Oxygen window — inspired/expired pressure delta

The oxygen window is the pressure gap between the air you breathe in and the gas you exhale. This difference exists because your body consumes oxygen while producing carbon dioxide.

Decompression works better when this window is wide. It affects how fast nitrogen leaves your tissues because the lower pressure in your lungs pulls gas out of your blood. During a deep dive at 30 m, a larger window helps prevent DCS. You see this effect most clearly during staged decompression stops.

Don’t hold your breath during ascent. If you restrict gas exchange, you shrink this window and increase your risk of nitrogen bubbles. Always maintain a steady, rhythmic breathing pattern to keep the pressure delta high.