Fran Pavley would like to celebrate a series of recent decisions aimed at improving air quality, but she knows better than to get too excited just yet.

"We are not popping it yet," she said of the celebratory champagne bottle, "but it's chilling."

A judge ruled Wednesday that California has the authority to regulate greenhouse gases. As an assemblywoman in 2002, Pavley wrote a bill that required automakers to cut tailpipe emissions by 25 percent from cars and trucks. Pavley claimed the ruling as the fourth victory in the country this year that will lead to cleaner air and less pollution.

Then on Thursday, the Senate passed an energy bill that would mandate increased fuel efficiency in cars, which would in turn lead to cleaner air. Both the House and the president have said they will approve the bill.

The recent moves have environmentalists cheering that progress is being made to clean up dirty air in California and nationwide.

"It's a great week for air quality, especially when you consider how long all these actions have been in flux," said Al Sanders, conservation chairman of the Los Padres chapter of the Sierra Club. "We have the prospect of moving in the right direction."

Though excited by the prospects, Pavley still is guarded. The law that started on her desk still has to be granted a waiver from the U.S. Environmental Protection Agency, and she's not positive it will be granted.

The EPA may make a ruling by the end of the year.

Seventeen other states are poised to follow California's lead with similar legislation regulating greenhouse gases.

But what may happen between now and the time those laws take effect may depend as much on consumer demand as legislation, said Chris Denove, vice president of Westlake Village-based J.D. Power and Associates.

"I don't think the laws are going to make as big of an impact as a change in consumer behavior," he said. "It's definitely a reality as the price of gas goes up."

He thinks consumers will continue to vote with their wallets to demand cars that burn cleaner fuel and get better gas mileage. Also, the myriad technologies car manufacturers are working on, including clean-burning diesel, hydrogen fuels and hybrid cars, may do enough to meet any new emission standards, he said.

Moving toward the direction of burning less gas, however it is done, leads to cleaner air in the county, said Mike Villegas, executive director of the Ventura County Air Pollution Control District. The main sources of air pollution in the county are mobile point sources, including automobiles.

Although Pavley's bill is directed at greenhouse gases, it would help clean up the air through other, unintended ways. If the measure takes effect and helps keep temperatures from rising, it will mean less smog, Villegas said.

"Since temperature is one of the things that drive smog formation, there is the potential that climate change can lead to worse air quality," he said.

Likewise, if the energy bill comes to fruition, it will mean fewer reactive and volatile organic compounds in the air, which lead to smog. Smog is linked to chronic lung ailments.

"Ultimately," he said of burning less fuel, "there would be a benefit."