The smoke over the Port of Montreal has dissipated, but the fire in a container filled with 15,000 kilograms of lithium batteries prompted firefighters to issue a warning about how common these incidents have become.

With the increasing use of electronic gadgets, e-bikes and electric vehicles, safely handling and transporting batteries is crucial to fire prevention, they warned.

On Monday night, an evacuation order was issued for nearly 100 people living closest to the fire-stricken area, and a shelter-in-place notice went out to hundreds more who were told to close their windows and doors and shut off ventilation systems. The neighbourhood was also plunged into darkness, with traffic lights down while firefighters cooled the container to control the fire.

"Lithium battery fires are always hard to fight because they are capable of producing their own energy," says division chief of the Montreal Fire Department Martin Guilbault. "When they heat up, they heat up the next battery and start a fire that is a chain reaction process. When you have a fire like that, the only thing you can do is to put water on it to cool down the batteries."

That process is called thermal runaway, and for those in the Hochelaga-Maisonneuve neighbourhood of Montreal near the port, this meant hours of smoke.

"It smelled like toxic gas, says Maude Bugolt. "It was very intense. The smell was everywhere."

Earlier this year, fire safety associations warned battery fires are a growing threat. In Toronto, there were 55 in 2023, a 90 per cent increase from the previous year. There have also been striking images of battery fires from plants in South Korea, and of a dog chewing on a battery pack, igniting a blaze, and burning down a home in Tulsa, Oklahoma.

McGill professor George Demopoulos says batteries are inherently unstable, and that this property allows them to be used as an energy source, but nowadays, they are generally safe.

The problem with lithium-ion batteries is their volume. They are ubiquitous, and an increasing number of manufacturers are now getting into the electric field.

"Batteries today are safe," says the expert in materials engineering, who is also associate director of the McGill Centre for Innovation in Energy Storage and Conversion. "But because everybody is excited, there are so many manufacturers and so many players in the market. Quality control is crucial because the devices are delicate. If we go for the cheapest devices, we could compromise safety."

He also says new types of safer batteries are under development.

Demopoulos says he doesn't know the details of what was in the container at the Port of Montreal but says those trying to determine why the fire broke out will look at several aspects of handling. For instance, he says, it might be important to look at how long the container was in the port and whether it was exposed to high heat.

For the upcoming fire prevention week in early October, Montreal's fire department is focusing on battery fires.

"Lithium batteries are a relatively new risk for us," says Guilbault. "The main reason for fires is that people are not using the right batteries that go in your device. You should not buy another cheaper battery or charger, because you may save a couple of dollars, but you are increasing the risk."

He also says there are several other precautions people should take, like avoiding parking e-bikes by the door of your house. If the battery sparks a fire, you may be unable to escape. Overall, Guilbault says to pay attention to potential risks.