There are no regulations on the wear rate of tyres, and few on the chemicals they contain, yet new research shows eliminating the worst tyres could benefit the environment hugely
Car tyres may represent a greater threat to the environment than exhaust fumes, with a new study suggesting tyre wear produced almost 2,000 times more particle pollution.
Air pollution causes millions of premature deaths annually across the globe, and for years the focus has been on reducing the noxious fumes released from car tailpipes but we should be turning our attention to tyres, say analysts.
Tyres are made from synthetic rubber, a derivative of crude oil, and contain a number of toxic organic compounds, including known carcinogens. As they make contact with the road, they release tiny particles measuring less than 23 nanometres, which pollute the air, soil and water. Tests carried out by independent emissions testing company, Emissions Analytics, reveal that tyres produce more than one trillion of these ultrafine particles for each kilometre driven.
These particles can be inhaled or ingested and enter organs via the bloodstream, making them of particular concern to health. In addition, as the number and weight of cars on the roads is increasing, more particles are being thrown from the tyres as they wear.
“Tyres are rapidly eclipsing the tailpipe as a major source of emissions from vehicles, but the nature of tyre wear is poorly understood,” said Nick Molden, CEO at Emissions Analytics, which carried out the research. “Tyre wear emissions are now more than 1,850 times the tailpipe particulate mass emissions, as the latest petrol and diesel internal combustion engines have become so clean.”
The study was prompted by an initial estimate of tyre particle emissions, which came to a ‘bewildering’ 300,000 tonnes of tyre rubber in the UK and US, just from cars and vans every year, said Molden.
“Tyres vary significantly in chemical composition, and potential toxicity, and so eliminating just the worst tyres could lead to big environment gains.”
Tyre pollution could become a major issue for regulators, but currently there are no regulations on the wear rate of tyres, and few on the chemicals they contain, which can vary substantially. The study has shown low-cost changes could cut tyres’ environmental impact.
“You could do a lot by eliminating the most toxic tyres,” said Molden. “Tyres vary significantly in chemical composition, and potential toxicity, and so eliminating just the worst tyres could lead to big environment gains.”
Battery electric vehicles (BEVs) are considered the environmentally-friendly alternative to fossil-fuelled cars, but their environmental credentials are under scrutiny; they are heavier than conventional cars, so could produce more tyre particles.
“Battery electric vehicles present a particular challenge for tyre wear emissions, as their extra weight and torque can significantly increase emissions, although careful driving and use of regenerative braking can offset them,” explained Molden.
The likelihood is, however, that within the next few years BEVs will become lighter and have comparable weights to fossil-fuelled cars.
Dr James Tate from the University of Leeds’ Institute for Transport Studies told The Guardian that it is very important to note that BEVs are becoming lighter very fast. “By 2024-25 we expect BEVs and [fossil-fuelled] city cars will have comparable weights.”
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