The warnings from the Reagan administration were dire. Unless Congress amended the Clean Air Act in the lame-duck session, major industries would be forced to shut down, states would lose billions of dollars in federal aid and the nation would suffer "great environmental and economic dislocations."

Congress apparently was not convinced. The House and Senate have gone home for the year without changing the stringent federal air pollution law and without extending the Dec. 31 deadline for cleaning up the nation's air.

That means that, as of New Year's Day, more than 400 counties across the country will be in violation of national clean air standards, facing all those punishments threatened by the administration.

But as the New Year approaches the potential victims of these federal sanctions--local officials and industry leaders--seem as unperturbed as Congress. Like several House and Senate leaders, they said the administration appears to have overstated the case.

"I must confess that the people in our industry aren't unduly alarmed," said Fred Weber, executive vice president of the Edison Electric Institute, an organization that represents electric utilites.

"It could take six months to two years" before any funds are halted, said S. William Becker, head of an organization of state officials who would be affected by a freeze in federal aid.

At the heart of the confusion is one of the most complex and controversial environmental laws on the books. Congress and the administration, industry and environmentalists wrestled over it throughout the two-year session, but the factions were so divided that no proposed changes came to a floor vote.

Advocates of a stiff clean air measure charged the administration with "blowing smoke" about the dangers associated with the Dec. 31 deadline in hopes of watering down other portions of the act during the lame-duck session. However, House and Senate leaders turned down White House requests to put the issue on the lame-duck agenda, putting off the fight until the 98th Congress.

The drive to reauthorize and revise the act is expected to become the top environmental issue of the next Congress, as it was in the 97th.

Meanwhile, with Dec. 31 only a week away, the impact of the clean air deadlines and federal sanctions remains uncertain.

The Environmental Protection Agency has said that 421 counties, in every state except North Dakota, have failed to meet the act's standards for controlling at least one of five major industrial pollutants -- sulfur dioxide, carbon monoxide, ozone, nitrogen dioxide and particulates.

EPA officials across the country are now collecting air quality data, and are expected to publish a list in late January of the areas that remain too polluted, along with potential sanctions to be imposed.

EPA Administrator Anne M. Gorsuch said this week that she will be forced to deny construction permits to certain companies in polluted areas, even if the permits are needed for plant improvements that reduce pollution. She also said the law requires her to cut off highway aid and grants to clean air programs in those areas.

But Sen. Robert T. Stafford (R-Vt.), chairman of the Environment and Public Works Committee, which has studied the Clean Air Act for two years, has taken strong issue with Gorsuch's reading of the law.

In a long and chastening letter to the EPA chief, he argued that many of the punishments in the law are discretionary. He also wrote that federal sanctions are triggered in most cases when local governments and industries fail to follow clean air plans, not when those plans fail to work.

Efforts to establish this occurred in the first debates over the Clean Air Act, according to a Senate transcript. At the time, Sen. Ted Stevens (R-Alaska) was worried that Fairbanks would lose highway aid even if local officials made a good-faith effort to control their most vexing pollutant -- ice fog.

The author of the highway aid provision, then-senator Mike Gravel (D-Alaska), promised his fellow Alaskan that the law would do no such thing.

"If that happens," Gravel said, "I will come to the floor of the Senate and slash my wrists."