As the depth increase, the air that is breathe gets denser. More effort
is needed to breathe in and out. The heart would also need to work harder
by pumping at a greater strength than what it is normally used to.
The dense cool air under pressure can also cause problems to the sinuses
and to the lungs especially those that have a history of asthma (even childhood
asthma) or rhinitis (running nose). Some of these problems can be life threatening:
Pulmonary barotrauma
Cerebral air gas embolism
Sinus barotrauma
Aural barotrauma
The underwater environment presents the diver with a weightless environment,
up and down can be difficult to discern, sounds and vision are distorted,
added to this is the disorientating effects of nitrogen narcosis.
As such the underwater environment can be disorientating particularly at
night. And someone who is anxious, it can be particularly worrisome.
A proper meical screening and education is able to allay the fears of new
diver and increase his enjoyment and appreciation of diving and make him want
to come back for more.