Scrubbing Out The Spores

No

one ever pretended it would be easy finding the person or people responsible for the anthrax attacks, but mopping up the messes they have made in post offices and government buildings seemed like a pretty straightforward --if painstaking--business. As the Environmental Protection Agency experts assigned to decontaminate the Hart Senate Office Building are learning, however, cleanup may be the hardest part of the job.

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The biggest problem with sanitizing a structure like the Hart Building is that it's so enormous: nine stories tall and 10 million cu. ft. in volume, with a 100-ft. atrium at its center. Perhaps the most direct way to clean the place is with Sandia foam, a shaving cream-like decontaminant that works by oxidizing and destroying the anthrax spore's outer shell. But it's not clear how you would apply the killer suds to a structure as complex as the Hart, or how you would do it without gunking up computers and other equipment.

Two weeks ago, the Senate leadership announced it had decided to go the gas-bomb route, in which the entire building is sealed off and flooded with chlorine-dioxide gas. The toxic fog would seep into rugs, drapes and anywhere else anthrax may have landed--including the building's own respiratory system, its network of ventilation shafts. But gas, too, has drawbacks, including the damage it can do to artwork and furniture and the fact that it doesn't work as effectively if the temperature isn't maintained at 70[degrees]F and humidity at 50% to 70%. "Doing this on an enormous scale needed a second look," said EPA Administrator Christie Whitman.

The plan got that second look, and it was scrapped--or at least scaled back. Last week the EPA began spreading Sandia foam on a contaminated stairwell and freight elevator. Next, the ventilation system, Senator Tom Daschle's office and perhaps a neighboring office will be treated with chlorine dioxide. Only if tests show that parts of Hart are still contaminated will officials reconsider gassing the whole building.

Even as Senators were being assured that their workplace would soon be safe, postal workers were clamoring for the same promise. Washington's Brentwood sorting facility remains closed until it can be cleaned, and postal employees in New York City filed a suit--which a federal judge rejected on Friday--to have the Morgan processing center, where anthrax also turned up, shuttered and sanitized. Morgan's infected machines can likely be cleaned with foam, but Brentwood, where the anthrax was aerosolized, probably needs a full gas bombing. Unlike Hart, the warehouse-like Brentwood may be a good candidate for building-wide gassing, since it has no carpeting or decorations to damage.

But even the best decontamination may never make a workplace completely safe. CDC anthrax expert Bradley Perkins stresses that eradicating every last trace of anthrax from a contaminated building may be impossible. Below a certain, as-yet-unspecified level, the risk to human health would probably be negligible.

No matter what shortcomings gas bombing has, it does have a few unintended benefits. Toxic as chlorine dioxide is to anthrax, it's also murder on mice, roaches and all manner of other vermin that may elude conventional extermination. But as the gas dissipates, it leaves behind a fine, white powder that looks rather like the contents of the original letter sent to Daschle--the last thing skittish Senate staff members and postal employees want to find on their desks and machinery when they return to work.