Case Studies

Washington, DC

The Issue: Anthrax Contamination

The Solution: Facility Decontamination with ClO₂ Gas

In October of 2001, a letter containing over two trillion Bacillus anthracis (i.e. anthrax) spores was inadvertently opened inside Senator Tom Daschle's suite of offices in the Hart Senate Office Building (HSOB) on US Capitol Hill in Washington, DC, thereby triggering an immediate evacuation and extended closure of the entire HSOB facility.

Sabre was promptly mobilized to assist governmental efforts in devising a viable remedial treatment solution to widespread anthrax contamination found throughout the Daschle Suite and its complex heating, ventilation and cooling (HVAC) systems after the spore release. A team of scientists and engineers from various Federal public health agencies working with Sabre quickly determined that a fumigation of the entire Suite and accompanying HVAC systems with chlorine dioxide (ClO₂) gas was the best possible means of addressing this dangerous contamination.

Once a decision to fumigate the facility with ClO₂ gas had been made, Sabre's project responsibilities bifurcated into two different roles. One team of Sabre personnel, working in conjunction with the USEPA Emergency Response Team (ERT), designed and conducted a series of pilot-scale experiments to determine the application conditions (i.e. concentration, contact time, temperature and relative humidity) under which anthrax spores would be inactivated by ClO₂ gas.

This research work was necessitated by the fact that ClO₂, although long proven effective as a sporicide in liquid form, had never been utilized as a structural fumigant prior to this occasion.

While one Sabre team conducted ClO₂ application research in cooperation with ERT personnel, a second Sabre team designed and constructed the various processes and equipment that would generate ClO₂ gas and distribute it throughout the Daschle Suite and its HVAC systems to eliminate the anthrax contamination.

After the appropriate ClO₂ application conditions had been established, the generation and distribution processes designed, and the required equipment constructed and put into place, the Daschle Suite and its accompanying HVAC systems were fumigated by Sabre in December of 2001.

Extensive sampling of the Daschle Suite and its HVAC systems following fumigation determined that the Sabre ClO₂ generation and distribution processes had been highly effective in inactivating anthrax contamination previously found in those locations. As such, a unanimous decision was made by the Environmental Clearance Committee (ECC) assembled to review the data that the HSOB was safe for re-occupancy. The facility was subsequently reopened to the general public in early 2002.