According to the Wall Street Journal, the U.S. Environmental Protection Agency is working on tougher truck emissions standards for 2007.

The EPA could announce the plan in the next few weeks, although details aren't expected until next year. The plan is expected to link fuel and vehicles to reduce emissions of nitrogen oxide by 85% to 90% from 2004 standards, and particulates by 80% to 90%. The agency is reportedly considering mandating low-sulfur diesel fuel in order to help reach these goals.
That possibility worries trucking companies that are already seeing fuel costs cutting into already thin profit margins. California, which already requires a lower-sulfur diesel, has the highest diesel prices in the country.