The number of people in the District who smoke cigarettes has declined dramatically, according to two new studies, a development that health officials described yesterday as a major accomplishment.

They said that the greatest decrease in cigarette smoking, the single most important preventable cause of death in the city and in the nation, is among black residents, particularly among black men.

"All the jumping up and down, all the screaming, all the educational efforts have paid off . . . people are really listening" to anti-smoking appeals, declared Georges C. Benjamin, D.C. commissioner of public health.

The studies, by the federal Census Bureau and the D.C. Commission on Public Health, indicated that cigarette smoking has been decreasing here and in many other parts of the nation since the mid-1980s, but the decline in the District appears to be the most striking.

The D.C. study is based on telephone interviews conducted by Benjamin's department in keeping with survey techniques developed by the federal Centers for Disease Control in Atlanta. That study concluded that there were about 20,000 fewer cigarette smokers in the District in 1989 than in 1985.

City officials said they sampled about 1,500 residents each year in their smoking surveys.

The federal study, a part of a national look at cigarette smoking trends, is based on personal interviews conducted by the Census Bureau for the National Heart, Lung and Blood Institute.

That study measures the "quit ratio" by determining how many cigarette smokers throughout the nation have actually quit smoking.

About 53.5 percent of the District's adult smoking population had quit smoking at the time of the 1989 study, officials said. That was a dramatic improvement over the 1985 figures, when only about 31.8 percent of the District's adult smoking population had quit cigarettes. No state recorded a change of that magnitude.

"Having these two studies come out together, both showing a decline in cigarette smoking, that is cause for great celebration," said Marc Rivo, a deputy administrator in the health department. Rivo is the coordinator for tobacco prevention and control in the District.

Cigarette smoking among blacks in the District has long been blamed as the major cause of a sharp disparity between the health of the city's blacks and whites.

Benjamin said that he could envision a "narrowing in the black-white health gap" if the current trend continues.

Virginia and Maryland also have experienced a decrease in the number of people who smoke cigarettes, but the changes there have not been as dramatic as in the District, the studies indicated.

Health officials in both states hailed the continued decrease in cigarette smoking.

In Virginia, Linda Redman, director of health education and information for the state health department, said the health department's telephone surveys in 1989 indicated that about 25 percent of adult residents over age 18 were smoking, compared with about 32 percent in a 1982 survey.

Meanwhile, the number of people who have quit smoking in Virginia continues to rise. The personal interviews conducted in 1989 by the Census Bureau found that about 48 percent of adult smokers had quit smoking that year, compared with about 36 percent in 1985. That was the third largest change in the nation.

Redman said that the decline in cigarette smoking among residents of Virginia, a state long tied to the tobacco industry, showed that people there are "no different from people in other states."

In Maryland, John Southard, director of the office of chronic disease prevention for the state health department, said cigarette smoking has been declining significantly there since the early 1980s.

About 35 percent of Maryland adults smoked cigarettes in 1982, according to surveys, Southard said. By 1988, about 25 percent were smoking, he said. Figures for 1989 are not available.

D.C. Health Commissioner Benjamin said that he and his predecessor, Reed V. Tuckson, and other leading health officials, including U.S. Secretary of Health and Human Services Louis W. Sullivan, have fought to educate the public, particularly the black community, about the hazards of smoking cigarettes.

"Tobacco is probably the only legal product that, when used as intended, can kill people," Benjamin said.

One 1985 study published in the Journal of the National Medical Association estimated that cigarette smoking alone accounted for more than 900 District deaths annually.

The telephone surveys of District residents found that about 17 percent of whites smoked cigarettes in 1989, about the same as in 1985, officials said.

The surveys found that 24 percent of blacks smoked in 1989, down from 31 percent in 1985. The decline was greatest among black men, dropping to 24 percent from 35 percent, the surveys found.