11.   Officials said they now are testing different methods of treating all mail, including using electron beams, X-ray technology and chlorine dioxide.

12.   Oxygen delignification, they said, not only would have reduced the need for chlorine dioxide in the mills.

13.   She added she was concerned that steam and high levels of humidity in the building needed to make the chlorine dioxide effective might have hurt rare Senate books.

14.   Scientists pumped in chlorine dioxide, a yellow-green, bacteria-killing gas proposed for use in the partly contaminated Hart Senate Office Building.

15.   The gas, chlorine dioxide, is commonly used to sterilize laboratory equipment but has never been used on a whole building, experts said.

16.   The three charges against the Vancouver, British Columbia-based forest-products company all confirmed that chlorine dioxide was spilled into Powell River.

17.   The suite of Senate Majority Leader Tom Daschle was evacuated and gassed with chlorine dioxide after an anthrax-tainted letter was opened in October.

18.   These preparations, which contain bacteria-killing chlorine dioxide, are only available through professionals.

19.   After repeated delays, building was declared safe last week after several attempts to decontaminate it with chlorine dioxide, a toxic gas.

20.   Chlorine dioxide begins breaking down as soon as it is released, while methyl bromide is more stable.