LOS ANGELES, SEPT. 28 -- Gov. George Deukmejian (R) has signed legislation banning smoking on airline flights that begin and end in California, the first law of its kind in the United States and a psychological boost to an intense campaign for a national ban.

The new law, passed by large margins in both houses of the state legislature, also bans smoking on intrastate bus and train trips and in 75 percent of the space in airports and other public transit centers.

"This is an historic event," said Mark Pertschuk, director of the Berkeley-based Americans for Nonsmokers' Rights. "Once again, California has adopted a measure that will be an example for the rest of the country and the rest of the world." Ann Tonjes of the Association of Flight Attendants called the new law "an important step in the right direction."

The law takes effect Jan. 1 and applies to the San-Francisco-to-Los-Angeles air corridor, the busiest in the country. But experts expect it to be tested first in the courts.

Although he signed the bill, Deukmejian said he believes that only the federal government can regulate passenger smoking, a view expressed by several airlines. The state legislative counsel, Bion Gregory, has argued that states have the power to ban smoking because it is not an airline service subject to federal regulation.

Last year, the National Research Council, an arm of the National Academy of Sciences, reported that airline cabin ventilation was "in violation of the building codes for most other indoor environments" and that the nation's 70,000 flight attendants were exposed to smoke levels similar to those of a person living with someone smoking a pack a day.

When the study recommended a federal smoking ban on all domestic flights, Transportation Secretary Elizabeth Hanford Dole said the issue needed more study. Asked today for the department's view of the new California law, spokesman Hal Paris said, "We haven't taken a position yet."

Tonjes applauded in particular the law's expected impact on flight attendants working for PSA, the state's largest airline. PSA spokesman Bill Hastings said the airline has 525 flights each day, half of them within California and apparently covered by the law.

But he added that the airline had not decided how to respond to the law: "We believe the existing system {of smoking and nonsmoking sections} works well. We have gotten very few complaints from passengers. We think the real question is whether the state has the authority to do this."

The California law, authored by state Sen. Nicholas Petris (D-Oakland), includes language banning smoking "except to the extent permitted by federal law." That phrase probably will have to be interpreted by a court, perhaps in response to an airline's request for an injunction or a state suit against a recalcitrant airline.

Lisa Ramer, an aide to Petris, said the senator decided to propose the bill after an Oakland woman wrote to say the smoke on a bus she rode three times a week was making her sick. He extended the proposal to airlines after reading U.S. Surgeon General C. Everett Koop's 1986 report on "involuntary smoking" -- nonsmokers sharing the same air with smokers.

"Involuntary smoking is a cause of disease, including lung cancer, in healthy nonsmokers," the report said. " . . . The simple separation of smokers and nonsmokers within the same air space may reduce, but does not eliminate, the exposure of nonsmokers to environmental tobacco smoke."

The Petris bill passed the Senate 24 to 6 and the Assembly 46 to 24, but only after raucous debate. Republican Sen. Ed Davis, a pipe smoker and former Los Angeles police chief, labeled the bill's supporters "health fascists."

Democratic Sen. Dan Boatwright supported the bill but noted that smoking was still allowed in the Senate chamber and suggested the legislators "clear up our own house first." He pointed to fumes rising from a cigar in the ashtray of a close-by colleague. "This is one of the most vulgar, dirty, disgusting, stinking things I've ever laid eyes on!" Boatwright said. "Believe me, that thing is gross!"

Sen. Joseph B. Montoya, a Democrat, said the bill would be bad for his party because it would affect the "mostly uneducated" working class rather than the "yuppies and liberals we find here in the legislature who support these kinds of things."

Sen. Art Torres, also a Democrat, disagreed: "I think we ought to send a message to the rest of the country that California is going to lead the fight now for clean air, whether on the ground or up in the air."

Since many of the bill's critics had been Republicans, some politicians wondered whether the Republican governor would sign the bill. Pertschuk said his organization successfully campaigned to flood Deukmejian's office with calls and letters favoring the ban.

The U.S. House of Representatives voted 198 to 193 in July to ban smoking on all flights of two hours or less, as proposed by Rep. Richard J. Durbin (D-Ill.). The proposal faces powerful opposition in the Senate from tobacco state senators.