Dallas ? It’s a scenario that’s almost too hard to believe: A parent or day-care worker, busy with the distractions of modern life, leaves a helpless child in a vehicle with the windows sealed shut.

Already this year, at least 36 children in the United States have died after being left in a car or truck.

Wednesday, outdoor temperatures were about 100 degrees when 8-month-old Jordan Thomas of Dallas was forgotten inside a day-care center’s sport-utility vehicle. Inside, temperatures soared to a blistering 130 to 140 degrees.

Little Jordan never had a chance.

There are the inevitable questions, like how someone could simply overlook a child. Experts and advocacy groups admit it’s often just carelessness or a simple oversight. But experts said a few, simple precautions could drastically reduce the number of such tragedies.

“The screaming message here is that for any period of time you don’t leave a child unattended in a car,” said Jan Null, an adjunct professor of meteorology at San Francisco State University who is tracking the child deaths.

Null said interior temperatures can soar to 105 in less than a half hour on a 72-degree day. Cracking the windows only slows the heat from building up like a greenhouse.

Janette Fennell, founder and president of the advocacy group Kids And Cars in Kansas City, Kan., said most cases of heat deaths involved either new parents or those who have recently changed their driving routine. Fewer than 2 percent of such deaths are considered negligent.

“The lion’s share are loving, caring, devoted parents. We’re talking educated people who love and adore their kids,” Fennell said. “It says a little bit about the society we live in today. We’re rushed, we’re hurried; one little change can mean the difference between life and death.”

Fennell said placing items, like a bag of diapers in the front seat or a purse or briefcase in the back with the child, can be a valuable reminder.

“Put something that you have to have today in the back seat, where it’s going to force to you check the back seat. Eventually, it becomes a habit,” she said.

According to the Web site operated by Fennell’s group, just eight states — California, Connecticut, Florida, Illinois, Maryland, Pennsylvania, Texas and Washington — make it illegal to leave a child alone in a vehicle.

Kansas is among 10 other states considering similar legislation.