What attribute of smoke helps to indicate the stage of the fire?

The color of smoke is a critical attribute that helps indicate the stage of a fire. Different materials produce smoke of varying colors, which can inform firefighters about the materials burning and the intensity of the fire. For instance, light gray or white smoke may suggest that the fire is in its early stages and that materials such as paper or wood are burning. Conversely, thick black smoke often indicates that synthetic materials or plastic are involved, suggesting a more advanced and potentially more hazardous fire stage.

The color can also reflect the amount of oxygen present in the fire, with yellow or brown smoke potentially indicating smoldering conditions, while a flame's direct state can be deduced from the hue and amount of smoke being produced. Understanding smoke color allows responders to make timely and informed decisions regarding their tactics and safety measures for firefighting and rescue operations.