After delay, workers fumigate Senate building again

Letters addressed to two U.S. senators contained dangerous amounts of anthrax.

WASHINGTON (CNN) -- Health workers began their second attempt late Friday to fumigate portions of the Hart Senate Office Building, more than two months after it closed because of anthrax contamination, an EPA spokeswoman said.

Workers had planned to begin fumigating the ventilation system in the building's southeast quadrant at 10 a.m. on Friday, according to Lt. Dan Nichols of the U.S. Capitol Police. But officials halted the process because the humidity level in the building was not high enough to carry the gas.

The fumigation work finally began around 5:30 p.m. EST, and was expected to continue for another 24 hours.

An attempt nearly two weeks ago to neutralize the anthrax spores in the heating, ventilation, air conditioning (HVAC) system had to be aborted because of a mechanical problem.

Under the direction of the Environmental Protection Agency, chlorine dioxide gas was pumped through the ventilation system, but a mechanical error kept the gas saturation from reaching proper concentration levels necessary to kill the anthrax.

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Other areas of the building were fumigated at the beginning of December.

House Minority Leader Richard Gephardt said earlier this month the anthrax problem in the Hart building "was more serious than any of us thought."

"I'm told by the experts that it's going to take a long time to make sure that all the spores are out of the building," he said. "And even when they're at that point, there'll still be the possibility of spores being left behind."

The EPA will take environmental tests of all the offices before the building is reopened, which they still hope will happen by the end of January.