Scuba divers breathing air at high pressure underwater may suffer from 'bends' on ascending. The gas chiefly responsible for the bubbles that block capillaries is:

1. At high pressure, the solubility of atmospheric gases in blood rises (Henry's law). 2. On ascent, pressure drops and dissolved gas escapes as bubbles. 3. The dissolved nitrogen forms bubbles in the blood, blocking capillaries and causing the bends. _Source: syllabus Chemistry Ch 1 "Solutions", p.7_