A Nov. 2 article on anthrax decontamination of the Hart Senate Office Building incorrectly described the size of the building. The building has a volume of 5 million cubic feet. (Published 11/3/01)

Federal scientists have begun testing an unproven fumigation technique that they hope will be effective in decontaminating the Hart Senate Office Building and perhaps other buildings tainted by anthrax spores.

The Environmental Protection Agency is pumping chlorine dioxide gas into a sealed trailer at the Brentwood postal facility in Northeast Washington at concentrations many times higher than those considered dangerous to humans in an effort to "scope" the gas's effectiveness, said EPA mid-Atlantic regional spokesman Patrick Boyle.

"This has never been used in a large application," Boyle said. "They know it will kill spores, but no one has tried to apply it to a room. There are issues of temperature and humidity, of whether we should do it in stages, or all at once."

Despite practical inexperience, however, research by the Defense Department's experimental arm suggests the gas will work as a building decontaminant, because it has shown "promise" in limited tests against live biological agents, a statement from the Defense Advanced Research Products Agency said yesterday. A DARPA spokesperson refused to identify the agent involved in the tests.

The rush to bring the new technology into play underscored both the nation's sketchy preparation for biological warfare and the need to find a method of coping with it that can work in different circumstances if other buildings around the country need to be decontaminated.

The EPA presented chlorine dioxide as the preferred solution for the Hart Building during a meeting with about 25 senators in the Capitol on Monday afternoon. Boyle said a special review panel led by the Senate's sergeant-at-arms will make the final decision on whether to go ahead with the plan.

The Hart Building was closed after the office of Senate Majority Leader Thomas A. Daschle (D-S.D.) received a letter containing anthrax spores. Contamination was found in at least three other congressional buildings and at Brentwood, which processed the Daschle letter. Two Brentwood postal workers have died from inhalational anthrax and two others have been hospitalized.

Since the initial anthrax outbreak at American Media Inc., a tabloid newspaper company in Boca Raton, Fla., officials have used a variety of localized methods to scour surfaces to eliminate bacteria encased in hardy spores, which are known to retain their virulence for decades.

But the decontamination plan outlined to the Senate is the first attempt to present a method of sterilizing entire buildings without damaging papers and equipment with corrosive liquids.

Chlorine dioxide has been used for almost 60 years as a bleaching agent for wood pulp, and it has gained popularity in recent years as an environmentally friendly way to purify drinking water. The gas breaches the spore walls of pathogens to make it impossible for the bacteria to germinate.

Don Denby, a vice president of Canada-based Sterling Pulp Chemicals, a multinational chlorine dioxide company, said the EPA has tested chlorine dioxide extensively in water and sewage treatment.

The chief advantage of chlorine dioxide is that it kills anything it can reach but does so without creating harmful byproducts. The only residue is a trace of powder-like salt.

"A lot of chemicals could be used [in Hart]," Denby said. "They've looked at different technologies, and chlorine dioxide looked good because they saw the data on drinking water."

The DARPA statement, meanwhile, said the agency had tested chlorine dioxide fumigation because of "a standing interest in developing and demonstrating technologies to make military buildings less attractive targets for bio-chemical attack."

EPA consultant Paul Schaudies said on Monday that there were "laboratory tests" of chlorine dioxide against anthrax bacteria "ongoing this week." EPA sources said DARPA was testing the gas on anthrax at Dugway Proving Grounds in Utah.

As outlined by Schaudies, the fumigation process envisioned by the EPA would take about two weeks. The Hart Building would be sealed off with duct tape and plastic, and a chlorine dioxide generator or generators would be brought into the building.

By using Hart's ventilation system, the generators would raise the gas concentrations to about 400 parts per million and hold them there for two to three days. Effectiveness would be monitored over several days by reading spore strip "markers" impregnated with a harmless bacterium and spread around the building.

Boyle emphasized that the EPA does not know how strong the mixture needs to be. The Brentwood trailer experiments have used concentrations as high as 1,000 parts per million to sterilize mail, he said, a concentration far stronger than any federal standard for danger levels to humans. He said no one will be inside the building during fumigation.

The cost of this procedure is not known; it generally depends on the cost of the chemicals used to generate the gas, Denby said. Also, several sources noted that the Hart Building encompasses 5 million square feet, posing engineering challenges beyond anything yet contemplated.

At American Media, it is still unclear how extensive the cleanup will be, and who will pay. Company officials were planning to meet today with the EPA to ask the government to assume full responsibility. The EPA dipped into emergency "Superfund" accounts to pay for extensive anthrax testing but said this week it never intended to pay for decontamination of private buildings.

Should chlorine dioxide become a standard, easy-to-use biological warfare decontaminant, it would mark a considerable improvement over past anthrax cleanups, which have proven to be extremely complex and have dragged on for years -- and even decades.

In one well-documented case, the British government needed 36 years and 280 tons of formaldehyde to eradicate anthrax bacteria from Gruinard Island, a dot of land off the Scottish coast used in biological weapons testing in the 1940s.

In New Hampshire, workers in protective suits tried spraying with formaldehyde to decontaminate a textile mill that had become infested with anthrax spores from a tainted wool shipment. After the company went bankrupt, federal officials in 1971 razed the building, doused the rubble with bleach and buried it.

Some anthrax experts are convinced that the cleanup this time will be easier. Harvard University biologist Matthew Meselson, who investigated the deadly release of anthrax at a Soviet weapons plant in 1979, said chlorine dioxide has been shown to be effective in controlled scientific experiments. He applauded the decision to use the marker bacteria to "tell if your solution is working."

"It's not just a shot in the dark," he said.

Other anthrax experts said it may not be possible to eliminate spores from every surface in a large, modern office building.

"You can clean up a laboratory, perhaps, but labs don't have things like rugs and computers," said Meryl Nass, a Maine physician who has investigated biological and chemical weapons attacks for the Federation of American Scientists.

"You're not going to get every last spore," Nass said.