The board, which passed the ban unanimously, did give restaurants a slight break by relaxing what had been considered a tight deadline for compliance. Restaurants will be barred from using most frying oils containing artificial trans fats by July and will have to eliminate the artificial trans fats from all of their foods by July 2008.

Restaurant industry representatives called the ban burdensome and unnecessary.

"We don't think that a municipal health agency has any business banning a product the Food and Drug Administration has already approved," said Dan Fleshler, a spokesman for the National Restaurant Association (NRA).

Officials