The asbestos ceilings in six District of Columbia public schools are scheduled to be replaced this year in an effort to eliminate any health threat posed by the cancer-causing material.

The asbestos problems, which are not considered major by environmental experts, are due largely to ceilings in classrooms, closets and corridors where small areas of asbestos have started flaking.

"Three years ago we wouldn't have gotten excited about the small amounts of exposed asbestos we have found," Herbert T. Wood, chief of the Bureau of Occupational and Institutional Hygiene of the D.C. Department of Environmental Services, said yesterday.

"But in recent years, the standards say that any asbestos exposure can lead to a potential problem," Wood said.

In a 1977 annual inspection of the city's 200 public schools for environmental health hazards, officials identified six schools that needed asbestos materials removed.

Those schools are Drew Elementary, at 56th and Eads Streets NE Houston Elementary, at 1100 50th St. NE; Maury Elementary, at Tennessee and Constitution Avenues NE; Richardson Elementary, at 53rd and Blaine Streets NE, Backus Junior High School, at South Dakota Avenue and Hamilton Street NE, and Hamilton Junior High, at Sixth Street and Brentwood Parkway NE.

Although public school maintenance crews have already sprayed all of the exposed asbestos areas in the six schools with a sealant to stop flaking, plans have been made to remove the asbestos materials.

"Whent the problem first came up it was thought that asbestos was only a problem when the particles were airborne," said David Huie, director of buildings and grounds for D. C. public schools. "We went in and sprayed the ceilings to stop the flaking. After more research, they found that once the seal is broken, the hazard remains."

Huie said the school system decided to eliminate the problem by removing the asbestos.

William Jones, assistant director for program management in the D.C. Department of General Services, said the cost of replacing what Huie estimates at between 30,000 and 40,000 square feet of asbestos has not been determined.

The most extensive asbestos removal will be at Richardson Elementary School, where the ceilings will be replaced in eight classrooms, a corridor, two storage rooms and the teachers' lounge.

In other schools only small areas of asbestos will have to be replaced, such as the ceiling in the girls' restroom at Drew Elementary and the acoustical materials in a speech room at Houston Elementary.

Gary Gardner, toxic substances coordinator in Region III of the Environmental Protection Agency, said that absbestos becomes hazardous when the material loosens and microscopic particles fill the air and are breathed in.

"It is estimated that one asbestos particle could take as long as 10 hours to reach the floor from the time it breaks off from the ceiling," Gardner said.

He said that the most frequently used methods of controlling asbestos include installing a new ceiling beneath the asbestos ceiling, spraying flaking asbestos with a sealant, or removing the hazardous ceiling.