A release of toxic bromine gas into the air in an industrial area of Burnaby sent four workers to hospital and forced the evacuation of 80 others.
The Burnaby Fire Department says in a statement that they responded to a report of an airborne chemical in the 8,000-block of Wiggins Street late Thursday.
A statement from the department says they used portable air monitoring systems to detect the noxious gas and find its origin.
It says four workers in a nearby business who were experiencing symptoms of exposure, including nose, throat and lung irritation, were treated with oxygen on site and then taken to hospital.
All four are in stable condition and the department says the evacuation of other people was temporary while crews determined it was safe to return.
It says Burnaby fire crews monitored the plume and ventilated all affected buildings, and while the statement didn't identify the origin of the gas release, it says there's no ongoing risk to exposure of the chemical.
