Decompression (diving) but in later experiments signs of what was later to become known as decompression sickness were observed. Later, when technological advances allowed the use of pressurization of mines and caissons to exclude water ingress, miners were observed to present symptoms of what would become known as caisson disease, compressed air illness, the bends, and decompression sickness. Once it was recognized that the symptoms were caused by gas bubbles, and that re-compression could relieve the symptoms, Paul Bert showed in 1878 that decompression sickness is caused by nitrogen bubbles released from tissues and blood during or after decompression, and showed the
Scuba skills her breath during ascent, which can occur during an emergency free ascent. As lung overexpansion injury is potentially life-threatening, entry level diver training emphasizes developing the habits of not holding one's breath while diving on scuba, and slow continuous exhalation during simulated emergency swimming ascents. Techniques for clearing blocked Eustachian tubes during ascent are also generally taught at entry level. Uncontrolled rate of ascent can increase risk of decompression sickness and lung overexpansion injury even when diving within the no-stop limits of the decompression tables, so the skills of buoyancy control during ascent are important for diver safety and are