Why are so many American children dying alone in cars?

Researcher has answer for why 38 a year on average die like this.

There are many similarities between Arizona and the UAE.

Both are desert states with similar populations - about seven million for Arizona and just over eight million for the UAE. And in the summer, temperatures regularly hit the mid-40s in both locations.

But in one respect they differ. Figures show that in the past two decades at least 23 children have died in Arizona after being left in hot cars.

That figure is many times higher than the UAE, where such tragedies still make headline news.

When it comes to the US as a whole, child deaths from hyperthermia, to use the scientific term, begin to look like an epidemic. Since 1998, more than 500 children have lost their lives in such incidents.

Jan Mull, a meteorologist at San Francisco State University, has devoted much of his time to collecting the statistics on children in cars and hyperthermia.

His research reveals that last year 33 children died in overheated cars and that the toll for this year already stands at 10. The worst year was 2010, when 49 died. On average, the annual death toll is 38 children.

Mr Null's research also reveals that nearly half of all fatalities occurred in children aged one year or younger.

While most deaths, of course, occur in states with high summer temperatures - Texas, Florida and California top the list - some children died with an outside temperature in the low 20s.

Of the children who lost their lives, just over half were being looked after by caregivers. Parents were responsible in less than a fifth of all cases.

Behind those figures are parents who will haunted by guilt for the rest of their lives. In one case, a father tried to grab a gun from an attending police office to end his own life.

Whether the law in the US steps in to administer further punishment, though, is a lottery.

By the end of last year, only 19 out of 50 US states had passed laws making it an offence to leave a child unattended in a vehicle. Arizona was not one of them.

Research by the Associate Press in 2007 found that when punishment was handed down by the courts, about half of those found guilty went to prison.

Parents received harsher sentences than caregivers - typically about four years - with the stiffest jail terms given to mothers.

One of the most controversial cases involved Miles Harrison, from Washington DC, who left his adopted son Chase, 21 months, strapped in back seat of his car for nine hours after forgetting to drop him off at day care.

After a high-profile case in 2009, Mr Harrison was acquitted on charges of involuntary manslaughter on the grounds that while he was "plainly negligent", prosecutors had not proved he had shown "callous disregard for human life".

But individual cases do not fully explain why 537 American children have died in unattended vehicles since 1998. Mr Mull thinks his research provides a possible answer.

Before the introduction of front-seat airbags in the early 1990s, children were often placed in the front seat of cars.

Since legislation required children to sit in the back of cars, the number of fatalities from hyperthermia have increased ten-fold in the US.

Parents, it is thought, may simply forget that their children are still in the car.