Severe limitations on pore-stress concentration effects on mechanical properties are shown. First, the porosity dependence of materials with dilute porosities is not consistent with significant variations in stress concentrations with the stress state. Second, in non-dilute porosities, pore stress concentration effects are reduced due to pore-stress interactions as pore spacings decrease. Such reduction of stress concentrations is seen as supporting the concept of the minimum solid area correlating with properties in porous materials, and the similarity between the porosity dependence of mechanical properties and electrical and thermal conductivity. Finally, crack-pore interactions often limit the effects of pore-stress concentrations, e.g. due to small pore sizes. However, some effects of pore-stress concentrations may occur due to tensile failure from a few or an isolated pore, or more general porosity under compressive loading, but even in these cases pore shape-stress concentration effects are significantly mitigated.