Another way electric cars clean the air: study says brake dust reduced by 83%
175 comments
·May 28, 2025ChiefNotAClue
llampx
I recently bought an EV and love it. I barely ever touch the brakes and the wheels stay clean, unlike my old BMW where the front wheels turned gray from brake dust very quickly.
Some comments here are looking for a 100% perfect solution, which doesn't exist. Transportation is polluting. Sorry but even public transportation is polluting, even if it is more efficient when its above a certain utilization. Where I live, some buses are EV and it is a joy to ride them compared to diesel ones.
With an EV there is less local pollution, less noise pollution, more dynamic response when needed and no need for wasteful oil "changes" where the old, dirty, useless oil doesn't just magically disappear.
jvm___
Is tire wear worse for aquatic life than brake dust?
jabl
There is an additive called 6PPD added to tires to prevent them from degrading in the atmosphere, and it has been found that when this thing reacts with ozone in the air it forms another compound 6PPD-quinone which is highly toxic to some fishes. Weirdly enough it's highly toxic to some species of salmon but not to other salmon species.
Presumably there's work ongoing to find an less damaging replacement, but I haven't heard of any.
cyberax
Tire wear right now is worse, because tires contain an anti-oxidant that gets oxidized into a compound that is highly toxic to aquatic life.
The work is underway to standardize on a replacement. This time with even more tests.
chneu
I wonder if this will be like lead in av-gas. Lol.
null
verisimi
So it's even more good news. Yet another way EVs are better.
HenryBemis
It's not you, it's definitely me. I cannot tell if there is irony or a 'straight-faced' comment that you wrote.
Either way, like always, time will tell. We (humans) almost never 'get it right the first time'. And perhaps EVs have been around for quite a while now, it's still 'a while'. So I wouldn't be surprised if the lobby for "7PPD" (or whatever replacement) convinces us that "7PDD" is the best and even makes fish taste better, only to find out that it causes terminal cancer (see smoking, sugar, etc.)
rasz
unless you are a salmon
https://ecology.wa.gov/blog/january-2023/saving-washington-s...
scuderiaseb
So putting this aside, the elephant in the room is still the weight of the EVs, tire wear is one thing but the roads are also being worn at a much faster rate due to the weight of the cars. When EVs do have to brake and regenerative is not enough it needs to stop more inertia due to this high weight.
JumpCrisscross
> the elephant in the room is still the weight of the EVs
The elephant in the room for road wear are trucks [1]. Cars are almost negligible.
bryanlarsen
A Tesla 3 is 5% heavier than a BMW 3. First generation ICE conversions were heavy. Cars properly designed from the ground up for EV aren't as much.
scuderiaseb
Yeah but they should get lighter ideally and not heavier because the BMW 3 ICE has also gotten unreasonably heavy.
I'm a huge proponent of biking and electric bikes but there is too bad infrastructure, storage, safety concerns etc that are not being addressed properly. For instance I wish I could buy a Cargo bike and use that for grocery shopping and most other transportation of my kids but I don't have room in our bike storage (where I've had two bikes stolen) and I don't have room in our storage room and live in an apartment. The cars parking take up more square meters than the squaremeters of the building or close to it while the bike storage is a fraction of that.
Tade0
Audi had an interesting proposition regarding making electric cars actually clean the air as opposed to just avoiding emissions:
https://www.audi-mediacenter.com/en/press-releases/audi-urba...
ICE cars already do that in a way, as they suck a significant amount of air through their intake filters (CADR = displacement x RPM).
Audi's filter was supposed to have been more fine-grained to catch brake dust and tire particles, but sufficient legislation never materialized, so the project was shelved.
nosianu
That reminds me of a Louis de Funès movie ("La Zizanie", film de Claude Zidi de 1978)
Air cleaning scene: https://youtu.be/lpmxrgrbKDc (French)
(He was responsible for first poisoning the air by burning tires, so that he could demonstrate his machine to the potential Japanese investors)
https://en.wikipedia.org/wiki/La_Zizanie_(film)
This Audi proposal is somewhat similar in my mind. They want to profit from both parts, providing both the problem and the solution. I'm not against it per se.
Tade0
You've reminded me that I was taught French early enough to instinctively follow the rhythm of the language, but today that alone won't suffice if the vocabulary isn't there.
I've known Louis de Funès from Les Gendarmes and such classics as La Soupe aux choux or L'aile ou la cuisse.
I didn't know the movie you linked, but now I'm thinking I'll pick up French again - if only to hear the whole body if his work in its original language.
Schiendelman
Wouldn't an electric car with good filtration bringing cabin air in from the outside do this inherently?
Tade0
The figures are sufficient, but only when the blowers are at full throttle. A room air purifier does around 300m3/h, while the blowers eat through around 150m3/h at max speed. Problem is that hardly anyone uses them like that, considering the noise.
Meanwhile a car with a 1.5l engine turning at an average of 1500RPM will suck through 135m3/h.
There's no data available for Audi's system, but at this size they could easily go way beyond 300m3/h.
Schiendelman
Sure, so maybe an order of magnitude lower impact than a room air purifier. But it sounds like they could conceivably be a net benefit already. Or perhaps once we change tire formulations to be less toxic.
merek
> It turns out that BEVs (battery electric vehicles) reduce the amount of brake dust by 83%, according to a new analysis by EIT Urban Mobility (a body of the European Union) and Transport for London. The study looked primarily at London, Milan and Barcelona.
> The primary reason for this is the use of regenerative braking, meaning that electric vehicles can slow down without rubbing friction brakes. Other vehicles that use regenerative braking reduced brake emissions too, with Hybrids reducing them by 10-48%, and PHEVs by 66%.
Technically not cleaning the air as the title says, but still a major improvement.
jbverschoor
Cars clean the air because the AC filters capture particles
aziaziazi
I clean the air because my lungs capture car particles.
silon42
That's why I have an e-bike, so I breathe less when cycling/commuting into the city.
tsoukase
Technically we all disinfect the water through our kidneys too
HPsquared
Some diesel engines can clean the air, but only if the air coming in is very polluted. They'll catch and burn particulates, and they'll chemically scrub NOx. This only applies if the air outside is very polluted, though
01HNNWZ0MV43FF
Once again hybrids capture most of the benefit of electricity, and slide silently under the radar :(
epistasis
Brake dust is such nasty stuff, yet we place schools and homes right next to the rivers of pollution that we call highways. I'm hopeful that we will legalize the building of less car-dependent housing, but until then at least EVs will help.
Helmut10001
Just adding: On highways, there will be less "breaking" vs. (e.g.) highly frequented intersections in cities.
johnea
You... definitely don't live in southern California 8-/
andrepd
Exactly. EVs are a band-aid, but the true cure is simply viable alternatives to driving.
SequoiaHope
Yep. I’m finally in a place to bike to work and elsewhere and it’s remarkable how much I can get done without a car. But the infrastructure sucks and there’s so much room for improvement.
lostlogin
Looking forward to your commute is so great. Have you treated yourself to a nice bike?
andrepd
Moving to a place where I can bike anywhere safely has been one of the best changes to my quality of life.
It's really not even complicated to do the bare minimum: whenever there are 2 or more lanes, fence one off with concrete dividers to make a bike lane. Whenever there's just 1, pave it with stones and add bumps, and cars and bikes can co-exist.
Bang, I just made your city safer, healthier, and the car traffic quicker. You're welcome.
ndsipa_pomu
I do agree, but I'd like to point out that EVs aren't necessarily car-shaped. E-scooters and e-bikes can do wonders in transporting people without so many of the issues that driving produces (e.g. congestion, tyre pollution, collisions etc).
chneu
[flagged]
Gibbon1
I have a full sized van. I know how much is costs to drive it. That's also why I own a Prius.
I see men commuting in late model pickups down 880 and I think it'd be the same as me tossing a dollar bill out the window every mile.
jimbob45
A lot of people need trucks for their work. Hispanics in gardening and construction in particular.
cyberax
It's the inverse. Bikes are a temporary 19-th century fix for the lack of easily available personal cars.
lostlogin
It took me 15 mins to get home 8km away just now. My colleague has a 500m shorter route and took 55mins. Cars are better?
piva00
Cars are a 20th century fix for the lack of easily available, comfortable, and fast public transportation. It's a shame the USA got stuck in the mid-20th century on that front.
blitzar
How else are the Little Darlings going to get to school if not positioned by a highway?
Animats
Works for modern trains, too. I was watching one of the new electric CALTRAIN multiple units pull into a station. The motors did all the braking except for the last few feet of stopping. The friction brakes normally go on below 5 MPH, and are rather noisy for disk brakes. Emergency braking is friction brakes only.
formerly_proven
The brake dust from low-noise train brakes smells so incredibly nasty (burning ABS, pretty much) but the operators and OEMs claim it’s <<safe>>. Bonus points for the Bombardier bi-level coaches, where the AC air intake is right above the wheelsets and takes a healthy gulp of that brake dust and smell and distributes it to the passengers inside (because the smell is just as pungent inside as outside a few seconds after coming to a stop I doubt the filters, if any, are doing much). Frankly I’d not commute with it.
tlb
Filters catch particulates, but not gases. Heated ABS releases chemicals like 1,3-Butadiene, a small molecule (4 carbons), gaseous at room temperature, and mildly gasoline-smelling. It's bad for you in high concentrations.
matt3210
Are they “cleaning” or just not producing as much dirty? Semantics…
senectus1
worth defining tho.
freetonik
Many people complained when VW "dared" to use drum brakes in the rear of ID.3, but it's a good idea, I think. Drum brakes do not pollute (as much), are cheaper, and easier to maintain. In the front, there are still regular disk brakes, and together with regen (recuperation), the overall use of polluting disk brakes is minimized. I'd be curious to see how much brake dust pollution is produced on average in this setup, compared to a regular ICE car with 4 disk brakes and no regen.
teo_zero
Is there an explanation why BEVs fare better than hybrids in terms of brake dust? They use the same principle, so I expected similar performances.
The article gives no clues, only these results:
> It turns out that BEVs reduce the amount of brake dust by 83% [...] Other vehicles that use regenerative braking reduced brake emissions too, with Hybrids reducing them by 10-48%, and PHEVs by 66%.
joeyh
Hybrids have a smaller battery, so C rate limits maximum regen. For example, a prius can regen at 2 kw, while a model 3 can regen at 76+ kw.
trklausss
As a driver of a diesel car: Sure thing. But driving style is what is behind this result.
With electric cars, your "engine" (motor) brakes for you. This is something that already happens in ICEs though: you can just let the car roll, don't drive in a rush etc.
However, everyone is in a rush: illegally overtaking, tailgating, honking... The conditions and social behavior on the road push for inefficiencies.
Schiendelman
EVs (or many of them) teach you this behavior - because you get regeneration back into the battery, there's a little incentive to taking your foot off the accelerator earlier and letting the car recover energy. There's a reason people are talking about this for electric vehicles and not for anything else.
trklausss
Yes, but you can do that with an ICE too. I achieve 60mpg//4l/100km with my diesel, also with highway driving. It's doable, but if you let your car roll for a red light, everyone is pissed at you.
The main difference is as you say: EVs brake way more when you are not pressing the throttle, before even needing to touch the brakes. It also helps with mileage.
Schiendelman
"Can do" isn't really that relevant when you are talking about populations. People can be vegan. They can buy carbon credits. They can live in smaller apartments to reduce their consumption. None of that is relevant, only what they actually do at population scale.
atoav
I was living on the 4th floor next to a main road once. I could wipe a thick layer of gray dust from my balcony furniture eevery two days. This surprised me initially, since it was high up and a big garden separated the road and the house.
The worst thing was the noise. When I lived there I tuned it out, but when I slept for the first night in my new flat it felt like someone lifted a huge rock from my chest.
Cars in cities are a really thing to tolerate from the standpoint of people who bear the cost of them being there, EVs help reducing two of the main issues with cars. Issues like space use remain (housing prices skyrocket while there is a ton of empty space used for storing cars while nobody drives). Who knows, maybe EVs can solve this one too one day.
cyberax
Anybody who ever driven an EV, would have told that the initial scare about brake dust was pure nonsense.
EVs barely use frictional brakes, with regen performing most of the braking action. Frictional brakes only really come into play to slow down from around ~5 mph to a complete stop.
And even that can be eliminated by essentially running the motor backwards, at low torque. This mode of braking is sometimes used on train engines as an emergency braking method.
jabl
How does this generally work wrt brakes needing to be used occasionally to not rust shut? Even with an ICE car if you don't drive a lot, and drive in a fuel efficient way (e.g. coasting towards red lights) this can be an issue resulting in an expensive surprise when you need to replace disks long before they are worn out.
olex
Some EVs (Teslas are ones I know of) have software that occasionally lightly applies the brakes to keep them clean.
Also, on EVs with LFP batteries the brakes do get used a bit more, because a full and/or cold pack usually can only take very limited power from regenerative braking. Depending on the implementation in the vehicle, brakes are either applied automatically to still allow for one-pedal-driving (aka. "brake blending", making the difference unnoticeable to the driver), or throttle-pedal regen is simply capped and the driver has to use the brake pedal when they notice that regen power is not sufficient.
lnsru
Have Tesla with badly corroded rear brake discs. Software does clearly not help here. It was very bad at the end of winter. Now it’s getting better in spring. I am curious how does it look in autumn. Trying to use mechanical brakes occasionally. I had same story with corroded rear brakes on BMW. The solution was mechanical handbrake.
tyfon
With my cars I just put them in neutral and brake down a hill once a month.
Never had any issue with rust.
cyberax
There were actually cases of that happening with some EVs (Chevy Volt, AFAIR).
They fixed it by having the software to apply frictional brakes once in a while to keep the rotors clean.
I have an EV with 150k miles, and the brake pads are barely worn. They are going to outlast it.
incomingpain
I drive completely in '1 pedal mode' which essentially lets regen do the braking for me. I maybe need to use actual brakes once every few days.
I would say something as well. The less noise from an EV changes people. They'll not look both ways when crossing a road and just walk out right in front of you.
To those wondering about tire wear:
"Despite the slightly higher levels of tire wear from EVs, brake dust was found to be more unhealthy, as brake dust is much more likely to become airborne (>40%) than tire wear is (1-5%). So EVs create a lot less of the worse thing, and a little more of the less-bad thing."