A decompression chamber, or divingchamber, is an air-tight compartment capable of withstanding high pressures, used to house one or more divers or other personnel working in pressurized environments while they are gradually returned to normal atmospheric pressure. Decompression chambers are necessary to avoid decompression sickness (the bends), in which nitrogen is released into the blood and tissue causing acute pain in the joints, dizziness, nausea, and paralysis. Deep-sea divers usually work in teams so that work progresses while divers who have been relieved are progressively decompressed in submerged chambers at various depths.