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Off the Deep End? What You Should Know About Pool Chemistry

Now that pools are getting busy again for spring and summer training, we thought it fitting for us to take a deep dive into pool chemistry. Fortunately, science writer Reilly Fogarty’s got the scoop on what’s cooking in your favorite pool. Water sports anyone? Dive in.



By Reilly Fogarty
Header image by GUE instructor Steve Millington, SOCAL SCUBA DIVING

When divers dream of adventure, it’s not often that their mind wanders to images of the shallow end of the local YMCA pool. Adventures may not often take place in waist-deep water, but a chlorinated escape from our terrestrial confines can do a great deal for our health and safety. Between fitness, training, and cooling off on a hot summer day, you’ll spend a lot of your life in a pool, so you should know what you’re swimming in. Here’s the scoop on what’s going on in your favorite pool.

Swimming in History

Pools have been used for recreation, religion, and fitness for longer than history has been recorded. The first man-made swimming pool is thought to be the Great Bath of Mohenjo-Daro, a thirty-by-twenty-three foot bath created sometime in the 3rd century BCE. This structure was predated by a pair of religious pools located in Sri Lanka built nearly a century before. The first heated pool is credited to Gaius Maecenas, who may have been the architect of a bath heated by fire pits in Rome around the first century BCE. It’s not hard to see why ancient societies wanted the pools—from religious ceremonies to block parties, the uses for pools haven’t changed dramatically over the centuries.

Pools have been around for more than 2000 years.
Pools have been around for more than 2000 years. Photo by Saqib Qayyum / CC BY-SA . See

From these earliest pools sprouted dozens of similar structures across the globe. The logistics of building and maintaining the pools limited their use to only the most affluent until their popularity exploded during the mid-19th century with the rapid advent of new building technologies. Six indoor pools were built in London in 1837, and then the creation of the modern Olympic Games in 1896 rapidly spread public demand for public pools. 

Leaps in technology in the 20th century brought chlorination and filtration systems to pool design, and made pools easier to both build and maintain. The brick and tar construction of early history gave way to a flexible alternative, gunite, and soon after above-ground pool kits hit the market. Once the cost to build a pool dropped to levels attainable by common folk, they came to American backyards in droves. How to keep all those pools clean, however, was another issue. 

Pathogens & Pool Noodles

Once upon a time, the only way to clean a pool was to drain it and refill it regularly. Pools were often built on downward slopes to help drain them, and the water was cycled frequently. In the late 19th century people began to worry about large bodies of freshwater becoming disease ridden.

The first attempt to sterilize a pool in the U.S. using chlorine was at Brown University in 1910. The 75,000-gallon/284 kiloliters Colgate Hoyt Pool was chlorinated by graduate student John Wymond Miller Bunker, who used a bleaching powder, hypochlorite of lime (calcium hypochlorite), which had been recently discovered as a method to treat drinking water, at a concentration of 0.5 ppm. The pool remained sterile for four days. Bleaching powder, including both calcium hypochlorite and sodium hypochlorite (both a form of chlorine) instantly became the standard in pool sanitation, and spread across the world. 

Laws dictating pool sanitation appeared, and soon after diatomaceous earth filters hit the market. The filters use powdered rock to capture particles in the water and are frequently combined with skimmers, devices that filter larger objects from the surface of the pool through a mechanism similar to a storm drain. Pool use continued to increase in popularity and owners dabbled in a number of purification systems, from ultraviolet light, to ozone gas, to the chlorine and salt chlorinator systems most pools use today. 

Chlorine can cause irritation of the eyes and airways. Photo by Ted Harty, 

Purification systems aren’t without their flaws. Put too much chlorine in a pool and you risk irritating your eyes and airway, causing rashes, breathing difficulties or even chemically burning the fine hairs off your body. More commonly, the combination of chlorine with the ammonia found in urine can create compounds called chloramines, or cyanogen chlorides. Chloramines cause the typical “over-chlorinated pool smell” we associate with hotel pools, and can cause skin and eye irritation, as well as exacerbate allergies or asthma. Cyanogen chloride can interfere with the body’s ability to use oxygen and can be fatal—thankfully it’s volatile and rarely forms in dangerous concentrations and degrades quickly when it does. 

Pee isn’t the biggest concern for pool hygiene, despite the fact that swimmers leave, on average, about a shot glass worth of urine every time they jump in.

Pee isn’t the biggest concern for pool hygiene, despite the fact that swimmers leave, on average, about a shot glass worth of urine every time they jump in. [Ed.note: Fitness and competitive swimmers urinate in the pool!] We tolerate the hazard and complications of chlorination because of the microbial risks associated with large numbers of people effectively bathing together. The World Health organization (WHO) points to Shigella and Escherichia coli O157 as bacteria of particular concern for swimmers. 

Competitive swimmers urinate in pools.
Competitive swimmers urinate in pools. Photo from Abbie Fish,

Bacterial outbreaks are relatively rare among pool use but these bacteria, as well as a host of viruses, protozoa and fungi can be passed from swimmer to swimmer with relative ease. Both bacteria cause vomiting fever and diarrhea, although E. Coli O157 can cause hemorrhagic colitis and haemolytic uraemic syndrome (HUS) in severe cases. Giardia and Cryptosporidium are two protozoa that also pose a risk to swimmers, both being carried with fecal material. Both are highly resistant to disinfectants, are very infectious, and are shed in high densities by those infected. Diarrhea, cramping, vomiting and fever are common symptoms of both. Adenovirus, hepatitis A, norovirus and echovirus round out the list of common contagions in pool water, each with their own unique symptoms. 

There are a number of less common viruses and bacteria that can pose a risk to swimmers, but it’s worth noting that very few instances of group infection can be traced back to pool water. For the most part, modern pools are quite safe, and a combination of sterilization (to kill pathogens) and filtration (to control fecal release and other contaminants) can effectively keep a pool safe. 

The Mystery of Chlorine

Interestingly, the mechanism of chlorine sterilization is not fully understood. Research from the mid-20th century seemed to show that chlorine would react with some biomolecules as a result of it’s division into hypochlorite and hypochlorous acid in water. Later work indicated that chlorine likely reacted with a variety of bacterial targets and specific nucleic enzymes and membrane lipids – this was called the “multiple hit” theory, as explained in this 1998 Scientific American article titled, “How does chlorine added to drinking water kill bacteria and other harmful organisms? Why doesn’t it harm us?

Chlorine can eliminate a wide range of contamination factors.
Chlorine can eliminate a wide range of contamination factors. Photo by

More recent work suggests that chlorine specifically attacks cell walls by altering them physically and chemically, killing microorganisms by interrupting cell functions. Mechanically this theory involves a few steps. First chlorine disrupts the structure of the cell wall. This allows components of the cell that are critical to its function to escape, which causes a chain reaction of function termination, and eventually cell termination.

What this means effectively is that chlorine can kill a wide range of pathogens in relatively low doses. The concentrations used in public pools and water supplies are carefully monitored and designed to be small enough that ingestion of a normal amount allows only enough chlorine into the intestinal tract as can be neutralized by the action of the digestive system. That’s not to say that chlorine isn’t toxic – it can be extremely dangerous and must be handled with care – but like many poisons the dose determines the lethality. Because the concentrations used in pools are so low, the amounts that humans are likely to ingest are not harmful. 

At low concentrations chlorine in the body can be neutralized by harmlessly reacting with food in our stomachs, material in our intestinal tracts, or by the acidic environment of the stomach.

At low concentrations chlorine in the body can be neutralized by harmlessly reacting with food in our stomachs, material in our intestinal tracts, or by the acidic environment of the stomach. The Environmental Protection Agency (EPA) works closely with water utilities and environmental groups to reassess safe chlorine levels in drinking water and pools on an regular basis, and these guidelines along with those from the CDC should be used to determine what chlorine concentrations are safe for normal use.

Bug Count

The Centers for Disease Control  do provide some recommendations for specific chlorine and levels for pool use. Free chlorine in a concentration of a minimum of 1 part per million (ppm) in a pool, or 3 ppm in a hot tub, and a pH of 7.2-7.8 provides a safe concentration for swimmers and should kill most bacteria within a few minutes. Because bacteria levels are so difficult to measure in real time, testing is expensive, and equipment is scarce, regulations focus on mandating minimum free chlorine levels that are based on the environment rather than changing sanitation regulations that are based on bacterial load. This works on the assumption that known chlorine concentrations will kill common bacteria in a reasonably effective manner, and free chlorine indicates a sanitized body of water with a margin of safety. 

Something that might be confusing is the common chlorine smell found around high-traffic pools. This is actually caused by chloramines, the byproduct of a reaction of chlorine and urine, and can give off a strong odor and irritate the eyes, skin and airway. While the smell would seem to indicate that there is too much chlorine in the water, the opposite is actually true—eliminating the smell requires the superchlorination of the pool. Superchlorination, or “shocking” oxidizes the chloramines and leaves only free chlorine by flooding the body of water with chlorine levels five to ten times the normal concentration. Bathing during superchlorination is ill-advised, but the process should be done once a month in most cases, or once a week in hot weather. 

The risk posed by fecal contamination is much greater than general bacterial shedding, and diarrheal contamination is significantly higher-risk than a formed fecal incident. Both types of contamination require a fairly rapid response to minimize infection risk, effectively removing swimmers, isolating the hazardous material and superchlorinating the pool to disinfect it. The primary concerns with fecal contamination are Giardia and Cryptosporidium. While Giardia can be eliminated in as little as 20 minutes through superchlorination, Cryptosporidium is chlorine-resistant and can take as long as 25.5 hours to be safely removed. 

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Treating Pools

Methods to treat pools have changed over the centuries, but only chlorine and a few similar chemicals have proven really effective. From alternatives like ultraviolet purification, to ozone, to constantly moving water, chlorine alternatives have failed for centuries and left us with traditional chlorine, bromine, and cyanuric acid. 

Chlorine used as free chlorine is fairly straightforward to use—it’s added to the pool and kills microbes. The disinfectant can be added as a liquid, tablet, stick, or granular powder. These products are typically a sodium, lithium or calcium base bonded to chlorine to stabilize the product and prevent dangerous accidental exposures. When dissolved in water the bonds between the chlorine and it’s stabilizing compound break and the free chlorine is released. This free chlorine is actually not the compound that disinfects the pool, but it must be broken down one more step to hypochlorous acid through dissolution in water. We can estimate hypochlorous acid concentration fairly accurately through the known reaction with water, so it’s easier to deal with these chemicals as “chlorine” in broad terms. 

There is a bit of an art to keeping chlorine levels in check, as too little chlorine will allow bacteria to grow and too much will cause skin and mucous membrane irritation, but chlorine sanitization is more labor than rocket science. The average public pool should have somewhere between 3 and 5 parts per million of free chlorine, while jacuzzis may require up to 10 parts per million, due to the hot environment providing an incubator for bacteria. 

Salt water pools are now common as well, but these too rely on chlorine. In a salt water pool a salt cell or generator breaks down the components of salt water via electrolysis. This reaction results in the formation of chlorine in basic and acidic analogs as sodium hypochlorite and hypochlorous acid, and these are used to sanitize the pool. Salt water pools can be a nice alternative to traditional chlorine pools, but they don’t feel like the ocean, since most residential salt systems require salt levels around 4200 parts per million, while the ocean has an average salt concentration of about 35,000 parts per million. 

Bromine is a relatively recent alternative to chlorine. It is similar in structure and behavior to chlorine but less pH sensitive, and it’s reaction in water leaves bromide salts in solution which can be recycled. The downside to bromine, however, is that it’s very unstable in sunlight. Chlorine will degrade in sunlight somewhat, but Bromine quickly becomes ineffective in direct light. This means that it can be used to sanitize indoor pools but won’t do much good if used outdoors. Concentration levels for most pools are similar to chlorine, as are the side effects and signs of overuse. 

Cyanuric acid is the solution to the instability of chlorine in strong ultraviolet light. The acid can be added to a pool to stabilize the chlorine in solution. It does this by binding to the sodium hypochlorite ions released by the chlorine after reaction with pool water, and shielding them from UV rays. This allows free chlorine to be effective approximately three times as long as it would otherwise be. Because Cyanuric Acid binds to active sites on the hypochlorite ions, it can decrease the active sites available for reactions with target pathogens, so levels that are too high will reduce chlorine’s effectiveness and may require fresh water dilution. 

Watersports anyone?

If there’s one thing divers are good at, it’s producing astonishing amounts of urine as soon as they put on a wetsuit. Unfortunately for us, neither dive equipment or urine reacts well with chlorine. There are no color-changing indicators to show who pees in a pool right now, but pee does react with chlorine to produce chloramines. 

Chlorine and urine, including their joint reaction, can be harmful to dive gear. Photo by GUE instructor Steve Millington,

This is a two-part concern for us, and serious enough that the CDC has to send out warnings every year. Pool urination simultaneously removes free chlorine from the pool, decreasing the pool’s ability to self-sanitize, and creates a chemical irritant called chloramines. The byproduct of the reaction of chlorine with the amines in urine, chloramines cause respiratory irritation, skin rashes and can irritate the eyes and mucus membranes. They also produce the smell we typically associate with over-chlorinated pools. 

As if that wasn’t enough, chlorine also degrades rubber like that’s it’s job. Black harnesses will fade to brown, o-rings and wing bladders will degrade, and regulators will need shortened maintenance intervals. Want to save your gear, your pool and your skin? Pee before you dive, rinse your gear well and keep that pool chlorinated. 

Want to save your gear, your pool and your skin? Pee before you dive, rinse your gear well and keep that pool chlorinated. 

Additional Resources:

W. Bunker: The Hygiene of the Swimming Pool, American Journal of Public Hygiene, 1910 (20:4), 810-812.)

The BBC: University Of Alberta Scientists Study Urine Levels In Pools

For more information on pool safety: CDC Healthy Swimming Resource

House Method: How to Childproof your Yard (And Pool)

Reilly Fogarty is a team leader for risk mitigation initiatives at Divers Alert Network (DAN). When not working on safety programs for DAN, he can be found running technical charters and teaching rebreather diving in Gloucester, Mass. Reilly is a USCG licensed captain whose professional background includes surgical and wilderness emergency medicine as well as dive shop management.

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Is a Just Culture needed to support learning from near misses and diving accidents?

Human factors coach Gareth Lock delves deep into the meaning, impact, and need for “Just Culture” in diving, as well as creating a psychologically-safe environment that enables divers to highlight and challenge possible safety issues. Lock argues that both are essential, and offers practical suggestions for building the culture we deserve.




Text and photos courtesy of Gareth Lock

The heavily regulated aviation industry is often praised for its effective Just Culture, which has facilitated an ultra-safe operating environment. What purpose could a Just Culture serve in diving, and why should we care when we are in an unregulated environment? Aviation is ultra-safe—regulatory agencies implement safety targets and demand continuous improvement of safety performance. Nevertheless, adverse events still happen. Why? Because of the complex nature of operations and the variability of human performance. It isn’t because of ‘stupid pilots’ and/or ‘pilot error.’ 

The following two stories centre around a similar adverse event—a departure from a point on the runway the crew weren’t expecting—but have very different outcomes when it comes to the opportunities to learn and improve. As you read them, consider which one has more parallels with diving and the diving community.

Case #1

A crew of four pilots taxi out at night to depart from Miami, Florida to Doha, Qatar on a Boeing 777 with 279 people onboard. Due to busy radio communications and an internal misunderstanding as they navigated around the airfield at night, the crew mistakenly entered a runway at a point that was further from the departure end than their performance planning assumed. This meant that the runway distance available to them was 2,610 m/8,563 ft instead of 3,610 m/11,844 ft. The crew had not noticed this problem before they asked for departure clearance.

After they received departure clearance, they accelerated down the runway to reach take-off speed. Very shortly after the crew ‘rotated’ (pulled back on the stick), the aircraft struck the approach lights of the opposite runway, causing damage including puncturing the skin of the aircraft. Fortunately, the puncture did not breach the pressure hull. The crew were unaware of the impact and carried on their flight to Doha without any further issues. On arrival, while taxiing in, the ground crew noticed the damage and informed the flight crew.

This event was widely reported in the media. It was also investigated internally and by local aviation authorities. The CEO’s response was, “We will not accept any kind of lapses by pilots because they have hundreds of passengers whom they risked,” and all four pilots were fired. Scarily, and I believe falsely, he also stated that “At no time was the aircraft or the passengers put in any harm’s way.” However, the aircraft was still on the ground when it left the runway, and if the crew had to abort their take-off just before rotate speed, the aircraft would have likely gone off the end of the runway and into the waterway—and probably the housing estate outside the airfield perimeter—with the loss of the aircraft and possibly passengers and crew. 

Case #2

The flight crew were operating from a Caribbean island with a single runway after they had arrived the night before as passengers. Neither the Captain nor the First Officer had been there before. They boarded their aircraft in the dark just before their passengers arrived. Once everyone was onboard, they left the parking area via the single entrance to the runway, and they turned to go to their departure end. The airport diagram they were using for navigation showed a single large concrete turning circle at the end of the runway. As they taxied down to where they thought the end was, they came across a large concrete circle and so started their turnaround process to line up facing the other way to depart.

They gained departure clearance and started to accelerate down the runway to reach their rotational speed. After rotating, they noticed that the lights at the other end of the runway passed under them more quickly than they expected for a runway of this length.

Once they arrived back in the UK, independently, both the Captain and First Officer looked online at Google Earth as they had an uneasy feeling about what had happened. What they found was that there were two concrete circles on the runway and not just the one as marked on their taxi diagram.

They immediately got a hold of their dispatch team and let them know that the airport diagram they had operated with wasn’t accurate and could cause a major problem. They also raised an Air Safety Report (ASR) within their airline so others could learn from the circumstances. The crew were congratulated for reporting this event, even though their departure safety margins had been reduced. The charts were amended as a consequence.

Given that pilots are reported to make between three to six errors per hour, which airline would you rather operate with—the one that welcomes and congratulates its operators for reporting mistakes, or the one that punishes them? Furthermore, how important do you think the perception (or illusion) of safety is for the first airline’s customer base? The absence of reported near misses, incidents or accidents does not mean that your system is safe. Paradoxically, those organisations who report more and learn from those reports have fewer adverse events, especially repeat events.

What is a Just Culture?

A Just Culture was originally mentioned in 1997 as part of James Reason’s work in Managing the Risk of Organisational Accidents where he describes it as being part of a Safety Culture. There were five sub-cultures that made up a safety culture: just culture, reporting culture, informed culture, flexible culture, and a learning culture. The image below shows their interaction in more detail. My personal view is that Just Culture supports everything else, but it could be argued that if you don’t have a Reporting Culture, you don’t need a Just Culture.

Reason recognised that a wholly Just Culture is unattainable, but that there needs to be some line between errors or unwanted outcomes caused by system design and human performance variability, and those caused by gross negligence, sabotage, or reckless behaviour. As he highlights, The difficulty is discriminating between these few truly ‘bad apples’ and the vast majority of unsafe acts to which the attribution of blame is neither appropriate nor useful.” Sidney Dekker, author of Just Culture goes further and says, “It isn’t so much where the line is drawn, but who draws it.” In the world of diving, it is often online peers or the lawyers who draw the line. The former rarely have the full context and don’t understand human error and human factors, and the latter aren’t necessarily interested in wider organisational learning, as they are focused on their claim.

What does a Just Culture do?

A Just Culture facilitates the sharing of conditions or outcomes which aren’t expected or wanted—e.g., near misses, incidents, and accidents. The sharing happens because there is a recognition and acceptance within the team, organisation, or sector that human errors are part of normal operations and that professionals come to work to do a good job in spite of the limitations and constraints which are part of their job. These limitations and constraints create tensions and conflicts between doing what is written in manuals and procedures (Work as Imagined) and what really happens (Work as Done) to achieve the results for which they are being rewarded (e.g., productivity goals). Sometimes it isn’t possible to complete the job by following the rules because of these conflicts—conflicts which often have commercial drivers as their source. For example, pilots might not be able to do all their pre-departure checks in the correct order and at the right time because of limited ground time on turnarounds. For the aircrew, this can be business as usual, but in the event of an accident investigation, this would be picked up as deviant behaviour. 

This is like dive centres who are commercially driven and face local competition. They would like to up their productivity (to make up for reduced costs), but this means that standards might be bent every now and again to make things work. This could mean diving deeper than maximum depths to make use of boats for multiple clients and/or courses, not completing the minimum dive time or the minimum number of dives which increases instructor availability, increasing the number of students in a class to maximise revenue or deal with a shortage of instructors/DMs, or not having surface cover when needed because they couldn’t be sourced or they cost too much to include in the course fees. There is also the very real issue that some standards are not valid or that organisations accept unauthorised protocol changes but don’t do anything about that. 

Proceduralising a Culture? Isn’t that an Oxymoron?

Understanding this context is not easy, so part of Reason’s initial work was the production of a flow-diagram or process which showed managers how they could look at an event and determine where culpability might lie and how it should be dealt with. This framework has been reproduced by multiple different organisations like Shell, the Keil Centre, and Baines Simmons. 

Each of these processes is a decision tree, with the outcome determining what sort of action should be taken against the individual—sometimes it is punitive. On the surface, this sounds like a good idea. The problem is that these processes rarely consider the rich context that is needed to understand how it made sense for someone to do what they did, with biases like hindsight, outcome bias, severity bias, and the fundamental attribution bias getting in the way of understanding what really happened. This often leads to punishment when it is not applicable. Furthermore, which of the many individual contributory or causal factors do you examine as part of this ‘process?’ Most of the time, the focus is on the ‘sharp end’—those doing the work, rather than further up the organisational chain and the conditions.

Some organisations have inserted two additional tests to help managers determine if this was an individual problem or a systemic one. The substitution test asks if someone with the same knowledge, skills, and experience, and under the same pressures and drivers, but without knowledge of the outcome, would do the same thing. If they would, then it is likely a system issue. The other test concerns whether this event/action has happened before to either the organisation or to the individual. In both cases, if it has, then it highlights organisational weakness either in system design or training/coaching of the individual after the first (or subsequent) event.

The problem with such process-based approaches is that they can’t create a culture, therefore they can’t be part of a Just Culture. Fundamentally, a culture can’t be proceduralised—a culture is based on the relationships and interactions between individuals of a group, team, organisation, sector, or nation. Ultimately, it is ‘how things are done around here,’ often without those involved knowing why! We love technology to make things easier, but in this case, a process flow chart doesn’t help create a Just Culture.

Build the organisational learning into the investigation process

Things have changed in some organisations though. BP decided to review and rewrite their Just Culture process because they realised it wasn’t working as intended—the goal of the policy was to facilitate learning from near-misses, incidents, and accidents, but they were missing too much. Their rework meant that they asked learning-focused questions as part of their investigation process. Rather than asking the Just Culture questions at the end, in isolation and with limited information, they required the investigators to ask the questions during the investigation to generate the rich context needed to understand the event. Consequently, they found that 90% of their incidents were systemic in nature and were not caused by human error of those operating at the sharp end. You can see an extract from their investigation flow-diagram below. While this is a process, the purpose is to facilitate discussion and learning during the investigation rather than using an isolated judgement at the end.

Bitar, F. K., et al., (2018). From individual behaviour to system weaknesses: The redesign of the Just Culture process in an international energy company. A case study. Journal of Loss Prevention in the Process Industries, 55, 267–282. 

Does diving need a Just Culture?

The simple answer is yes. It also needs a psychologically-safe environment. In my opinion, psychological safety is needed before an event to allow latent conditions to be highlighted and challenged, whereas a Just Culture is needed after an event to allow discussions to take place around the context and how it occurred. Psychological safety supports the discussions under a Just Culture.

The diving community needs a culture that follows those same initial concepts from James Reason in 1997, the recognition that errors are normal, that the skills and experience of those involved within the current operating environment must be considered, and that only when gross negligence or sabotage are present should we look at punitive action. This means that when adverse events occur in diving and they are not subject to legal action, then the events should be used for learning. Unfortunately, the legal systems do not currently address the needs of a Just Culture because the goal is to find someone or some organisation to blame and which will facilitate damage claims. In my opinion, this poses a problem in the US where litigation is rife, particularly in diving, often for minor events. Unfortunately, in some cases, litigation is the only way to get some form of damages, or even an apology.

Diving learning from Healthcare and Wildland Firefighting?

Fortunately, it doesn’t have to be that way. Following a discussion with a colleague at Lund University, Sweden where I am currently studying for a MSc in Human Factors and System Safety, I was told that there are hundreds of hospitals in the USA who have made inroads into reducing litigation claims and increasing patient safety by undertaking Communication and Resolution Programmes (CRPs). These CRPs have reduced litigation, increased individual and organisational learning, increased patient safety, and, ultimately, have reduced insurance premiums because problems are resolved in a different manner. These programmes are based around a common understanding of human error, performance-shaping factors, and a Just Culture. Fundamentally, if you don’t understand human error, then you can’t create a Just Culture. Regarding Wildland Firefighting, I have previously written on that in InDepth.

In the sports diving sector, we don’t have a standardised, structured investigation process which is based around learning with most investigations looking at proximal causes rather than systemic ones, and often looking for blame. Even in the commercial sector, the HSE and OSHA are focused on non-compliance rather than learning opportunities. This means that building the ‘Just Culture’ questions into the learning process isn’t possible (at the moment). However, as a culture is based on the relationships and interactions between those within a team, organisation, or sector and the language they use, we can certainly start to develop one by changing the language we use to facilitate the sharing of, and learning from, near misses and incidents/accidents. Producing documentaries like ‘If Only…’ is a great way to get the concepts across by telling a story, and stories are how we learn. 

I know of one GUE community who have set up their own ‘Learning Forum’ on Facebook which allows the open, critiquing (but not critical) discussion of adverse events and near misses—a forum I support. The Human Diver: Human Factors in Diving Facebook group also supports a learning-based approach with very mature conversations taking place when adverse events are discussed.

How can you help build this culture? 

Start by being curious and limiting your judgments. While it is hard, try not to fall foul of the cognitive biases that I mentioned earlier, ask the simple question, How did it make sense for them to do what they did?”, and you might be surprised at the answers you get back. Asking “How?” moves the focus to the context; “Why?” and ‘“Who?” are all about the person which invokes a blame response. At the organisational level, asking the same questions can highlight gaps in your own processes, procedures, expectations, and leadership. If instructors are consistently breaching standards, is it because the standard is unachievable or does not add the value you think it does to the operation? Firing them without understanding why they breached the standard is an example of a failed Just Culture. It can be uncomfortable to ask this question, but asking it is essential for improvement. Plus, in this scenario, you don’t need an accident to create learning because the latent conditions are already present. All you need is a genuine curiosity and a desire to learn and improve.

Additional Resources:

Human Diver: They broke the rules! So…?

InDEPTH: Human Factors page

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Gareth Lock has been involved in high-risk work since 1989. He spent 25 years in the Royal Air Force in a variety of front-line operational, research and development, and systems engineering roles which have given him a unique perspective. In 2005, he started his dive training with GUE and is now an advanced trimix diver (Tech 2) and JJ-CCR Normoxic trimix diver. In 2016, he formed The Human Diver with the goal of bringing his operational, human factors, and systems thinking to diving safety. Since then, he has trained more than 450 people face-to-face around the globe, taught nearly 2,000 people via online programmes, sold more than 4,000 copies of his book Under Pressure: Diving Deeper with Human Factors, and produced “If Only…,” a documentary about a fatal dive told through the lens of Human Factors and A Just Culture.

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