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Pool safety is not something to be taken lightly. Water recreation provides a lot of fun, exercise, and social interaction, but it also holds hazards. Pool chemicals, including chlorine and acid, are unstable substances that can be lethal when not handled properly. Chlorine is necessary to keep water clean and sanitary. There needs to be at least 1 part per million (ppm) of chlorine in pools and 3 ppm in hot tubs to maintain a safe environment. Acid serves to balance pH levels.
Just as lifeguards and flotation devices help protect swimmers, precautions and proper equipment can reduce the risk of severely dangerous chemical reactions.
In general, the chemicals used to treat pool water are added to moving water in the pool’s circulation system, which allows the chemicals to mix at an appropriately diluted concentration. Unfortunately, if the circulation system fails, the two chemicals can be exposed to one another at high concentrations, creating a substance very similar to mustard gas. Since mustard gas is two-and-a-half times heavier than air, it sits on the surface of the water, directly exposing swimmers.
On June 4, 2019, that is exactly what happened at Pleasant Grove Veterans Memorial Pool in Utah. A safety system malfunctioned, and too much chlorine and acid were released into the pool[2]. Nearly 50 individuals, including small children, were hospitalized due to prolonged exposure to the gas.
That same year, 14 children were exposed to an overdose of chlorine at the LaSalle Park public pool in Burlington, Ont[3]. Eight ambulances arrived at the scene and swimmers had to be evacuated. The pool was closed for the remainder of the day.
A similar accident occurred in San Jose, Calif., in 2018, where 35 people were sent to the hospital after inhaling chlorine gas that had settled at the top of the pool[4].
Dozens of such incidents happen in public pools across North America every year, injuring hundreds of individuals, sometimes causing long-term respiratory complications. The injuries are terrible on their own, and commercial pools can also lose income and public trust as a result.
The good news is pool-related mishaps are generally preventable. Electrical failures and operator errors are the most common causes of chemical accidents.
So, with proper training and some procedural adjustments, the risk can be considerably reduced.
In the U.S., a pool operator training course is required by law in most areas. There are two accepted courses: the Pool and Hot Tub Alliance’s (PHTA’s) Certified Pool Operator (CPO) program, and the Aquatic Facility Operator (AFO) program, sponsored by the National Recreation and Parks Association (NRPA).
In Canada, CPO certification is required by health departments in most provinces. Pool professionals can check with their local health department for specific options and regulations.
These training classes are invaluable in helping operators maintain a safe environment for swimmers. The certification ensures employees know the current regulations and guidelines, how to test and balance water chemicals, disinfection processes, facility safety procedures, how to react in an emergency, and more. Certification classes can range from a 16-hour, in-person course to home study options that might take up to six months to complete. Hybrid courses, with at-home study followed by limited, socially distanced in-person instruction, have emerged over the last year to accommodate the restrictions brought on by COVID-19.
Complex concepts such as geometry, chemistry, hydraulics, and electricity are part of pool operations and need to be explained in a way users will understand and remember. Luckily, training by a certified instructor ensures public and private pool operators are familiar with the chemicals, procedures, and potential hazards associated with operating a pool, and have been taught how to handle any malfunctions in the circulation and chemical equipment.
As aquatics technology has become increasingly sophisticated, sanitation and safety have improved. But more complex technology means local operators need increased training to learn how to safely handle each component. Anyone who has not been trained on the use of equipment, chemicals, and processes should not have access to the machinery. This is a liability as well as a safety concern—just as technicians are not expected to know cardiopulmonary resuscitation (CPR) and should not be left in charge of swimmers, lifeguards do not know the protocols for chemical safety and should not be in the vicinity of potentially dangerous equipment.
In addition to training, proper equipment plays a vital role in keeping swimmers safe. Accidents happen most often when the circulation pump fails due to mechanical or operator error. The water stops flowing, but the chemical pumps continue operating, leaving the chlorine and hydrochloric acid to mix at a high concentration and combine into a dangerous compound. Traditionally, an alarm called a flow sensor is installed in the circulation system so the operator is alerted to a malfunction. This is the primary safety system, but it is by no means perfect.
The surprisingly straightforward solution is to tie the chemical pump directly to the electrical system. This type of setup ensures that during an electrical failure, both the chemical and circulation pumps stop operating. The two systems are now both flow and electrically locked. In this way, the chlorine and hydrochloric acid never mix while the water is stagnant. A simple mechanical device can merge the electrical systems, creating the much-needed secondary safety system.
After multiple accidents in Utah, including the one mentioned earlier, the state health authority updated the health codes that require public pools to update their equipment to fit this model. Redundant systems have existed for years for automated heating, electrical, and chemistry equipment. Unfortunately, until recently, backup devices for the chemical feed system were non-existent. It took multiple tragedies and injuries to bring this issue to the forefront.
In 2018, there were around 5000 publicly owned pools and splash pads in Canada[7]. All these pools would benefit from a redundant chemical pump safety device. Other public pools not owned by the government should also consider a safety upgrade. This includes hotel pools and spas, school swimming pools, homeowners’ association pools, and any other water feature used by people.
Where the safety of bathers is concerned, the pool industry needs to be driving innovations and changes that solve problems instead of waiting on government regulations to do so. While it is not always a legal requirement, the World Health Organization (WHO) also recommends dosing pumps be designed to shut down if the circulation system fails.
Canadian law does require pool owners “take such care as in all circumstances of the case is reasonable to see that persons entering the premises, and the property brought on the premises by those persons are reasonably safe while on the premises,” according to the Occupiers’ Liability Act, Occupier’s Duty. This means pool owners can be held liable for chemical accidents that might have been reasonably prevented.
The primary safety system, the flow interlock device, works in most cases to prevent chemical incidents in public pools. But the possibility of a malfunction means every swimmer is not safe. A secondary, electrical interlock device is inexpensive and protects individuals from injuries and public facilities from liability.
In the event of a chemical accident at a public pool, a facility operator should call 911 or the local emergency number immediately. Remove anyone who has been exposed from the area. If it is safe to do so, turn off the chemical and circulation pumps. Have an emergency response plan ready that all employees are familiar with. Only allow properly trained people to work with the chlorine/pH control feed and recirculation systems. And, of course, practice regular maintenance of all chemical equipment to prevent failures.
Not only should an emergency response plan be at the ready, it is also important to periodically test equipment and staff. Natural disasters do not always give advanced warning, so in the event of an earthquake, tornado, flood, fire, or routine power outage, it is crucial to know the equipment will shut down as it should.
All public pool operators should explore the nominal cost and time it takes to install a secondary chemical dosing safety device. Just as other sensitive systems need redundancy, chemical pumps should be carefully monitored and regulated using more than one process. What may be a short-term expense or inconvenience could, in fact, protect the lives and ensure the safety of bathers at an aquatic facility.
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