Illuminating end for germs
Chemists in France have devised a method to kill bacteria in flowing air in an attempt to combat diseases like SARS in high-risk areas such as hospitals and commercial aircraft.
Valérie Keller and colleagues at the Louis Pasteur University in Strasbourg have designed a purification method using titanium dioxide, a powerful oxidising species that damages microorganisms when illuminated with UV light.
This photocatalytic reaction has already been effective in water-based systems but this is the first example of it being used for photokilling gas-phase bacteria.
Keller's group designed a vessel where contaminated air passes over the illuminated photocatalyst at room temperature. The process was extremely efficient and removed over 99 per cent of the contaminant Escherichia coli from the air stream. This non-pathogenic bacterium was chosen as a model for the system because of its similar size to Legionnella pneumophila, the microorganism that causes Legionnaires' disease.
The worldwide reaction to the recent SARS epidemic in Asia illustrates the level of public concern about the spread of disease by airborne agents. The next step is to test the ability of the new method to remove viruses like SARS and pathogenic bacteria from the air stream.
The purification process has the potential to replace existing industrial-scale purification methods of filtration, thermal treatment and disinfection with chemical agents. 'We need to treat larger volumes of flowing air contaminated by the biological agents [to meet industrial requirements],' said Keller.