11.   But still other companies are resisting the effort to bring them into compliance with pollution standards, federal officials say.

12.   But still other companies have resisted the effort to bring them into compliance with pollution standards, federal officials say.

13.   But the lawsuits filed Wednesday allege the companies greatly expanded their power-generating capacity and thus should meet the tighter pollution standards of new plants.

14.   California environmental regulators voted this month to eliminate the more lenient pollution standards that have long prevailed for diesel-powered vehicles.

15.   Chief executives from Japanese and U.S. automakers vowed to continue working together to fight tighter pollution standards in the United States.

16.   Construction vehicles are not subject to the same air pollution standards as ordinary cars and trucks.

17.   Depending on the use, pollution standards on the streams may vary.

18.   Ditto disputes over federal regulations, or grazing rights, or pollution standards.

19.   During the last three decades, federal law has imposed increasingly strict air pollution standards on new power plants.