (ETS) is a product of two of the three types of tobacco smoke produced when a person smokes a cigarette.

The first type of smoke that makes up ETS is exhaled mainstream smoke. Exhaled mainstream smoke is the smoke that is first of all inhaled by the smoker upon taking a puff of a cigarette and then breathed out into the air from his lungs.

The second type of smoke that makes up ETS is called sidestream smoke. Sidestream smoke is the smoke that drifts upwards and into the air from the tip of a burning cigarette.

Finally, the third type of smoke that is produced on smoking a cigarette, but which does not make up ETS is mainstream smoke. This is the smoke that is inhaled by the smoker himself, through the cigarette and which stays inside the body.

Mainstream smoke and exhaled mainstream smoke are not the same, as they differ chemically. After inhaling cigarette smoke into the lungs, some of the smoke stays in the body, along with some of the chemical substances, whilst the rest is exhaled together with the remaining chemical substances. The exhaled smoke undergoes several chemical changes upon coming into contact with enzymes from the tissues of the human body before being released into the air. Mainstream smoke is the smoke that stays inside the smoker's body and is not breathed out into the air.

Although the health risks that a passive smoker may occur are considerably less than those of an active smoker, secondhand smoke still contains many of the chemicals and carcinogenic compounds that are also breathed in by the active smoker. Nevertheless the active smoker chooses to smoke himself, whilst the passive smoker is forced to do so against his will.