ScienceAugust 26, 2026

prebreathe

PREE-breedh

Definition

A specific medical protocol in which an astronaut breathes pure oxygen for an extended period prior to a spacewalk to clear dissolved nitrogen from their body tissues.

Etymology

Formed by the prefix 'pre-' meaning 'before' and the verb 'breathe,' this term emerged in aerospace medicine to describe the preparatory act of gas exchange required before exposure to reduced atmospheric pressures.

In the news

The article describes the prebreathe procedure as a critical safety routine that prevents astronauts from developing decompression sickness when they transition from high-pressure cabins to low-pressure spacesuits.

Before every spacewalk, astronauts spend hours breathing pure oxygen inside their own bodies for one specific reason — to stop their blood from doing to them exactly what nearly happened to test subjects inside vacuum chambers on Earth

Read the full article ↗

Space Daily

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