31 Jul 19

Tyre and brake pollution: a new environmental worry

Switching to electric vehicles will not eliminate pollution, according to a new report, which raises concerns over the particulate matter (PM) found in dust created by tyre and brake wear.

The UK Government-commissioned study serves as a warning to fleets that converting to zero emission powertrains will not necessarily mean carte blanche to drive into air sensitive areas.

Tighter regulations have significantly cut the volume of particulate matter (PM) in tailpipe exhaust fumes, prompting governments to look seriously at sources of non-exhaust PM. These include the dust released into the air from brake wear, tyre wear and road surface wear on every vehicle journey.

Water course pollution

When it rains, plastic particles from tyres enter the water stream, with damaging consequences for marine wildlife.

A Norwegian Environment Agency modelling study suggested that a large fraction of microplastic pollution in the Norwegian marine environment originated in from tyres.

And late last year, a report commissioned by Friends of the Earth indicated that vehicle tyres are the single biggest cause of microplastic pollution in ‘surface waters’ – meaning rivers, lakes, wetlands and oceans - in the UK.

Industry standards for testing

This month, the UK Government has called for industry to support the development of standardised methods for measuring emissions from tyre and brake wear, with the goal of creating a new international standard.

“As other emission sources of PM are addressed, it is estimated that the non-exhaust component will increase in importance, growing from less than 8% of national emissions in 2017 to 10% in 2030,” it said.

Thérèse Coffey, UK Environment Minister, said: “It is not just fumes from car exhaust pipes that have a detrimental impact on human health but also the tiny particles that are released from their brakes and tyres. That is why an ambition of our Clean Air Strategy is to address all sources of particulate matter, including those from transport. Emissions from car exhausts have been decreasing through development of cleaner technologies and there is now a need for the car industry to find innovative ways to address the challenges of air pollution from other sources.”

Responding to the Government, Mike Hawes, Chief Executive of the Society of Motor Manufacturers and Traders, said: “Brake, tyre and road wear is a recognised challenge as emissions from these sources are not easy to measure. A United Nations global group, including industry experts and government, is working to better understand, and agree how to measure, these emissions. Maintenance of the road surface, as well as further investment in new vehicle technologies, is essential to reducing these emissions, without compromising safety and we welcome further research in this area.”

EV advantages

Electric vehicles with regenerative braking technology are likely to have lower levels of PM emissions from braking than conventional vehicles. But the heavier weight of battery-powered vehicles could also increase tyre wear.

Further ideas to combat non-exhaust emissions include a reduction in the number of vehicle journeys, a shift to other modes of transport, and road charging to cut congestion (stop start traffic creates more brake and tyre PMs). Improvements in road surfaces and road designs could also reduce the volume of PMs.

Authored by: Jonathan Manning