What does light grey smoke usually indicate?

Light grey smoke typically indicates that paper or cloth is burning. When these materials combust, the resulting smoke tends to take on a lighter grey color due to the organic composition of the materials being burned. This color can be indicative of a fairly complete combustion process, where the organic fibers are breaking down and producing a lighter smoke rather than the denser, darker smoke produced by other materials.

In contrast, the other materials mentioned in the other choices usually produce darker or distinctly colored smoke. For example, burning gasoline often results in black or dark grey smoke due to the hydrocarbons present, while plastic and rubber tend to emit thick, black smoke with a pungent odor. Recognizing smoke colors can be crucial for assessing fire scenarios and understanding the materials involved in a fire situation.