"We have workable solutions here. This shouldn't be a matter of choosing between clean air and affordable energy," said Jeremy Nichols, a spokesman for WildEarth Guardians, a nonprofit environmental group based in Denver. "Let's not settle for a second-rate plan that does not cut the haze, and does not ensure adequate protection of public health."Nitrogen oxide can worsen the breathing problems of people who have asthma. However, the rules dispute is focused on reducing pollution-caused haze near some of western North Dakota's most environmentally sensitive areas, including the Theodore Roosevelt National Park and the Lostwood National Wildlife Refuge. The agency says its preferred approach will also improve the view in the Boundary Waters wilderness area in northern Minnesota, and in South Dakota's Wind Cave and Badlands national parks. The EPA's Bismarck rules hearing ends Friday. The agency is taking written comments on its proposal until Nov. 21. Wayde Schafer, a North Dakota spokesman for the Sierra Club, said the EPA's move would freshen the state's air quality everywhere. "If you can see the air," Schafer said, "how is that not a health problem?" Executives for companies that own power plants and coal mines in western North Dakota testified against the proposed EPA rules. They included Basin Electric Power Cooperative, of Bismarck; Montana-Dakota Utilities Co., of Bismarck; Allete Inc., of Duluth, Minn.; Great River Energy, of Maple Grove, Minn.; and Minnkota Power Cooperative, based in Grand Forks. For Minnkota's Milton R. Young power station in western North Dakota, the EPA rules would require the cooperative to spend $500 million to install "unproven" pollution-control equipment, compared with the $35 million the state Health Department's plan would require, Dalrymple said. Robert "Mac" McLennan, Minnkota's president, said the 130,000 rural electric ratepayers who buy the cooperative's power have already seen their rates rise 34 percent this year to pay for a $425 million investment in pollution controls.