Bulldozers, tractors, irrigation equipment, and other diesel-powered off-road machines will be subject to stricter emissions standards under a new plan announced yesterday by the U.S. EPA. The plan calls for cutting emissions by up to 95 percent, a move that would bring the standards for off-road vehicles in line with those for cars and trucks for the first time in decades. Off-road diesel engines are second only to power plants in emissions associated with lung cancer, asthma, and other health threats. The tougher rules are expected to prevent 9,600 premature deaths per year and save tens of billions of dollars annually in medical expenses and lost productivity. Environmentalists praised the plan, with the Natural Resources Defense Council hailing it as the most significant public-health improvement since unleaded gasoline.