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 Schools International Assistant Instructor) followed by Open Water Instructor and above. SSI's training program for children aged 8–12 years is called Scuba Rangers. The training program for technical divers is called TechXR (Technical Extended Range) and includes decompression diving, trimix and other courses that exceed the limit for recreational divers. SSI scuba certifications are recognized throughout the world (such as RSTC - Recreational Scuba Training Council, EUF - European Underwater Federation, CUA - China Underwater Association and others). SSI was founded by Robert Clark in 1970, and was one of the pioneers of professional scuba training. They were the first organization to