In an ideal setting, Philadelphia’s air would be cleaner. There would be more trees and more green space, like up to 42K acres—almost half of the city’s area—more. This, according to a December 2010 Parks and Recreation study on the city’s urban tree canopy. Urban canopy is “a vital asset that reduces storm-water runoff, improves air quality, reduces the City’s carbon footprint, enhances quality of life, contributes to savings on energy bills, and serves as habitat for wildlife,” the authors write. Made possible by an America Recovery and Reinvestment Act grant through the USDA Forest Service’s Northern Research Station, the report found one-fifth of the City of Brotherly Love, less than 20K acres, was covered by green space. Chinatown, North and South Philadelphia have the least amount of greenery, with only 3 percent. The Wissahickon and Pennypack Park neighborhoods boast the highest existing…