Dr. Anthony Crocco’s message is simple: don’t leave your children in a hot car.

To bring that message home, the chief of pediatric emergency at McMaster Children’s Hospital in Hamilton, Ont. gave a firsthand demonstration Wednesday to show just how dangerous a hot car can be.

“This isn't something that we see parents doing on purpose -- its usually just an oversight,” Dr. Crocco told CTV Toronto from the scene. But, he said, a “few minutes can actually be quite devastating for that child.”

Dr. Crocco’s ‘Hot Car Challenge,’ which saw the physician swelter in the backseat of a car, was livestreamed on his hospital’s Facebook page with a ‘do not try this at home’ disclaimer. Paramedics were close at hand, watching a heart monitor Dr. Crocco was connected to and making sure that the doctor had enough oxygen.

“Well, temperature's 40,” Dr. Crocco reported soon after entering the vehicle, which was parked outside the hospital. “In other circumstances, if I was on a beach, this would be wonderful -- I'd be in the shade and it would be great, but I'm starting to feel uncomfortable and feeling like I'm sweating.”

Five minutes in, Dr. Crocco was becoming increasingly uncomfortable.

“His breathing rate increased just slightly,” local paramedic Michelle Greenspoon observed. “His heart rate increased just slightly, so those are signs that his body is compensating.”

Before entering the vehicle, Dr. Crocco explained that extreme temperatures can heat up a car in a very short time. Kids, he said, will quickly start sweating. If they stay in the car much longer, things become incredibly dangerous.

“And then you actually stop sweating, and when you stop sweating your body no longer can control the heat and your heat starts to rise,” Dr. Crocco said.

That can create a risk of heat stroke, seizures -- and even death.

Last year in the United States, there were 37 hot car deaths. While Canada doesn’t keep official statistics on hot car deaths, Hamilton paramedics responded to two incidents alone.

“They’re helpless,” Greenspoon said as Dr. Crocco sweated. “So I think there's a lot of, there's an emotional connection to that which I think is the hardest part about it.”

With the temperature hovering around 40 degrees Celsius in Hamilton on Wednesday, Dr. Crocco lasted about 15 minutes before he decided that he had had enough.

Covered in sweat on a stretcher and clutching a water bottle, Dr. Crocco said if he is affected by this heat on an overcast day, imagine how much worse the experience could be for a child.

“Very, very quickly these children’s temperatures are going to rise to a very dangerous level,” he told reporters. “So the message is don't let that happen.”

With a report from CTV Toronto’s Sean Leathong