Some questions to clarify situation:
#1 why are you using self illumination?
#2 why are you using fresnel (falloff?) in translucency?
#3 what's the issue you want to solve? Is it green colour cast on the white paper, or something else?
Regarding the dirt, yes it's possible to add it on all objects and it can be done either with layered material, or in single material, it's down to your preference, but it has to be done per material. There's no way to add global dirt in one place on everything, unless you want to render an element with custom texmap and blend it over the image in photoshop.