A fire at a polychlorinated biphenyls (PCBs) reclamation plant in Cornwall, Ontario, was sparked by an exploding light bulb, officials say.
Fire investigators say the high pressure bulb at the Aevitas plant exploded on February 24, 2014, igniting cable paper wrap.
Fire officials said the amount of PCBs in the area of the fire was extremely low and there was no risk to public safety.
Several nearby streets were closed for a few hours as a precaution.
One employee was treated by paramedics at the scene for smoke inhalation.