The EPA rules represent the first national limits on mercury and other toxic air pollutants that are expect to affect 1,200 coal-fired units at 525 power plants. The EPA has said the rules would keep 91 percent of mercury in burned coal from being released into the air and cut down on the number of illnesses and deaths linked to toxic pollutants.Stanley Wauneka said his community of San Juan on the Navajo Nation is divided between those who are concerned about pollution and health impacts, and those who see the power plants and the coal mines that feed them as economic drivers for a reservation where half the work force is unemployed. A gray haze hangs close to the horizon each day as he drives to work at a local government center just four miles from Four Corners Power Plant. "If they would put in some modern technology, that would really help cut down on the pollution," he said. "It would really help the people's understanding that these things can be improved. If the company can do that, then the people would be more in favor of prolonging the power plants in the area." APS spokesman Damon Gross said shuttering the three units at Four Corners that produce 560 megawatts of power will cut mercury emissions at the plant by 61 percent. APS still needs regulatory approval to move forward with the plan. The two remaining units have so-called bag houses installed that catch the bulk of mercury emissions, but additional upgrades are planned under the anticipated EPA rule, APS said. Critics of the EPA rule limiting mercury, arsenic and other emissions at the power plants have characterized the rules as inefficient and costly. Emerson Farley, a trustee with the Nal-Nish Federation of Labor who works at Four Corners Power Plant, said the union made up of trade groups from around the Navajo reservation has been advocating for EPA to minimize its mandates and take a more job-friendly approach to regulations. He said statements about pollution affecting people's health don't ring true with the plant's employees, who are close to the source of emissions.