■Decompression stop and decompression time
There is a limit to the amount of nitrogen in human tissues that prevents nitrogen from forming bubbles.
This limit amount is called the maximum allowable inert gas pressure (M value) in the tissue and is determined for each depth.
When the accumulated amount of nitrogen exceeds the decompression stop depth M value during ascent, a decompression stop is required.
The decompression time is the time required to keep the nitrogen accumulation below the M value.
The M value is different for each tissue, and decompression stop is performed to reduce the amount of nitrogen accumulated in a specific tissue below the M value.
In leisure diving that the dive time is limited, most of the decompression sickness in which nitrogen is bubbled in tissues (kidney, stomach, brain, central nervous system, skin, muscle) whose half time is about 80 minutes or less.
This is the reason why over 80% of the symptoms of decompression sickness that occur during leisure diving are piercing pains in joints (especially shoulders, elbows and knees) and muscles, and weakness in limbs.
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