An ammonia leak is being blamed for the deaths of three people at an arena in Fernie, B.C. — but the City of Vancouver says it still believes ammonia is the safest option for cooling its rinks.

Donnie Rosa, the director of recreation with the Vancouver Park Board, says all eight of the city's rinks use ammonia refrigeration systems, and the city is confident in their safety.

"My folks know these plants inside and out," Rosa said. "We've always been very hyper aware of the training around ammonia and dealing with ammonia."

No perfectly safe refrigerant

Critics such as Lou Roussinos, a former chief inspector with the province, have raised concerns about ammonia-refrigerated rinks due to the acute toxicity of the chemical.

Rosa acknowledges that ammonia is not without its risks. But she says the city's engineering staff have concluded that it's the best of the available options.

"You can smell it at well below hazardous levels, so it tends to alert occupants before there's truly a hazard level," Rosa said. "[And] it's lighter than air, so you can disperse it. You can get rid of it."

The two other main options are carbon dioxide and halocarbons, such as freon, but they present safety concerns of their own.

"They are asphyxiants. They're heavier than air. They're odourless and they're invisible," Rosa said. "Anything else that we've looked into is a greater safety concern than ammonia."

Halocarbons have also fallen out of favour in recent years, in part, because they are potent greenhouse gases.

Montreal reached same conclusion

The City of Montreal also recently concluded that ammonia was the safest option for its ice rinks.

Jean-Paul Lacoursière, a chemical engineer and consultant in Montreal, says modern ammonia refrigeration systems use as little as one sixteenth as much ammonia as older, outdated systems.

Lacoursière reiterated Rosa's concerns with ammonia alternatives and said the solution is, instead, to ensure that all ammonia-based systems are up-to-date, properly designed and regularly inspected, and that staff are adequately trained in emergency measures.

With files from CBC Radio One's On the Coast and The Early Edition.