A Safety Turtle sensor is strapped to the lifeguard's rescue tube. In the event of an emergency, the alarm will sound the moment the lifeguard immerses the tube in the water, immediately notifying all staff. (Image courtesy Terrapin Communications Inc.) The video is chilling: in an underwater scene a young woman plunges into the deep end of a swimming pool. She breaches the surface, then sinks to the bottom.

Other swimmers enjoy themselves above - they don't see her. For 10 seconds she lies still on the bottom. Moments later, a figure dives into the pool, scoops up the victim and brings her to the surface.

The scene is from one of Poseidon's underwater cameras. Developed in France and first sold in 2000 by MG International-Poséidon, Poseidon is an anti-drowning detection system that analyzes video streams in real time and alerts lifeguards to people in trouble in the pool.

The Canadian Red Cross says recreational swimming is the second-leading activity that leads to drowning in Canada. Most drowning victims are young males and those who swim alone.

A death from drowning is a tragedy, but when it occurs in a pool supervised by lifeguards, the question often asked is: how could this happen?

Drowning can be silent and quick. A swimmer in trouble can enter what lifeguards call a "drowning spiral" within seconds. Once caught in that spiral, the victim becomes immobile, cannot call out and loses consciousness in as little as 12 seconds.

When lifeguards are able to intervene and begin resuscitation within 30 seconds, the victim stands a good chance of recovery. As the amount of time involved in a rescue goes up, the chances of a successful resuscitation fall.

"The National Drowning Prevention Alliance in the U.S. has brought together a lot of research into lifeguarding and the environmental factors that affect lifeguard effectiveness," says Dr. Bob Lyons, an Ottawa engineer who has developed a different kind of pool alarm system called Safety Turtle. "Lifeguarding is not an easy job."

Jim Lombard, CEO of the YMCA Metropolitan Birmingham in Alabama, agrees. Two of his pools use Poseidon. "Real-life conditions can make the lifeguard's job all but impossible."

Lifeguards must deal with pools crowded with bathers, light glare and choppy water surfaces. They also have the challenges of differentiating a swimmer's normal playing behaviour from surface distress, and seeing the bottom of the pool during high-use periods.

How Poseidon works

The Poseidon system gives the lifeguard underwater "eyes." It's made up of overhead and/or underwater cameras, a central computer, an LED display panel and a waterproof touch-screen. The cameras' analog video feeds are converted to a digital signal by a device called a frame grabber - made by Montreal-based Matrox Imaging - so they can be analyzed by Poseidon's software.

The software algorithms analyze a floating object's volume and texture to determine if it is a person or just an object in the pool. Once an individual is identified, Poseidon searches for unusual behaviour by comparing the swimmer's position over consecutive images. When the software detects a motionless presence at the bottom of the pool for 10 seconds, an alarm and siren are activated.

The monitors immediately show the location of the victim, allowing the lifeguards to bring him or her out of the water quickly and start resuscitation.

Safety Turtle

The Safety Turtle takes a different approach to preventing drowning. Designed primarily to safeguard children, particularly around household pools, it's a personal device that triggers an alarm when immersed in water.

At a starting price of $270, a Safety Turtle system includes a base station and a wristband equipped with a sensor inside a plastic, turtle-shaped housing. When the sensor is immersed in water it sends a radio signal to the base station, which sounds the alarm.

Lyons himself had a personal near-drowning experience, which led him to develop the device. "There is no question that parents must supervise their children and teenagers at all times," he says.

He also cites a U.S. Consumer Product Safety Commission study that found that, when it comes to drowning prevention for children, "supervision can and does fail."

Many YMCA pools in the U.S. have adopted Safety Turtle as a communications tool for lifeguards, too. The sensors are attached to the guard's rescue tube, a flotation device that the guard must take when entering the water. By automatically signalling a water rescue, staff elsewhere in the facility immediately know the lifeguard needs assistance.

The system can be configured to call emergency services automatically, but YMCA operations prefer to do this manually after second-responder assessment, explains Lyons.

Does technology make us less vigilant?

While Poseidon, Safety Turtle and other safety systems are accepted and used in the U.S. and overseas, very few are used in Canada.

Michael Shane, safety management director at the Ontario chapter of the Lifesaving Society, says he isn't aware of any pools in Canada that use such technologies, but he acknowledges "we should evaluate new technologies to be sure they can offer lifeguards additional information."

Lyons adds that some aquatic safety organizations "believe that technology [used for aquatic safety] will encourage complacency. The lifeguard's job is to act in emergency situations. The technology gives them an additional layer of defence."

Lombard agrees. Even with Poseidon installed, the lifeguards watch the pool - not the monitors. But he says his lifeguards appreciate the extra support that Poseidon brings.

"It even makes [them] more vigilant, because they don't want the system to 'beat them.' Poseidon actually gives them a confidence boost, which helps them do their jobs," he says.

Lombard adds that the pool users feel safer as well, and as a result his organization will spend more than $1 million to install Poseidon in all of its 16 pools over the next few years.In the Poseidon system, overhead and underwater cameras send video feeds to a central computer where they are processed and analyzed with sophisticated software algorithms. (Image courtesy Poseidon Technologies Inc.)