Could anyone raise the risks of tunneling and compressed-air working? Thank you.?

Answer 1

the risks of tunneling is simple enough... collapse. but it is the usual necessity of working in a compressed air environment that makes tunnel work, and many other underground work more risky. in order to have enough oxygen, and to keep water out in some cases, air must be pumped into the workplace, and compressed. however, when returning to the surface, it must be done very slowly, or else the worker will get what is known as 'the bends' where nitrogen air bubbles from the decompression actually bubble in the bloodstream, and cause a slow painful death as you can imagine....

see: decompression sickness
http://en.wikipedia.org/wiki/Decompression_sickness

Answer 2

If someone works in compressed air for any lenghty period, the blood takes up more nitrogen than usual and all tissues become saturated with high levels of nitrogen, which is not a problem. If there is a sudden blowout of the compartment, the nitrogen comes out of solution and forms bubbles in the blood (like popping open a can of soda). This causes pain in joints and muscles tending to make the patient bend (and is called the bends). If the victim is placed in a decompression chamber the bubbles can be re-compressed and the pressure lowered slowly enough to avoid bubbles. Another problem that especially affects younger workers with denser bones is that if decompression is improperly performed, the expanding nitrogen in the dense ends of bones having poor circulation may be deprived of oxygen by an expanding blanket of nitrogen which could lead to bone necrosis (bone death) and embrittlement of bone tissues.

Answer 3

Yes, ignore safety regulations and common sense, and you will raise the risks of this work.