You don’t know smelly until you’ve been in the vicinity of a massive factory farm, or, as they say in the biz, a “concentrated animal-feeding operation.” State and local air-quality officials fear that the stench and, more importantly, the accompanying air pollution from such facilities won’t get under control anytime soon because the U.S. EPA is considering an industry-proposed plan to study the problem for at least two years before taking concerted action to address it. If the EPA takes this route, large farms would get amnesty from state and federal enforcement actions while the study was underway as well as from liability for past violations of the Clean Air Act. “The practical impact is EPA is considering huge loopholes for animal-feeding operations that will wreak havoc with state and local enforcement authorities,” said S. William Becker, head of an association of air-quality officials.