Diesel industry and California Air Resources Board officials held a press conference to highlight the key policies and events that led to the transformation of clean diesel technology over the past two-plus decades.
The event showcased the major advances in clean diesel technology spurred largely by stringent emissions standards and regulations established by California and CARB.

According to the Air Resources Board, from 1990 through 2015:

* Fine particulate matter (PM2.5) from heavy-duty diesel trucks will have declined by nearly 74%; from non-road construction machines by 63% and 73% in farm equipment.

* Oxides of nitrogen - a component of ozone or smog formation-will have declined by 21% in heavy duty trucks, 52% in non-road construction equipment and 65% in farm equipment.

Today, more fine particles come from brake and tire wear than from all on-road diesel engines, said Allen Schaeffer, executive director of the diesel technology forum, at the press conference. He added that because of these major advances, it would take 60 of today's new diesel trucks to equal the particulate emissions of just one truck made in 1988.

"Today's diesel engines emit about 90% less of these pollutants than they did when we first started this effort," said CARB Chair Mary Nichols. "And while we still have work to do, especially in turning over the fleet of older vehicles that are out there on the roads, the fact is that we've seen actual air quality improving, especially around our ports where we first started the effort to really turn over the fleet."

In addition to the press conference, an outdoor technology showcase event included examples of modern clean diesel technology including:

* Heavy-duty truck and engine technology from Cummins, Detroit, Mack Trucks and Volvo Penta

* Light-duty pickup trucks from GM and a RAM with a Cummins 6.7L Turbo Diesel

* The most advanced emissions control technology from Cummins, Donaldson, MTU, and Volvo Penta