You are talking to a friend who is a welder. He wants to know more
about scuba diving. This is what you tell him:
"Scuba
diving can be dangerous for welders who are sometimes required to be underwater
for long lengths of time. When someone stays underwater, they can experience
air embolism. That's when the blood flow gets blocked by air bubbles.
"They
can also get the bends when resurfacing, which is awfully painful. The bends
is a decompression sickness. It is caused by bubbles of inert gas forming
in the body.
"There is sometimes the danger of carbon monoxide toxicity
at a work site. This means that you are breathing air that has been contaminated
with carbon monoxide. That's a poisonous gas.
"A welder using
scuba equipment can't do continuous dives. That's because of the
residual nitrogen. Dissolved nitrogen remains in the body as a result of an
earlier dive within 24 hours. You don't want to be a victim of nitrogen
narcosis while underwater, because of the narcotic effect nitrogen has at
increased pressure.
"When a diver goes deep in the water, the air she
breathes becomes more compressed. This means that as the diver returns to
the surface, the air expands. The air cannot be allowed to expand too quickly.
"A
diver should have decompression stops on the way up. These stops are the time
a diver stops and waits at a certain depth to allow nitrogen elimination before
surfacing. If she doesn't, she may develop decompression sickness, such
as the bends I just told you about."
"There sure is quite
a bit of reading and writing that has to be done," says Mark Capadouca, an
underwater welder. "That's because there is quite a bit of schooling
to become certified. There is a lot that has to be learned."