Sulfur dioxide emission standards for coal-fired stationary boilers generally range from 1.2 pounds per million Btu of heat input for large boilers constructed after August 17, 1971 to 5 to 6 pounds of SO2 emissions for other large boilers constructed on or before August 17, 1971 and for boilers located in nonrural areas. These standards generally prohibit the use of coal with sulfur contents > 0.6 percent for new large boilers and > 2.5 to 3.0 percent in other boilers. Low-sulfur western coal shipped in unit-trains and mechanically blended with higher-sulfur coals located close to the boilers provides a method of increasing the production of the high-sulfur Iowa coal as well as the consumption of low-sulfur western coal and, at the same time, of reducing the total cost of the projected 1980 coal consumption in Iowa.