Which condition contributes to the production of toxic gases in a fire?

The production of toxic gases during a fire is significantly influenced by the combustion process, particularly when it involves carbon-containing materials. Incomplete combustion occurs when there isn't enough oxygen available for a material to burn fully, which leads to the formation of harmful byproducts such as carbon monoxide and various volatile organic compounds. These toxic gases pose serious health risks to individuals exposed to them during a fire situation.

Complete combustion, in contrast, occurs when there is sufficient oxygen, resulting in carbon dioxide and water as the primary products, which are much less hazardous. The use of non-flammable materials would typically not contribute to the production of toxic gases, as they are designed to resist ignition and combustion. Excessive water application, while primarily a means of extinguishing a fire, does not inherently lead to the creation of toxic gases; instead, it helps to mitigate the fire and reduce the harmful effects associated with it. Thus, the condition that is most directly associated with the generation of toxic gases is the incomplete combustion of carbon-containing materials.