Toxic smoke

In light of the recent industrial fires occurring throughout the island, we are going to take closer look at some of the questions raised by residents in response to this type of event in their “backyards”.

In responding to a fire, the risks associated with that response must also be determined. Part of that determination of risks includes: What are the suitable methods of protection that must be utilised by responders while doing their job? Will the residents in the immediate vicinity of the fire need to be evacuated for their own protection? Will atmospheric conditions worsen the situation?

Every time there is a fire, regardless of its size or type, there will be smoke, due almost entirely to the material that is burning, the effects from that smoke on plant and animal life may be minimal or severe in effect. The immediacy in extinguishing that fire will dictate how long that smoke remains in the atmosphere.

In addition, the long term or short-term effect on the environment will also be dictated by the length of time it takes to extinguish that fire. This time line also dictates the severity of its effect on human, plant, and animal life.

These questions and many more must be answered by responders en route to the incident site. However, in most cases responders are already prepared with personal protective gear as part of the standard equipment for scenarios of this type.

The residents on the other hand, are not in possession of such equipment; therefore, their level of preparedness must augmented by public information bulletins that will advise them of the situation. This information must contain all of the pertinent data necessary for them to make an informed decision about what to do in response to this very sudden disruption in their lives.

Let us take a closer look at what is unfolding in their neighbourhood. First and foremost, there is the smoke, which is a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is mixed into the mass.

It is commonly an unwanted by-product of fires (including stoves, candles, oil lamps, and fireplaces), but may also be used for pest control fumigation. Defensive and offensive capabilities in the military (smoke-screen), cooking (barbecues) or smoking (tobacco). Smoke inhalation is the primary cause of death in victims of indoor fires. The smoke kills by a combination of thermal damage, poisoning and pulmonary irritation caused by carbon monoxide, hydrogen cyanide, and other combustion products.

Toxic fumes are gases that are poisonous or dangerous to people. There are different levels of toxicity, meaning some fumes (gases) are more dangerous than others. For instance, carbon monoxide can be present in your house. It is a toxic fume that comes from car exhaust or furnaces.

In very, very low concentrations, you may only show mild symptoms like a headache or even none if you come and go a lot. In higher concentrations, however, it will be lethal. In other words, it will kill.

Many compounds of smoke from fires are highly toxic and/or irritating. The most dangerous is carbon monoxide leading to carbon monoxide poisoning; sometimes with the additive effects of hydrogen cyanide and phosgene. Smoke inhalation can therefore quickly lead to incapacitation and loss of consciousness.

Sulfur oxides, hydrogen chloride and hydrogen fluoride in contact with moisture form sulfuric, hydrochloric, and hydrofluoric acid, which are corrosive to both lungs and materials. This reaction can occur when water is introduced to extinguish the burning materials.

When asleep, the nose does not sense smoke, nor does the brain.

But, if the lungs become filled with smoke, the brain will be stimulated and the person will wake up. This does not work if the person is incapacitated or under the influence of drugs and/or alcohol.

Reduced visibility due to wildfire smoke will effects drivers. Smoke can obscure visibility in buildings, impeding occupants trying to exit. In fact, poor visibility due to thick smoke in building fires is one of the leading causes of victims dying in fires because of the striking similarity that each floor shares, and disorientation caused by the smoke.

The most common cause of death in fires is the inhalation of noxious gases rather than thermal injury. Hydrogen cyanide gas, the most toxic product of combustion, seldom is recognized as a significant hazard in smoke inhalation.

Fire research conducted in Akron, Ohio, in the United States on toxic poisoning showed that toxic amounts of cyanide were found in four of the six fatalities studied from house fires. Those cases illustrated the increasing frequency of cyanide poisoning in household fires, and attributed the toxicity to the increased use of synthetic polymers in building materials and furnishings.

Prompt recognition of and therapy for cyanide intoxication may reduce the morbidity and number of delayed deaths in fire victims. The key point in the diagnosis of cyanide poisoning is a high index of suspicion.

The clinical presentation of cyanide intoxication, its diagnosis, and subsequent treatment of possible smoke inhalation victims must be discussed as of pre-emergency medical response strategy. Additionally, a pre-hospital protocol for treating smoke-inhalation victims who may have been exposed to any toxic fume or vapour must also be in place. It is important that we understand that toxic materials are not deliberately placed in the homes of residents; but during a fire, it is a direct side-effect of the materials used for developing some of the modern synthetic materials used in constructing homes and multi-story buildings worldwide.

Therefore, recognition of what can happen when these products burn is the first step in reducing casualties.

The composition of smoke depends on the nature of the burning fuel and the conditions of combustion.

Fires with high availability of oxygen burn at high temperature and with small amount of smoke produced; the particles are mostly composed of ash, or with large temperature differences, of condensed aerosol of water. High temperature also leads to production of nitrogen oxides.

Sulfur content yields sulfur dioxide, or in case of incomplete combustion, hydrogen sulfide. Carbon and hydrogen are almost completely oxidized to carbon dioxide and water.

Fires burning with lack of oxygen produce a significantly wider palette of compounds, many of them toxic. Partial oxidation of carbon produces carbon monoxide, nitrogen-containing materials can yield hydrogen cyanide, ammonia, and nitrogen oxides.

The translation of the above simply means that anytime there are plastics, woods, fabrics, left over domestic cleaning fluids, tires, refrigerators, old shoes, umbrellas, papers products, metals (old cars, engine parts), plastic and metal recycling, and landfills, available in any combination and there is a fire, the quality of the air will become toxic to human, plant, and animal life.

The issue here that must be considered is the planning and preparedness actions required to reduce that effect on residents and the environment.

Next week we will examine the hard politically charged questions: Is the appropriate personal protective equipment available to responders that will safely allow them to enter a toxic environment to save a life? Should responders enter a toxic environment to save a life?

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