Of the six types of asbestos, only four are used commercially. These are chrysotile, crocidolite, amosite and anthrophyllite. Of these, crysotile or white asbestos accounts for 99% used in USA. In it natural state or well contained and maintained in products, asbestos do not pose a real hazard. It is when asbestos is broken down and fibres are released that there is concern.

Asbestos fibres are very thin and sharp. The fibre is 2,000 times thinner than a human hair. It measures under 0.3 microns or one millionth of a millimetre in diameter and five microns in length. It is not visible with the naked eye or through a microscope.

When released, the fibres remain in the atmosphere for a long time and can be carried great distances. When the fibres are inhaled, they stick to the lung tissue and are not expelled by breathing out or coughing. Some remain in the lungs, others gravitate into the pleural lining.

Asbestos exposure can lead to disease and develops over a long period of time. Asbestos related diseases are asbestosis, pleural plaques and lung cancers. The lung cancer can be either cancer of the lung itself or mesothelioma, a cancer of the lung lining. These cancers can take between 20 and 50 years to develop.

A recent article in a UK Newspaper highlighted the case of a Hospital Consultant who developed mesothelioma. He cannot recall any exposure to asbestos. It may well be that he was inadvertently exposed to asbestos without his knowledge i.e. such as living in the vicinity of a factory that leaked asbestos into the atmosphere.

Professor Peto has shown that new cases of mesothelioma will continue to increase in the early part of the twenty first century. He also said, ?Every single person in the UK has asbestos in their lungs. It is the level of exposure that is important.?

We also know that people who has a history of asbestos exposure has a greater risk of lung cancer if they smoked. In a survey in 1992, 2602 individuals with lung cancer were interviewed. One in eight was exposed to asbestos and of these a third still smoked. A US study suggested that non-smokers exposed to asbestos have a five times greater risk of lung cancer. If they smoked, then the risk increased by a factor of 11. Smoking and asbestos exposure increases the risk of developing lung cancer to 52 times that of the general population.

At present no one knows how many lung cancers are due to asbestos exposure because of the long latency period and that cigarette smoking remains the major cause. Mesothelioma, however, is caused by asbestos exposure and this has been the basis of numerous high value legal claims.

As for the future, in the USA and Europe, asbestos related diseases will gradually increase to a peak. Of concern, however, are areas of conflict. In the Middle East, when a building was bombed, or when numerous buildings were bombed during the invasion of Iraq, do we have any idea how much asbestos was released into the atmosphere?

We are, however, certain that during the 9/11 disaster, asbestos fibres were released. When the Twin Tower collapsed, there were 400 tons of asbestos in the structure. The toxic cloud that hung over Manhattan, contained high level of asbestos. It is estimated that over 100,000 people suffered asbestos exposure. The greatest exposure was amongst first responders. Deborah Reeve was the first to die from asbestos related disease after 9/11. She was a first responder and paramedic. She died in March 2005 from mesothelioma. This concerned experts because mesothelioma takes a very long time to develop. They concluded that her exposure must have been excessive.

A study result showed that 70% of recovery and rescue workers who were active during and after the World Trade Centre collapse had some form of respiratory problem. A six year follow up study showed that sufferers with respiratory problems continue to have the same ailments.

?In the six years since the attacks,? Nadler said, ?We have accumulated a mountain of evidence that thousands of those exposed are suffering from chronic respiratory disease and, increasingly, a variety of rare cancers.?

Hopefully, as experts predict, within the next few years asbestos related diseases will peak and the annual new cases will drop. If not, could it be mankind's crouching tiger?