'Look before you lock': why leaving your child in the car in warm weather can be fatal

Even on mild days, a child left in the car could be in danger in minutes
Hannah FoxPrincipal researcher & writer

Principal researcher/writer at Which? delivering award-winning health, baby and safety investigations, including our annual sunscreen tests.

Close-up of a baby sleeping peacefully while buckled into a red and black car seat near a bright window.
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While many parents think they would never leave their baby or child in the car, many end up doing just that, often because they're rushed, distracted or sleep-deprived.

It's why ANEC (a non-profit association that defends consumer interests in the creation of European technical standards) is campaigning for parents to 'look before you lock' - that is, to check the back seat of their car to make sure they're not leaving a child unattended, either intentionally or unintentionally.

Find out why this happens, what the dangers are and how to avoid them.

How does it happen?

An infant sleeping with a pacifier in a teal and black car seat, bathed in warm sunlight.

Left behind in the car unknowingly

An over-tired or distracted parent who's rushing around with errands can experience a memory lapse and forget to take their child out of the car to drop off at nursery or take back into the house. 

Known as 'Forgotten baby syndrome', it can have a number of causes, including a change in routine, severe sleep deprivation, stress, a quiet or sleeping child, distractions during the drive, and false memory creation, where they think they did drop their child off.

Left intentionally for a 'quick errand'

While it may seem like a hassle to unstrap a child or wake a sleeping baby to get them out of their car seat, leaving them in the car so you can pop into the shops is still very dangerous and should be avoided, even if it's only for a short time (see 'Why is it dangerous?' below).

A man in a suit kneels outdoors near a car trunk beside a infant car carrier, with a toddler standing nearby and a dog in the background.

Trapped after entering an unlocked car

A child may remember they've left a favourite toy in the car, or like to sit on the front seat and pretend to drive, so they will try to get into an unlocked car.

The danger here is that some cars may automatically lock their door behind them (and many cars have child locks activated on the rear doors), so they can't get out. Plus, it's not always easy to see if a child is in the car if they're small and crouched in the footwell.


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Why is it dangerous?

A woman stands outside an open car door, carefully adjusting the harness straps on a young girl sitting in a pink-patterned car seat.

Since 1998, there have been more than 1,400 fatalities worldwide linked to children being left in vehicles, according to data collected by Kids And Cars Safety. Most victims are under five years old.

Even with outside temperatures below 20°C, or the window left slightly open, the temperature inside a car can reach life-threatening levels within minutes. 

In fact, 80% of the increase in heat happens within 10 minutes of the car being left, and risks increase even more quickly when cars are parked in the sun, even on a mild day.

Heatstroke

Children are much less able than adults to regulate their body temperature, and a child's body can overheat 3-5 times faster than an adult's. This can put them at high risk of heatstroke, especially if left in a car.

Symptoms of heatstroke in children include:

  • High fever
  • Skin changes - the child may look hot, flushed or red, and their skin will feel dry to the touch rather than sweaty
  • Extreme lethargy
  • Limpness
  • Confusion or irritability
  • Rapid heartbeat and fast breathing
  • Vomiting, seizures or a loss of consciousness.

How to keep your baby or child safe

An infant wearing a white headband lies in a rear-facing safety seat in the back of a car while a man drives.

Look before you lock

Children in rear-facing seats are harder to spot, especially if they're asleep or silent, so always check the back seat.

A change bag or favourite toy on the front seat can act as a visual clue that the child is with you.

To be extra safe, you could place an item that's vital to you - a wallet, work pass, handbag or even a shoe - on the back seat to ensure you have to open the rear door to retrieve it.

A man packs a backpack into an open car trunk while a woman nearby holds a young child carrying stuffed animals outdoors.

Communicate

If you're travelling with a partner or family member, announce and confirm who is getting the child or children out of the car, as miscommunication and confusion could mean neither of you removes them.

Make use of at-car or drive-through services

Things such as coffee stops can be done via the drive-through, while many petrol stations let you pay at the pump if you're getting fuel. Using these services reduces your risk of leaving your baby or child alone in the vehicle.

A happy toddler with bright blue eyes smiling and clapping their hands while strapped into a car seat.

Keep your vehicle locked when it's not in use

Make sure that children won't climb into your car by keeping it locked.

Keep keys well out of reach, as many kids are intrigued by keys and buttons, and may be savvy enough to know how to use electronic car keys to unlock them.

Use built-in or extra detection systems

Some models of cars have built-in systems that will alert you if they detect anyone in the back seat when the car is locked.

Some of the car brands that offer this include Hyundai, Toyota and Tesla, as well as some Nissan models. Some systems are more sophisticated than others, so you may need to do some research to find the one that's right for you.

You can also buy clip-on sensors that attach to the harness of a child car seat to warn parents via their phone if they've left the child in the car, such as the Cybex SensorSafe.


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If you see a child alone in a car

Call emergency services and follow their instructions.

A woman with blonde hair and sunglasses drives a vehicle while a baby sits in a red car seat in the back.

What is ANEC calling for?

ANEC is calling for urgent action, including regulation to ensure consistent safety measures worldwide. It wants any technological solutions for this problem to have clear performance requirements. 

It would like to see an increase in the number of cars that have sensors that detect the presence of children. It also wants rules to be developed to cover both passenger cars and school buses.

ANEC's concerns are shared by The Royal Society for the Prevention of Accidents (RoSPA). Its road safety manager, Caitlin Taylor, says: 'Never leave a child alone in a car, even for a few minutes. 

'On a warm day, the inside of a parked car can reach dangerous temperatures within minutes, and because a child's body heats up far faster than an adult's, heatstroke can set in very quickly - opening a window or parking in the shade barely helps. 

'And it doesn't take a heatwave - cars can become dangerous on mild days too. Anyone who sees a child left alone in a car should call 999.'


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