Diesel truck rules.

The Air Resources Board will conduct a workshop in El Monte on Wednesday to begin crafting regulations to reduce diesel emissions from heavy-duty on-road trucks.

The meeting comes just weeks after the board passed a landmark and hard-fought regulation limiting diesel emissions from an estimated 180,000 off-road construction vehicles.

The on-road diesel regulation is expected to be even more far-reaching; it would apply to all trucks with a gross vehicle weight exceeding 14,000 pounds. The goal is to reduce diesel emissions by the year 2014 to levels that can be achieved on 2004 model engines that have diesel particulate filters on them. Currently, only a small fraction of trucks on the road have these filters.

In a parallel series of hearings, the air board is trying to determine how many of the hundreds of thousands of diesel trucks using the state's roads and highways should be subject to the rule. To give some idea of the potential scope, in its hearing notice, the agency states: "This regulation includes, but is not limited to: long and short haul truck-tractors, construction-related trucks, agricultural trucks, wholesale and retail goods transport trucks, tanker trucks, and package and household goods transport trucks."

Whatever regulation does come forward, it's certain to meet stiff resistance from truckers and from the wide array of industries that rely on diesel trucks to transport their goods.

The hearing is scheduled to start around 10 a.m. Aug. 22 at the Air Resources Board Auditorium at 9534 Telstar Ave. in El Monte. For more information, log onto the board's Web site at arb.ca.gov.