A Suffolk family is grieving after the death of their 5-month-old son on Friday.

According to a spokeswoman for the Portsmouth Police Department, dispatchers received a 911 call at 3:49 p.m. Friday about a child not moving or breathing at the Children’s Harbor Child Care in the 600 block of London Street.

Police and medic units were dispatched and found the baby, Jeremy Rivera, unresponsive. Citizens were attempting to resuscitate the child, but he was pronounced dead at the scene.

Detectives learned that the father of the child left his home in Suffolk about 9:30 a.m. and arrived at his place of employment in Portsmouth around 10 a.m. Around 3 p.m., the father left work and drove to Children’s Harbor, where he intended to pick up the child.

After arriving at the daycare, he got out of his vehicle and began to walk towards the building, but moments later he discovered his child in the back seat of his minivan, still strapped into his car seat.

The boy was taken to the medical examiner’s office and was scheduled for an autopsy. The cause of death has not been determined, and detectives are reviewing the case with the commonwealth’s attorney’s office in Portsmouth. No charges have yet been filed, and the father’s name is not being released.

If the death is determined to be caused by high body temperature, it would be the 12th such death of a child this year in the United States. The majority of such cases happen when a parent or caregiver forgets the child is in the back seat, according to Jan Null, who has been collecting data on similar tragedies since 2001.

Since 1998, there have been 538 hyperthermia deaths of children left in cars, Null said. More than half were children left in cars unintentionally. About 30 percent resulted from a child playing in an unattended vehicle, and about 17 percent were a child intentionally left in a vehicle by an adult.

Null, a meteorologist at San Francisco State University, became an ad hoc statistician for the phenomenon when a child died after being left in a car in the Bay area. As a meteorologist, he was asked the inevitable question of how hot it can get in a parked car.

In the experiment he performed and later published in Pediatrics, he found that the temperature inside a car typically rises 40 to 50 degrees above the outside temperature in the first hour and then plateaus. Cracking a window has no effect on the inside temperature.

This means that on a mild 80-degree day, the temperature inside a car will be 125-130 degrees in mere minutes.

“These can be deadly temperatures for an adult,” Null said. Children’s bodies are not as able to regulate their body temperature as adult’s bodies.

When a child’s body temperature reaches 107, organs begin to shut down, and “death can follow fairly quickly,” Null said.

Kate Carr, president and chief executive officer of Safe Kids Worldwide, said the death of a child forgotten in a car is tragic, but avoidable.

“This is not bad people,” she said of the families it affects. “This is educated people; people who have jobs; people who are good parents. This happens to some families that are great families, and they love and take care of their kids, and they have a tragedy, because they forgot something.”

In many cases in which the child is forgotten, Carr said, it happens when there’s a change in routine — for example, the father dropping off the children at daycare instead of the mother, or vice versa.

“Instead of going to daycare, you go to your office and you just go about your day,” she said.

In cases where the child is left intentionally, Carr said, it most often happens when the adult thinks they will “only be a minute” while running an errand.

Carr also said it can happen at just about any time, anywhere. Such deaths have been recorded in 46 of the 50 United Sates and in 11 months of the year.

“It doesn’t have to be July in a Southern state,” she said.

Carr’s organization recommends parents and caregivers remember the acronym ACT.

The A stands for avoiding heatstroke by never leaving your child alone in the car, even for a minute, and consistently locking unattended vehicle doors and trunks.

The C stands for creating reminders and habits. Some good reminders and habits are:

• When you drop off your child, call or text all other caregivers so everyone knows where the child is.
• Place a purse, briefcase, gym bag, cell phone or some other item you will need at your next stop in the back seat.
• Keep a large teddy bear in the child seat when it’s not in use. When you place the child in the car seat, put the teddy bear in the front seat.
• Ask your babysitter or daycare to call if the child does not show up when expected.
• Set an alarm on your cell phone as a reminder to drop your child off, especially if it’s a change in routine.

The final letter, T, stands for taking action if you see an unattended child in a vehicle. People should dial 911 immediately if they notice a child left in a parked vehicle, Carr said.

Lastly, Carr said, the community can support families it happens to by not being judgmental.

“It’s not our job to judge the families that this happens to,” she said. “It’s our work to try to prevent it.”