THE HAGUE • Dutch inventors have unveiled what they called the world's first giant outside air vacuum cleaner - a large purifying system intended to filter out toxic tiny particles from the atmosphere surrounding the machine.

"It's a large industrial filter about 8m long, made of steel... placed basically on top of buildings and it works like a big vacuum cleaner," said Mr Henk Boersen, a spokesman for the Envinity Group, which unveiled the system on Tuesday.

The system is said to be able to suck in air from a 300m radius - and from up to 7km upwards. It can treat some 800,000 cubic metres of air an hour, filtering out 100 per cent of fine particles and 95 per cent of ultra-fine particles, the company said.

"A large column of air will pass through the filter and come out clear," said Mr Boersen, speaking on the sidelines of a two-day offshore energy conference in Amsterdam.

Fine particles are caused by emissions from burning wood and other fuels as well as industrial combustion, and have "adverse effects on health", according to the European Environment Agency.

About 90 per cent of EU residents are exposed to levels of such particles - which can be carcinogenic - above those recommended by the World Health Organisation.

As for ultra-fine particles, they are released by emissions from vehicles as well as planes, according to Envinity, and can "damage the nervous system, including brain cells, and also cause infections".

Governments, businesses and airports are already interested in the project, Mr Boersen said.

Another air-purifying system called the Smog Free Tower was installed in Beijing last month and launched by Dutch artist Daan Roosegaarde.

Using patented ozone-free ion technology, it can clean up to 30,000 cubic metres of air an hour as it blows past the tower, collecting more than 75 per cent of the harmful particles.

AGENCE FRANCE-PRESSE