We often joke that where there is smoke there is fire. As fires burn they produce smoke. It is a fundamental of fire.
Smoke is the result of incomplete combustion and carries a variety of toxic by-products. Smoke includes three major components: particles, which are solids, vapors, which are finely suspended liquids, and gasses.
Smoke particles include unburned, partially burned, and completely burned substances. Unburned substances are just that, unburned items. They are lifted into smoke by the thermal column produced by the fire. Partially burned particles result from incomplete combustion. Completely particles are typically ash.
Smoke contains vapors. Vapors are small droplets of liquid suspended in the air. Some of the vapors are the result of us applying water to the fire. Other droplets result from products as they burn. When items burn they produce droplets that become part of smoke.
Smoke also contains a wide variety of gasses. What gasses are in smoke will depend on what is burning. If wood is burning it will produce different gasses then burning plastic.
Smoke can be highly combustible. So as we enter a smoke filled structure, we need to remember we are entering a highly combustible environment. This can be just as dangerous as the toxic gasses, carbon monoxide, hydrogen cyanide, and phosgene, that are contained in smoke.
We also have to remember because smoke is the result of fire, it is hot. The temperature of smoke will vary depending on many things including the stage of the fire, what is burning and the distance the smoke has travelled from the fire. The heat contained in smoke can cause burn injuries to skin and the respiratory tract.
As we fight fire we need to think about these things.
We need to think of smoke as a fuel. Fuel behaves in predictable ways when they are combined with the right mixture of oxygen and heat. Smoke with burn when heated sufficiently in the presence of oxygen. Hot smoke is extremely flammable.
We need to read smoke. We need to use monitors to check for toxins. We need to monitor the temperature of smoke.
We can do these things through educating ourselves on how to properly use our gas detectors and thermal imaging cameras. We can watch the darkness and turbulence of smoke. While fighting fire we can check the temperature of smoke by aiming the stream at the ceiling and if it vaporizes into steam the smoke is extremely hot. If we get drenched by falling water the temperatures are lower.
We need to evaluate what we are sensing and make determinations what to do. Is it safe to operate in that smoky environment or is it time to back out.
Can we control smoke? Yes. We can ventilate the structure. We can make cuts in the roof. We can use positive pressure ventilation or whatever tactics our department’s allow.
We can also cool smoke. We have always been taught to put water on the fire. But we can also cool smoke by injecting water into the smoke. Remember the basics of firefighting, we use water to cool fire as a means of extinguishing it. We can cool smoke by putting water into it.
Its important we understand smoke. Our lives depend on it.