The possibility of contracting Anthrax through the mail has given Americans the jitters. But a small company that builds steam sterilizers for hospitals and research labs may have found a way to foil terrorists' plots using steam. "It's common knowledge that steam penetrates paper," says Arthur Trapotsis, director of research and development at Consolidated Machine Corp., Allston, Mass. "We decided to inoculate some of our mail with a spore-forming bacteria similar to Anthrax used in the medical industry for sterilization testing. We were looking for two things: Can the steam penetrate the envelope and sterilize the bugs inside? And, does the envelope stay intact? The answer to both is yes."

The scheme's success relies not only on moist heat to destroy the bacteria but also on a new filtration device called the Bug Buster that keeps spores from escaping the sterilization vessel into the surrounding room.

Such a filter could allay new fears of dangerous spores on the outside of envelopes becoming airborne during mailroom cleaning procedures that rely on airjets to blow dirt off conveyor belts.

"People don't necessarily need to worry about their mail," says Trapotsis. "All they have to do is run it through one of these sterilizing machines every morning, just as hospitals run medical instruments through everyday. These machines are very efficient and will make mail and packages free of bacteria."