Last Updated

03 Jan 2003

Source: Newsday, November 7, 2001.

AMERICA'S ORDEAL

Inhalation Anthrax Disperses

By Earl Lane, WASHINGTON BUREAU

Washington - As federal officials try to find the best method to rid the Hart Senate Office Building of anthrax spores, some experts say it is not necessary to sterilize every nook and cranny of the million-square-foot building.

The small, easily breathable spore particles that are the most dangerous to human health behave like a gas, according to Michael Osterholm, a University of Minnesota specialist on bioterrorism.

Upon release as an aerosol - as occurred when an anthrax-laced letter to Senate Majority Leader Tom Daschle (D-S.D.) was opened on Oct. 15 - such particles will remain airborne and disperse out of a building within a matter of hours, Osterholm said, via either the ventilation system or natural air circulation.

"Wherever air leaks out, it will get out," Osterholm said yesterday. He said an aerosol with particles in the range of 1 to 5 microns across "is like a perfume. It's in the air. It will float forever." The powder sent to Daschle has been described as pure and finely milled, with many particles in the 1.5 to 3 micron size. (A human hair is about 100 microns wide.)

Larger anthrax particles tend to settle out in a fairly predictable pattern close to the point where the puff of powder was released, according to David Franz, a former deputy head of the Army's biodefense program at Fort Detrick, Md.

"There may be contamination that hangs around," Franz said. But such particles are likely to be larger and pose a risk for skin anthrax, which is highly treatable, rather than the more deadly inhalation anthrax.

The Working Group on Civilian Biodefense, a group of academic, government and military specialists, concluded in a 1999 consensus paper that "decontamination of large urban areas or even a building following exposure to an anthrax aerosol would be extremely difficult and is not indicated."

The authors of the paper, published in the Journal of the American Medical Association, cited a U.S. Army study that concluded that the resuspension of airborne anthrax spores, once they have settled to a surface, is not a significant risk to personnel, even in areas contaminated by a million spores per square meter where trucks and helicopters are active.

Investigators have not disclosed the number of positive findings of anthrax spores within the Hart building nor the size of the spores involved. But they have described the general locations where spores have been found, including Daschle's office suite on the 5th and 6th floors of the building; a freight elevator; a ventilation duct on the 9th floor and a stairwell between the 8th and 9th floors.

"We have done remediation in isolated areas," said Lt. Dan Nichols of the U.S. Capitol police force. Workers used an antibacterial foam on Monday to clean the freight elevator and the stairwell, Nichols said.

The federal Environmental Protection Agency, charged with doing the cleanup, has been considering use of chlorine dioxide gas to fumigate the entire building. A peer review group from industry and academia raised concerns over the weekend on the scope of the job and some unanswered questions.

Daschle told reporters yesterday that "the EPA has advised us that the original plan to gas the entire building is not one that they now subscribe to." He said the gas will be used to clean up his suite and that of Sen. Russell Feingold (D-Wis.) as well as the heating and ventilation system. The antibacterial foam will be used for other "hot spots," Daschle said.

Osterholm said he is concerned that an overly aggressive approach to the Hart building cleanup could set a precedent for other facilities. Even when a few spores are found in a building, he and others said, it may not represent enough risk to justify the cost of area-wide decontamination.

Staff writer Elaine S. Povich contributed to this story.