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Personal Injury – Pressure while diving or tunnelling

For Employers’ duties see HERE

Pressure is experienced most commonly in diving and tunnelling. Commercial diving and tunnelling are very dangerous occupations in themselves without the designed, pressured environment representing a further hazard to the worker.

Tunnelling is also performed under pressure in an enclosed chamber, called a caisson, at the face of the tunnelling. The caisson keeps out underground water.

Divers suffering from “the bends” are the stuff of emergencies in comic books; unfortunately it can happen in real life. Underwater pressure ensures nitrogen from the compressed air is kept in solution in the blood stream. If the pressure is removed too quickly, the nitrogen forms bubbles in the blood and gives the worker cramps or even leads to unconsciousness and death. Apart from pain and incapacity there will be other symptoms such as skin mottling.

Tunnellers can get the bends just like divers. Decompression under proper procedures is required in each case.

In the long term chronic decompression sickness causes bone necrosis. Apart from divers it is estimated that as many as 25% of compressed air workers suffer from bone necrosis. If this occurs in the joints it leads to disablement. About 3% of general compressed air workers and 0.2% of divers are disabled from this cause.

Among tunnellers in Ireland and Britain, a remarkably high number come from Donegal. They select themselves by being recruited by experienced foremen forming a “team” which the employer then hires as a group.

A medical code of practice for work in compressed air has been established, incorporating the Blackpool Decompression Tables. Compressed air workers should have X-rays of joints every two years at least. They should be X-rayed on commencement, in order to have a base for comparison.

In addition to this and other dangers, divers breathing oxygen or a mixture of oxygen and helium may suffer oxygen necrosis below depths of 25 ft. in the case of pure oxygen, and greater than 500 ft. in the case of the mixture. The onset of coma and convulsions can be sudden but is ordinarily preceded by minor feelings of discomfort. The remedy is to immediately surface and breath fresh air.


  1. Edward could you please mail me on [email protected], am interested in knowing about the high number of tunnellers from Donegal, it’s an interesting fact and I would like to know why this is, who i can speak with etc. Might make a good story for the paper. Thanks

  2. I have never before encountered the medical diagnosis of oxygen necrosis. The link provided in the article leads to the Wikipedia definition of “Necrosis” and offers no definition of the term “oxygen necrosis”.

    I would respectfully request additional information and clarity on this subject.

  3. Dear Gordon,

    I believe you are correct, but my blog is a legal blog and not a medical blog.

    While the term may not be current the concept appears to be correct.

    Here is a passage from a pdf at

    “Using annexin V binding in the murine lung bronchus
    cells, we found that the majority of cells were undergoing
    necrotic cell death when exposed to hyperoxia for 72 h.�

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