The rule varies across engine sizes, but most producers will reduce nitrogen-oxide levels in new engines to 0.3 grams per brake-horsepower-hour and particulates to 0.01 g/bhp-hr by 2014. Under the new rule, EPA is not requiring pollution controls on existing machines in the field.
Off-road fuel also is discussed. Refiners will need to lower previously-unregulated sulfur content in off-road fuel to 500 ppm by 2007, and again to 15 ppm by 2010. Industry observers say this sulfur requirement is feasible, but it will require capital investment, including control-equipment retrofits, on some existing plants.