By on March 11, 2020

Anyone who’s laid a substantial amount of rubber in a local parking lot will tell you that the scent emitted doesn’t smell particularly healthy for the environment (burnt clutch smell is even less appealing — don’t ask how I know). And while the typical driver doesn’t burn through tires via successive smoke shows, regular road use effectively does the same thing over a much longer timeline — and a new study claims it’s up to 1,000 times worse than what actually comes out of a vehicle’s exhaust system.

The report, penned by UK-based independent research firm Emissions Analytics, has circulated within the media for a few days and claims that pollution stemming from tire and brake wear is a growing problem. With European lawmakers clamping down on tailpipe emissions, the firm suggests “non-exhaust emissions” will be the next big regulatory challenge. 

From Emissions Analytics:

Non-exhaust emissions (NEE) are particles released into the air from brake wear, tyre wear, road surface wear and resuspension of road dust during on-road vehicle usage. No legislation is in place to limit or reduce NEE, but they cause a great deal of concern for air quality.

NEEs are currently believed to constitute the majority of primary particulate matter from road transport, 60 percent of PM2.5 and 73 percent of PM10 — and in its 2019 report ‘Non-Exhaust Emissions from Road Traffic’ by the UK Government’s Air Quality Expert Group (AQEG), it recommended that NEE are immediately recognised as a source of ambient concentrations of airborne particulate matter, even for vehicles with zero exhaust emissions of particles — such as EVs.

While the data seems legitimate, it should be said that the particulate matter that’s causing alarm likely doesn’t contribute to climate change. The Environmental Protection Agency (EPA), however, has faulted PM2.5 and PM10 for posing health risks, as both are easily inhaled.

As for the role of electric vehicles, Emissions Analytics cites them as part of the problem. Despite shifting their emissions to the nearest power station, added battery weight means EVs tend to be heavier than a similarly sized internal combustion vehicles. Weight turns out to be one of the best predictors of how much non-exhaust emissions an automobile will emit. That led analysts to similarly point to the crossover trend, which has also pushed consumers into heavier vehicles.

For testing purposes, Emissions Analytics used a “popular family hatchback running on brand new, correctly inflated tyres.” It found the car emitted 5.8 grams per kilometer of particulate matter vs the regulated exhaust emission limit of 4.5 milligrams per kilometer. It plans on doing additional testing moving forward, claiming that it has uncovered a serious oversight in the market’s regulatory activities.

“It’s time to consider not just what comes out of a car’s exhaust pipe but particle pollution from tyre and brake wear. Our initial tests reveal that there can be a shocking amount of particle pollution from tyres — 1,000 times worse than emissions from a car’s exhaust,” Richard Lofthouse, Senior Researcher at Emissions Analytics, stated. “What is even more frightening is that while exhaust emissions have been tightly regulated for many years, tyre wear is totally unregulated — and with the increasing growth in sales of heavier SUVs and battery-powered electric cars, non-exhaust emissions (NEE) are a very serious problem.”

Another issue was the prevalence of cheap rubber, which have a tendency to create more airborne particles than something with a little more grip. However, much of this can be mitigated by where and how you drive. Putting more heat into the tires and brakes translates into worsened emissions, but there are more ways to do that than simply treating nearby roads as your own personal racetrack. Heavier vehicles with larger tires will emit more NEE by default and EVs with aggressive regenerative braking settings could nudge up the parts per million over something with a little less rolling resistance.

Previous studies would seem to indicate that non-exhaust emissions are a larger issue in an urban environment. In addition to there being more people to inhale said particulate matter, higher density traffic has a tendency to kick it up into the air and channel it into residential areas. Meanwhile, rural settings will see more particulate settling by the roadside, far from the places people actually live.

We’ve reached out to Emissions Analytics to gain some insight into the methodology used for testing and will update this article accordingly.

[Image: FCA]

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47 Comments on “Study Suggests Tires Create More Pollution Than Exhaust Emissions...”

  • avatar

    Another day, another excuse for another tax in Europe.

  • avatar

    5.8 grams per kilometer… those tyres will be worn down to nubs in no time.

    I wonder how they did their measurements.

    • 0 avatar

      The weight of a person each year for the average Murkin driver. In other words, about the weight of two sets of tires with two spares and then some. Either this is fake news from the extremist left, or more likely a misquote, and it was 5.8 mg/km.

      • 0 avatar

        It must be a typo. If 5.8 g/km was accurate, the average small car would shed its entire mass in about 260 kilometers.

        And while there may be no regulations regarding the mass rate per mile or kilometer of non-emission particulate generation, there are regulations regarding the composition of such particulates (or rather, the components that generate them.)

        • 0 avatar

          “If 5.8 g/km was accurate, the average small car would shed its entire mass in about 260 kilometers.”

          5.8g/km is 3.3 lbs over 260 km. What the numbers really say is that a car would shed twice its weight in tire wear over its lifetime, which is still stupid. If you get 40,000 miles on a set of tires and you lose 1/3 of the tire’s 10 lb weight, you’re still only losing about 60 lbs over the life of the car.

  • avatar

    At least Europe regulates particulate emissions from GDI engines.

    • 0 avatar
      Art Vandelay

      Yeah and they’ll come down on you for breaking those standards…unless you are a homegrown company, then they’ll give you a slap on the wrist and ensure that the deck is stacked in favor of that company in order to transition to the next thing.

      I am no Musk fan, but I can’t wait for Europe to continue to push the EV and for Tesla to bury VW as that transition progresses. Arrogant a-holes trying to convince the world they are smarter while cheating getting their butts handed to them by an arrogant a hole that is at least smart. Can’t wait to see the Germans circle the wagons.

  • avatar

    Another lame survey. I am so sure that China’s air pollution problem is from too much spinning tires on their powerful and well built 8 cylinder cars that drag race with the approval of Xi Wang Chung.

  • avatar

    Shouldn’t we ban sand dunes and deserts? Think of all the particulates that Mother Nature spews into the air.

  • avatar

    Oh JHC on a popsicle stick. Another day, another lame reason to enact laws governing a growing population you’re scared of. Seriously, without these “studies” done by what I’m sure are…super “nonpartisan” down to EARTH folks, politicians would have nothing to do…not like any in this country outside the WH are doing anything as it is.

    • 0 avatar
      SCE to AUX

      It is lame. Research papers don’t typically contain the word “frightening”.

      Besides, BMW wheels seem to attract every particle of brake dust, anyway, so I’m sure at least they aren’t emitting it into the air.

  • avatar

    something like only 1% of “studies” are peer reviewed because they don’t follow scientific method

    it’s not science, it’s advocacy – another interest group looking to feed at the public trough

  • avatar

    Somebody check my math, but my current tires will last 80,000 miles or about 128,000 km times 5.8 grams per miles or about 250 pounds over the life of the tires. The little bit of the tread doesn’t come close. Does this include the pavement and the dust thrown up on a gravel road. This is junk science.

    • 0 avatar

      @65corvair: Yes, you are onto something. It’s junk science. A Michelin Energy Saver A/S 215/50R17 weighs 9525.44 grams. For one tire, 5.8 grams per mile divided by 4 is 1.45 grams per kilometer for a single tire. By my calculations, at 1.45 grams per kilometer, the tire will be completely consumed (as in totally disintegrated/vanished into thin air) and you’d only have a rim after 6,569.267 kilometers or 4,802 miles. Michelin says it’s a 60k mile tire.

      • 0 avatar

        From the report link: “Non-exhaust emissions (NEE) are particles released into the air from brake wear, tyre wear, road surface wear and resuspension of road dust during on-road vehicle usage.”

        So you have to count tire wear on my car, plus brake wear on my car, plus road wear, plus all the PM2.5 and PM10 stuff kicked up when I pass by (my and everyone else’s tire/brake/road wear from previous road usage). [Fine beach sand is 90 microns and out of scope.]

        My question would be: If I’m in the middle of nowhere and the fine particulates settle back down before anyone inhales them, no harm no foul?

        I suppose a busy city street is packed with the stuff. HEPA filter would catch PM2.5 and PM10, correct? So if I ran a rubber-tired vehicle in a tunnel and filtered the air escaping above ground, all good? (Assume that all vehicles in the tunnel also have HEPA filtration for the occupants.)

  • avatar
    R Henry

    “a new study claims it’s up to 1,000 times worse than what actually comes out of a vehicle’s exhaust system.”

    –Well, I guess electric cars are NOT going to save Earth!

  • avatar

    so, let me get this straight: people who have chosen to base their livelihood on being involved in pollution, are facing a world of electric cars–and therefore the end of their livelihood.

    So, they manufacture something else to keep them gainfully employed, they hope.

  • avatar

    This number seems inaccurate by a couple ordesr of magnitude but the idea that tire and brake wear contribute more to particulate pollution than exhaust emissions at this point is probably correct. EVs will eliminate most of the brake wear (regen) but make up for it with more tire wear (heavier), which probably means EVs and gas cars are a wash with respect to NEEs. But particulates isn’t the only thing we have to worry about. Tire wear won’t cause smog-forming NOx, won’t throw nearly as many VOCs into the air as cold engines do, and won’t heat the planet. It’s still worth tranisitioning to EVs.

  • avatar
    Jeff S

    How about the carbon dioxide emitted by humans after exhaling and the methane gas produced from humans and not just from cows. Maybe it’s time to regulate the amount of farting coming from humans and to levy fines for over farting. Sounds about as logical as emissions from tires.

  • avatar
    Art Vandelay

    Silly commentators. Clearly the intent of posting this was to say “Now see…them Teslas pollute just like muh 1978 Plymouth Volare with the trusty 318 that is so much better than any of your post Reagan admin BS. FREEDOM…MURICA! Lectric cars are for Commies!

    You all failed

  • avatar

    I look at it this way: four tires weigh less than a tank of gas. If you get 40 mpg and have a ten gallon tank, and change tires every 40,000 miles, those tires last 100 tanks. Burning gas doesn’t destroy the gas, it just transforms it. And replacing tires doesn’t transform the entire weight into pollution, only the outer quarter inch, so …

    Anyway, I don’t see how a very few pounds of tire can out-pollute thousands of pounds of fuel, especially when everybody freaks out about CO2 as a greenhouse gas instead of embracing it as plant food.

  • avatar

    The one way to solve problem with tires is to get rid of automobiles, roads and freeways and ride only Railroads. You know, the railroad is a mighty good line,
    Come on and ride the railroad, one more time.

  • avatar

    “it should be said that the particulate matter that’s causing alarm likely doesn’t contribute to climate change.”

    I get so tired of the PC climate change arguments, when we completely ignore the largest contributor to climate change; population.

    If we really care about climate change, let’s discuss population control. Seems to be a taboo subject.

  • avatar

    And with all those taxes,Western European counties are prosperous first world countries, particularly Scandinavia. Taxes are not inherently evil.

  • avatar

    Ban tires.

    • 0 avatar

      They’re hard to do without for last mile.

      From an emissions pov, they should be augmented with a set of steel wheels running on steel track, or maglev. With the car being powered by electricity drawn from the road/rail-way.

      Then you would not only have almost no particulate emissions, but it would even turn EVs into useful vehicles, while making autonomous for most of the journey cars realistic, instead of just silly hype.

  • avatar

    Clearly this study is flawed in many ways, but it does highlight one question certainly worth asking: Where *does* all that worn tread go? As the tire wears down the particles of rubber have to end up someplace or there would be black dust built up on the side of highways much the way you see sand. Some no doubt runs down the storm drains but you still don’t find black bits in the storm system…does it degrade to something else? Blow away?

    Brake dust: I use a subway station that has two platforms that have been out of service for years. They are covered with a 1/4 inch of brown dust from the train brakes. So all that friction material ends up somewhere as well. Brake material is likely pretty resistant to degradation so it ends up being visible, at least in this case.

    So, as flawed as this study may be, questioning where all this stuff ends up is not unfair to ask. Anybody who lives near a busy street is well aware of the black dust that ends up on the window sills of their house. Is that from the above issues? The pavement? Ultimately all that dust is getting sucked into your lungs.

    • 0 avatar

      @Golden2Husky: I think you meant to say “Ultimately some of that dust. . .”. If you can see it, not all of it ends up in your lungs. That said, your point is well taken. Where does it all end up? I’m guessing much is carried away by air flow/wind and distributed over an area large enough that it is not easily evident to the casual observer.

  • avatar

    Burnouts are pretty stupid though.

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