Research: Electric, hybrid and other eco-friendly cars fill the air with as many toxins as dirty diesel vehicles, scientists have found (file photo)

Electric, hybrid and other eco-friendly cars fill the air with as many toxins as dirty diesel vehicles, scientists have found.

The greener alternative produce more tiny particles from tyre and brake wear because batteries and other parts needed to propel them make them heavier.

It happens because when eco-cars accelerate or slow down the tyres and brakes wear faster, in turn producing more particulates. More particles are also whipped up from the road surface because of the extra weight.

These extra emissions are almost equal to the toxic particulates saved by reduced engine use, according to Jonathan Leake at The Sunday Times.

The research, led by Peter Achten and co-author Victor Timmers of Edinburgh University, is published in the journal Atmospheric Environment.

Achten said: 'We found that non-exhaust emissions, from brakes, tyres and the road, are far larger than exhaust emissions in all modern cars.

'These are more toxic than emissions from modern engines so they are likely to be key factors in the extra heart attacks, strokes and asthma attacks seen when air pollution levels surge.'

The research used technical data from the motor industry and government research agencies, including direct tests of brake, tyre and road wear rates.

The aim was to show that non-exhaust emissions a vehicle produces its directly related to its weight.

Scientists found that electric and eco-friendly cars weighed around 24 per cent more than conventional vehicles, a discovery that linked to anecdotal complaints from greener car owners that their tyres wear out faster.

A leading professor at the University of Hertfordshire, Ranjeet Sokhi, also led a study into the impact of non-exhaust emissions.

After installing particulate air pollution monitors in the southbound Hatfield tunnel on the A1(M), which has 49,000 vehicles a day travelling through it, scientists found that each one produced 34-39 micrograms of particles per kilometre. But only a third came from the engine.

The greener alternative, including hybrid cars (similar to the one pictured), are said to produce more particles from tyre and brake wear because batteries and other parts needed to propel them make them heavier

HOW THE WEIGHT OF CONVENTIONAL CARS COMPARE TO ECO VERSIONS Model Volkswagen Golf Fiat 500 Ford Focus Smart coupe Toyota Prius V Petrol/diesel version 1,390kg 1,149kg 1,500kg 820kg Hybrid petrol/electric Eco-car version 1,617kg 1,427kg 1,719kg 1,055kg 1,514kg % Difference +16.3% +24.2% +14.6% +28.7% N/A Source: Journal Atmospheric Environment Advertisement

Everything else was from small pieces of bitumen whipped up from the road, rubber from tyres and brake dust.

Professor Sokhi said the findings highlighted the significance of non-exhaust emissions and a need for legislation.