Clean air in the skyline view of Knoxville, Tennessee is the result of years-long efforts to reduce emissions.
Source:
Nathan C. Fortner (User:Nfutvol at en.wikipedia), CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/>, via Wikimedia Commons
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Last modified:
16 May 2021 - 2:42pm