An eco-friendly car which can filter dirty air into a balloon hit the streets of London today to clean up the capital's most polluted areas.

The hydrogen car's manufacturers say the vehicle leaves the roads less polluted than it finds them and that introducing 10,000 of the cars would have the same effect as planting 60,000 trees.

A route designed by makers Hyundai saw the NEXO travel through London's most polluted spots including Oxford Street, Park Lane and Marylebone Road.

The Hyundai car's filtration system is claimed to have eliminated 99.9 per cent of the pollutants, emitting them into a trailing balloon.

A 'clean air' demonstration showing Hyundai's new hydrogen fuel cell car, the NEXO. The car's filtration system is claimed to have eliminated 99.9 per cent of the pollutants, emitting them into a trailing balloon

Research from University College London identified the capital's dirtiest roads which contain high levels of pollutants including Nitrogen Oxide (NO2) and Particulate Matter (PM).

The route mapped out by Hyundai and UCL - covering the city's most polluted areas - starts in Bow and crosses the river into south London.

It goes past Elephant and Castle and into the centre of London, passing Marylebone and Westminster before heading along the Thames and back to the East End.

The three worst spots on the route were Marylebone Road, the corner of Oxford Street at Marble Arch, and Park Lane.

Researchers from UCL began by pumping dirty pollutants from a balloon into the vehicle.

The amount of air which passed through the car was equivalent to the total amount of air a typical adult would breathe over 100 years.

The vehicle's air purification system filters 99.9 per cent of very fine dust (PM2.5) and shows the exact amount of air purified on the display panel in the car each time you drive

The dirty particles were then filtered out through the car's filtration system - which removed 99.9 per cent of the pollutants - and emitted into the second balloon.

The vehicle's air purification system filters a very fine dust and reveals the exact amount of air purified on the display panel in the car each time you drive.

When driven for one hour, 26.9kg (59.3 lbs) of air is purified - the same amount 42 adults breathe in an hour.

Sylvie Childs, Hyundai's senior product manager for NEXO said: 'We are all concerned about air quality and what affects it.

'At Hyundai, we are committed to improving the efficiency and environmental performance of all our vehicles and have been investing billions in bringing a full range of low and zero emission vehicles to the market place.

'We believe that the availability of alternatives, like the NEXO fuel cell electric vehicle, will bring the UK closer to its zero emissions future.'

The dirty particles were filtered out through the car's filtration system - which removed 99.9 per cent of the pollutants - and emitted into the second balloon

'However, the responsibility for this cannot only rest with us, the manufacturer.

'We need the government to invest equally in incentives and infrastructure that would enable Brits to have better choices when it comes to the car they drive and how it can fit into their lives.'

Michael Whiteley, senior researcher at UCL's Electrochemical Innovation Lab said: 'The recent report from the Intergovernmental Panel on Climate Change (IPCC) indicates that much more needs to be done to mitigate negative climate change.

'Our research into fuel cell technology has found it to be a promising transport solution to consider as an alternative to fossil fuel dependent cars and battery electric vehicles which have long charging times.

'Our research stretches from fundamental material science to full automotive fuel cell power systems for automotive applications.

'Going forward, we're building an advanced propulsion facility where we will develop and evaluate hybrid, battery and fuel cell powertrains for automotive applications.'