Texas' state environmental agency yesterday approved a clean-air plan for the smoggy Houston metropolitan area that includes a 55-mph speed limit.

Thanks largely to refineries and petrochemical plants, Houston in the last two years has surpassed Los Angeles for the dubious honor of the nation's worst air.
The three-member Texas Natural Resource Conservation Commission unanimously approved the plan, which it called "aggressive." The plan is designed to bring the area into compliance with federal clean air standards by 2007, and is subject to approval by the U.S. Environmental Protection Agency.
If approved, the plan would limit speed limits to 55 mph in the eight-county area effective May 1, 2002. The speed limit on interstate highways in the Houston area is as high as 70 mph.
The plan also calls for unprecedented cuts in emissions at industrial plants, a ban on the use of diesel construction equipment during the morning hours, and stricter tailpipe tests for cars and trucks, according to published reports.