One hot June day in Louisiana, Tyler Cestia was supposed to drop his son off at a babysitter before continuing on to work. His two-year-old boy, Thomas, asked to ride in the "big boy seat," the child safety seat his older brother usually rode in, the one right behind the driver's seat. Once he was buckled in, it was nearly impossible to see him from the driver's seat, and he didn't make a sound.

"He was pretty quiet whenever we'd ride," Tyler Cestia said. "I keep it in my mind that he was asleep."

Cestia, a manager at a welding company, had a big financial audit coming up at work that day, and he had a safety presentation to give in the morning. With Thomas silent and not visible, the stop at the babysitter just slipped his mind. The outside temperature peaked at almost 90 degrees that day. Temperatures inside of Cestia's parked GMC Sierra pickup would have been well over 100 degrees.

Thomas died strapped into his safety seat, as his small body was simply overcome by the heat.

A deadly trend

Hot car deaths like Thomas's have happened at least eight times so far this year, a deadly trend that has come surging back amid cross-country heat waves and as more busy parents return to their workplaces, according to the auto safety group KidsandCars.org. It happened to at least 36 young children last year.

People are busy, life can be confusing and even the most attentive, caring parents can temporarily forget about a child in the backseat or think they made that stop at the daycare when, in fact, they didn't make the drop-off that day.

These deaths are horrible tragedies leaving behind enormous grief compounded with feelings of guilt. But now new technologies hold the promise of putting a stop to at least a great many of them.

Several companies, including Volvo, as well as the auto parts suppliers Hyundai MOBIS, part of the Hyundai Group, and Continental, have developed radar-like systems that operate inside the vehicle to detect the presence of any living being, whether a pet or a person. Hyundai MOBIS's system is already being offered in its models in the company's home market of South Korea and could come to the US next year, the company said.

Continental's child detection technology relies on radio frequencies usually used to communicate with a smartphone as part of a "phone as a key" system, which uses radio signals and sensors.

That existing sensor system can be repurposed to detect a car's own radio signal bouncing back off objects inside the car, providing a detailed three-dimensional view of the car's interior, said David Muscat, chief engineer at Continental. If one of these things is moving, even slightly, that indicates there's something alive inside the parked car.

Volvo claims its system, which will be available next year on some Volvo and Polestar electric vehicles, can detect a living being even in the cargo area. These systems, including Continental's and the others, are so refined they can detect even the small movement of a child breathing under a blanket.

"We can use that also to detect, to have an idea, at least, of the age because babies breathe faster than adults," said Muscat.

Existing technology

Today, many vehicles already have a "rear seat reminder" system to help reduce the chances of this sort of tragedy. Rear seat reminders operate based on a simple logic. If the vehicles' back door is opened and closed before the driver gets in and starts the vehicle, then, when the vehicle is turned off, a tone sounds and a warning appears reminding the driver to check the back seat.

Cestia's truck had a rear seat reminder but, he said, he somehow didn't notice it when he got to work. At some point he may have turned down the volume of the alert sound, he said, something he didn't even know was possible. It wasn't until the afternoon that Cestia had the horrible realization that he had never seen the babysitter that day. By then it was too late.

Thomas was one of at least four children to die after being left in vehicles despite a rear seat reminder alert, said Rollins.

Direct in-car detectors, which provide greater certainty that there really is someone in the vehicle, could initiate more urgent steps than just a gentle reminder in the gauge screen, said Rollins. They could honk the horn, contact emergency services, roll down the windows or turn on the air conditioning, even if no parent is around.

About one child in four who dies in a hot car got into the vehicle on their own, she said. Beyond that, in a smaller percentage of cases, a child is left in a car on purpose, often with no intent to cause harm but because the parent expects to be away from the vehicle for just a short time. (This is just one reason that leaving a child alone in a car isn't a good idea for any amount of time.) Direct presence-detection systems could help in these cases, too, by sounding loud alerts outside the car, like a honking horn, and by even contacting emergency services if there's no immediate response.

Rollins recommends another device to help prevent these incidents from happening: a teddy bear. A stuffed animal that rides in the safety seat when it's empty can be moved to the front seat whenever the child's seat is in use. Sitting up front, the plush animal serves as a reminder that there is a child still in the back. She also plays children's music in the car whenever her child is in the backseat.

Two weeks after his son died, Cestia learned he and his wife were going to have another child. These days, he drops his daughter off at the same babysitter his son went to. He bought his daughter a child safety seat with a heat sensor on the buckle that alerts him if she's buckled in and it's getting too hot. And he also listens for the rear seat reminder and habitually checks the backseat.

"It can happen to you. It really doesn't take very long of a lapse in judgment," he said. "It's just that quick."