Plain English Meaning

Air contains a lot of nitrogen, and some of it dissolves into your blood and tissues like fizz in a soda. If the pressure around you drops too fast, that nitrogen can form bubbles inside your body, which is dangerous.

Full Definition

Dissolved nitrogen gas absorbed into the bloodstream and body tissues from the air a pilot breathes. Under normal pressure this nitrogen stays in solution and causes no problem, but if the surrounding pressure drops quickly — such as during a rapid climb to high altitude after scuba diving — the nitrogen can come out of solution as bubbles, producing decompression sickness (the bends).

Context Anchor

Seen in pilot health discussions about scuba diving before flight, high-altitude flight, and decompression sickness.