Mountain domain Thin Air power and giants

[Just a Guess]

At level 8 the mountain domain grants a power called thin air. It is an aura that expands 5ft from you and calls our affecting creatures adjacent to you. Now how is it with creatures that are larger? Especially those big enough (huge+) that their head is not within 5ft from you any more. Will they be affected? As I read the power I'd say yes, as long as any part of them is adjacent to me it works. Am I right?

Thin Air (Su)::

At 8th level, as a free action, you can surround yourself with a 5-foot aura of supernaturally thin air that draws the breath from creatures adjacent to you. Creatures beginning their turn in the aura are fatigued (Fortitude negates). A fatigued creature that begins its turn in the aura must save or suffer from altitude sickness, taking 1 point of ability damage to all ability scores. At 16th level, the aura increases to 10 feet. Creatures that do not breathe are immune to this aura. You can use this ability for a number of rounds per day equal to your druid level; the rounds need not be consecutive.

Sure, most big creatures have good fort saves and are less likely to be affected. But that's not the point.

[Bob Bob Bob]

It's a supernatural power, it gets to break "reality". It works because they touch your aura. The "air" is the flavor, how it functions mechanically is clearly described. Maybe touching your aura sucks the air out of them? Probably using whatever magic power it is that distinguishes between creatures and objects. Find a fluff you like and roll with it.

[Just a Guess]

Thanks