SACRAMENTO, Calif. -- Environmental and public health groups are urging the California Air Resources Board to approve a landmark regulation to reduce diesel pollution emitted by older heavy-duty diesel vehicles when it meets late this week.

The Proposed In-Use Truck and Bus Rule and the Proposed Heavy-Duty Vehicle Greenhouse Gas Emission Reduction Measure will be presented to the Board for consideration at the Dec. 11-12 public hearing in Sacramento.

The new rules would require that older polluting trucks and other large vehicles be retrofitted or replaced.

The In-Use Truck and Bus regulation would apply to diesel-fueled vehicles with a manufacturer's gross vehicle weight rating greater than 14,000 pounds that operate in California, regardless of where the vehicle is registered. For fleets with 4 or more vehicles, the regulation would require the installation of exhaust retrofits in 2010 and 2011 and accelerated engine or vehicle replacement from 2012 to 2022. Implementation is delayed for fleets with one to three vehicles.

The Greenhouse Gas regulation will require 2011 or subsequent model-year 53-foot or longer dry-van trailers that travel on a highway within California to use EPA SmartWay certified technologies.

State grants and loans are available to help fund the improvements.

It was reported yesterday that CARB will consider a new study that links diesel emissions with cancer and lower mortality rates during the hearings.