The 2010 DAN Diving Fatalities Workshop

Workshop provides recommendations for safer diving.

Divers Alert Network® has long been the primary clearinghouse for diving accident

statistics. Among its many services to divers, the annual DAN® diving reports are a must-have for any serious researcher on the topic of dive safety. In April 2010 DAN went one step further when it hosted the DAN Diving Fatalities Workshop in Durham, N.C. The two-and-a-half-day workshop focused on learning more about the causes of dive fatalities and how to prevent them, especially as an industry. The information is valuable to training agencies as they develop or revise training programs, physicians who screen divers for participation in the sport and, perhaps most important, to divers who make personal decisions about if and how they will participate in our sport.

The presenters at the conference composed a Who's Who in diving medicine and physiology, but it also included key players from several of the training agencies and an audience full of experts ranging from Coast Guard safety officers to physicians. As you might expect from this distinguished list of participants, the workshop provided a significant supply of information, statistics and facts. It might have been easy to be overwhelmed by the amount of information imparted, but several clear and important points emerged.

As divers, we should start with an acknowledgement of all the industry has already accomplished. As an adventure sport, diving is a remarkably safe activity, and there is no doubt that its overall safety record is a result of cooperative efforts on the parts of the training agencies, the Recreational Scuba Training Council (RSTC) and a few research groups, most notably DAN.

Statistics from one of the largest training agencies in the world, collected over a 10-year period, show an incident rate of only 0.472 fatalities per 100,000 dives. If that number scares you, you probably don't want to see the statistics for sitting on your living room couch, and you certainly should give up driving your car. What's encouraging about this data is not just diving's overall low fatality rate, but the fact that this rate has remained consistent or shown improvement over the last decade.

What has also changed — and is continuing to change — is the data gathered in relation to the actual causes of death. As one would expect, drowning and arterial gas embolisms rank in the top three causes of diver deaths, but these factors taken as solitary causes regularly fail to acknowledge the often pre-existing health issues. One of the extreme difficulties researchers face has always been separating the mechanism (or cause of death) from the manner of death. Researchers may know the actual causes of death; however, what led to the cause of death is frequently not as obvious, especially when local officials or pathologists make assumptions.

The classic assumption is that the person was a diver, he was in the water, he is now dead; therefore, he drowned. As simplistic as this may sound, it is a resounding comment voiced by presenters at the conference. In many diving hot spots, the resources for comprehensive investigations or even complete autopsies are simply not available, and this obviously impacts the quality of reported data. It was noted that drowning as a cause of death is ineffective in determining what actually occurred in an incident. Yet in the data presented at the conference, 61 percent of the dive fatalities listed "drowning" as the cause of death. Significant efforts are under way to improve the quality of data reported and to obtain more complete information. (It is also interesting to note that the legal panel presenting at the workshop listed a lack of information as the No. 1 reason personal injury lawsuits are filed in the industry.)

In an effort to improve accident data, researchers are trying to obtain information that paints the complete picture of an accident. There are a few different versions of this chain of events, but they are all very similar and contain the following elements: a triggering event, a disabling or harmful event and, finally, a disabling injury.

The triggering event is the first event in the chain; it can be something as simple as a flooded mask on an inexperienced diver or as complex as overexertion in a person with a cardiovascular condition. In all cases, the trigger typically leads to some form of harmful action or agent. The disabling injury then follows.

For example, let's say our inexperienced diver with the flooded mask panics and rushes to the surface. The flooded mask is the trigger, and the bolt for the surface is the harmful action in response to the trigger. If he or she failed to exhale on the ascent, that failure would lead to the disabling injury: lung rupture and the consequent air embolism. Because of the air embolism, the diver may lose consciousness while still in the water and drown.

The legal panel noted that in the accident reports available for study, less than one-third have triggering-event data and less than one-half include harmful- or disabling-action information. The lack of detail leaves us to fill in the blanks and reconstruct the circumstances using on-site investigation, gear examinations, witness interviews and discussions with friends and family members.

Interestingly, two of the most common concerns, especially among new divers, have proven to be the least likely contributing factors to accidents. Equipment failure and marine life injuries are extremely rare. Not surprisingly, areas where divers notoriously cut corners, such as inadequate training or lax buddy practices, are far more likely to contribute to accidents. Forty percent of the fatalities took place during a period of buddy separation; 14 percent involved declared solo dives.

Experience also plays a key factor; about half of all fatalities involved divers with 20 or fewer dives (less than 8 percent of those were students participating in training). The activities and the experience levels involved in the dive incidents provide significant circumstantial data about how the diver arrived in a situation, which in turn led to a triggering event. Although circumstantial, this data is important to the researcher as it provides valuable information on how to prevent accidents long before the triggering event begins.

Knowing the root causes of triggering events probably provides us with the best information for preventing accidents. In the more than 940 fatality statistics studied, DAN identified five significant root causes:

  1. Some sort of pre-existing disease pathology in the diver
  2. Poor buoyancy control
  3. Rapid ascent or violent water movement
  4. Gas-supply problems
  5. Equipment problems

In many cases the numbers indicate that more than one root cause was present at the time of the incident. These root causes have been identified as leading to the triggering events in 346 cases. The most significant triggering events identified were air loss, entrapment or entanglement, gear issues (which could include operator error), rough water and buoyancy issues. Not surprisingly, the causes of death in most of these incidents were either asphyxia (to include drowning) or arterial gas embolisms (AGE).

Some of the data, however, are surprising, and these surprises lead us to questions that can positively impact the industry. For example, insufficient gas was the trigger in 63 percent of fatal AGE cases and in 32 percent of drowning cases. This finding leads us to question the response divers may have to this emergency and, most important, the methods they use to prevent the situation from occurring in the first place.

This specific example was addressed by the experts at the workshop and led to a discussion that examined relevant elements of prevention, including the role training can play and improvements that could be made to equipment.

This kind of in-depth examination and discussion is the process that is stimulated by the examination of accident statistics, and it is how favorable outcomes result from what may seem to be only an academic exercise. The issues raised at the DAN Diving Fatalities Workshop included questions about general health, specific medical conditions, the screening processes used by physicians, the frequency of refresher training, the processes for evaluating diver skills and even the possibility of using a rating system to identify dive sites by risk category.

Of course, there were also questions about how to improve both the amount and quality of dive accident data included in the statistics. An obvious answer is a plea to every diver to provide diving data — both accident and non-accident related — to DAN. As one would expect from such a well-qualified panel, the end result of the workshop was a set of recommendations for the questions raised. The only question remaining is whether divers will use the recommendations to improve their personal safety and the overall safety of our sport.

Recommendations For Safer Diving
Although designed primarily for dive and medical professionals, the workshop provided several takeaways for every diver. For the official workshop recommendations, download the complete proceedings from DAN.

Personal decisions:
  • Maintain a healthy body weight; statistically, a body mass index (BMI) of more than 30 significantly increases your risk of death while diving.
  • Never dive with uncontrolled health issues such as elevated blood pressure, cardiovascular issues or uncontrolled cholesterol.
  • Improve your exercise tolerance. You should be able to achieve an exercise output of at least 13 metabolic equivalents (METs) for short periods of time and do sustained exercise at an output of at least 6 METs (ability to swim 110 feet per minute over sustained periods of time).
  • Be honest with yourself, your instructor and your physician about medical issues; educate yourself about health-risk factors like smoking and how they can impact your health for diving.
  • If you have symptoms of potentially impending health problems, especially cardiac issues like fatigue or chest pain, do not dive until you have been checked by a physician.
  • If you are a patient being monitored for chronic problems, follow the recommendations of your physician. Remember that diving is different from, and not as forgiving as, some other sports.

Diving decisions:
  • Follow established training guidelines.
  • Familiarize yourself with procedures for dealing with entanglement.
  • Learn to avoid uncontrolled ascents by utilizing safe diving procedures, and practice out-of-air drills in case the unavoidable occurs.
  • Never go into an overhead environment unless properly trained and equipped — not even a little ways and not even with a guide.
  • Have a sharp and functional cutting tool on every dive, and position it within easy reach.
  • Complete a skills refresher course at least once per year or more often if you lack confidence in the currency of your skills.
  • Complete only dives that are well within both your fitness and skill limitations.

For dive professionals:
  • Do a pre-assessment with divers prior to any deep dives in advanced courses.
  • As part of every dive briefing, provide divers with the most realistic view possible of the conditions so that divers can make informed personal risk assessments.
  • Develop a procedure manual that provides standards for your operations, and use it to improve consistency and the safety of your operation. A recommended guideline is the International Organization for Standardization (ISO) 24803 standard for recreational diving service providers.

© Alert Diver — Summer 2010