For Sarah Swaney, a crackerjack sales agent for new houses, 1979 was a very good year. She made her way into the select "$5 Million Circle" at Long and Foster Realtors in Fairfax County and earned about $33,000 on her 50 sales.

But in 1980 Swaney is no longer in the $5 Million Circle. She's no longer selling houses at all. Instead she works at another firm as a word processor -- and earns a third of her old income.

Separated, and the mother of four children, Swaney says, "I'm not coping. I guess I'll last until my savings run out."

When the metropolitan area's housing industry was gripped by recession at the beginning of year, Sarah Swaney was one of the hundreds who were squeezed out.

Joining her were carpenters, laborers, roofers, bricklayers, surveyors -- and engineers like Henry Kaiser, who worked at his profession for 25 years without being laid off. Until the recession of 1980.

"It looks pretty bad," said Kaiser, who was laid off by Matthews and Wheatley, a Fairfax civil engineering firm that is heavily dependent on home construction. "There's not really much I can do except to look at the want ads."

Kaiser is collecting unemployment checks, but says $112 a week doesn't quite make it."

Commercial construction in this area has continued strong, particularly in downtown Washington, where a number of office buildings are in the works.

But statistics maintained by the Northern Virginia Builders Association tell how tight the squeeze has been for homebuilders in the suburbs. The fourth quarter of 1979 showed a 10 percent drop in construction in Northern Virginia, association vice president Robert Johnson said.

In the first quarter of 1980, he said, there was a 17.4 percent drop, and the second quarter, from April through June, saw an additional 23 percent decline.

The outlook is no brighter elsewhere in the metropolitan area, where an estimated 100,000 people are employed in the building industry.

In suburban Maryland, where housing construction had begun to pick up after a period of doldrums, new-construction starts for 1980 were originally projected to reach 4,500. But the Suburban Maryland Home Builders trade association now sees only 2,500 starts for the year.

"It's frustrating," said Steven Eckert, spokesman for the Maryland group. "People in the industry are trying to provide housing and do a good job, and these vicious cycles in the economy just destroy efficiency. That will have a very negative impact on the price of housing."

With the Northern Virginia building industry employing at least 60,000 people directly, the continuing decline in construction could "cause a helluva lost of repercussions," Johnson said.

"What happens," he continued, "is that if a worker can't get re-employed or get into another trade, he leaves the area. We're going to lose some of our most talented and skilled people."

That is already happening. At Beacon Masonry Corp. in Fairfax, 75 percent of the 200-person bricklaying force has been laid off, and many of the journeymen have gone back to where they grew up -- usually small Southern towns in the Carolinas, West Virginia, Kentucky or Tennessee.

Luther Johnson, one of the bricklayers let go, went with his family to Shelby, N.C., where his wife had relatives. After surviving on unemployment checks for several months, he found another bricklayer job there.

Some laid-off bricklayers have been able to find work at other companies, but there are no guarantees. Henry Graham, for example, was laid off by General Masonry last September, when the first tremors of bad times were felt. Just before Christmas, he landed a job with the Burleson Construction company. But work ran out in March, and since then, Graham, who has 15 years experience, has been waiting out the recession at his home in Northwest Washington.

"I was making $600 a week working six days at General Masonry," Graham said. "Now I'm down to $122 a week unemployment. I've got to make it. It's the best I can do. I just hope it (the recession) will end soon."

Everyone else in the housing industry is hoping the same thing, but top officials don't see the situation improving soon.

The Northern Virginia Builder's Association's Johnson said: "The market is going to be off a good 50 percent for the rest of the year. I can't see a return to normal before February 1981."

As grim as they are, the statistics do not begin to tell the story of the recession's impact, according to William Moore, president of General Masonry."We're not dealing with a bunch of numbers," he said. "We're dealing with people, with families. When we tell a man we don't have any work, he has to go home and tell his family. It hurts like hell."

With few new residential construction jobs getting under way, given the uncertainty of the market, suppliers of building materials have been hit hard.

United Materials and Services Inc. of Vienna, which sells items like masonry for building, has decided to close down its seven-person Baltimore office, according to sales vice president Joseph Sumler. The firm's residential business is down 60 percent, and only a surge in commercial work has prevented overall sales from falling below 35 percent, he said.

Belt-tightening has extended right up to the office of President John F. Cissel. When his secretary left of her own accord, no one was hired to replace her.

We haven't replaced her," said Sumler, "and we won't."