How Safe Is Diving?
An UpdateBy Alex Brylske
Many years ago, when I first told my mother that I wanted to learn to scuba dive, her reaction was probably not unlike that of many moms. But her way of expressing it may have been a bit different. In her usual unflappable demeanor, the only question she asked me was, “Are you crazy?” Over the three-plus decades that have passed since that conversation, I have come to understand that she wasn’t really doubting my sanity. (At least, that’s what I choose to believe.) She was instead, in a more colorful and roundabout way, merely asking the question that occurs to anyone who has ever strapped on a tank, or the loved ones of those who do: How safe is diving?
Six years ago I explored this question in a feature article and came to the conclusion that, in the grand scheme of things, diving is pretty darn safe. So given the passage of time and the increasing popularity of diving, it seems appropriate to once again take a close look at the issue of diver safety.
A Matter of Perception
First, to get a complete picture, we need to look at perceptions before delving into facts. This is necessary because diving has long suffered from a bad public image. As proof, just think back to the last time you heard about diving in the news. Most likely, it involved a death or some sensational accident. Luckily, that’s beginning to change.
Today, scuba divers are depicted in ads hawking everything from Band-AidsTM to denture adhesive. I think it’s finally safe to assume that the general public no longer equates diving with jumping the Grand Canyon on a motorcycle. Yet the perception that scuba diving carries no risk is just as inaccurate as the overblown assumption that it’s a form of subaquatic suicide. The short answer to the question “Is diving safe?” is very simple: No, it’s not. At least not according to the formal definition of the term safety, which is “freedom from danger, risk or injury.” Completely avoiding the risk of injury is a virtually impossible state to achieve. Even lying in your bed carries with it the potential that something may go wrong. This is why the question of safety requires more than a simple yes or no answer. In fact, safety can be such a subjective term that it’s almost impossible to discuss it in any objective context.
Invariably, questions involving safety can be answered with objectivity only when viewed from the perspective of risk. The first thing you need to know about risk is that it’s not an all-or-none issue, but a continuum. On one end there’s the absolute assurance that nothing could possibly go wrong (which isn’t very realistic). On the other, there’s the absolute certainty of death or injury (which isn’t very smart). The real question, then, is not one of trying to agree on how safe diving is, but how much risk it involves. The final and perhaps most subjective question of all is whether that risk, once known, is acceptable.
One thing that hasn’t changed since we last visited this issue is the perception of seasoned divers. Just a few weeks ago I had a conversation with an “old salt” that I believe portrayed a widely held assumption about diver safety among many experienced divers. My friend was convinced that diving has gotten a lot less safe in recent years. He cited several personal observations of incompetent divers narrowly escaping injury. Sensing a debate, he was initially taken aback by my initial reaction I agreed with him. Indeed, I told him, there probably are more incidents and near-misses today versus 15 or 20 years ago. But to understand why, we need to look a little deeper. (I think the pun was lost on him.)
Today’s diver is fundamentally a different individual than his or her predecessor. Not long ago, divers were a single-minded bunch who did little else as a leisure activity. Twenty years ago it was commonplace for divers to log 50-100 dives annually because, to the participant back then, diving wasn’t just a sport it was a way of life.
Today, of course, that attitude has changed dramatically. Many divers have a more limited, though no less sincere, interest than their counterparts of years past. In fact, some confine their diving interests exclusively to vacations or only when conditions are very favorable. I’m not encouraging or disparaging this “fair-weather” mentality, merely making the point that it results in significant periods of inactivity between dives. As knowledge and skills decay when they’re not used, it’s understandable that we often witness divers experiencing minor difficulties. Still, does an increase in incidents mean that diving is becoming less safe?
Incident vs. Accident
For the discussion to go anywhere but in a big circle, we need to establish some definitions. In this case, I’ll make a clear distinction between an “incident” and an “accident.” For the latter, I’ll use the National Safety Council’s definition, as I did back in 1993. In tabulating its annual inventory of accident statistics, its criterion for a sporting accident is “any injury which requires treatment in a hospital emergency room.” In my own definition, an incident is any unexpected, potentially hazardous occurrence such as panic, exhaustion or an out-of-air emergency that results in no injury.
I will be the first to admit that there are probably lots more incidents today than in the recent past. But I also believe that this is to be expected, because there are far more divers. Personal opinions and anecdotes aside, however, the only way we can answer the question “how safe is diving?” is with data. And unfortunately, we are no closer to having reliable information on diving incidents today than we were three years ago. So because of our minimal insight into incidents, we’re again forced to turn to data on diving accidents for an objective picture of the true risks in scuba diving.
Therein lies yet another problem. While data on diving fatalities have been collected and analyzed for nearly 30 years, the records still aren’t as extensive on the equally important issue of nonfatal diving accidents. In fact, few broad-based statistics on nonfatal diving injuries even existed until the Divers Alert Network (DAN) began doing such an analysis in 1987. Since then, DAN has published a diving accident report each year and, since 1989, has included data and analysis of fatal diving accidents.
Recently, DAN published its accident analysis for 1997. (The delay is due to the time required to collect and analyze the data.) It showed 972 total nonfatal cases of decompression illness (both decompression sickness and air embolism), the primary cause for most diving injuries requiring hospitalization. Some good news is that, by comparison, the totals for 1994, 1995 and 1996 were 1,163; 1,132; and 935 respectively.
One might assume that with these numbers it would be a simple matter to determine an accident rate for diving by dividing them into the total number of dives made during that year. While such logic is solid, the same problem holds true today as it did back in 1996: There’s still no accurate estimate of the number of dives made each year.
Likewise, the number of active scuba divers is still only speculative, with estimates continuing to range wildly between fewer than 1 million to over 3 million (within North America). However, even without a solid “denominator” for the number of accidents that occur each year, we can draw some broad conclusions.
Considering the number of divers trained annually and the number of active divers, even the most conservative estimate of the number of dives made each year would certainly yield a figure in the tens of millions. So, with only somewhere around 1,000 cases of decompression illness annually, logic tells us that the risk of injury in diving must be quite small. In fact, as Table 1 shows, the risk of sustaining an injury serious enough to require treatment while scuba diving is below that of bicycling, waterskiing, roller skating, swimming, tennis, fishing and even golf! I am, of course, not disputing that when an accident does occur, the kinds of injuries that result from diving are often far more serious than in tennis, fishing or golf. But that doesn’t change the fact that, even when the data are normalized, fewer injuries requiring emergency medical treatment occur to divers than to tennis players, fishermen and golfers.
In 1993 some pointed to increasing nonfatal accidents since DAN began reporting data as evidence that diving safety was on the decline due to the erosion of diver competence. However, while this increasing trend continued through 1995, it’s interesting to note a substantial decrease in 1996. And the rise in 1997 was only by 37 cases. The other good news about the declining trend in nonfatal accident statistics is that it’s occurring as diving is becoming popularized and accepted by society as a mainstream recreational activity.
Yet even with all the cause for optimism, the analysis of nonfatal accident data is still as inconclusive in 1997 as it was in 1993. So as before, to get a more complete picture we must look to data on diving fatalities. Here we have a much longer track record. Information on fatal diving accidents involving U.S. residents has been collected and analyzed at the Underwater Accident Data Center of the University of Rhode Island since 1970 and is now included in DAN’s annual report of diving accidents.
Table 2: represents the total number of fatalities involving recreational and technical divers per year from 1970 to 1997. As was the case when we last visited this issue, figures range from a high of 147 deaths in 1976 to a low of 66 deaths in 1988. From 1970 to 1997 a total of 2,853 deaths involving recreational and technical divers occurred. This figure, incidentally, includes even those victims who did not hold a diving certification. In 1997 there were 82 fatal diving accidents (four of which involved uncertified divers who had no training whatsoever). This figure is 10 less than the 92 fatalities reported in 1993. From these data, the fatality rate is estimated within a range of 8.2 deaths per 100,000 participants (assuming there are only 1 million active divers) to 2.73 deaths per 100,000 participants (assuming there are 3 million active divers). How does scuba diving compare with other so-called high-risk activities? By comparison, according to data provided by the U.S. Parachute Association, in 1997 there were 32 fatalities in a population of 308,000 sky divers. This represents a fatality rate of 10.38 per 100,000 participants. So it appears that the chances of a fatal accident are only slightly higher if you dive from the sky versus under the sea. But what about another activity that many equate with scuba in terms of risk flying.
Here the picture is very different. Based on data from the Aircraft Owners and Pilots Association’s Air Safety Foundation, in general (noncommercial) aviation for 1997, there were 331 fatal accidents (resulting in just over 667 total fatalities) among a population of 616,342 pilots. If we count only the pilot participant, this translates into an accident rate of 53.7 fatalities per 100,000 participants. That’s more than six and a half times even the highest estimated diving fatality rate.
On average, just under 107 recreational divers per year have died since 1970. Interestingly, however, since 1984 the average number of fatalities has dropped to only 87.21 per year. And even though there was a slight increase of 2.6 in the average death rate for the period of 1984 through 1993, the overall decline in the average number of fatalities over the past 14 years versus the 13 years prior to 1984 is a very positive indication.
But that’s not all. What these figures fail to consider is the burgeoning popularity of diving in recent years. While the average diver may not be as active as his predecessor, there are now as there were four years ago lots more divers than in the past. Here, once again, while we don’t know exactly how many dives are made each year, we can conclude with confidence that far more dives have taken place in the past 14 years than in the 13 years previous to that. The only question is how many more.
Thus, we can deduce that over the past 27 years and particularly over the past 14 years as recreational scuba diving has become a more popular activity, the trend regarding fatal accidents has declined significantly. While even one accident is too many, we nonetheless have much to be proud of when it comes to our safety record. So how safe is diving? That’s a question every diver must answer for himself, but I’m not about to lose any sleep over it.
Table 1: Occurrence of Sports Injuries for 1996 Sport Number of Participants Reported Injuries
Source: Accident Facts, 1998 Edition (detailing 1996 data), National Safety Council.
Figures include those who participate more than one time per year, except swimming, which included those who participate more than six times per year. Injuries include only those treated in hospital emergency rooms. Golf injuries do not include injuries involving golf carts. Scuba figures based on industry estimated average number of active divers, and number of fatal and nonfatal accidents reported in 1996. All data represent the United States and its territories only.
Lessons from the Diving Accident Statistics
As mentioned in the accompanying article, according to DAN’s 1993 Report on Diving Accidents and Fatalities, there were 972 cases of treated decompression illness (DCI) cases reported. Of the total reported, DAN received 634 Diving Accident Report Forms detailing the cases. After excluding many cases due to insufficient information and other exclusion criteria, 452 were analyzed and included in the report. The following are some observations and opinions based on the report.
The majority of divers with DCI are between the ages of 25 and 50. Also, reflecting an aging diving population, the number of DCI injuries reported in the age range of 45-49 increased from 6.6 percent in 1996 to 12.8 percent in 1997.
There is a continuing upward trend for injuries in advanced divers from 28.4 in 1996 to 31.9 in 1997. Divemasters accounted for 10.6 percent and instructors 8.4 percent. Seventy percent of injured divers are male. Male divers reporting DCI tended to have more years of diving experience both in number of years and total dives than female divers.
Divers with fewer than 20 dives, or who have been diving for less than two years, accounted for 40 percent of the DCI cases reported in 1997. This was the first year when the major equipment problem reported by accident victims was lack of familiarity rather than equipment failure. Divers using computers continue to be less likely to fall victim to air embolism.
As emphasized in 1993, there are three vital messages you should take from this report:
• All divers need to learn more about DCI symptoms and first aid measures. That means the biggest favor you can do for yourself and your buddies is to take a rescue or oxygen administration course. Don’t wait until next week or next month. Do it now. Results from DAN’s analysis clearly show the importance of oxygen first aid.
• All divers, but especially those over 40, must maintain a regular routine of exercise designed specifically to maintain sufficient cardiovascular fitness. This means sustained exercise for at least 20 minutes at least three times a week.
• All divers should maintain their skill proficiency by diving more regularly. Or, if they confine their diving activities to vacations and other sporadic occasions, they should prepare for these excursions well in advance by making a couple of “tune-up” dives under calm, controlled conditions or, better still, by taking a formal refresher course.