Bug killer fights airborne diseases

A new device developed to fight bioterrorism will protect office workers and hospital patients from airborne diseases, its US manufacturer claims.

Originally designed to combat last year’s spate of postal anthrax attacks, the virus-killing air cleaner AiroCide TiO2 consists of a tabletop-sized metal box that bolts on to ceilings or walls and runs off mains electricity.

Fans draw in air and potentially fatal airborne spores, passing them through titanium dioxide-coated tubes lit by ultraviolet lamps. When the ultraviolet light strikes the titanium dioxide, it creates positive and negative electrical charges that tear apart water molecules in the air to produce highly reactive hydroxyl radicals.

Plants in space

These disrupt organic molecules and are deadly to dust mites, anthrax spores, tuberculosis bacilli, cold viruses and other airborne pathogens. Any surviving the bombardment by the hydroxyl radicals face destruction by the high-energy ultraviolet rays.

Tests commissioned by manufacturers KES Science & Technology show the unit kills up to 93.3 per cent of airborne pathogens.

The technology is based on another product, Bio-KES, developed in the early 1990s by scientists at the NASA-supported Wisconsin Center for Space Automation and Robotics.

While looking for a way to reduce decay-promoting ethylene in space-based greenhouses, allowing plants to be grown during long missions, the research team found that ultra-thin layers of titanium dioxide exposed to ultraviolet light converted ethylene into carbon dioxide and water, both of which are used for plant growth.

They worked to develop a coating technology to apply titanium dioxide layers to other materials, and in 1995 the first ethylene Bio-KES cleaner allowed potato plants to be successfully grown in space. A third-generation cleaner is now being used in the International Space Station as well as by some grocers and florists to prolong plant life.

But last year researchers discovered the gas removal unit could be modified to kill viruses and bacteria by increasing the number of germicidal ultraviolet bulbs used from six to 52, creating the bio-active hydroxl radicals.

‘The discovery of the AiroCide TiO2 came about by accident, really,’ said John Hayman, president of KES Science and Technology, which was originally licensed to manufacture the Bio-KES units. ‘At a management meeting just after the September 11 attacks, a member of staff asked if we thought the device might be able to kill anthrax.’

Precautionary protection

Shortly afterwards, the air cleaner was born. ‘As the unit has no filter you do not end up with a person in a space suit dealing with a concentrated amount of spores,’ said Hayman. ‘The addition of the ultraviolet light means more radicals are produced, giving the device more kick. In effect the anthrax, smallpox or whatever is fried.’

One AiroCide TiO2 unit can clean 420m3 of air in 24 hours, and can be used in offices to reduce sick building syndrome, as well as in hospitals, operating theatres and immigration holding centres where virulent strains of TB are suspected.

While the unit does not draw spores out of carpets and upholstery, it helps protect individuals from unwitting exposure to diseases, where symptoms may only become apparent when it is too late for successful treatment.

…as UK makes first mobile particle detector

The first portable device for detecting the presence of potentially hazardous ultra-fine airborne particles will be launched in the UK later this year.

Engineering group Radamec Electronic Systems has refined particle detection technology previously confined to the laboratory into a device small enough to fit into the boot of a car.

It will offer the new Ultra-fine Particulate Monitor (UPM) to local authorities, environmental agencies, the automotive industry and others concerned with pollution control.

Bob Doughty, Radamec sales and marketing director, said the UPM was developed in response to growing concern over the presence in the air of particles so small they elude current mainstream monitoring technology.

‘There is increasing evidence about the harmful effects of these particles, which are carried right to the bottom of the lungs where the body’s natural defences are at their weakest,’ said Doughty.

The device, developed in conjunction with environmental monitoring specialist Booker Systems, can detect and count particles as small as five nanometres, even when they are present in very low concentrations.

The UPM grows the particles in a saturated vapour until they become large enough to be detected and counted by the device’s laser-based high-precision optical system.Doughty said Radamec expects the portable UPM to be used to monitor specific areas where there is a high level of traffic or industrial emissions. It could also be used inside buildings or aircraft cabins, where occupational health specialists increasingly regard air quality as an important issue.

Existing detection equipment costs about £60,000, and is so bulky it is impractical to move it outside a laboratory, said Doughty. The Radamec UPM is a 355mm cube weighing a few kilograms and will cost a quarter of the price.

Radamec sees the automotive sector, which is under growing legislative pressure to reduce harmful emissions, as a particularly promising market.

The device has just completed trials at an automotive test centre and is undergoing final modifications by Radamec and Booker engineers.

Doughty said Radamec hopes to manufacture the first units for sale in the commercial market by the end of the year.