Cleanup crews will use liquid chlorine dioxide to clean the nine areas of Daschle's office where fumigation did not kill the anthrax.

CNN: Fumigation largely succeeding in clearing anthrax

Antibacterial foam and chlorine dioxide gel were used to clean those offices.

CNN: Fumigation largely succeeding in clearing anthrax

The report said the hospital had made an "investment in measures to control legionella" including the introduction of a silver and copper ionisation disinfection system, to replace its chlorine dioxide one.

BBC: 'Legionella concerns' remain at Basildon hospital

Diversa, a California biotech, has isolated an enzyme from a volcanic crater in Russia that is now being used to help whiten paper, reducing the need for chlorine dioxide, an environmental pollutant.

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Rupert said the same chlorine dioxide treatment will be used on the building's heating, ventilation and air conditioning system (HVAC), where spores had been found after the letter was opened in Daschle's office.

CNN: Fumigation largely succeeding in clearing anthrax