Bio-Defense Research Group Inc., a Columbia start-up, is betting that memories of the anthrax scare that focused so much attention on air-circulation systems in big buildings will help sell its sole product, a device that it says not only kills anthrax but also disables a variety of germs and even radiation.

The company is testing prototypes of the device, which zaps airborne threats with ultraviolet light as they pass through heating and cooling ducts, but executives said they expect to begin selling it by the end of the year.

The device would have saved millions of dollars in cleanup costs at the Brentwood postal facility in Washington, which processed two letters containing anthrax spores in the fall of 2001, said Jefferi K. Lee, the company's president and chief operating officer.

Lee sees a wide market for the product, called PathAway, beyond organizations worried about terrorist threats. Hospitals, buildings with mold spores, hotels, sports arenas, cruise ships and schools are all places where people are packed close together and likely to pass on germs.

The company says its system neutralizes airborne pathogens by assaulting them with ultraviolet rays that destroy their DNA or make them incapable of multiplying. Lee said the product has achieved a 100 percent neutralization rate for anthrax spores in tests using a government-approved bacterial stand-in for anthrax.

Preston D. McGee Sr., 38, the chief executive, founded the company in October 2002 after successfully bidding for a license to develop the technology for commercial sale from the Applied Physics Laboratory at Johns Hopkins University. McGee, who has a doctorate in biotechnology, developed protocols for vaccines against biological weapons while a scientist at the Defense Department, according to Lee.

The company is negotiating with venture capitalists, but so far McGee has raised the firm's $2.5 million in funding entirely from himself, family and friends, Lee said.

Bio-Defense has only sold one unit so far -- to the lab at Johns Hopkins for further testing. Scientists there are doing further testing on Path-Away. Lee said the company is in talks to sell the product to other companies and the Defense Department.

President Jefferi K. Lee thinks PathAway, Bio-Defense Research Group's product, will appeal to a wide market.