Question

why is olluton never strictely a local promblum

Answer 1

Wow ok. Well what I think you are trying to ask is. "Why is Pollution never strictly a local Problem?"

Answer 2

Pollution in general is never strictly local, because all parts of the biosphere and ecological cycles (like the water cycle, nitrogen cycle, etc) are all connected. For example, groundwater contaminates not only affect the water resources of a local population, but those contaminates are also distributed into the overall cycle, and can affect people downstream and etc.
Compliments of @wach