Many people won’t realise that e-cigarettes are powered by lithium-ion batteries … and that’s the reason they sometimes catch fire.

This happened recently on board a passenger plane which had just landed at Chicago’s O’Hare International Airport.

A spokesman for the airline company said the small fire was put out by flight attendants who are trained to fight high-energy battery fires and none of the 138 passengers and six crew on board were hurt.

The airline confirmed the fire had been caused by the batteries going into what is known as thermal runaway.

This happens when one cell in a battery overheats it can produce enough heat – up to 900°C (1652°F) – to cause adjacent cells to overheat too.

The Federal Aviation Administration (FAA) in the USA has reported 225 battery incidents happening in cargo or baggage since 1991 and many of these involved lithium batteries. Ominously, of those, 46 were reported in 2017.

A spokesman for the airline said: "Shortly after landing in Chicago from Las Vegas a passenger’s e-cigarette experienced what is called a thermal runaway event which resulted in a small fire on board. 

“Our flight attendants quickly extinguished the fire and the plane taxied to the gate. We are thankful for our flight attendants who quickly put their training to use to keep our passengers safe."  

* One way to tackle such incidents is to use an AvSax fire containment bag which can deal with fires in personal electronic devices and are now carried on aircraft operated by 65 airline companies across the world – including some of the biggest and best-known.

AvSax  – which won the Queen’s Award for Enterprise in 2018 - has been used 28 times to deal with emergencies since the start of 2017.

More than 13,000 AvSax are now carried on aircraft worldwide. Deployment is so effective that extremely expensive diversions to alternate airports are avoided.