The Clinton administration has approved new regulations that are expected to cut air pollution from heavy-duty trucks and buses by more than 90 per cent over the next decade. The federal standards will require new large trucks and buses to meet stringent tailpipe emission limits and direct refiners to produce virtually sulphur-free diesel fuel.

The rules were announced on December 21, 2000, by the White House and the US Environmental Protection Agency as part of a flurry of regulations being churned out in the last days of the Clinton administration and crafted to head off challenge by an incoming Bush administration. While President-elect George W Bush has not expressed any views on the truck rules, some Republicans have criticised the new sulphur requirements for diesel fuel. The rules apply to new trucks and replacement truck engines sold beginning 2006.