New method for anthrax decontamination developed

In October 2001 letters containing anthrax spores were mailed to several news media offices and two U.S. senators, killing five people and infecting seventeen others. Clearing the Senate office building of the spores with chlorine dioxide gas cost $27 million, according to the Government Accountability Office (GAO). Cleaning the Brentwood postal facility outside Washington, D.C. cost $130 million and took twenty-six months.

Now there is a cheaper way to decontaminate a building after an anthrax attack. Georgia Tech Research Institute (GTRI) scientists, in collaboration with Stellar Micro Devices (SMD)of Austin, Texas, have developed a rapid, nondisruptive and less expensive method of decontaminating bioterrorism hazards. The researchers

created flat panels which produce X-rays and ultraviolet-C light to kill anthrax spores within two to three hours without any lingering effects. The technique also kills spores hidden in places like computer keyboards without causing damage. “This is certainly an improvement over previous techniques,” said Brent Wagner, the study’s principal investigator who is principal research scientist and director of its Phosphor Technology Center of Excellence (PTCOE). “The UV-C attacks spores on surfaces and the X-rays penetrate through materials and kill spores in cracks and crevices.” X-ray irradiation is used commercially to sterilize medical products and food by disrupting the ability of a microorganism to reproduce. UV-C also prevents replication, but both types of radiation can penetrate the outer structure of an anthrax spore to destroy the bacteria inside.

The current decontamination standard — chlorine dioxide gas — kills microorganisms, but cannot reach hidden spores, the scientists said. After its use, hard surfaces must be cleaned with liquid chlorine dioxide and people cannot re-enter a fumigated area until the gas is neutralized with sodium bisulfite vapor and vented.

The new decontamination system resembles a coat rack with radiation modules arranged on rings at various heights that face outward to broadcast radiation throughout a room. Since the X-rays and UV-C are lethal at the flux densities used, the system operates unattended and is turned on outside the affected space. UV-C light in the modules is produced using the optical and electrical phenomenon of cathodoluminescence. Numerous electron beams are generated by arrays of cold cathodes, each acting like the electron gun in a cathode ray tube. “When an electron beam hits a powder phosphor, it luminesces and emits visible and/or non-visible light,” explained Hisham Menkara, a GTRI senior research scientist.

GTRI became involved in SMD’s