The “art of reading smoke” might sound like it comes from ancient Native American lore, but this term describes a sophisticated system used by trained fire-science professionals to assess danger from a fire and implement appropriate suppression measures. Since modern construction materials and methods continue to change — favoring newer composite substances over traditional woods and metals, for example — the art of reading smoke must also evolve. With the ability to “read smoke” comes the ability to identify what the top priority is when faced with a raging fire — is there a need to conduct a search and rescue, or is the best action to tackle the fire from a certain angle? These questions and more can be answered when the firefighter is trained to read the different types of smoke.
The Four Attributes of Smoke
Fire science states that smoke takes on four attributes when it exits a building: color, density, velocity and volume. There are valuable and potentially lifesaving messages to be decoded in each of these four attributes.
- Volume: The main message that the volume of smoke transmits is the type of material being burned as well as the characteristics of the space. A hot fire burning on dry, flammable material near a well-ventilated area may not emit much smoke, but that same fire burning in a poorly ventilated area can quickly begin to billow. A fire burning into dampened material will produce lots of lighter-colored smoke with very little flame. If a firefighter who holds a fire science bachelor degree is looking at a fire, his or her training can help decode these important messages quickly and accurately.
- Density: Smoke density is often the most terrifying part of a fire for civilians to witness. This is because with denser smoke, it is much harder to see into the structure to discover what is occurring. The smoke density, more than any other attribute, is a measure of how severe the fire is. The denser the smoke coming from the fire, the more fuel there is intermixed with the clouds of smoke, making the smoke more flammable. Thick, dense smoke also sucks oxygen from the air and can quickly cause unconsciousness if inhaled. A first-responder with an emergency management masters degree might remember this by recalling a simple phrase: “Where there is dense smoke there is deadly fire.”
- Color: The color of the smoke is the firefighter’s best indication of the fire’s location and the materials being burned. Since most fires begin by emitting white smoke, a light or white smoke is often a sign of the start of a fire. Color alone can tell a firefighter a lot about how long the fire has been raging, what type of fire it is, what material is being burned and how dangerous it is. Brown smoke indicates wood is being burned, which often means the fire has consumed the contents of a room and moved into the structure itself. Black smoke can indicate that the fire is spreading quickly and that the smoke is beginning to act like the flames; black smoke indicates a very dangerous fire. As smoke often changes colors as the fire progresses, being highly attentive to these signals can help a firefighter decide what to do in a high-pressure situation.
- Velocity: Finally, velocity in a fire is the primary way to tell how hot the fire is and where it is centralized. This all points back to how densely the smoke has built up within the structure and how likely it is to create a situation known as a “flashover,” which is when the fire begins to spread quickly over the surrounding area. Because velocity is controlled by heat absorption and the volume of space, the smoke has to fill before it begins to run out of room. Highly pressurized smoke will show its velocity by finding other “escape holes,” such as through vents or under doors, and will emerge with turbulence.
Author Bio: Sarah Jakorwsky is a fire science major. She developed a passion for fire safety issues at age 10 when her family home burned to the ground. Her ultimate career goal is to become a fire science instructor.