Carbon Monoxide and Hydrogen Cyanide: The “Toxic Twins”

What are the Toxic Twins?

In the aftermath of fires or combustion-related incidents, two particularly lethal gases often emerge; Carbon Monoxide (CO) and Hydrogen Cyanide (HCN). Known as the Toxic Twins, these gases pose a severe risk to life. Individually, each gas is dangerous, but their combined presence amplifies danger and poses a safety threat.

Carbon Monoxide (CO)

Carbon monoxide is a colourless, odourless, and tasteless gas formed as a result of incomplete combustion of carbon-based fuels such as coal, wood, oil, or gas. Because it has no detectable scent or appearance, it is virtually impossible to identify without the aid of specialised detection equipment.

CO is particularly dangerous as it binds to haemoglobin in the blood far more readily than oxygen, effectively displacing it and reducing the body’s ability to transport life-sustaining oxygen to vital organs.

Hydrogen Cyanide (HCN)

Hydrogen cyanide is a volatile and highly toxic gas that is typically released when materials containing nitrogen, such as plastics, foams, wool, or synthetic fabrics, are burned. It is colourless or sometimes pale blue, with a faint almond-like odour. However, not everyone can detect its smell due to genetic variability, making it difficult to identify without instrumentation.

HCN impacts the body’s ability to use oxygen at a cellular level, preventing cells from producing energy and leading to internal suffocation.

A Lethal Synergy

While both CO and HCN are deadly on their own, their combined presence dramatically increases the risk of death. When inhaled together, they create a synergistic toxic effect:

• CO deprives the bloodstream of oxygen by binding with haemoglobin, preventing effective oxygen transport.
• HCN inhibits the body’s ability to utilise the little oxygen that is delivered, by disabling cellular respiration.

Together, this double-hit effect can lead to rapid unconsciousness and death, often within just a few minutes of exposure. This makes the Toxic Twins especially dangerous for first responders, victims trapped in fires, or workers in enclosed environments with poor ventilation.

ARA-X4: Your Toxic Twins Defence

With gases as dangerous as the Toxic Twins, workers need to be confident in their protective equipment. ION Science’s ARA-X4 multi gas detector is the ultimate safety shield against harmful gases. With the flexibility to configure up to four sensors, including CO, HCN, O₂ (leaded or lead-free) H₂S, SO₂, and LEL, ARA-X4 is trusted by workers to ensure safety in first response and confined space applications.

• Multiple Sensor Options
  • Flexibility to choose O₂ (leaded or lead-free), CO, H₂S, LEL, HCN, and SO₂ sensors to suit specific application needs.
• Instrument Warranty
  • Reliable instrument performance backed by a 5-year warranty
• Safe Mode
  • Displays a “SAFE” icon when no alarms are triggered, ensuring peace of mind for operators
• User-Friendly Design
  • Green & red backlighting, along with a clear, easy navigable interface
• Flip Screen
  • LCD screen features a ‘flip’ function, to flip the screen based in instrument orientation for easy readings
• Simple PC Software
  • Easy to navigate for streamlined data logging download and instrument configuration