A few more of Polyak's Pittsburgh slide shows…. http://www.slate.com/articles/health_and_science/the_green_lantern/2008/10/what_the_heck_is_clean_coal.html https://picasaweb.google.com/jrpolyak/October102014AnotherFridayInPittsburgh?feat=email https://picasaweb.google.com/jrpolyak/October82014PittsburghAtSunset?feat=email