Turning aside protests from some homeowners that their "quality of life" was threatened, the Fairfax County Board of Supervisors has approved a federally subsidized project that would provide 100 apartments for the elderly in the Burke area.

The supervisors, caught in the middle of a divisive community issue, heard not only from the protestors but from an equally well-organized group of supporters, who said they would welcome the project if its height were reduced to four stories and other concessions made.

In approving the special exception sought by the project's sponsor, the Arlington Assembly of God Church, the supervisors got all the concessions.

Some residents who live near the site said they feared the project would be used not only to house the elderly but drug addicts and alcoholics undergoing rehabilitation.

Resident Burton Rubin, after warning that under federal rules for the hanidcapped, the project might be required to accept drug addicts and alsoholics, said: "We want to keep addicts out of our community."

But Assembly of God attorney Richard M. Millman said: "We are not intending to treat drug addicts or alcoholics. We will not have the facilities for that kind of treatment. . . I think the issue is a red herring."

The most persuasive argument at the hearing, held Monday, may have come from 79-year-old Dorothy Lieberman, who lives in a similar project in Silver Spring. "Some of these days you're going to be senior citizens. . . . It's not always going to be honey as it is now," she told the protestors.

Lieberman, praising the facilities in Silver Spring, added: "I can now live with dignity and respect."

The supervisors, who approved the project 8 to 0, also heard testimony that there are 1,100 elderly on the waiting list for subsidized housing in Fairfax.