Road Pollution Doesn’t Just Come From Exhaust

Alumni from Innovation Design Engineering at Imperial College London and the Royal College of Art want to raise awareness of a road pollution source we rarely consider: tire wear. If you think about it, it is obvious. Our tires wear out, and that has to go somewhere, but what surprises us is how fast it happens. Single-use plastic is the most significant source of oceanic pollution, but tire microplastics are next on the naughty list. The team calls themselves The Tyre Collective, and they’re working on a device to collect tire particles at the source.

Tires become positively charged as you drive, like a Van De Graaff generator, so the team postulates that the most efficient way to collect the waste is to mount electrostatically charged plates where the plastics discharge. Road dust should pass through instead of gumming up the system since it is not charged. In an odd twist, hybrid vehicles are more dangerous regarding this type of pollution than their 100% petrol counterparts since they have to support a battery and electric motor.

When the tire dust is collected, it isn’t dumped out, because it can be reused as a pigment or even refined back into new tires. They’re collecting 60% of thrown particles in a lab setting, and they’re improving. What goes around comes around.

48 thoughts on “Road Pollution Doesn’t Just Come From Exhaust

  1. Tire dust isn’t particularly hazardous for the environment. It breaks down biologically in a few months.

    The problem with most plastics in the environment is that they’re solid macroscopic pieces and micro-organisms that eat the hydrocarbon chains have a hard time getting at it. They can only eat the plastic at the ends of the polymer chains, so the smaller the particle the more the ends of the polymers are exposed, and the quicker it can be eaten. A whole tire thrown in the ditch will take decades to break down, but the same tire ground into dust and sprinkled over the roadside will disappear within 6-24 months depending on the local climate.

    1. Contrary to propaganda, most plastics won’t last more than 2-4 years in the environment. The biggest issue are the plastics with fluorine, chlorine, or PE/PP which take up to 40 years to break down because they have no “natural predators” so to speak. Most other plastics just get eaten after a while.

      1. PLA tends to disappear somewhat quickly.
        PTFE (Teflon) on the other hand lingers for decades…

        The material as you say matters a lot in regards to the question.
        Though, some can leave “gunk” behind that isn’t as good for the environment.
        While other “non pollutants” can cause other issues as well.

        Like dumping tons of sugar into a lake is likely not beneficial to its ecosystem. Even if sugar is easily biodegradable. (Some organisms even use an increasing sweetness in the water as a sign of spring. Plants apparently do leak som of their hard work into their surroundings, especially as other organisms munches on them. So dump sugar into a lake late autumn and things gets turned on its head.)

        1. Well, yes, you dump a load of biodegradable material around and the local ecosystem changes.

          Kinda like how the farm compost pile has different bacteria than without. The question is, so what?

      2. I have never read any credible scientific source that claims that “most plastics won’t last more than 2-4 years in the environment”. Where do you come by that? Why do you say propaganda? Microplastics appear to last a long time in the environment. Get eaten? Hmm. And what do those buggers excrete? I appreciate your posts here but that bit of information raises an eyebrow for me: could you provide one of your sources?

        1. Microplastics are a problem with some types of plastics, because the digestion of the plastic generally happens at the ends of the hydrocarbon chains. Enzymes can’t cut to the middle of the strand, so for very long polymer chains, they simply can’t find the ends from the bulk of the material and the plastic is very hard to break down. However, this only applies to a handful of very resilient types of plastics, such as PP and PE – other types of plastics are actually quite easy to break down. When they tried to make shopping bags out of PCL, they started rotting in the pallets in storage with any amount of humidity present.

          The “buggers” excrete CO2 and water – the result of oxidizing hydrogen and carbon, the basic constituents of plastics.

        2. The information is a little bit difficult to find, since it’s spread around in so many different sources, but for example:

          https://onlinelibrary.wiley.com/doi/abs/10.1002/jobm.19780180305
          Cellophane: “biodegradation rate of 85% after 52 days”
          “The endproduct (30% protein, 60% soluble sugars, 10% residual substrate) will probably be useful as compost.”

          The reason I say propaganda is because the public discussion about plastics is lumping all plastics with things like PVC, PTFE, PP, PE, that do not break down easily, which is branding all plastics as problems, yet most of the disposable plastics we use, such as the rubber in our tires, are in fact biodegradeable and will vanish completely in a couple years.

    2. Will “disappear”? That sounds like a dream come true for plastics manufacturers and if true, i would imagine that they would have proven it. Sounds easy to prove to boot. Please provide sources. I honestly don’t believe it right now. What do you mean by “disappear”? You mean like, “no longer visible” (but still there)? Please explain.

  2. “In an odd twist, hybrid vehicles are more dangerous regarding this type of pollution than their 100% petrol counterparts since they have to support a battery and electric motor.” should probably be phrased to state that they tend to weigh more due to having a battery bank and an electric motor.

    But other than that. Tire wear and particles building up due to that is indeed a rather large source of pollution.
    Though, it isn’t just the rubber on the wheel that gets worn down and spread into the environment, the road surface also wears down. Though, tar covered grit is likely less problematic compared to vulcanized rubber.

    Though, the amount of wear on a tire is also proportional to the contact pressure between the rubber and the road. Ie, a larger heavier vehicle with similar sized contact area will have more wear than a lighter car. (Though, lighter cars tends to have smaller wheels, since if the contact pressure gets too low, then water planing gets really easy… But with smaller wheels, the amount of pollution is reduced through that alone.)

    Then there is also stress related wear when accelerating and breaking. So being in a hurry and also breaking hard is not recommended.

    If this electrostatic device will be the solution to the issue is though a good question.
    And how it handles dirt, mud and snow is another question as well.

  3. A device to collect tire particles? Hm, I would like to see a device to collect tarmac particles! You’d be surprised how quickly tarmac wears out here in the Nordic countries, what with our studded winter-tyres eating at them and the large temperature-swings between winter and summer cracking them.

      1. I’d certainly read the article with great interest. You most likely can’t even imagine how bad the tarmac-dust in the air can get in the spring, when the weather is still too unstable to swap to studless summer-tyres, but there’s also not enough ice and snow on the road to protect it from the aforementioned studs. I mean, it can get *real* bad.

        1. I wonder if this type of system could capture any of it, I doubt it builds up much charge but it probably does some..

          Seems to me like the most effective system is just aerodynamics – have a flow of air over the tyre area, probably filtered by cyclone to deposit the dust – then its just another element to the standard service – empty the catch box. And catching anything massive enough means the catch box is probably going to a great source of all the metals lost from the cat etc – so actually a valuable recyclable resource rather than a significant cost to deal with.

    1. I know a number of States that have banned tire studs and tire chains for that reason.
      ( Colorado still requires truckers to have tire chains available if they are crossing the mountains – OK, it has been 20 years since I lived there, the law may have chainged -pun intended)

      (But I still keep a set of tire chains in my vehicle during the Winter. I will mount them if there is an emergency, or the roads are totally ice.)

      So, a lot of these States now salt the winter roads, and car owners pay for it in rust.

      1. I would assume Finnish winters are much, much harsher than e.g. Coloradoan ones; banning studded tyres is a complete impossibility given the enormous amounts of snow and ice we get. Besides, even with studs you’re still slipping and sliding all over the place at times — the number of crashes and deaths would go straight through the roof, if studs were banned.

        As an aside, we also use salt, but mostly only at busy intersections and only in the spring and autumn. No amount of salt would be enough to keep roads ice-free in the winter, when, at worst, you can have so much snow pour down in a single day that it reaches to your knees. We just have to make do with good tyres and plowing the snow off the road.

        1. Any amount of snow and ice is just the same. Doesn’t matter if it’s for one week or six months. Modern all-year tires are good enough to have negligible difference to standard studded tires and cause drastically less wear on the road surface.

          If anything, people put too much trust on studded tires. When you drive them on bare asphalt in the fall and spring, the studs get worn out very quickly and lose effectiveness. Then people use the same tires for three, five, even ten winters, and think it makes a difference.

          1. Plus, in places where they mandate studded tires AND salt, that’s just adding injury to injury, because the road surface will be clear most of the time and the studs get to do their damage, and the corrosive environment eats away at the studs as well.

            So basically anywhere south of the polar circle, which is where I believe most people in Finland live as well.

          2. Studs vs plain rubber isn’t even a contest – studs are often going to be far grippier are very rarely less (worse for the road though). Can you drive safely on normal tyres in those conditions… maybe – personally I seriously doubt it.

            Now people going ‘Oh I have ‘magic’ tyres I can drive like its a dry summers day on racing on slicks’ (or who drive around on worn-out tyres). Those people are going to be a problem no matter what…So should expect their Darwin award in short order (hopefully without any collateral damage). You drive to the conditions – always!

          3. Nope. I have driven with “modern all-year tyres” and it was a horrible experience. There is absolutely no contest when compared to studded tyres, the studded ones win hands-down. There is a reason why almost no one uses them over here.

      2. https://drivinglaws.aaa.com/tag/studded-tires/
        Looks like not many states have banned them, although acting like rubber studs have any meaning is practically banning studs.
        Funny how Alaska and Michigan and Minnesota, the states you probably need them the most, have practically banned studs. But you can use studs in California.

        It’s funny how after the winter the ground is all white, not from snow, but from salt. That’s one big minus to northern states in my book. I want to keep my cars. Even though otherwise as a northener, if i had to live in the states, i’d otherwise prefer northern atmosphere.

        1. There’s probably a good reason to it. Studs eat the road surface quickly, yet don’t offer that much advantage in stopping the car on snow. Studs have a marginal advantage on bare ice, but most people will be driving on old worn tires anyways, so the better suited rubber composition and pattern of all-year tires beats old studded tires.

          In Alaska, you have many more miles of road per inhabitant, so you don’t want to wear it out too soon.

          1. Also have to consider the usual conditions inform the choice of vehicle – won’t get as many sports cars or little eco city cars out in the more often ice filled wilds – they just don’t work well there even on a good day. So the states that can assume everyone has better cars for the horrible conditions can ban them more easily as they are not as needed. Where if you expect everyone to drive cars that really are not suited to low grip situations you will want them to have chains/studs as an option when the weather is even a little bit hostile – or everything shuts down and you get lots of crashes.

          2. Marginal? Where i am people prefer studded tires and i sure as hell won’t be driving without them in the winter. Looking at videos in youtube about car crashes in the winter in USA and i’d say in a lot cases studs would’ve stopped the carnage.

          3. > Looking at videos in youtube about car crashes in the winter in USA and i’d say in a lot cases studs would’ve stopped the carnage.

            Looking at those videos, what I see mostly is people skidding on bald ice with snow or water on top. I’ve been in that situation with studded and all-year tires, and I can tell it made no difference. You hear a bit more scraping with the studded tires, which may give the illusion of grip, but the car still ain’t stopping. You get maybe 10% more grip, unless the snow packs under the wheel and lifts the studs off the ice.

          4. “Looking at videos in youtube about car crashes in the winter in USA and i’d say in a lot cases studs would’ve stopped the carnage.”

            If you are referring to the YouTube videos of massive pile-ups that occur on icy roads, they could be averted by increasing the distance between vehicles.
            IIRC, from Drivers Ed, one needs 9 times the distance to stop on ice than on dry pavement,
            so instead of a “2 second Rule”, an “18 second Rule” needs to be considered.
            But, most of those pile-ups occur in States where drivers think that Tailgating is a Constitutional Right, and the 2 second rule is for wusses. B^)

          5. No. They couldn’t. I’ve been in situations where the slick spot is just over the crest of the hill, and 1 MPH is more than enough to initiate a slide all the way to the bottom of the hill, so NO amount of following distance will help. I was in one accident in Redmond, Washington, where I had all the following distance in the world, but I ended up on the sidewalk because I had zero control (luckily, nobody was on the sidewalk). The car behind me also had plenty of following distance, because it was at least thirty seconds later that he ended up in my trunk. Keep in mind that I was fully off the road at that point.

            I’m not talking about serious hills here, I’m talking about the ones where you don’t even remember there being a grade there unless you’ve been on it on a bicycle. I don’t know if studs help in this case, but I should think they would – otherwise I don’t know why people would buy studded tires.

    1. If that were the case, then we would have an interesting way to build exceptionally thin coatings.

      And considering that vulcanized rubber on a microscopic scale looks more like cotton, due to being a cross-linked set of fibers, then the one molecule thing is most likely incorrect.

      1. Funnily enough, it’s not far off, on average.
        You’ll get roughly 50 000 km out of a tire, or 25 million revolutions. For a 5 mm tread wear over that lifetime, you lose on average 0.2 nanometers per revolution. The H-C-H bond in a carbon molecule chain is 0.2 nm.

        1. If these 50,000km were all coasting with racing slicks on a smooth glass road, that would make sense. However, this is not what happens in real life. You are accelerating and braking with treaded tires on a rough surface. So instead of your tire uniformly coating the roadway with rubber, instead the rough surface bites into and rips tiny pieces out of your tires, especially when accelerating and braking where slippage occurs.

  4. Since I was a kid, I figured the lack of wind-blown drifts of tire and brake bits along the roadways meant it must be decaying in some way. I’m not clear on the concern. In the US at least, brakes are not asbestos anymore. And along major busy highways that are 70 years old I don’t find mounds of the debris unless it is hidden in the diesel soot. These folks must have government money.

    What’s next? Flying cars?

  5. This sort of thing misses the forest for the trees. The cars and the roads are the problem, not the microscopic dust that may or may not be collected from tires. Defund the highways and the problem solves itself.

  6. My dad’s house was painted white but looked gray. He was 1 house away from a busy 10-15° steep street. Tire dust. It’s gone in 4 yrs? But constantly replenished and in the air. His tall house 100 ft from that street and past an intervening house was grey to the top! People have to breathe that stuff. Where is a carbon tax when you need it… Make tires a luxury a d hazard and fine those who do not meet the miles due. These guys doing donuts? Hate crime.

    1. Driving a car is what’s called non-elastic demand. People have to drive, no matter how much it costs, to keep the economy running. That’s why, increasing any tax on driving won’t actually affect how much people drive, until it suddenly does and then your whole economy comes crashing down because people can’t afford to drive to work any longer.

  7. Anyone else here who has driven long enough to have seen the era before “all-season” tires were common?
    IF so, did you notice how much more the “all season” and wet rated tires throw water and dust into the air?
    The (tread design of) all season tires is almost like having a rolling nebulizer.
    Being on the road at the beginning of rainfall was always a slick time, but then along came the all season tires to loft and spray your windshields with the oily dirty spray, to boot.
    Any bike riders will surly have noticed which ones keep you provided with a mini fog bank.

    As for funneling the wheel wash (air flow) through charged collector plates or a “cyclone” trap?
    Hmm, going to be tough to do that one in an era where we no longer have drip rails (gutters) around the windows, due to drag coefficients.
    Then let’s not forget styling trends that are (and nearly always have been) deemed to be far more important than the function (or often the usability) of a device.

  8. Coal Planets, Factories, Cargo-liners and Freight are putting out over 90% of the garbage. But oh Oh OHHHH! We gotta focus on individuals because you know there are that many people breathing!!!

    I’m Tyred of this bullshit.

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