The idea is actually very simple: construct a tower fitted with 200-400 trees in areas of high pollution. Basically, it works like a gigantic filter—scrubbing smog and converting CO2 into oxygen.
Furthermore, the trees inside the structure would be nourished using a windmill-powered pump system, so it would not significantly contribute to our energy consumption. Would something like this actually work? Maybe—that is until the wind kicks up and we have trees falling all over the streets of L.A. [Core77]