Definition
A condition in which nitrogen dissolved in the body's tissues and blood comes out of solution as gas bubbles when ambient pressure drops, typically during rapid or high-altitude ascent. The bubbles can lodge in joints, the spinal cord, the lungs, or the brain, producing symptoms ranging from joint pain and skin itching to neurological impairment, respiratory distress, and collapse.
Plain English
When you go up to high altitude quickly, the lower air pressure can make tiny gas bubbles form inside your body, almost like opening a fizzy drink. Those bubbles can cause pain in your joints, breathing trouble, dizziness, or worse, depending on where they end up.
Context Anchor
Pilots encounter this term in high-altitude flight training, pressurization discussions, and guidance about flying after scuba diving.
Derivation
From 'decompression' (the release of pressure) and 'sickness' (illness). The name describes the cause directly: the illness that happens when pressure on the body decreases too fast for dissolved gases to stay in solution.
Why Pilots Care
It can produce joint pain, dizziness, confusion, or paralysis, requiring immediate descent and possible medical care that ends the flight.
Analogy
Think of a sealed bottle of soda. While it's capped, the gas stays dissolved in the liquid. Open it suddenly and bubbles appear everywhere. The body works the same way when pressure drops too fast.
Grounding Statement
If a person moves from higher pressure to much lower pressure too quickly, gases that were safely dissolved in the body can come out as bubbles.
Intuition Check
Decompression sickness is not the same as simply being short of oxygen. Oxygen shortage is one altitude risk; decompression sickness is a bubble problem caused by a pressure drop.
Example Sentence 1
After a morning of scuba diving, the pilot waited the recommended hours before flying to avoid decompression sickness.
Example Sentence 2
The pilot experienced joint pain from decompression sickness following an unpressurized climb above 18,000 feet.