Symptoms in humans which result from a sudden reduction in atmospheric pressure. It is also called dysbarism, caisson disease, the bends, and compressed-air illness. It is most commonly seen in two groups of subjects: those who rapidly ascend in nonpressurized airplanes to altitudes in excess of 18,000 ft (5500 m); and divers, scuba divers, sandhogs, and professional workers in hyperbaric chambers who work under increased ambient pressures and are decompressed.