The regulations are intended to reduce smog and to decrease the amount of cancer-causing soot emitted by burning diesel fuel. Trucks and buses with engines from model years 1996-1999 are currently affected. Most are required to install new filters. But Bruce Tuter with the Air Resources Board says some owners - for example those with small fleets - may qualify for an extension:
Tuter:"The economy's tough right now and these filters are not inexpensive - $10,000 to $20,000 dollars in many cases, so a small owner, at least he buys himself a couple of years to decide to maybe get a new truck, or, you know, a couple of more years to get ready to put a filter on."