Breathing is the most natural thing in the world, right? Day in and day out. You scarcely notice.
Breath in, breathe out. Can anything be more simple and routine?
It requires more knowledge because it's not the same. For
over a century we have known that you can't just provide air to divers and
expect them to be safe. You need more to guarantee safe diving every time you
go down.
Okay, now the fun part. Let's take a quick peek at some
basic physics to understand what's going on. Pretend there is a person in front
of you and that person gives you a little shove in the chest. You'd fall backward,
right? However, if another person were to stand in back of you and push forward
at the same time, you would remain still and not fall backwards. This is
because the person behind you counteracted the force of the person in front of
you.
The result is that you get a bit squeezed by the two
opposing forces. When you are under water the same thing happens, with one big
difference. The difference is that the force is coming from all sides at once,
not just front and back. Another big difference is that the force is coming
from within your body. Fortunately, there is 'oppositely directed force'
provided by the strength and stiffness of your tendons, muscles and rib cage.
Without this force, you'd collapse due to the pressure. How much pressure you
ask?
For every 33 feet (10 m) you dive down the pressure goes up
by 1 atm (one atmosphere). That's about 14.7 pounds per square inch all over
your body surface mass. To balance that pressure, your body pushes outward.
Most people don't know that your muscles and ribs are a little flexible. In
order to gain enough rigidity to counter-balance the pressure, your ribs
collapse inwardly just a little bit.
This collapsing compresses your lung a little bit. Breathing
becomes harder at deeper depths because it's harder for your lungs to
counteract the additional pressure. The fact that air is easy to compress just
adds to the difficulty. Water, for example, takes a lot of force to compress.
The air in your lungs compresses to a degree, as a result. To
breath properly your lungs have to expand against the collapsing we discussed
earlier. They also have to deal with the compression of the air and the extra
air needed to provide the body with enough oxygen.
It's just these issues that modern-day diving regulators and
tanks are built to handle. When diving down deeper in the water, the regulator
and tank system combines to provide air that is at the ambient pressure of the
ocean water. Using modern tanks and regulators, divers can go down to moderate
depths and still breath easily.
Once you get into really deep water, things change a bit.
The topic of really deep water diving is beyond the scope of this article.
Conserving precious oxygen is one of the ways professional divers help their
equipment help them. When you are underwater, you're moving in a dense fluid.
This slightly increases the amount of oxygen you need.
Professional and or highly skilled scuba divers swim and
move in a slow and apparently leisurely manner. They do this to conserve energy
and oxygen.
Less breathing conserves oxygen. Another way professionals
conserve oxygen is by keeping a cool head. When scuba diving it's not hard to
get excited about all of the amazing things you are seeing. A key challenge is
to avoid getting any more stressed than necessary when trouble strikes. For
example when visibility is low and you get stuck on some underwater debris. If
you stay calm your heart rate does not go up nor does your need for oxygen. Stay
calm, breathe right, dive safely and live to see another day.
