I will say the alphabet (c. 1700–1500 BC) by Semitic-speaking peoples in the area of the eastern coast of Mediterranean Sea.
No polution, better communication & records, unifying humanity, etc.
My second/third choices:
The flushing toilet by Sir John Harington of England (c. 1591)
Followed by toilet tissue in 1857 by Joseph Gayetty of the USA
I won't even speculate what went on during those 266 missing years between these two inventions???
Find more invention dates HERE