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Silent killer

Admit it: the fire was out, everyone was safe, the pot on the stove was a blackened mess but other damage was minimal, and you flipped off your face piece.

February 1, 2013  By Laura King

Admit it: the fire was out, everyone was safe, the pot on the stove was a blackened mess but other damage was minimal, and you flipped off your face piece.

Car fires and dumpster fires are among the most dangerous for hydrogen cyanide, or HCN, along with kitchen fires and overhaul operations. The best protection against HCN exposure is to keep breathing apparatus on until the air has been tested by an HCN monitor and is clear.



Burlington, Ont., Capt. Stephen Jones wishes you hadn’t.

According to the Columbia Fire Department in South Carolina, which studied 40 fires over eight months in 2008, the byproducts of combustion from an average kitchen fire contain 75 parts per million (ppm) of hydrogen cyanide, or HCN, making the seemingly bread-and-butter, pot-on-the-stove calls among the worst offenders for HCN. Car fires, dumpster fires and overhaul operations are almost as bad.


At 50 ppm, HCN is immediately dangerous to life and health (IDLH); its toxic twin – carbon monoxide – is IDLH at 1,200 ppm.

Burlington, a composite department of 203 career firefighters and 65 volunteers, followed the lead of the Columbia Fire Department and is the first department in Canada with an operating guideline for HCN. All of Burlington’s trucks are equipped with HCN detectors; the department tracks HCN levels at all structure fires and records firefighter exposure to the toxic gas.

And that’s largely thanks to Jones, an 11-year career firefighter who stumbled onto the HCN issue at an International Association of Fire Chiefs hazmat conference in Baltimore in 2010 and felt compelled to better protect his colleagues from exposure and learn more about the effects of deadly gas on fire victims.

“Really the message is to use your air,” Jones said in a interview. “Never be off your air.” While remaining on air is the obvious antidote to HCN problems for firefighters, there is plenty of evidence to suggest that at minor incidents or during lengthy overhaul, not all responders – no matter how well trained – observe best practices.

“That’s where we get complacent,” Tony Bavota, deputy chief  with Burlington Fire, says of kitchen fires. “Or doing overhaul not on air.”

Essentially, Bavota says, the benchmark for removing BA has changed.

“Our process, like several other departments, is that we check carbon monoxide levels on the fire ground and when those levels are within a permissible range, those BAs would come off. They would come off during overhaul and in a lot of cases firefighters wouldn’t wear them during the incipient stages of a fire because smoke wasn’t visible, but we know now that can be when that gas is the most dangerous.”

In October, the Burlington Fire Department adopted a detailed, seven-page SOG on hydrogen cyanide monitoring at fire calls (see sidebar). And now, Jones has been asked by the Ontario Ministry of Labour to write a guidance note on HCN for all Ontario fire departments.

For Burlington, the cost of HCN monitors and the calibration gas was about $5,000. Calibration gas needs to be replenished every four to six months, so there is an annual operating cost, Bavota says, and the monitors will be put on a replacement cycle.

While exposure to high levels of HCN can be deadly, long-term exposure to lower levels can cause significant health problems.

 “Certainly, at a high enough level, acutely, we can be in real trouble,” Jones says. “But we also know that there are long-term effects. HCN affects the thyroid gland, and does a number of other things – it causes nervous instability, it can alter the sense of taste, and it can cause headaches and fatigue.

“In some cities that have engaged in wellness studies – Largo, Fla., and Las Vegas – they’re finding much higher levels of cancers, and thyroid nodules. We’ve said for the longest time that this has to do with smoke and exposure but we know more now, that the cyanide is causing this.”

HCN exposure doesn’t cause thyroid cancer, but it can lead to thyroid problems, which may be precursors to cancer.
Thyroid cancer is not among the cancers included in presumptive legislation in North America, but firefighter groups in the United States are pushing for it to be recognized, and the Ontario Professional Fire Fighters Association – which is lobbying for broader presumptive legislation ­– invited Jones to speak at its annual health and safety seminar in February.

Another effect of HCN exposure is vertigo, which Jones says he is witnessing more often among firefighters. In Burlington, making young firefighters aware that conditions such as vertigo among their colleagues may be a direct result of HCN exposure, is helping to alter the philosophy about wearing breathing apparatus.

“Certainly there’s a culture change but it was a relatively easy one,” Jones says. “Still, people need to be reminded because we’re creatures of habit. But when this information was presented, it was kind of that moment of silence in the room when everybody thought, oh man, I’ve been making some pretty significant mistakes in terms of my own health and safety; we all know we shouldn’t take off the BA, yet for some strange reason we do it, and I don’t know why we do it.

“I think that culture of the old smoke eater is gone, yet you’ll still be in there shovelling and wearing this 60-pound pack on your back, so if you’re wearing the air why aren’t you wearing the mask?

“In terms of accepting it, it was easy – but it was also actually a little bit scary; we’ve got four or five people who’ve been off with vertigo and the guys were thinking, was I at that scene when those guys were exposed to that?”

Burlington’s four newest recruits will be monitored for HCN exposure, along with their colleagues.

“They will essentially be our test group,” Jones says. “If we can get them to always be on air, let’s see what happens in 25 years – do they get the same cancers we get? Will they be in a decidedly better situation because they always had that mask on? They didn’t go on air at the front porch – they went on at the truck.

“We probably won’t see the benefits for quite some time, so it’s a bit of faith that we’re doing the right thing and this is what you have to do: stay on air. And these absorption studies that are out there now show we’re getting attacked through our skin, and there’s nothing we can do about that, so let’s do something about what we can and keep our air on.”

Canadian numbers on cyanide poisoning – or smoke inhalation – weren’t immediately available, but according to the American Council of Governmental Industrial Hygienists, workers who were exposed to concentrations of between four and 12 ppm of HCN over seven years reported more headaches, weakness, throat irritation, changes in tastes and smells, and nervous instability.

And the United States Cyanide Poison Treatment Coalition reported that over 10 weeks in 2009, 583 civilians were transported with smoke inhalation, and 261 of those patients died. Fifty-five firefighters were transported in the same period; none died. In February 2010, 191 civilians were taken to hospital for smoke inhalation in the United States, along with eight firefighters. Eighty-nine of the civilians died; none of the firefighters died.

Even more worrisome for first responders, therefore, is the effect of HCN on fire victims, and the lack of available treatment for smoke inhalation.

HCN exposure can cause thyroid problems, vertigo and other health issues. In Burlington, Ont., the department is monitoring all structure fires for HCN and tracking firefighter exposure to the potentially deadly gas.


The old cyanide antidote kits – or CAKs – were designed for people who suffered cyanide poisoning in industrial applications, and are no longer manufactured. The CAKs had a number of contraindications, including decreased oxygen and an increased heart rate, and were not administered in hospitals to patients who presented as a smoke-inhalation victims.

The new treatment for HCN poisoning – and smoke inhalation – goes by the trade name Cyanokit, and contains hydroxocobalamin, which is administered through an IV. Hydroxocobalamin is a form of vitamin B-12 that binds circulating and cellular cyanide molecules to form cyanocobalamin, which is excreted in the urine.

Jones says the kits are new to Canada and have not yet made their way onto ambulances or into hospitals.

“The literature supports that you are not going to revive a patient who is VSA without the administration of hydroxcobalamin,” Jones says. “And herein lies our challenge. We’re working toward getting a better understanding by our EMS partners that this is what we need. Hydroxocobalamin can be administered by any BLS or ALS paramedic.”

Jones says that at $700 per kit, and with a three-year shelf life, the kits are affordable for hospitals and EMS.

For Burlington, the next step in broadening awareness of HCN and the treatment for smoke-inhalation patients is an information session on March 7, to which the Burlington Fire Department has invited its EMS partners.

And, when the guidance note on HCN is released by the Ontario Ministry of Labour, more Ontario firefighters will be aware of the issue and the treatment.

“With the guidance note coming out, we will probably start getting some push to our EMS providers, and we will work at establishing a meeting with our base hospital so we can get kits available in a hospital setting,” Jones says.

In Halton Region – which comprises Burlington, Oakville, Halton Hills and Milton – Jones hopes to have two Cyanokits on all supervisory vehicles (a supervisory vehicle must attend at all structure fires).

“Ideally, the kits would be available to firefighters and civilians,” Jones says.

On a larger scale, researchers have determined that in some major incidents, such as The Station nightclub fire in Rhode Island in 2003, in which 100 people died and dozens more were injured, many of the fatalities were likely a result of HCN poisoning.

Donald Walsh, a PhD with the International Emergency Medicine Disaster Specialists / Chicago Fire Department, studied the nightclub fire. The National Institute of Standards and Technology investigation into the fire determined that within seconds of ignition “the concentration of cyanide poisoning in a fire situation of the toxic combustion products carbon monoxide and hydrogen cyanide soared and oxygen levels plummeted to create conditions incompatible with sustaining life.”

Walsh writes: “Experience with the Rhode Island nightclub fire, in which cyanide is likely to have contributed to morbidity and mortality, and data from studies . . . show that cyanide can be rapidly lethal – a daunting challenge for first responders working to save lives. While daunting, the challenge is not insurmountable. Effective management of cyanide poisoning in a fire emergency is possible. The first responder’s awareness that cyanide poisoning is highly probable in smoke-inhalation victims of close-structure fires constitutes a first step in effective management of smoke inhalation-associated cyanide poisoning.”

Meantime, Jones is focusing on educating the fire service and its EMS partners.

“When you go to a fire call and people are saying, hey, get your mask on . . . the message definitely has been well received,” Jones says. “The challenge will be to keep it in front of them all the time. It’s sort of this automatic response; if this information is there, in your face – hey, guys, cyanide, thyroid problems, cancer, keep your mask on – then it makes a difference.”

For Bavota, the safety issue goes beyond the department.

“We have one additional member in the fire service and that’s the family of the people who work for us,” he says. “And when you implement a program like this, you can report back to these folks that you’re doing everything you can to protect them.”

*    *    *

The Burlington Fire Department hosts a free information session on HCN on Thursday, March 7, from 8 a.m. until noon, at the Ron Joyce Centre, Degroote School of Business, 4350 South Service Rd., in Burlington. Please e-mail to confirm your attendance. For more information on HCN, e-mail


Excerpt from the Burlington Fire Department’s SOG on HCN

  • SCBA is required at all fires that present a smoke condition, including smoke investigations and kitchen or cooking fires.
  • Turnout gear is to be washed following structure fires that heavily soil and saturate gear with products of combustion.
  • All structure fires are to be monitored using an approved HCN detector.
  • SCBA is not to be removed until the atmosphere can be monitored and deemed safe. The IC or safety officer will announce when the conditions are acceptable for removal of SCBA.

The following conditions shall warrant atmospheric monitoring:

  • When SCBA has been used during a working structure fire, ventilation is complete and the removal of SCBA has been requested.
  • At vehicle fires within a structure or parking garage.
  • At cooking fires where there is damage to the container and surrounding surfaces.
  • When personnel are found operating inside the structure without SCBA,
  • The HCN detector is to be used immediately in the area where crews were found to be operating.
  • The HCN level shall be communicated to the IC along with the personnel who were found to be operating in the area.
  • The IC must determine and record the length of time the personnel were operating in the area.
  • If readings and operating time are of sufficient length, and signs and symptoms are present, personnel are to be transported to the hospital for immediate evaluation.

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