HAVE YOU ever wondered how the PLO's Yasser Arafat always manages to appear with a week-old growth of beard that mysteriously never grows any longer?

Are you aware of Russia's secret plan to attack our cities with missiles armed with condemned Pintos as warheads, "pinpointed to land on . . . every major expressway, tying up traffic for miles"?

Have you heard about Drowning, "the new bimonthly publication devoted to people who can't swim," the only magazine that fulfills "your desire to learn more about what happens when you sink to the bottom of the sea"?

If not, then you've somehow missed several of Art Buchwald's columns during the past few years, a grievous educational gap you can now correct with his latest compilation. But why read old Buchwaldia (1978 through early 1981) when you can read his new pieces in any of 550 newspapers worldwide? Because, aside from being entertaining, a collection of Buchwald's columns forms a unique social history, conveying the essence and spirit of our times more accurately than any dry analysis of current events.

Buchwald hears with perfect pitch the babble of cockamamie politicians and bureaucrats, the twaddle of assorted "newsmakers," and the cacophony of our latest fads, trends and media hype. Who else could give us the National Hydrogen Bomb Lobby: "We are only advocating ownership of hydrogen weapons by law abiding citizens. If someone commits a crime with one, he should get a stiff jail sentence."

An Environmental Protection Agency official defending the lowering of smog standards: "When we set certain anti-pollution standards we expect Americans to live up to them. If they're going to get sick even after we've announced that these standards are perfectly safe, it's their fault not ours."

A conversation with the Great Exalted Economist (he wears Pierre Cardin robes and lives in a mountain top cave) who explains how to deal with inflation: "We can do many things, but it has to get worse before it gets better.

"That's bad."

"It could be good. If it gets worse before it gets better, it is better than if it gets better before it gets worse."

"I never thought of that."

"That's why I'm an economist."

Stealing his ideas from the newspapers, as he cheerfully admits--"because whatever is on the front pages is far funnier than anything I could possibly make up"-- Buchwald manages with startling consistency to turn this dross of news into satiric gold. Virtuoso that he is, he makes the devilish job of writing humor look easy. His columns have appeared thrice weekly for so long, in fact, that we take his skill for granted.

Yet, few satirists are as relentlessly inventive and successful with so wide a range of comic techniques. Buchwald attacks his subjects with everything from fabricated memos, letters and first-person narrative to fly-on-the- wall reproductions of imagined conversations. But perhaps attacks is too strong a world because Buchwald's humor is usually affable and mild.

Whether spoofing the availability of mechanical parts for human bodies, ("Look, I just came in for a tune-up. My body's 50 years old and I don't want to put a lot of money into it") or giving us a New Yorker's suggestion that nuclear wastes be dumped in New Jersey ("We'll throw it out the windows of the Metroliner at night when no one is looking"), Buchwald is always good for a chuckle.

But long-time readers who remember his stinging lampoons on the premises of the Vietnam war know he's at his best when he's morally outraged at some new hypocrisy or cruelty. Given a clear target, Buchwald forgoes the lightweight humor for bitingly funny and thought-provoking satire.

Remember when the Reagan administration said it could support "a moderately repressive autocratic government which is also friendly to the United States"? Buchwald put that in perspective by creating a conversation between ambassadors from MRAG countries:

"They're finally making sense in Washington. As I see it, as long as we torture our opponents in moderation, and repress our people for their own good, and only shoot the people who deserve it, we can have good relations with the United States again."

"Colonels, I don't know about the rest of you. But as head of the Moderate Repressive Junta, I recommend we give human rights a try."

Or perhaps you remember Voting Day 1980? Buchwald ingeniously cast it as a Death Row scene, with the condemned voter being dragged into the booth:

"Suddenly there was a scream from behind the curtain.

"McNally had pulled the lever for one of the three presidential candidates, and his scream would be remembered by everyone in the room for the rest of their lives."

Like his previous collections this isn't a book to read straight through. There's no unifying theme, no pacing, and no development beyond what fits into Buchwald's standardized word count. The columns simply follow each other with no connective commentary or dates as though they'd been randomly clipped and pasted up. Still, Buchwald's legions of fans will enjoy having so much of a good thing.y