Beginning January 1, 2007, nitrogen oxides and particulates must be reduced from 2004 levels (the current standard) by 90 percent. Allen Schaeffer (executive director, Diesel Technology Forum) says this can be achieved in a couple of ways. First, the sulfur content of diesel fuel will be reduced from 500 parts per million (ppm) down to 15 ppm. Second, exhaust filters or soot traps likely will be in all diesel exhaust systems.
But the year 2010 is the real milestone. Based on today's emissions standards, all nitrogen oxides and particulates must be 98 percent cleaner than the mandated levels are today. Bottom line: By 2010, diesel exhaust will be as clean as gasoline exhaust. Possible new technologies to achieve these reductions include the use of urea, which is injected into the exhaust stream, and new generations of catalytic converters.