The Caryatides are smiling at the gas lines. A wan smile.

The ladies, who have been supporting the marble roof of the Erectheum on the Acropolis in Athens for 2,390 years now, have gone through a lot - Venetian artillery fire, the indignity of fronting for a Turkish harem and counterproductive preservation efforts, among other things.

But nothing has damaged their strking beauty as much as the ever increasing air pollution.

Only one of the six Caryatides - the one the British ambassador to Turkey, Lord Elgin, abducted in 1810 - has managed to keep her looks. Jolly good care in the British Museum you know.

Her five sisters are being put into the Athens museum for geriatric attention as soon as their stand-ins are ready.

But diminishing oil consumption - if that is what the fuel crisis will lead to - many at least contain the catastrophic damage air pollution is inflicting on the Acropolis marbles, the main stay of Western civilization.

"There is no question," says John E. Yocom, chief engineer of the Research Corporation of New England, "that this problem now has the full attention of the Greek government and the scientific community, as well as specialists concerned with the preservation of art works. But the effort to protect the Acropolis is almost entirely protection and preservation.

"The problem is broader: Greece needs comprehensive environmental planning and protection."

Yocom, writing in a recent issue of the "Journal of the Air Pollution Control Association," does not blame all the damage on the poisonous emissions of accelerating automobility. It started about a hundred years ago, he asserts.

"In 1938, a photograph was taken of a portion of the frieze on the Parthenon and compared to a plaster cast on the same section made in 1802. This plaster cast showed that only minor damage had occurred during 2,240 years of the frieze's existence. The (frieze in the) photograph, on the other hand, was almost unrecognizable because of the rapid deterioration during the intervention 136 years of increasing industrialization." Yocom reports.

Specifically, the damage results from the impact of sulfur dioxide combined with moisture on calcium carbonate, the chemical substance of marble. Most of the sulfur oxides come from burning oil for heating in the densely populated Athens area.

The use of heavy fuel oil with as much as 3.5 percent sulfur has now been outlawed in Athens. Preservationists also propose that all new houses and all houses in the immediate vicinity of the Acropolis be heated electrically or by solar power. They also urge that gasoline-powered trucks and cars be banned from the area.

Such proposals, however, are as much in conflict with conventional notions of growth and progress as anywhere else. That is why a real oil shortage seems a more realistic hope.

Another source of corroding air pollution, according to Yocom and Greek scientists, is iron in the air. The iron comes in part from steel mills and other heavy industry in Piraeus, the harbor of Athens, and in part from reinforcing pins stuck into the marble during well-meaning preservation efforts earlier in this century.

There are a lot of iron pins in Parthenon, which had remained almost entirely intact - surviving use both as a Christian church and a Turkish mosque - until, on Sept, 26, 1687, Venetian artillery attacking the Turk-held Acropolis scored a direct hit. It made a greater bang than the Venetians intended, because the temples were used as a powder magazine.

The Turks subsequently sold a good part of the ruins as "souvenirs." Lord Elgin bought - and thus saved - many of them.

He also carried away one of the Caryatides and replaced her with a plaster cast. In exchange, Elgin sent the city of Athens a town clock. The clock somehow got lost, however.

The Erechtheum, which is guarded by the Caryatides, is the most venerated temple on the Acropolis and generally considered the finest example of Greek Ionic design. It also got more iron pins than the rest.

Built in 421 B.C. of Pentelic marble, the Erechtheum is complex in plan, featuring two levels and three porticoes. Originally dedicated to Athena Polias, Cecrops and Erectheus, it was subsequently used as a Byzantine church and then as a harem for the Turkish commandant of the Acropolis.

Now it is cracking.

The steel posts inserted earlier in this century to relieve the Caryatides of the weight of the roof have corroded to such an extent that the entire porch is in danger of collapsing.

Following an international meeting to save the temple in 1977, the Greek government is now hard at work to reconstrct the porch with replicas of the original Caryatid now in the British Museum. They will be cast in cement mixed with marble dust. The impostors are to hold up a titanium beam.

If mixing, the cement and procuring the titanium should take too long reports Yacom, the old ladies will be temporarily enshrined in a transparent, air-tight enclosure filled with conditioned nitrogent.

I am sure they would rather move to the Acropolis Museum to conemplate the follies of the new gods of technology. CAPTION: Picture, The Acropolis, damaged by pollution