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Tires Emit Pollution. And EVs Make the Problem Worse

    • 1793 posts
    November 13, 2022 11:06 PM EST

    The Tyre Collective does not yet have a name for its device. Hanson Cheng, one of the London-based startup’s three co-founders, calls it a “box.” Built to attach behind the wheel of a car, truck, van or bus, it’s designed to capture emissions from an oft-overlooked source: tires.To get more news about car tire, you can visit official website.

    Every vehicle sheds tiny bits of its tires as it rolls, but “where the rubber meets the road” is a bit of a misnomer: The tires on most passenger vehicles contain little natural rubber. Instead, they’re made from a stew of petrochemicals, particles of which ultimately wind up in soil, air, waterways and oceans.
    The International Union for Conservation of Nature pegs tires as the second leading source of microplastic pollution in oceans, and one 2017 study found a global per capita average of .81 kilograms in tire emissions per year, ranging from .23 kg per year in India to 4.7 kg (roughly 10 pounds) in the US. That may seem minor stacked up against the nearly 300 pounds in plastic waste the average American generates each year, but microplastics are tiny by definition — and an insidious source of toxins that researchers are only beginning to understand.
    “When we talk about zero emissions, a lot of that conversation is about electric vehicles,” says Cheng, 30. “But there's a whole world of non-exhaust emissions that also needs to be addressed.”

    Switching to electric cars helps to lower carbon emissions — even after accounting for manufacturing and charging batteries — but it actually exacerbates the problem of tire emissions. EVs typically weigh more and accelerate faster than their gas-burning counterparts, which adds to tire wear. The EV transition will also keep the world’s fleet of cars growing until nearly 2040, well after the peak for gas-burning cars that’s expected in the next two years, according to BloombergNEF, a clean energy research group.
    “Most of these EVs are big monstrous things, so it's perfectly intuitive that they will be chewing up tires faster,” says Nick Molden, founder and CEO of the UK-based research shop Emissions Analytics. Results from the company’s latest road tests, published in May, show that under normal driving conditions a gas car sheds about 73 milligrams per kilometer from four new tires. A comparable EV, the company estimates, sheds an additional 15 milligrams per kilometer, or about 20% more.

    For decades, tailpipe emissions — both the greenhouse gases that contribute to global warming and the particulates that cause air pollution — have overshadowed the tire problem. That means researchers are only beginning to catalog what’s even in tire emissions. Across the different tires it studied, Emissions Analytics found an average of more than 400 organic compounds. “Part of the work we're doing is to try to resolve what on earth these compounds are,” Molden says. “If we can't identify them, then we can't even fathom what the toxicity may or may not be.”

    One landmark study makes the potential stakes clear. In 2020, researchers in Washington state solved a decades-old mystery of why storm runoff was causing mass deaths of coho salmon: 6PPD, a preservative commonly used in car tires. When exposed to sun and air, 6PPD transforms into a chemical called 6PPD-quinone, which turns out to be highly toxic to coho salmon — causing them to circle, gasp at the surface and then die within hours.

    “In our lab it’s usually just one or two hours,” says the study’s lead author, Zhenyu Tian, now a professor at Northeastern University. “In the field, they struggle for an afternoon, and they die.”

    That stark finding set in motion a hunt for 6PPD alternatives that can help keep tires from breaking down in the elements without killing salmon or other fish. In May, California’s Department of Toxic Substances Control announced plans to add tires containing 6PPD to its list of hazardous products, a move that would force manufacturers to evaluate safer alternatives. But there’s no guarantee that the industry will be able to find a workable substitute. “[They] didn't even know that the 6PPD-quinone existed until the Washington researchers found it,” says Anne Cooper Doherty, the DTSC’s head of chemical and product evaluation, adding that it could be years before 6PPD-free tires come to market.

    “Our members are committed to supporting the alternatives analysis work in California,” says Sarah Amick, vice president of environmental health, safety and sustainability at the US Tire Manufacturers Association, a trade group representing a dozen of the world’s largest tire brands.