The Chemistry of SCUBA
PART A INTRODUCTION Scuba diving is a form of underwater diving, which involves the diver using Self-Contained Underwater Breathing Apparatus (SCUBA) to breathe underwater, completely independent of surface air supply (US Navy, 2006). Scuba divers carry their own breathing gas source (usually compressed air) which enables them to stay underwater for long periods of time (Brubakk, Alf O; Neuman, Tom S, 2003). At sea level, every living and non-living particle experiences 1 atm (atmospheres) (Jacob, Daniel J, 1999), but below sea level, the pressure increases by 1 atm for every 10 metres (33ft, 1 bar or 14.7 psi) (Brubakk, Alf O .; Neuman, Tom S, 2003). Total pressure being exerted on the body is expressed as ATA (atmospheres absolute). Therefore, as a diver descends into water, they experience increasing pressure which if not taken into consideration, can endanger that person's life. In this report, Scenario 2 will be investigated in Part A, which portrays a common case of decompression sickness. Decompression sickness (DCS; also known as 'the bends') is a condition that arises from scuba diving or high-altitude events where dissolved gases (mainly nitrogen) diffuse rapidly out of solution (blood and tissues) causing bubbles to accumulate inside the body which can affect almost any body area (eMedicineHealth, 2018). The condition is caused by rapid changes in pressure whilst hurriedly ascended out of the water, causing the formation of gas bubbles which can result in severe joint pain. Dizziness, headaches, tingling/ numbness and a skin rash (Drugd.com, 2018). The scenario also displays a good example of neglecting the recreational dive planner (dive table), which is "designed specifically for planning recreational dives on air (compressed) only" (PADI, published date unknown). Part A will discuss the mentioned factors that caused Anna's symptoms as well as recommendations to prevent these issues in future dives. DISCUSSION In Scenario 2, Anna was scuba diving at Byron Bay, where she dived firstly at a depth of 20 metres for 26 minutes. She then took a break and came out of the water for 8 minutes. For her second dive, she swam to a depth of 26 metres for 22 minutes and stayed at this depth for 32 minutes. Anna panics and quickly ascends to the surface due to spitting out her regulator. As she reaches the water surface, she begins to feel immediate joint pain, dizziness, headache, tingling/numbness and a skin rash. Firstly, the dive table (Fig 1, 2) suggests that an 8-minute surface interval between the 2nd dive at 26 metres (m) for 32 minutes is not ideal after a 1st dive at 20m for 26 minutes. The surface intervals in the dive table ranges from a minimum of o - 4 minutes to a maximum of 2 - 5 hours, but Anna only took 8 minutes, which indicates that the residual nitrogen in her body has not been allowed enough time to diffuse out of her tissues. The dive table also recommends a maximum bottom time of 10 minutes at a