Today, during the Great American Smokeout, the world's smokers will spend $1 on cigarettes for every $4 their nations spend on the arms race.

The American Cancer Society, which sponsors the annual smokeless day, estimates that about 30 percent of the nation's 53 million smokers will join the smokeout. The purpose of the day is to improve the nation's health, but cigarettes also cost Americans $21.2 billion last year plus an estimated $15 billion in medical care, lost wages and disability.

About one out of four smokeout participants, perhaps 4 million smokers, will succeed in quitting -- for 24 hours.

But after almost 20 years of anti-smoking campaigns by health authorities and some parts of the American government, the effect on the public has been mixed.

Since the 1964 surgeon general's report first linked cigarette-smoking with health hazards, American consumption has risen from about 500 billion to 600 billion cigarettes a year.

Still, there now are about 33 million "quitters" in the United States and per capita consumption of cigarettes has declined slightly each year since 1974.

Quitting, however, seems to depend on who you are. Women are smoking more, male professionals less. Teen-age smoking, which peaked in the early 1970s, is down. But, among teen-agers, girl smokers outnumber boys about 5 to 4. Smoking among teen-age girls is up almost 50 percent since the late 1960s.

Women still smoke less than men. But as women moved toward working-place equality in recent years, they also appear to have adapted to executive-suite hazards and stresses -- from heart attacks to smoking. Women earning more than $25,000 a year smoke more than any other group of females. Even among health professionals, the number of women smokers is "much higher" than men, according to the surgeon general.

Women now suffer from a higher death rate from lung cancer than cervical cancer. A smoking woman's chances of developing lung cancer -- once thought to be primarily a male disease -- are 8 to 12 times higher than that of a nonsmoking woman.

Stresses such as unemployment and divorce send cigarette consumption soaring. Divorced men top the list. Sixty percent of them smoke. About 55 percent of divorced women partake of the weed. Among unemployed men, the rate is 57 percent compared to a national average of 37 percent.

Smoking patterns have changed in other dramatic ways in the United States. About 65 percent of American cigarette consumption now comes in the so-called low-tar, low-nicotine brands -- a dramatic change from 20 years ago.

While there is some disagreement about the "benefit" derived from the low-tar brands, most researchers believe the health hazard is reduced substantially--assuming the consumer would continue to smoke. Pathologists are beginning to find less tissue damage in autopsies on smokers of low-tar cigarettes. Researchers for the Cancer Society also have found that smokers of the "new" cigarettes find it easier to stop smoking altogether.

But virtually all researchers, except some working for the tobacco industry, agree that quitting is much safer than switching. E.C. Hammond, a Cancer Society researcher who believes the movement to low-tar cigarettes is a major health advance, nevertheless says the reduction in lung-cancer risk is only 20 percent less than it is for other smokers.

So the American Cancer Society is using publicity and hoopla -- an ice-carving contest to produce the best "cold turkey" is scheduled in Pittsburgh -- to get Americans off the habit for 24 hours today.

The American Tobacco Institute said money spent on the hoopla would be better used for research to find what causes a normal human cell to turn cancerous. And throughout most of the rest of the world, where the cigarette habit often is more rampant and the health hazards far less publicized than here, it will be just another day of puffing.

While Americans will be asked to spurn cigarette packets carrying a government health warning, smokers in Taiwan will be encouraged to purchase bright little packages with a different slogan: "Maintain self-respect and self-reliance. Stay calm in the face of adversity."

To stay calm in the face of 24 hours of adversity, the Cancer Society suggests that smokers try everything from lemon drops to carrot sticks to avoid the woes of withdrawal and maintain their self-respect by making it through the day.