About 1,400 federal workers assigned to a Hyattsville building who were given administrative leave Monday and Tuesday to allow for asbestos removal were sent home before closing time yesterday. About 250 had complained of sore throats, tearing, itching and other skin and respiratory ailments, government and union officials said.

Federal officials said they could not immediately determine what was causing the problems in the building leased by the government.

Dale Bruce, a spokesman for the General Services Administration, said the asbestos found in a basement boiler room had been removed but that test levels in the air near the cafeteria exceeded the federal safety standard.

As a precaution, he said, a decision had been made to open windows rather than to turn on the air-conditioning system and fans that might spread the potentially hazardous material. He said the testing would continue.

Bruce suggested people got sick from the fresh air. "With the air conditioning down for four or five days and the windows open," he said, pollens or other "environmental contaminants" could have caused sickness.

The employes in the building work for the Department of Health and Human Service's National Center for Health Statistics and the Treasury Department's Financial Management Services. Both agencies sent their employes home in midafternoon.

"The employes are up in arms," said Ben Carter, vice president of Chapter 202 of the National Treasury Employees Union and a claims clerk at the 10-story building located at 3700 East West Hwy.

According to Bruce Cohen, an epidemiologist who is also chief shop steward for Local 41 of the American Federation of Government Employees, which represents the HHS employes, the building has had a long history of environmental problems caused by fungus on the ventilation system fans.

Bruce confirmed that the ventilation fans had been a problem in the past but said it had been resolved by the building management and GSA. He said the problem occurred because the building's air-conditioning system was not used during the weekends, allowing fungus spores to get into the system.

Cohen said the union asked the National Institute for Occupational Health and Safety two months ago to inspect the building, which the GSA has leased since 1968. No findings have been reported.

It was only recently, he said, that the union learned of the asbestos problem discovered last October as part of a GSA survey of buildings owned or leased by the government. He said the asbestos removal was poorly planned and executed.

Cohen said there is asbestos elsewhere in the basement, and perhaps in the building. "We just don't know the full extent of it," he said.

GSA's Bruce said the October report said "a majority" of the asbestos in the building was in the basement. He said its removal was delayed until after the winter to minimize disruption for the agencies. He stressed that it did not pose an immediate health hazard to the workers.

Cohen said his coworkers who flocked to the nurse's office yesterday suffered from "sick building syndrome." Local 41 President Joe Cook called it "an allergic reaction . . . exacerbated by fresh air . . . . It's not related to the asbestos. It was caused by the shutting down of the ventilation system."