caisson sickness

cais·son sick·ness

disease caused by rapid decompression; so named because it appeared in workers building tunnels or supports for bridges working in enclosed units under high atmospheric pressure to keep out surrounding water, called caissons. See: decompression sickness.
[Fr. caisson (fr. caisse, a chest) a water-tight box or cylinder containing air under high pressure used in sinking structural pilings underwater]