The technology is being rolled out to all of the U.S. Postal Service's 283 distribution and processing centers by the end of 2005 in response to terrorism concerns and to the fatal attacks of late 2001, when anthrax was sent through the mail.

With 1,000 employees, the Cincinnati processing center on Dalton Avenue in the West End is one of the largest in the United States. It handles 7 million to 9 million pieces of mail a day for portions of Ohio, Kentucky and Indiana.

The biohazard detection system goes online Saturday. Cincinnati is the 35th distribution and processing center to be equipped with the technology.

"Three years ago, we never thought that we'd have to become experts in biohazardous material, but that's the reality of the world we live in," said Ray Jacobs, a spokesman for the postal service.

As letters speed through sorting machines and pass under an air collection hood, air samples are transmitted through a hose to a cartridge to see if they match the DNA of anthrax spores.

If anthrax were detected, the mail center would be shut down. Emergency responders - Cincinnati fire, police and public health officials, including the FBI - would be called to isolate the contaminated mail.

Fifteen U.S. postal centers, including one in Cleveland, were equipped with the biohazard detection system at a cost of $3.7 million last year as part of a pilot program. The system has not picked up any trace of anthrax at those sites.

The program is expected to cost up to $600 million by the end of 2005, when all postal centers are equipped, Jacobs said.

Postal officials acknowledge that the system is not perfect:

• It cannot prevent anthrax attacks - only detect them.

• The test recognizes anthrax only, at least for now. Plans call for updating the technology so that it can detect other dangerous pathogens, but officials have declined to discuss which ones.

• The biohazard equipment is designed to test only first-class mail collected from mailboxes.

• While the system collects air continuously, testing is conducted once every hour, meaning that an anthrax letter could slip by unnoticed for a short period and contaminate part of the building.

E-mail mleingang@enquirer.com