not exactly (Score 0)

Close, but pollution doesn't go away completely. In fact, that is completely and unequivocally far from the truth. Lets discuss: Oak trees emit Isoprene (in large quantities, esp in texas), Lightning produces NOx compounds, Volcanos produce more pollution in one eruption than the US does in an entire year. Volcanos and dust storms are huge producers of particulate matter. I hope you don't mean to tell me that when humans are gone that these things will magically disappear as well....