The Ontario Recreation Facilities Association (ORFA) is reminding arena owners and operators about the dangers of ammonia, after an ammonia leak at a British Columbia arena killed three workers.

Ammonia is a colourless gas used in mechanical refrigeration systems, including those in ice rinks. It is toxic if inhaled.

Terry Piche, the technical director with ORFA, said that about 50 per cent of arenas across Canada still use liquid ammonia as part of their refrigeration process and that a malfunction in an arena can cause a leak.

"There are a series of pipes, safety valves and infrastructure that's in place. So it would seem that something failed catastrophically to end up where we are here," he said in regards to the B.C. deaths.

He added that about 80 per cent of the 750 ice arenas, 250 curling rinks and 1,000 "ice sheets" used by people in Ontario still use ammonia.

Ammonia refrigeration system

Ammonia refrigeration systems are used in 80 per cent of Ontario rinks, expert says. (Adrian Cheung/CBC)

Not simple to replace ammonia

"It's not just take one liquid out and put another liquid in," said Piche when asked why not just stop using ammonia.

"Ammonia is a fairly safe chemical to use if it's used as prescribed."

Piche said that it's critical people listen to staff when arena alarms go off.

"There is an immediate assumption by the general public that it's a false alarm and unless they see smoke or fire, nobody moves," he said.

"When you hear the alarm go off, listen to staff, don't argue with them and evacuate the building."