A s we drove through southwest Memphis, KeShaun Pearson told me to keep my window down—our destination was best tasted, not viewed. Along the way, we passed an abandoned coal plant to our right, then an active power plant to our left, equipped with enormous natural-gas turbines. Pearson, who directs the nonprofit Memphis Community Against Pollution, was bringing me to his hometown’s latest industrial megaproject. Already, the air smelled of soot, gasoline, and asphalt. Then I felt a tickle