what are its industrial uses?
One industrial application for it is leak detection.
Helium
One industrial application for helium is leak detection. Because helium diffuses through solids three times faster than air, it is used as a tracer gas to detect leaks in high-vacuum equipment (such as cryogenic tanks) and high-pressure containers. 
cause of joint pain in deep sea divers It is termed as "Decompression sickness”. It arises from underwater diving ascent. what are its different types? It was broadly classified in two categories. "Type I" for symptoms involving only the skin, musculoskeletal system, or lymphatic system, and "Type II" for symptoms where other organs, such as the central nervous system are effected. what results in it? It is caused by a reduction in ambient pressure that results in the formation of bubbles of inert gases within tissues of the body. is it caused by any particular gas? Yes a gas mixture of several such as nitrogen and helium to name a few. when was the second gas discovered? 1868
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Helium [SEP] Industrial leak detection
One industrial application for helium is leak detection. Because helium diffuses through solids three times faster than air, it is used as a tracer gas to detect leaks in high-vacuum equipment (such as cryogenic tanks) and high-pressure containers. The tested object is placed in a chamber, which is then evacuated and filled with helium. The helium that escapes through the leaks is detected by a sensitive device (helium mass spectrometer), even at the leak rates as small as 10 mbar·L/s (10 Pa·m/s). The measurement procedure is normally automatic and is called helium integral test. A simpler procedure is to fill the tested object with helium and to manually search for leaks with a hand-held device.