The four-day workweek, heralded by American labor leaders a generation ago as an imminent advancement for a leisure-seeking society, is arriving at last -- but not for the reasons its original proponents envisioned.

Barons of business and government officials are looking at a compressed workweek, flexible starting times and telecommuting schemes in a belated effort to stem environmental damage and ease traffic congestion.

The most ambitious of those plans is taking shape in Los Angeles, where the regional South Coast Air Quality Management District last year proposed sweeping legislation designed to mitigate traffic woes during rush hours and to clean up the nation's dirtiest air.

Their plan includes provisions that would impose fines on certain kinds of businesses and industries that fail to curtail their workweek from the traditional five days to four.

In Chicago, the impending move of the Merchandise Group staff of Sears, Roebuck & Co. from downtown to suburban Hoffman Estates has officials of the retailing firm considering a four-day workweek for some employees as one way to ease the anticipated gridlock around their new complex.

But Guy Eberhart, national communications manager for Sears, contended that the four-day workweek option is "not the most critical part" of the plan.

"The overall goal," he said, "is to provide the flexibility that will make us a competitive, desirable place of employment. You do that through a good work environment and amenities such as a fitness center and dining facility."

That notable lack of enthusiasm for the compressed 40-hour work schedule has been common in American business ever since social analysts in the early 1970s predicted that a four-day workweek was just around the corner.

"Whatever happened to the four-day workweek?" time management consultant Jaffrey J. Mayer of Chicago wondered aloud. "A better question is whatever happened to the five-day workweek. Inflation in the 1970s forced husbands and wives and couples living together to continue working. And the corporate restructuring and leveraged buyouts of the mid-1980s changed the entire American workplace and business landscape.

"The resulting downsizing of the work force has left fewer people to do much more work," Mayer added. "They've been forced to come in early, stay late and probably come in on the weekends to keep from becoming overburdened with work."

Those trends have made a mockery of the 1978 prediction by the Delphi Forecast research group that by 1990 the four-day, 32-hour workweek would be in place as "the new standard for {U.S.} industry."

Even the U.S. Chamber of Commerce and the head of the United Auto Workers forecast that the four-day workweek would be common by the turn of the 21st century, a projection bolstered by Labor Department statistics that showed more than 1.2 million American workers on a full-time four-day schedule in 1980 -- more than double the number in 1973.

But according to the Labor Department's Bureau of Labor Statistics, that rate of growth has appeared to slow during the last decade.

Roger Sanzenbacher, an economist in the Chicago office of the Labor Department, said the spreading phenomenon of two-income households has likely made the longer hours typically required of a four-day schedule less appealing.

"Flexible starting and quitting times seem to be much more popular now," said Sanzenbacher, whose own office permits workers to arrive in staggered schedules between 6:30 and 9:30 a.m.

But one vigorous advocate of creative work schedules, Tim Mescon, dean of the school of business administration at Kennesaw State College in Marietta, Ga., contends that America's corporate leaders have failed to use much imagination in their approach to gaining the dedication and best efforts of employees.

"Their 'creative' approach to productivity is having fewer people doing more," said Mescon. "We really haven't assessed the positive impact a four-day week could have on productivity and retention of workers. What is this magic of 40 hours? I think we should adopt a performance-based system instead of time-based."

Mescon noted that some industries have been forced out of desperation to come up with alternative ways of designing production and work.

"In the hospital industry," he said, "there is a chronic labor shortage, but not a talent shortage, because there are more than 1 million registered nurses who are not working as registered nurses because of the historical inflexibility to their needs. Now, you pick up almost any newspaper and you see ads for RNs, asking them to work two 12-hour shifts on the weekend and they'll pay you for 40 hours."

But the economic realities of other industries are not the same, and a mass conversion to a shorter week is not expected.

Suzanne Smith of the San Francisco-based New Ways to Work vocational resource center said that when her group was founded in 1972, it was a romantic notion to dream of 32 hours of work for 40 hours of pay. Today, however, "The American family needs 60 to 80 hours of paid employment each week to survive."