Space Invention May Protect Against Bioterrorism
Germ-killing device zaps anthrax spores inside buildings
THURSDAY, Feb. 7, 2002 (HealthDayNews) -- Technology created to maintain greenhouses in space could have an unexpected benefit -- protecting office workers from a bioterrorist attack.
Researchers have discovered that a device developed to remove a gas produced by plants also destroys airborne organisms such as anthrax.
The device's invention began with the need for developing better plant growth chambers for the space program. Growing plants produce ethylene gas, which makes them mature, but in a confined space too much ethylene could make fruits and vegetables ripen too fast aboard the space shuttle fleet.
In the 1990s, environmental chemistry and technology professor Marc A. Anderson at the University of Wisconsin-Madison discovered that when thin layers of titanium dioxide (TiO2) were exposed to ultraviolet (UV) light, they converted ethylene gas to carbon dioxide and water.
At the Wisconsin Center for Space Automation and Robotics, a NASA-sponsored commercial research institute, Anderson and other researchers at KES Science & Technology Inc., developed Bio-KES for use in fruit and vegetable sections of grocery stores and in flower shops.
Tests showed the device also killed airborne dust mites, and the researchers soon discovered it killed other disease-causing airborne organisms as well.
Pathogens, be it anthrax or other harmful organisms, land on surfaces within the device that are bathed in UV light. The light energizes the surfaces, producing oxidative particles -- free radicals -- that Anderson says may interfere with an organism's cell wall.
The unit is designed to keep organisms within it long enough that they eventually hit one of the randomly arranged TiO2-coated tubes inside.
"The device is fairly long, and there's a torturous path whereby these things are bouncing back and forth between particles," says Anderson. Eventually, they land on the surface of the TiO2 tubes, which he compares to flypaper for disease-causing bugs.
After the events of September 11 and the subsequent anthrax-by-mail attacks, KES Science & Technology decided to boost Bio-KES's ability to remove airborne organisms by installing more powerful UV lights within the device.
Laboratory tests revealed that the new device, called AeroCide TiO2, killed E. coli, Staphylococcus aureus, Streptococcus pyogenes and the bugs linked to the flu, tuberculosis and Legionnaire's disease.
However, in the wake of public concern over bioterrorism, perhaps most exciting was the discovery that it killed between 82 percent and 93 percent of anthrax spores. Anderson explains the device was tested using an organism called Bacillus thurengiensis, a non-lethal cousin of anthrax with the same properties as the deadly organism.
He says the devices remain active until the UV light bulbs burn out. On average, the bulbs last for about nine months each, and the TiO2 tubes don't need to be replaced.
Anderson says the average unit could clean the air in a room the size of a kitchen. However, the units can be modified or grouped together to clean a larger room.
"It would work better indoors and in reasonable confined spaces," says Anderson.
Mark Nall, the manager of the Space Product Development Office at NASA's Marshall Space Flight Center, says it could also be used in office mail rooms, break rooms, conference rooms or other common areas.
"This is a side benefit, which is extremely exciting for us right now, and certainly very timely," says Nall. "It's always helpful to produce something which is useful in homeland defense."
Anderson adds that the AeroCide TiO2 device could also prove useful in improving air quality in building air ducts. He says it filters out vapors from cleaning solvents, carpet fumes and formaldehyde, which is the No. 1 volatile chemical found in indoor air environments and has been linked to Sick Building Syndrome.