High summer temperatures can cause lithium ion batteries to explode.

Experts say that even the heat of your body can put the battery at an unsafe temperature.

But they can be even riskier if they are left in a hot car.

Lithium batteries are used to power everything from watches, cameras, phones, laptops and tablets through to children’s toys.

Burn experts now recommend carrying items powered by lithium batteries in a purse or bag and not in your pocket because if they do explode they can cause serious harm.

Sarah Fischer, the burn programme director at Via Christi St. Francis Hospital in Wichita, Kansas, said: "You can get a flame injury which can be devastating, but you add a chemical injury on top of it and it can be even worse.”

Unapproved USB chargers, like the ones you use to charge your phone, can also cause the battery to overheat.

And this graphic photo (left) shows a laptop exploding and catching fire.

There has been a huge rise in fire incidents involving lithium-ion batteries on board aircraft this year.

It is one of the few rising risks in aviation which is often regarded as the safest way to travel but such fires are now happening once every 10 or 11 days on a flight somewhere in the USA alone.

So far this year the Federal Aviation Administration in the USA has reported at least 18 incidents involving lithium-ion batteries on airplanes and in airports compared to 31 incidents in the whole of 2016. That compares with 16 incidents in 2015, nine in 2014, and eight in 2013. 

The batteries are used to power all modern devices ranging from mobile phones to laptops.

This has led to major airlines turning to new anti-fire devices such as AvSax which are carried on all Delta planes and one is seen in action (left).

The AvSax is a special fire-retardant bag used when lithium-ion batteries catch fire and has been deployed on planes several times already this year

Simply pour at least two litres of water into an AvSax and then drop the burning device into the bag. The water activates the polymer gel inside the bag causing it to expand around the device. Should the device keep on venting then the AvSax is tough enough to absorb the force.