Which factor does NOT affect the quality of foam produced?

The factor that does not affect the quality of foam produced is the type of ground surface. The effectiveness of foam as a fire suppression agent is primarily influenced by how well it is mixed with water and foam concentrate, rather than the substrate it is applied to.

Water quality, water temperature, and the type of foam concentrate all directly impact foam performance. Poor water quality can introduce contaminants that affect the stability and effectiveness of the foam. Water temperature can affect the viscosity and aeration properties of the foam, leading to changes in how well it adheres to surfaces and how long it remains effective. Different types of foam concentrates are designed to work under specific conditions and for various classes of fire, so the concentrate used plays a crucial role in the foam's capabilities. In contrast, the ground surface type might influence how the foam spreads or adheres, but it does not inherently affect the quality of the foam itself in the same way that the other factors do.