(CBS NEWS) -- A newly-proposed bill would require cars to be equipped with sensors, alerting drivers once the car is turned off that a child is in the back seat.

Some argue the technology might not find its way to the parents who need it most but advocates say the law is needed because the stakes are so high, reports CBS News correspondent Kris Van Cleave.

Miles and Carol Harrison always wanted a child and were overjoyed when they adopted Chase. But on a busy 90-degree day in 2008, Miles forgot to drop the 21-month-old off at day care, leaving him in the back seat of his car while he went to work.

"I have not forgiven myself," Miles said. "And it's heartbreaking because I did it, I killed my son."

"Nobody thinks it will happen to them, until it happens," Carol said.

Chase's death was one of more than 700 heatstroke fatalities of children left in cars since 1998 – an average of 37 per year. The first seven months of this year have been the worst in terms of heat-related child car deaths since 2010. These tragedies can happen quickly. When it's about 90 degrees outside, the temperature inside a car will rise above 130 degrees in less than an hour.

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