Amsterdam  - Dutch scientists have invented a fine dust reduction system that could improve urban air quality substantially.

Speaking to the German Press Agency dpa, Bob van Ursem, director of the Botanical Gardens of Delft Technical University, said the electrostatic system he has developed drastically reduces fine dust concentrations.

Air quality in metropolitan areas is polluted by dust and car exhaust fume particles, contributing to asthma and allergies. Reducing air pollution could therefore improve public health. Van Ursem and colleagues Jan Marijnissen and Rijn Roos recently launched the first large-scale test of their invention which in 2008 won the Intertraffic Innovation Award.

The three scientists, Dutch builder BAM and the Dutch government's Air Quality Innovation Programme placed the system in the 1,460-metre-long Thomassen tunnel near Rotterdam. After three months they will analyse to what extent their invention has cleaned up the air inside the tunnel.

Van Ursem, who is trained as a chemist, a biologist and a physicist, says the system "simply follows the basic rules of electricity. We create an electrostatic roof above or across highways and subsequently charge the fine dust underneath," he explains.

"By charging the particles, one can manipulate and control the fine dust."

Passive screens connected to earth at the roadsides are subsequently used to collect the dust repelled by the charge, removing a substantial part of the fine dust from the air.

"I developed my idea after watching the interaction between dust and dune plants," Van Ursem says. "I saw how dust dwelling in the air was drawn towards these plants. This made me think that perhaps electrostatic fields might be involved."

During tests, the researcher says, dust reduction results have been better than expected.

"In laboratory testing circumstances we have achieved a fine dust reduction of nearly 100 per cent," Van Ursem says.

The scientist, who has several other patented inventions on his name and has won a number of prestigious international awards, says the result of the ongoing test in the Thomassen tunnel may have different results.

"It is the first large-scale experiment," he emphasizes, "so I will be cautious."

The electrostatic set-up in the Thomassen tunnel consists of two sets of 24 aluminium racks attached to the tunnel walls. The 'active' racks attached to the left wall of the tunnel are equipped with a high-voltage power supply and two barely visible metal wires that carry an electrical charge. The 'passive' racks are affixed to the right wall with wire mesh stretched across them.

The wires on the active racks give the fine particles a positive electrostatic charge. These charged particles are then attracted towards the 'passive' racks, where they attach themselves.

"The dust will pile up and ultimately form a solid mass, that you can scrape off or clean using brushes and water," says van Ursem.

The scientist says that if proven successful, his invention could be a "major solution for big cities, industrial parks and motorways," particularly because "it is so versatile it can be adjusted to fit any city setting."

Van Ursem says his work has already raised interest from all of the big Dutch cities as well as Mexico City, Dubai, London, Berlin and Singapore. "From a technical point of view, the system is ready to be implemented starting next year," he says. (dpa)