Cyanide in house fires – be aware

Published:  08 August, 2012

Atmospheric monitoring study reveals dangerous levels of cyanide in house fire smoke – by Nic Lacey, Crew Commander at the Greater Manchester Fire and Rescue Service, UK.

The majority of firefighters are well versed in the dangers of asphyxia from smoke inhalation, and the threat of carbon monoxide poisoning from enclosed fires. However, far fewer are aware of the fact that there are dangerous levels of cyanide in house fire smoke.

We recently carried out an atmospheric monitoring study here at Greater Manchester Fire and Rescue Service (GMFRS) which has revealed that 33% of calls in a three month trial period exceeded health and safety executive limits for cyanide or carbon monoxide, and in 100% of calls their combined toxicity was sufficient to cause symptoms in the human body.1

We decided to implement our pilot study following an atmospheric monitoring training session that was delivered to several Greater Manchester operational watches based in Moss Side and Gorton Fire Stations by the US-based Fire Smoke Coalition, Inc. (FSC), in October 2011. The FSC is a US based educational organisation whose aim is to focus the required attention and resources on the consequences of breathing fire smoke, and has run an awareness campaign around the dangers of smoke inhalation, including those associated with cyanide since 1997.

Special Operations Chief Krusen, President of the FSC, visited our Manchester service to talk about the dangers associated with the deadly toxicants in fire smoke, with a primary focus on hydrogen cyanide (HCN) and carbon monoxide (CO), and the monitoring work the FSC has been doing in the US. Chief Krusen also delivered practical demonstrations of how to monitor the atmospheric conditions following a house fire.  These demonstrations strongly encouraged us to monitor levels of HCN and CO in house fire smoke as a matter of course.

 As firefighters, the majority of us appreciate that smoke consists of many hazardous components, however the actual effects of hydrogen cyanide are not so widely appreciated or indeed understood. If we consider how often  that we as firefighters and the public can be exposed to cyanide during fire scene operations the issue is clearly becoming a major concern. The smoke monitoring research has shown us that cyanide is present, and that greater awareness around the threat it carries is necessary.

In the UK, workplace exposure limits are stated in the Health and Safety Executive document ‘EH40’. It was noted that both during operational incidents and on subsequent ‘test burns’ on a range of materials these limits were being reached and exceeded.

The culture in the UK is to wear breathing apparatus (BA) to firefight; in fact we are required to by our procedures, but how many times do we allow crews to ‘drop their BA’ after the fire has been extinguished and the property ventilated? Perhaps sometimes we are guilty of doing this a little prematurely. We have noted high levels of both HCN and CO still present in the building some time after we have deemed it clear and safe to work, often wearing just a dust mask. We’ve all been involved in turning over and damping down and felt exhausted, this may be abnormal fatigue as a symptom of HCN/ CO exposure.

Cyanide gas stops the cells’ ability to utilise the oxygen carried to them by red blood cells and acts synergistically with carbon monoxide; cyanide stopping the cells using any oxygen that reaches them, and carbon monoxide interfering with the ability of the red blood cells to carry the oxygen in the first place. For this reason, hydrogen cyanide and carbon monoxide are known as ‘Toxic Twins’.3

Many first responders in the UK take carbon monoxide to be the only consideration when they arrive to rescue and treat victims from a burning building or vehicle. There is no specific treatment for carbon monoxide poisoning, with oxygen given as part of best supportive care helping to reverse the symptoms. A cyanide antidote suitable for victims of smoke inhalation is available but is not currently standard practice in treating fire victims in the UK. Ensuring you highlight the fact that the victim was rescued from an enclosed house fire – and is, therefore, likely to have been exposed to cyanide gas – may help inform their treatment.

Stark results early on in the monitoring project have resulted in nearby services taking notice. During a return visit to the UK, Chief Krusen delivered an educational seminar which members of other Fire & Rescue Services and other agencies such as the North West Ambulance Hazardous Area Response Team (HART) attended. This awareness training has been such a success that other fire services have started monitoring HCN and CO at fire scenes. West Yorkshire FRS and Staffordshire FRS amongst several other Services have all started monitoring projects since attending this event. Smoke inhalation is the single greatest cause of mortality in house fires,2 with 42% of deaths coming as a result of it. Cyanide is unquestionably a contributing factor. The presence of cyanide in house fire smoke is well established, as it is given off when a variety of household materials incompletely combust, including plastic, wool, wood, and foam in sofas and mattresses. This incomplete combustion commonly occurs in enclosed spaces, where the fire’s oxygen supply is quickly exhausted.

From the rapid progress of the atmospheric monitoring project on a regional level, it is becoming clear that it will be through local recognition of the presence of HCN in smoke that the seeds of national awareness are sown. In countries such as France and the US, the emergency services are much more accustomed to treating cyanide poisoning from smoke inhalation. This will become a familiar concept, just as it is abroad, when those involved in rescuing and treating house fire victims witness its presence and effects in practical circumstances.

Having made contact with many people around the UK, it’s clear that several other services are carrying out research into the long and short term exposure to toxins arising from fires. Ideally I would like to put these services in touch with the FSC and pool all of our research. This would give a greater number of fire service members access to a wealth of information and a wide range of empirical evidence to guide the way forward.

Familiarity and understanding of the presence of cyanide and how it interacts with carbon monoxide amongst the emergency services will inevitably improve patient safety, as members of the fire services who are aware that smoke inhalation patients have been exposed to dangerous cyanide levels can pass this on to paramedic teams to help inform their treatment.


If you are interested in monitoring cyanide levels at fires your crews attend, please contact Nic Lacey at GMFRS at


1) Greater Manchester Fire and Rescue Service data on file

2) Department for Communities and Local Government, 2010. Fire Statistics: United Kingdom, 2008; 20.

3) 01.05.2012

  • Operation Florian

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