LOS ANGELES, JAN. 2 -- Travelers got their first whiff of a new state law banning smoking on all commercial plane, train and bus trips that both begin and end within California's borders, and even some smokers thought it was a good idea.

The ban, which took effect Friday, was ignored by Amtrak, American Airlines and Alaska Airlines, whose officials said their operations are governed by federal rather than state laws.

United Airlines had threatened to ignore the law, but spokesman Rob Doughty in Chicago said Friday the airline decided to comply with it, "while maintaining that California lacks jurisdiction to ban smoking on commercial flights."

"The few responses we have had from passengers have been positive," Doughty said.

Among the first people to observe the new law were bus passengers on a morning trip from Oregon to San Francisco. When the Greyhound bus entered California, the driver announced that smoking was illegal and asked passengers to put out their cigarettes. No one objected, passengers said.

"I enjoyed not smelling that smoke," Augustina Sota of San Jose said of the nonsmoking part of her trip from Bend, Ore.

"You're kidding," said Karen Jones of San Jose, a smoker about to return home on a plane from Los Angeles International Airport, when told about the new law. "That's okay. I need prodding not to smoke anymore. I feel for the nonsmoker."

At the Santa Fe Depot in San Diego, where Amtrak trains arrive and depart, the rail agency's decision against enforcing the total smoking ban on intrastate trips produced mixed reaction.

"It's annoying," nonsmoker Marla Stone said of the decision as she waited to catch a New Year's Day train to San Juan Capistrano.

A smoker, Al Brookshire of San Diego, said he supported the state law despite his habit.

"I wouldn't want to be on a train with a bunch of people smoking -- and I smoke," he said. "They could start a fire, and then how am I going to get off? It's the same thing with a plane or a bus."