By LARRY FELKER, Belimo Americas, Reno NV
Everyone knows that inhaling smoke can lead to death, but the long-term effects on survivors can also be incredibly harsh and physically irreparable.
Smoke is lethal – that's clear. But few people truly understand why. We sense the toxicity of smoke through harmful effects, the unpleasant odor, for instance, but that's just the basic aspect.
Beyond the chemical hazards, hot smoke can cause damage to the skin, eyes, lungs, and even result in lifelong disabilities. Furthermore, it can impair visibility, hindering escape in fire incidents. Explosions or surface ignitions can occur if the concentration of smoke particles is significant enough and they are heated to their ignition temperature.
THE COMPONENTS OF SMOKE
When a fire ignites within a building or any object, smoke begins to form. This smoke comprises a large number of molecules and various particles that come together to form larger clusters. Common fuel sources from building structures to furnishings all contain carbon and hydrogen, while most modern materials (plastics and polymers) also contain sulfur and nitrogen. Even recycled materials can contain potentially harmful compounds. In fires, nitrogen and sulfur compounds produced are highly toxic, such as hydrogen sulfide, sulfur dioxide, hydrogen chloride, ammonia, and diverse organic compounds. Carbon black forms from incompletely burned carbon. Over 100 different toxic substances have been identified in smoke from building fires.
CO & HCN
In typical fires, carbon monoxide (CO) and hydrogen cyanide (HCN) are two of the primary hazardous compounds.
CO and HCN work differently. CO strongly binds to blood serum, impeding the transportation of oxygen and removal of CO2. As a result, respiration becomes hindered. HCN affects cellular structures, particularly the nervous system. The specific mechanism is more complex, but essentially, it inhibits the production of adenosine triphosphate (ATP), a molecule driving most cellular processes. With ATP production rates around 10 times per second, HCN is more rapidly harmful than CO, rapidly shutting down cellular activities.
CO2 typically forms at high temperatures, while CO is produced at lower temperatures. HCN is generated even faster at lower temperatures.
In the initial phase of combustion, when the fire spreads, the production of CO and HCN begins. The oxidation of HCN produces other harmful compounds and generates more CO. Using water for firefighting limits this by around 88% until firefighters arrive. However, even when water cools the fire, HCN production continues. Similarly, limiting oxygen promotes CO over CO2. Completely extinguishing the fire and quenching the embers is the most effective method, though it takes time.
Long-Term Effects of Inhaling Smoke
A greater concern than the immediate impact of smoke is the long-term effect of prolonged exposure to high levels of smoke. CO attacks other molecules, such as myoglobin and cytochrome oxidase in the body, harming the cardiovascular system and nervous system. HCN disrupts brain cells by inhibiting energy production. Many firefighters' heart attacks are suspected to be due to cyanide poisoning. The higher the cyanide concentration, the quicker the death.
Among the intermediate and long-term symptoms of smoke inhalation are hoarseness (damage to the vocal cords), coughing, difficulty breathing, more severe asthma symptoms, and reduced lung function. The most comprehensive reference on this topic is a study on the health effects of those responding to the 9/11 event. Smoke can cause or contribute to cancer, autoimmune diseases, sleep apnea, and Sarcoidosis.
In summary: Smoke from fires contains over 100 toxic substances, with CO and HCN being the most dangerous. While the immediate effects of inhaling smoke can lead to death or permanent injury, the long-term impacts are also very serious. Therefore, efforts to control smoke are crucial for the long-term health protection of both the general public and firefighters.
Residing in Nevada, the author is an expert in drive systems and fire and smoke prevention, managing fire and smoke products for Belimo Americas. Felker is also the Vice President of the Special Operations Force Against Smoke and Fire for the International Air Movement and Control Association. He is a member of the International Rules Council, the National Fire Protection Association, and the Society of Fire Protection Engineers, as well as a lifetime member of ASHRAE. He is a co-author of the book "Dampers and Airflow Control," published by ASHRAE Special Publications in 2010.
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