Sarnia Fire Rescue Services said a man suffered burns to his leg and hand on Saturday when vape pen batteries exploded.
Public Education Officer Mike Otis said the individual was at home when, without warning, vape pen batteries exploded in the pocket of their shorts, burning through the shorts, underwear and into their skin.
The person was taken to Bluewater Health for treatment.
Otis said it's believed the explosion was the result of a reaction between the batteries and keys in the person's pocket.
He said incidents like this have happened in many places.
"Loose vape pen batteries, or e-cigarette batteries, are dangerous to just be loose in your pocket," said Otis. "If they come in contact with other metals such as loose change, car keys, etcetera, they can actually cause an explosion."
Otis said many batteries have the potential to ignite.
He recommended not leaving loose batteries in your pocket, and putting tape over the top of batteries when they're being stored away.
Sarnia firefighters responding to the incident encountered a pungent haze in the home.
The batteries had burned through a rug and carpet under-padding.
Air quality testing was done to ensure there were no dangerous chemicals in the air.
For more information on battery safety, click here.