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This story was originally published by Grist and appears here as part of the Climate Desk collaboration.

As gas-guzzling cars are replaced by their electric counterparts, tailpipe emissions are on the decline. But cars have other negative impacts on environmental health, beyond what comes out of their exhaust pipes.

One of the bigger and lesser-known problems is tire pollution — or “tire and road wear particles,” in industry terminology.

Tires shed tiny particles with every rotation. Tire wear happens most dramatically during rapid acceleration, braking and sharp turns, but even with the most conservative driving, particulate pollution is an unavoidable consequence of car use. And it’s a problem that’s poised to get worse as drivers transition to EVs.

“We’re pushing for decarbonization by going to battery electric vehicles and in doing so, we’re pushing up tire wear emissions … which is going to prove difficult to solve,” said Nick Molden, founder and CEO of Emissions Analytics, a London-based company that performs independent tests on cars’ real-world tailpipe and tire emissions. Molden pointed out that tailpipe exhaust is dramatically reduced by filters and catalytic converters, which use chemical reactions to reduce pollution. Meanwhile, tires are a fundamentally open system, so there is no viable way to capture the polluting particles that fly off of them.

Emissions Analytics found that a single car sheds almost nine pounds of tire weight per year, on average. Globally, that amounts to six million metric tons of tire pollution annually, with most of it coming from wealthier countries where personal car use is more prevalent.

The amount of tire pollution emitted per vehicle is increasing as more electric cars hit the road around the world — some 14 million of them this year, according to the International Energy Agency. EVs tend to be significantly heavier than gas-powered or hybrid cars due to their larger, heftier batteries. The average battery for an EV on the market today is roughly 1,000 pounds, with some outliers approaching 3,000 pounds — as much as an entire gasoline-powered compact car. Emissions Analytics has found that adding 1,000 pounds to a midsize vehicle increased tire wear by about 20 per cent, and also that Tesla’s Model Y generated 26 per cent more tire pollution than a similar Kia hybrid. EVs’ more aggressive torque, which translates into faster acceleration, is another factor that creates more tire particulate mile for mile compared to similar internal combustion engine cars.

Due to its heavier battery and more aggressive torque, Tesla’s Model Y generated 26 per cent more tire pollution than a similar Kia hybrid. Photo by Getty Images/Grist

Tire particulate is a toxic slurry of microplastics, volatile organic compounds and other chemical additives that enter the air, soil and water around trafficked areas. The rubber, metals, and other compounds coming off tires settle along roads where rain washes them into waterways. Smaller bits of tire particulate linger in the air, where they can be inhaled, and the smallest of this particulate matter — known as PM 2.5, because each particle is 2.5 micrometres or less — can directly enter the bloodstream. A 2017 study estimated that tire wear is responsible for five to 10 per cent of oceanic microplastic pollution and three to seven per cent of airborne PM 2.5 pollution.

#EVs are a climate solution with a pollution problem: tire particles. #AirPollution #ClimateCrisis #TireParticles #TirePollution #PM25 #6PPD

One particularly concerning chemical in tires is 6PPD, which is added to virtually all tires to prevent rubber from cracking. But in the environment, 6PPD reacts with ozone to become 6PPD-quinone, a substance that has been linked to salmon die-offs in the Pacific Northwest. A 2022 study confirmed the compound is also lethal to rainbow trout and brook trout.

Further research has shown that the chemical is absorbed by edible plants like lettuce and has the potential to accumulate in them. A study in South China found both 6PPD and 6PPD-quinone in human urine samples. The human health effects of the chemical are not yet understood, but other chemicals found in tires have been linked to problems ranging from skin irritation to respiratory problems to brain damage.

6PPD is added to virtually all tires to prevent rubber from cracking. Photo by Getty Images/Grist

Given the intensifying realities of climate change, phasing out gas-powered vehicles rapidly is a must. But experts say the U.S. and other wealthy countries can accomplish this while also mitigating the environmental and health problems caused by EVs’ increased tire wear — namely by curbing car use overall.

Foremost, local policymakers can take steps to make U.S. cities less cripplingly car-dependent. Although that might sound like a daunting task, there’s historical precedent: The Netherlands used to be dominated by cars and experienced a higher rate of traffic fatalities than the U.S., until activist groups like Stop de Kindermoord (Stop Child Murder) mobilized in the 1970s to let policymakers know that they wanted less traffic on their streets. According to Chris Bruntlett, the co-author of Building the Cycling City, policymakers created the low-traffic, bike-friendly Dutch cities we know today by instituting traffic-calming measures. “Officials started with speed-limit reductions, parking restrictions, through-traffic limitations and lane narrowings and removals,” Bruntlett told Grist.

David Zipper, a mobility expert and a visiting fellow at the Harvard Kennedy School, says that city leaders can also remove subsidies for car ownership, such as free residential parking on public streets. “Once car subsidies are removed, fewer people in cities will choose to buy and own them,” Zipper said.

Of course, measures to reduce car use only work in tandem with investments in alternative transportation. The Infrastructure Investment and Jobs Act of 2021 provided some federal funding for transit and pedestrian and bike infrastructure, but making the most of these funds will require political will from state and local lawmakers. Zipper said that policymakers in some U.S. cities have begun to take positive actions — like Boston Mayor Michelle Wu, who has committed to expanding her city’s bike lane network until 50 per cent of the population lives within a three-minute walk of a bike lane.

Another way to reduce tire pollution is to trade big, heavy cars for smaller and lighter ones. Especially in the U.S., cars have grown significantly in size and weight in recent decades. Automakers began promoting SUVs in the 1980s because a legal loophole allowed vehicles designated as “light trucks” to skirt fuel-efficiency regulations. Nine out of the 10 best-selling cars in the U.S. last year were trucks or SUVs, and the International Energy Agency has found that SUVs were the second-largest cause of the global rise in CO2 emissions between 2010 and 2018.

One legislative solution to car bloat is introducing weight-based vehicle taxes, which encourage consumer interest in lighter cars and can be used to offset the cost of increased wear on roads caused by heavier vehicles. France implemented a weight-based car tax in 2021, charging consumers a penalty of 10 euros (about $10) for every kilogram above 1,800 (about 4,000 pounds) that their car weighs. This year, Norway also extended its weight-based vehicle tax to include EVs at a rate of a little more than a euro per kilogram above the first 500 kilograms (about 1,100 pounds) for EVs. Norway also taxes vehicles on their carbon dioxide and nitrogen oxide emissions. Taken together, these three taxes have the combined effect of dramatically incentivizing small electric vehicles.

In the U.S., some states already prorate vehicle registration fees based on weight, and Washington, D.C., recently overhauled its registration system to more heavily penalize larger cars. In D.C., owners of cars heavier than 6,000 pounds now have to pay $500 in annual fees. New York state lawmakers also recently introduced legislation that would similarly incentivize smaller cars.

Regulators can also take steps to minimize the harm caused by tire pollution — and in California, the process has already begun. In October, a new regulation implemented by the state’s Department of Toxic Substances Control, or DTSC, will require manufacturers of tires on the California market to research safer alternatives to 6PPD. Manufacturers that sell tires in the state are obligated to notify DTSC about products containing 6PPD by the end of November.

Karl Palmer, deputy director of safer consumer products at DTSC, believes that making tire makers conduct an “alternatives analysis” will ultimately result in products that are safer for the environment.

“We’re using California’s market strength to say, ‘If you want to park here, you’ve got to comply with our rules,’” Palmer told Grist.

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Whatever the question, cars are not the answer.

But this article is bizarre. If tires shed 9 lbs per year how do my 40 lb tires last 10 years? And they still contain 30 lb of sidewall at that point.
Yes, some EVs are driven aggressively but most are not because the driver is trying to be efficient.

And the ‘massive weight of EVs will collapse parking garages and highway overpasses’ meme is tiresome, pardon the pun. I am surrounded by multi-ton pickups every day that vastly exceed the weight of the EV sedans I see. Yes, the EV lightning and hummer are obese symbols of overconsumerism; but so are virtually all north American popular guzzlers. With a good public charging network 50 km of range could be feasible for 90% of journeys and ridiculous 500 km batteries would be unnecessary.

The problem is 100 years of car focussed infrastructure has destroyed our cities, made it unsafe and too far to walk or cycle and public transit - especially passenger rail - is a joke compared with virtually every other society on earth.

well stated.

Little question it has to be "9 lbs per tire", and only "per year" if you go through a set of tires per year.

Of course, stop and think about how many commercial vehicles are on the road 12 hours a day, and average them in; commercial trucks really do go through a set per year.

There's little doubt we should be adding a environmental fee to tires. If you make driving more expensive, there will be less of it. And, as everybody in such forums is repeating these days, we need a per-kg surplus added to all vehicle costs (initial price and yearly licensing), with maybe the first 200 kg free - to encourage the development of small, plastic, one-person electric three-wheelers, or some such. (Already popular in Asia...)

I am SSSSOOOOOO fuc*ing sick of these anti EV articles! This is a stupid article that ignores the biggest elephant on the planet…….trucks!
The biggest seller in all areas of vehicles sales in Canada last year was pick up trucks, up by more than 16% over all other classes of vehicle including EV’S. and EVERY SINGLE PICK UP weighs more than any EV. Even the lightest F-150 weights 600pounds more than the heaviest EV! They also require special tires which ALSO produce tiny particles of rubber, And that again doesn’t include all the commercial sized trucks and buses on the road! Who also weigh tons more and also produce particles from THEIR tires!
Just stop with all these anti-EV articles because if I follow the money I'm damned sure somewhere I’ll find a connection to the Oil and Gas Industry, who spend MILLIONS every year to produce reams and reams of garbage designed to convince people that EV’S are bad, burning oil is good!

I agree totally, this isn't specific to just EVs as this article seems to slant it towards, but it seems very anti-EV. We have bigger fish to fry than worry about tires that applies to all motorized vehicles. But I think you are right; follow the money and I wouldn't be surprised this is just another oil & gas propaganda to bash EVs.

The bigger issue is eliminating vehicles that burn oil & gas.

Global climate change is not a reason to ignore, explain away, or rationalize the local health hazards of personal transportation vehicles, whether electric, gas, or diesel.

It is a fact that EVs produce more particulate pollution from tire wear than their ICE-model equivalents.
"The electric F-150 weighs 700 kg more than its petrol-powered predecessor."
Transit buses produce far less tire particulate pollution per passenger mile than any personal automobile — car or truck.

The charge that the author must be working for the oil & gas industry because he identifies a very real health hazard aggravated by heavier electric vehicles is baseless. The article clearly makes a pitch for "low-traffic, bike-friendly cities" and public transportation:
"FOREMOST, local policymakers can take steps to make U.S. cities less cripplingly car-dependent. … Of course, measures to reduce car use only work in tandem with investments in alternative transportation."
The article is "anti-pollution" — or, if you like, "anti-car", including and especially EVs — not anti-EV and not pro-petrol in particular.

Particulate pollution from tire wear is a well-known issue, and it is a grave mistake to ignore it.
"Make electric vehicles lighter to maximize climate and safety benefits" (UofC School of Public Policy)
"Tax heavy cars and shrink batteries to consolidate the gains from electrifying transport."

Cars, including EVs, are a scourge of the urban landscape. Car culture is responsible for endless roads and road expansions, [traffic jams, property damage, strip mall blight, mega-mall culture, parking lot proliferation, and the health costs of sedentary lifestyles, social isolation, accidents, countless deaths and injuries, roadkill, loss of green space, smog, pollution, fossil fuels, and climate change.

EVs are not a green transportation solution. EVs enable sprawl, which makes efficient public transit impossible. Not a climate solution, much less an equitable one.
Ecologically, the idea that billions of people will use private vehicles in sprawled cities is a non-starter. Such a system will never be sustainable.

EVs and the urban sprawl they enable are hopelessly unsustainable. Kneecaps efficient public transit. Ignores the marginalized and those who choose not to drive. EVs are the yuppie response to climate change. No solution to the climate crisis is more shallow.

Simply swapping out gas engines for electric motors does not solve car culture, urban sprawl, and the huge footprint of personal single-passenger automobiles.
EVs merely shift extraction from petroleum to metals. An ecological nightmare.
With their massive footprint, cars would not be green even if they ran on fairy dust. Mining for metals, steel, plastic, manufacturing, end-of-life recycling and disposal.
The only sane and sustainable transportation future is smart urban design; amenities close to where people live; people living close to their place of work; ending sprawl; and massive investment in public transit, as well as cycling infrastructure.

EVs are the yuppie response to climate change. (Not for nothing that most of the first EV models were luxury cars beyond the reach of most citizens.) Wealthy progressives want EV subsidies so they can salve their guilty conscience over their outsize footprint without having to make any real change in their unsustainable lifestyles.
"Shifting to EVs is not enough. The deeper problem is our car dependence" (CBC)

"Rush to electric vehicles may be an expensive mistake, say climate strategists" (CBC)
"With their futuristic designs and new technology, EVs are the seductive consumer-friendly face of the energy transition.…For people with money and a conscience, EVs are doubly satisfying. They allow the affluent to indulge in the time-honoured pleasures of conspicuous consumption while at the same time saving the planet."

Urban planning advocate Jason Slaughter: "EVs are here to save the car industry, not the planet. Electric cars are still a horrendously inefficient way to move people around, especially in crowded cities."

Compared to doing nothing at all, EVs will speed up the energy shift.
Compared to public transit, EVs will slow it down.

If rising demand for metals (e.g. copper, lithium, cobalt, rare earths for magnets) outstrips supply, that will slow the energy shift down. An insufficient supply of metals exacerbated by a rush to buy EVS will create a chokepoint for the entire energy shift.

EVs require 2.5 times more copper than conventional ICE cars (Daniel Yergin, "The New Map, Energy, Climate, and the Clash of Nations", 2020). Per person per mile, the material inputs for cars are far higher than for public transit. Going the EV route increases requirements for (mining and processing of) metals, resources, and energy — potentially creating a large gap between supply and demand as well as multiplying environmental impacts.
"'The basic metal of electrification': Why famed energy analyst Daniel Yergin sees a copper crunch looming" (Financial Post)

We have bigger fish to fry than worry about tires at this stage. Let's tackle the reduction of CO2 first than muddy the waters with something that is less of an issue today.

Getting rid of cars requires redesigning cities. You have to discuss the topics together.

Here's an extreme thought I've thrown out among Libertarians and argued them into a corner: you should pay as you go. If you want to use public roads in a motor vehicle that imposes costs on the public, you have to be tracked everywhere (we can do that now), and you get charged by the block. Some money for residential, more on major roads, more for every bridge crossing (to pay for the bridge), and much more at rush hour, congestion taxed to the penny depending on traffic that day.

The amount would be calculated as closely as possible to pay back the public for the capital and operating costs of pavement, making the "streets" department revenue-neutral. As it is, I point out to the Libertarians, confirmed pedestrians who only used to have to pay for gravel for horses, are now obliged to pay for $50M interchanges that they don't use. Yes, people who bring them food and sweaters have to use roads, and those businesses can add their road costs to product costs, so that all costs reflect how much road was used.

The Libertarians shut up. They had to. I mean, that's their whole philosophy.

Or, I said, if you're going to flat-rate the societal road-costs on everybody, so that Kia subcompact drivers are subsidizing Ford Explorer drivers every day, you should also flat-rate all the buses and trains, make them all free, just like roads are free. What's the diff? (Which was the topic, free buses. I don't think I argued any Libertarians into free buses, but I think they admitted the logic of non-free roads.)