11.   Tests are under way to determine whether any of the letters contained anthrax spores or whether some of the mail had been contaminated by other letters.

12.   That report says one of three samples from NAU failed a sterility test, and workers in New Mexico were told the shipment contained live spores.

13.   These cases usually occur in people who handle animal hides or wool that contained anthrax spores.

14.   Three letters containing anthrax spores have been recovered.

15.   Virtually every breath you take contains mold spores, and although some people are more allergic than others, for most of us this is not a problem.

16.   Under laboratory conditions, one breath, containing enough spores, could prove a lethal dose.

17.   Wadsworth was already the destination for most of the powders, stains, scraps of paper or swabs around the state that were suspected of containing anthrax spores.

18.   Zhang hopes equipment could be fine-tuned to determine whether an envelope contains spores and perhaps detect the difference between anthrax spores and more benign powders.

19.   A soldier in combat can easily see if a suspicious cloud contains anthrax spores, sarin nerve gas or other toxic substances programmed into a computer.

20.   But he said it was thought unlikely that the powder contained anthrax spores.