(CNN) The bipartisan infrastructure bill that passed the US Senate this week would require new motor vehicles to have an alert system that would remind people not to leave their child or pet in the backseat.
The rule, under the Child Safety section of the bill, is an attempt to cut down on every parent's nightmare: hot car deaths, or when a child dies of heatstroke after being left in a vehicle on a hot day.
However, some politicians and prominent advocacy groups on the topic say the new rule doesn't go far enough to prevent such deaths. While the infrastructure bill requires cars to have an alert system, it doesn't require them to have a "detect and alert" system that can tell the difference between a child and, say, a dry-cleaned shirt.
"It is a technology that quite frankly will be completely inadequate at addressing the issue," said Amber Rollins, the director of Kids and Car Safety, a nonprofit organization dedicated to its namesake issue.
US Sen. Richard Blumenthal, Democrat of Connecticut, unsuccessfully pushed to add a rule requiring "detect and alert" systems to prevent hot car deaths, his office said. In a statement, Blumenthal said the legislation "make(s) important strides to address tragic hot car deaths."
The infrastructure bill will now go to the House for a vote before it can head to President Joe Biden's desk.
On average, about 38 children under 15 years old die every year from vehicular heatstroke, according to data collected by No Heat Stroke, a website run by San Jose State University lecturer Jan Null that tracks hot car deaths. No Heat Stroke has counted 896 hot car deaths since 1998.
In general, children are more vulnerable to heatstroke, and temperatures can rise rapidly inside a car on a warm day, according to the National Highway Traffic Safety Administration. Hot car deaths, both total and per capita, are most common across the South and the Sun Belt.
So far this year, 13 children have died in hot cars, including a 5-year-old child in Springfield, Virginia, on Tuesday. In that case, a parent drove the child and several siblings to a spot, but left behind the 5-year-old for up to several hours, authorities said.
"Officers responded here for what was reported as a 'tragic accident,' and at this point, I don't have any reason to doubt that," Fairfax County Police Department Lt. John Lieb said.
Indeed, the slight majority of hot car deaths -- 53% -- occur when a child is forgotten by a caregiver, No Heat Stroke has found. About 26% of deaths are children who gained access to a car on their own, and another 20% are children knowingly left in a car by a caregiver.
Alert system v. detect and alert system
The Senate bill states that no later than two years after the bill is passed, the Secretary of Transportation must issue a final rule requiring vehicles to have a system that alerts the operator to check the backseat after the engine turns off. This alert would be an audio and visual alert and may be combined with a buzz.
The way this technology would work is that the alert would go off in a situation in which the car's rear door is opened, the car travels somewhere and then parks. The idea is that the rear door may have been opened to put a child inside, so that alert would be a reminder to check the back when the car stops.
But Rollins, of Kids and Car Safety, noted a number of flaws with this "door logic" system. Most significantly, it can only tell whether a back door was opened, but it cannot tell the difference between a bag of groceries or a living, breathing human. This means that drivers will get a ton of false alarms and may start to tune out the alert.
Further, the alert system does not address instances in which a child gets into a car on their own or when a caregiver knowingly leaves a child in the car. These combine to account for just under half of all hot car deaths.
Instead, Kids and Car Safety and other groups have proposed a "detect and alert" system that would be able to detect a child by motion detection, radar, or another such method. The components for such a system would cost about $10 per car, they estimate.
"The bottom line is the cost is minimal and children's lives are priceless," Rollins said.
Rep. Tim Ryan, Democrat of Ohio, has introduced the Hot Cars Act in the House that would require such a detect and alert system. He said he was disappointed the Senate infrastructure bill does not include such language.
"While I support the overall bipartisan Senate infrastructure bill, I was disappointed that it does not include stronger requirements to prevent hot car deaths through a robust detection and alert system," he said in a statement to CNN.
Ryan continued: "We have the technology to ensure that these deaths do not continue to happen. Our cars can already ensure drivers do not leave their keys in the car, their lights on, or their trunk open -- none of which are life threatening. It is not unusual for the government to mandate safety features to protect lives. Cars are mandated to have seat belts, interior trunk-releases, and rear backup cameras. It is long past time that we ensure that this inexpensive technology is in every car on the road to help save the lives of children nationwide."
Advocates for Highway and Auto Safety, another advocacy group, similarly criticized this aspect of the infrastructure bill.
"The Senate bill provision accommodates the auto industry's completely insufficient response to address this well-known problem," the organization said in a statement.
"It's vital that the House provision prevail because it requires technology that can both 'detect' the presence of a small child and 'alert' the driver and others. For over two decades the auto industry has offered promises instead of comprehensive remedies to prevent children from these torturous heatstroke deaths and injuries."
CNN's Raja Razek contributed to this report.