What actually happens to the tire tread as it wears out, and is it harmful? – Jalopnik

Many people tout electric vehicles as a great way to reduce tailpipe emissions – because they produce no emissions themselves – but it turns out that the advent of electric vehicles is putting a new focus on a different kind of pollution – the kind that comes from your tires. As you drive a car, the relatively soft rubber of your tires breaks down against the hard surface of the road, releasing microscopic particles into the air and water. From there, they can follow an easy path to the animals and plants that live in that environment, including humans.

This is a growing area of ​​research, so there is still debate about the amount of damage these particles cause, but the early data doesn’t look good. For example, a recent review published in the journal Toxic substances found that research shows tire pollution can lead to “significant or harmful adverse effects on the organisms studied.”

There’s a lot too, and as mentioned, electric cars are responsible for more than their fair share. The average passenger car tire can lose about 6 to 9 kilos of rubber during its lifespan, and that lifespan is drastically shortened by the high weight of electric vehicles. Some people say that Rivian tires only last 6,000 miles before they need to be replaced. In contrast, the potential for these adverse effects may last much longer.

Natural rubber is extracted from the sap of certain trees and is considered both biodegradable and compostable. Yet the rubber in today’s tires is 40% natural and 60% synthetic, the latter ultimately being made from petroleum. So it contains hydrocarbons that, when released with tire particles, are toxic to plant and animal life and have been shown to cause cancer and birth defects. Just for your information, the connection between petroleum and hydrocarbons means that tire particles are a huge source of microplastics. And this is evident from an article published in the Journal of Environmental ManagementTire particles represent up to 90% of the microplastics washed from roads by rainy weather, and – looking at microplastics in soil and water – around 45% could come from tire pollution. The cabin of your car is also a hotspot for microplastics.

A further report published in Environmental research found a whopping 2,456 chemical compounds when tire rubber was examined. One of the most dangerous was a hydrocarbon called 6PPD; When released into the atmosphere through tires, it can combine with the ozone in the air, causing a chemical reaction to produce 6PPD quinone – which has proven fatal to salmon and has now been linked to neurological problems in humans. PAHs (polycyclic aromatic hydrocarbons) are among the other nasty ingredients in tires, posing a “significant hazard to human health and welfare,” as reported in Chemosphere. Oh, and the largest non-rubber material in tires is carbon black, or soot, which is classified as particulate matter – which in turn is associated with four million deaths a year.

Tire manufacturers are well aware of the problem and many, like Michelin, are doing something about it. This is evident from a recent study by the German Automobile Association ADAC subjected the French brand’s products to a comparison test of 160 tires and discovered that Michelins emit on average 28% fewer particles than the competition. It’s the result of a new, sharper focus on reducing wear, although you may not find this in every Michelin tire brand. Continental is another company investing in ways to reduce tire wear, claiming its tires lose 11% fewer particles than its rivals. On the other hand, some materials used to reduce tire wear can introduce their own harmful chemicals.

Complicating matters is that tires do not emit particles to the same extent throughout their lifespan. Data collected by Swedish automotive technology company Nira Dynamics suggests that brand new tires start emitting quite high levels of particles as they wear through the outer layer of rubber left over from the manufacturing process. The particle level gradually decreases until about 40% of the tread is gone and remains fairly consistent until about 60% of a tire’s life is gone. Once 70% of a tire’s tread is gone, particulate levels begin to rise and can increase by 200 to 300%. Worse still, because the particles from older tires are smaller, they are more dangerous because they can more easily penetrate further into the human body. It’s no wonder scientists call tire dust the “DDT of our generation.”