A new areawide coalition of business and labor groups to find methods of cutting health costs was announced yesterday, making Washington the 126th city in the nation to mount such an effort.

The new effort, called the National Capital Area Health Care Coalition, was unveiled at the local headquarters of the U.S. Chamber of Commerce, which is promoting such groups as ways of reducing corporate costs.

The coalition, a year in the making, has 97 members that pay $100 a year. The area's largest buyer of health insurance, the federal government, is not yet a member, noted Jan Ozga, director of the Chamber's clearinghouse on the nationwide coalitions, which he said began forming in the last two years.

A local office of Peat, Marwick Mitchell & Co., has given the group office space, and the group's director, Jim Brooke, is on loan from his job at C&P Telephone.

Private efforts to control costs are necessary, said John Gentleman, executive vice president of Martin E. Segal & Co. in Washington. Gentleman said that business and labor, which provide 96 percent of group health insurance in the country, have seen premiums increase about 15 percent each year, and double every five years.

"During the last two decades, the cost of health care rose more rapidly than the overall rate of inflation," said Gentleman.

Some solutions Gentleman suggested included the imposition of higher deductibles than those of $100 that were standard in policies written in the 1950s and '60s, partial payments by individuals on all health services, audits on hospital charges to make sure services were performed and were necessary, and greater use of home health care to cut down dependence on hospitals.