Pressure and Your Body Although you don't usually notice it, air constantly exerts pressure on you. If youve walked against a strong wind, though, youve felt its force, demonstrating that air can exert pressure.The air pressure that surrounds you now is simply the air's weight - the result of gravity holding the atmosphere against the earth. You don't usually feel pressure, though, because your body is primarily liquid which is incompressibte and distributes pressure equally throughout your entire body.

The few air spaces your body does have a vour ears, sinuses aad lungs have air inside them edual in pressure to the external air pressure. Although air is compressible, you don't notice pressure in body air spaces as long as the pressure's the same inside and out-side. But if the pressure changes, such as when you ascend to and from a higher altitude by flying or driving through mountains, the air in body air spaces changes volume, and you feel it in your ears. and sometimes in vour sinuses.Just as air exerts pressure on you. so does paten when ynu submerg

But because water m much denser and heavier than air. pressure changes much more signifi cantly for a gk en distance ascent or descent. As with air pressure, you don't teccl water presure except in your body 3nd one of the first things wull nmice is that ,you'll feel changes Quickly even when you ascend or descend only a metre These changes have some associated problem that you'll learn to avoid later in this section and during confined water Bali scuba dives.