Study Suggests Tires Create More Pollution Than Exhaust Emissions

study suggests tires create more pollution than exhaust emissions

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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  • Golden2husky Golden2husky on Mar 12, 2020

    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.

    • THX1136 THX1136 on Mar 12, 2020

      @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.

  • Goatshadow Goatshadow on Mar 12, 2020

    Burnouts are pretty stupid though.

    • See 3 previous
    • Golden2husky Golden2husky on Mar 13, 2020

      @Goatshadow No, when you are ready for new tires, why not have some fun with the old set?

  • Luke42 I like the Metris quite a bit, but I never bought one.Two problems kept me from pulling the trigger:[list=1][*]It was expensive for what it was.[/*][*]For the price they were asking, it needed to have a plug for me to buy it.[/*][/list=1]I wanted a minivan that could tow, and I test drove one and liked it. The Mercedes dealer stocked both cargo versions and conversion vans. It was a nice vehicle, and I really wanted one for a while.This is the inevitable fate of cars that I like, but don't actually buy.
  • Garrett I would have gone for one of these if it had AWD. If they had offered it, it could have done far better.
  • Michael500 Sorry, EV's are no good. How am I supposed to rev the motor to impress girls? (the sophisticated ones I like).
  • Michael500 Oh my dog- this is one of my favorite cars in human history! A neighbor had a '71 when I was a child and I stopped and gazed at that car every time it was parked outside its garage. Turquoise with a black vinyl. That high beltline looks awesome today!
  • ScarecrowRepair I'd love an electric car -- quiet, torque, drive train simplicity -- but only if the cost was less, if recharging was as fast as gas (5 minutes) and as ubiquitous. I can take a road trip and know that with a few posted exceptions (US 50 from Reno to Utah), I don't have to wonder where the next fuel station is, and if I do run out, I can lug a gallon of gas back.Sure I'd miss the engine sounds and the joys of shifting. But life is all about tradeoffs.