Did you know that 3, 000 American non-smokers will die this year from lung cancer? Those deaths are entirely preventable. Their lung cancer is caused by second hand smoke. Second hand smoke is smoke they have breathed in from other people's cigarettes. It is also known as involuntary or passive smoking. There is nothing passive however about the effects of this smoke.

It is lethal and it is dangerous. It may give as many as 300, 000 children under the age of one and half bronchitis and pneumonia. It could even be responsible for more than 35, 000 deaths from heart disease. There is no one left, even inside the tobacco industry who does not know that smoking causes lung cancer. This fact is indisputable.

What is sometimes disputed is the extent to which the smoke from other people's cigarettes damages those around them. Some in the tobacco industry play down this effect. They say that passive smoking is at worst a minor irritant. They say the recorded illness, deaths and cancers of those who have to live and work with smokers is a coincidence. They even have the audacity to suggest that those illnesses may be caused by diet or other environmental factors. Let us look at the facts.

There are two ways in which passive or second hand smoke can affect non- smokers. Mainstream smoke is that smoke that has already been inhaled and then exhaled by the smoker. Side stream smoke is the smoke that comes off the burning end or tip of the cigarette. Both of these sources are responsible for passive smoke inhaled by non-smokers. Second hand smoke is chemically similar to that inhaled by smokers. After 30 minutes exposure to second-hand smoke the blood flow to the heart is reduced.

On top of this a non-smoker who is regularly exposed to second hand smoke has a 20 to 30% increased risk of lung cancer. Tobacco smoke contains 4, 000 chemicals in the form of particles and gases. 200 of those chemicals are very poisons. 43 of those chemicals are proven to cause cancer. This lethal combination is what causes tobacco smoke to be classified as a Group A carcinogen.

Incredibly 85% of the smoke from a cigarette will not be inhaled by the smoker. Instead it will fill up the room. That means only 15% of the smoke from a cigarette is actually inhaled by the person smoking it. On top of this, many of the toxic poisons and gases in side stream smoke are present in higher quantities than in mainstream smoke. The poisons and irritants can even be inhaled deeply by the passive smoker because the smoke particles are smaller than those in mani stream smoke. As a carcinogen, tobacco smoke ranks alongside other cancer causing agents such as asbestos, arsenic, benzene and radon gas.

Tobacco smoke is full of carbon monoxide. This is a poisonous gas that inhibits the transportation of oxygen to the body's vital organs. Coming out of the tip of someone else's cigarette are double the concentrations of nicotine. There are three times the amount of the carcinogen benz o (a) pyrene, five times the amount of carbon monoxide and fifty times the amount of ammonia. On top of this the person quietly puffing away next to you is allowing arsenic, formaldehyde, vinyl chloride and hydrogen cyanide into the air that you are breathing.

In despite of this knowledge 43% of children in the US are exposed to second hand smoke in their own homes. Despite the attempts of many places to ban smoking there are still millions of people, who are at risk from the effects of second hand smoke. Many of these will die prematurely. It is perhaps though in children that we see the most alarming effects of the exposure to second hand smoke. Children's lungs are still developing at their young age. Exposure to second hand smoke means they will have a decreased lung function.

A child's airways are also smaller. This means a child will have to breath faster. The result is a child will breath in comparatively more of the poisonous chemicals than an adult in the same room. Exposure of children to second hand smoke leads to an increase in the severity and frequency of asthma attacks. There are perhaps a million asthmatic children whose aggravated symptoms are as a result of inhaling second hand smoke. The same exposure each year causes as many as 300, 000 lower respiratory tract infections, pneumonia and bronchitis in children under 18 months.

Again exposure to this smoke can cause a build up of fluid in the middle ear. The resulting complications means more than a million visits to physician's offices each year. The build up of fluid in the middle ear is the most common cause of childhood operations and childhood hearing loss. It is now thought that perhaps a many as 3, 000 premature deaths of babies known as Sudden Infant Death Syndrome, may be associated with exposure to smoke. No one is safe from the effects of second hand smoke. Exposure to passive smoking while pregnant may even harm an unborn baby.

It may lead to reduced lung function and an underweight baby. The fact is that few parents or prospective parents would continue to smoke if they really were aware of the potential harm they were doing to their children Extensive studies have been conducted in laboratories that show the ability of second hand smoke to cause cancer in animals and also damage their DNA. This type of DNA damage is recognised by scientists as being an instrumental mechanism in cancer development. This evidence is alarming enough for animals yet alone for human beings Dozens of studies in many countries repeatedly show a direct association between lung cancer in women who never smoked themselves but who were exposed to their husband's smoke. Recently some cities and some governments around the world have moved to world to ban smoking in some workplaces and public places. This is a welcome move.

It means that we can start to look forwards to a smoke free environment for ourselves and our children. Unfortunately the statistics tell us that there are still many millions of people who still insist on their 'right' to smoke. The children who are exposed to their smoke do not have such a choice. Protecting children and non-smokers from the effects of second hand smoke must be a priority for everyone. A smoker chooses to smoke but a non-smoker's risk is involuntary.

Exposure to second hand smoke is a real and present threat to our health. As a result there are many non-smokers who are needlessly dying from heart disease and lung cancer. Second hand smoking causes asthma, reduces lung function and bronchitis, pneumonia and causes middle ear infections. Many of these illness are inflicted upon small children. Bans on smoking in workplaces exist. So do bans on smoking in restaurants.

Unless they are rigidly enforced they won't make a difference. Smoking, unfortunately, cannot be banned in homes. Passive smoking should be shown for exactly what it is, a dangerous killer. Maybe then non-smokers, especially children, will not suffer from second hand smoke.