Washington Post: When it comes to the environment, traditional dry cleaning is downright dirty. The liquid solvent used at 85 percent of dry cleaners, perchloroethylene, known as “perc,” is unequivocally bad for people and the planet: It’s a central nervous system depressant and respiratory irritant that the Environmental Protection Agency deems a “probable human carcinogen.” According to the EPA’s Web site, it also seeps into air; breaks down into other chemicals, “some of which are toxic, and some of which …