Cryogenics experts 'at a loss' to explain Leduc gas accident deaths

Experts in the cryogenic industry say they are waiting for answers from an Occupational Health and Safety investigation into the deaths of three men last week in an industrial accident.

The workers — aged 31, 34 and 52 — were killed Nov. 15 at Millennium Cryogenic Technologies, an oilfield supply company in the Leduc Business Park.

Leduc Mayor Bob Young said the men were killed in a "gas accident."

OHS is leading the investigation and to determine what happened.

Fatalities involving liquid nitrogen, the key component used in cryogenic processes, are rare, said Glenn Johnston, president of the National Cryogenics Corporation, which operates out of Edmonton and Texas.

"We've been in the industry since 2007. And these are the only fatalities we've heard of, "Johnston said in an interview Tuesday with CBC Radio's Edmonton AM.

In a lab or workplace setting, cryogenics uses liquid nitrogen to freeze a space or a piece of equipment.

In Alberta, the technology is often used to treat mechanical gears or tools used in the oilfield industry to make them more durable.

It's extremely unlikely the men would have been killed by nitrogen exposure, said Johnston.

If they did die from exposure, it would likely have been due to inert gas asphyxiation, he said.

'We can't believe it'

High levels of nitrogen would only occur in a room where there is little or no ventilation, he said.

"It displaces the oxygen, and in a closed space is where we could get into a problem," Johnston said.

"We can't believe it. But one possibility out in Leduc is unfortunately that maybe it displaced the air, they got kind of tired and kind of just laid down and suffocated."

According to information on its website, Millennium Cryogenic Technologies cleans and treats oilfield equipment to improve its durability.

The company website said the method used was developed by owner Russell McKay, who founded the company in 2001.

Nitrogen is an invisible, tasteless and odourless gas that comprises about 78 per cent of the air we breathe.

A silent killer

According to the Canadian Centre for Occupational Health and Safety, when cryogenic liquids release gas, that gas is very cold and usually heavier than air.

The cold, heavy gas does not disperse well and can accumulate near the floor. Even if the gas is non-toxic, it displaces air.

It can be a silent killer in confined spaces.

"When there is not enough air or oxygen, asphyxiation and death can occur," the centre said on its website. "Oxygen deficiency is a serious hazard in enclosed or confined spaces."

According to the U.S. Chemical Safety and Hazard Investigation Board, "breathing an oxygen deficient atmosphere can have serious and immediate effects, including unconsciousness after only one or two breaths.

"The exposed person has no warning and cannot sense that the oxygen level is too low."

There have been numerous well-documented deaths involving nitrogen asphyxiation.

During a pool party in Mexico in 2013, eight people passed out and a 21-year-old man fell into a coma after liquid nitrogen was poured into the pool.

On Nov. 5, 2005, two contractors working at Valero Energy Corp.'s oil refinery in Delaware City, Del., died from nitrogen asphyxiation while doing repairs.

An investigation found the men collapsed after they were quickly overcome by nitrogen.

In 2015, a technician at a Las Vegas health spa collapsed and died while using a cryotherapy machine unsupervised.

Creating a oxygen-deficient atmosphere would generally take hours, Johnston said. It's hard to fathom, he said, that three men working together would fall victim to such a mishap.

"This would be over hours, not over minutes," he said.

"It's the same thing with carbon dioxide. You just don't fall over, you start feeling sleepy. That's one possibility, but it just seems so remote that that would happen to people that worked in the industry. So we're at a loss."

While nitrogen is classified as a dangerous good, working with it is generally considered low risk, said Jeff Worth, president of Alberta Cryogenics.

Workers should maintain proper ventilation, never work alone and wear personal gas monitors to ensure air quality is safe, he said.

"It's safe, as long as it's handled properly," he said. "It's kind of like anything in the world. Gasoline is way, way more dangerous than nitrogen, for example, but we all handle it every day."

Worth hopes the investigation will help inform any safety improvements that may be needed in the industry.

"It would be good to know the outcome," Worth said. "It's certainly disheartening. My heart goes out to the families."