Decompression sickness will develop, when excess concentrations of nitrogen or helium from the respiratory gas have dissolved into the body. The dissolved gases are removed from the body with exhalation. If the level of dissolved gases exceeds their natural rate of removal, bubbles are formed in the circulation and tissues as the pressure surrounding the diver decreases. The bubbles will cause decompression sickness typically manifested as skin symptoms, musculoskeletal pains and disturbances of the central nervous system. The only known and effective treatment is recompression and inhalation of pure oxygen.