When we think about automotive emissions, we’re usually thinking about the stuff that comes out of the tailpipe. Sadly, there areĀ other ways that our cars pollute the environment, and they can be rather nasty, too. New research suggests that in some cases, what’s coming off your brake pads could actually be worse for your lungs than the gases flowing out the exhaust.
The study is the work of researchers at the University of Southampton. As published in Particle and Fiber Toxicology, it explores how particulate matter from brake wear affects human lung tissue. In turn, it’s directly compared to diesel exhaust particulates, which are themselves known for their deleterious effects on human health.
To investigate this matter, the research team cultivated cells to mimic the lining of a human lung. These cells were then exposed to particulates from diesel exhaust as well as multiple types of brake pads. Testing showed that the brake dust was “significantly more harmful” in multiple measures related to lung disease.
Four types of brake pads were used to gain a representative sample of those used on public roads. Researchers ran tests on particulates from brake pads with low-metallic, semi-metallic, non-asbestos organic, and ceramic formulations. Diesel particulate matter was also used in the study as a point of comparison.
Brake wear particulate matter was generated using a wheel and brake assembly on a test rig which replicated typical braking activity across city, highway, and country driving conditions. Meanwhile, diesel particulate matter was collected from a 12.6-liter inline-six engine running on a test bench at 1,200 rpm to emulate highway driving conditions.
Across multiple tests, non-asbestos organic and ceramic pads showed the greatest negative effects on the lung tissue, even exceeding the effects of the diesel engine’s emissions. This led researchers to investigate the commonalities between the two to determine the causal factor at play. It was determined that copper content in the brake dust from these pads was the cause, with diesel exhaust and low- and semi-metallic brake pads having significantly less copper content.
So-called “non-exhaust emissions” have been a rising concern for some time. They primarily consist of airborne particulates released from brakes, tires, and the road surface itself. While exhaust emissions have been gradually pushed downwards by cleaner air laws for much of the last 50 years, these non-exhaust emissions have largely remained unregulated. Notably, electric vehicles have long been touted as a solution to transport-related pollution, but while they readily eliminate tailpipe emissions, they still produce particulates from their tires and brake dust. In the latter case, it’s reduced somewhat by the use of regenerative braking, but not entirely.
In many countries, non-exhaust emissions actually exceed exhaust emissions as far as particulates are concerned. Regulatory change is on the way in some jurisdictions, however, with upcoming Euro 7 standards set to put limits on brake dust output in particular.
As automotive technology stands today, these non-exhaust particulate emissions will be around for some time. However, studies like this one may be the seed for future regulation to ensure non-exhaust emissions are cleaner in the future, too.
Image credits: Lewin Day, research paper
Top graphic image: depositphotos.com
“they still produce particulates from their tires and brake dust. In the latter case, itās reduced somewhat by the use of regenerative braking, but not entirely.“
I would argue EVs reduce brake dust relative to traditional vehicles at least as effectively as our modern emissions systems reduce smog compared to 1970’s tech. Hint: there’s no appreciable smog in any US cities anymore. That’s a heck of a lot better than “somewhat” and close enough to “entirely” not to worry about. I go pretty easy on brakes and still expect to need 3 sets of pads or more in 200k miles on an ICE vehicle. I would be shocked to use more than 25% of *1* set of pads on an EV in 200k miles. I barely use the friction brakes on an EV enough to keep rust off the discs.
Now particulates from tires are obviously a big concern with any heavy and/or powerful vehicle. The good news there is manufacturers are figuring out how to make longer lived tire formulations and we can at least hope EVs will go on a diet with improving battery tech.
Smog isn’t a technical or chemical term. It’s commonly usually used when stale, polluted air takes on the appearance of a fog. The rising problem in sunbelt cities such as Denver, where I live, is ground-level ozone. Roughly half the days last summer, our air violated clean air regs for ozone. So that battle against air pollution is far from over. Ingredients contributing to ozone include NOx from cars, but also VOCs from perfumes and air fresheners and paints.
I’m surprised ceramics are so high as wheels get very little dust from them compared to anything else. Of course, this problem material might be particulate matter that doesn’t tend to cling and goes airborne and able to do more damage due to its small size, so that observation doesn’t matter. Since they’re primarily pointing to copper as the issue, I wonder what it would look like if they tested copper-free ceramics. Either way, I might just use this as an excuse to swap to semi metallics, which have better feel.
Sounds like maglev trains are the only transportation solution to produce (near?) zero local pollutants.
Science, facts, and regulations that get in the way of profits are un-American.
NO MORE RULES, LAWS OR REGULATIONS.
OR NON-WHITE IMMIGRANTS!
STUPID PINKO COMMIES.
When I lived outside Tokyo in the early 90s – we could see the lousy air quality.
You could obviously see the smog day after day unless it was right after a rain.
And when you blew your nose, you could see what was being filtered before hitting your lungs.
Because it would come out black.
Time to call up that company that wants to intall vacuum cleaners or whatever behind everyones wheels.
I didnāt even know that ceramic pads contained copper. I checked the last two I bought (Bosch QuietCast and Akebono ProACT) and apparently those are no Cu and low Cu, respectively. But it seems like Akebono is phasing out Cu due to some state requirements. So something of a mixed bag. I am aware that some people stare at the brake pads at RockAuto more obsessively than others.
Keep in mind, all of that brake and tire dust ends up washed into the storm sewers, which leads to your local streams and creeks. The dust is almost worse than salt for aquatic life, including fish and birds.
Better find that Pandora moon to move to pretty quick.
Just avoid braking asbestos you can.
A Picard GIF would give himself a concussion if he heard this.
We should change all the traffic lights to yellow.
Then people would know to be cautious but nobody would need to stop.
Roundaboutify the world!!!
I’m not worried. I read in that Motley Crue biography that those guys would sometimes go through 4 or 5 sets of pads in one night, and that was back when a lot of them still had asbestos in them. They turned out okay. They even coined the phrase “nobody puts the brakes on a Crue show” as a subtle nod to their secret weapon.
Iggy Pop, too.
I’m not sure Niel, Mars, Sixx, or Lee “turned out okay”.
That was part of the joke, but yeah š
They obviously didn’t test Callahan brake pads. Tommy would never.
FIFY:
(…) Notably, heavier electric vehicles have long been touted as a solution to transport-related pollution, but while they readily eliminate tailpipe emissions, they still produce more particulates from their tires and brake dust. In the latter case, itās reduced somewhat by the use of regenerative braking, but not entirely.
Tires shed a quarter of all microplastics released in the environment. This poses a much higher threat to human and animal life than either exhaust emissions or brake dust.
Buht bro, duh, we come here for the burnouts and the track days. Yuk, yuk yuk…
Don’t get me wrong, I’m all for track days, just not with BEVs — a tool not suited for that job.
Came here to say this, thanks for putting it better than I would. Tire dust is a huge problem that’s only just being noticed. And the proliferation of heavy passenger vehicles (whatever the drivetrain) has made it so much worse.
Came here to say this, too, but Iāve heard as a high as 42% of microplastics are tire dust. My to-do list precludes looking it up, so Iāll just say microplastics are bad. Donāt be a microplastic.
My father has antique cars. I grew up changing what I am sure were asbestos drums with my face 2′ away. It was common to use compressed air to blow the dust out of the drums before service. I am sure it was very bad for my health but so far so good. Well, except for that weird head twitch and that growth on my back.
(the growth is a 3rd arm)
We’re lucky to be alive. When I was young we used our bare hands to wash car parts in gasoline. Except for blue saliva, I’m fine.
So my teenage job at the full service car wash where I got to scrub brake dust off the rims before the car entered the wash bay may have doomed me to an early death? Oh well, I had a good run.
Well, they’re now saying that a lot of skin cancer in middle/old age is caused by sun exposure when we were young. So we’re all fucked.
Not to mention all that lead we breathed in as kids in the 60s-70s.
No, noāitās okay. The lead just made our generation stupid and violent. Life expectancy wasnāt affec*ā<erg>ā¦thud!
I have a solution no more brakes. Who needs them anyways can’t stop won’t stop y’all.
Nonsense, this is just more fake news from people trying to sell you e-lectric ve-hicles with that regeneratron braking! Well I’m gonna get in my diesel Sil-ver-ay-do 6900 and roll coal while standing on the brakes to get me a 1.9 em-pee-gee! That’ll own the libs!
Hoping that’s snark. Forgot the /s tag.
I’d hoped the extent of it made it obvious, but god damn, Poe’s law is alive and well, innit. Yep, sarcasm.
Good ‘ol Proposition 65 warning on the brake pad boxes is more relevant than originally thought.
But only if you live in California. Outside of CA, it’s smooth sailing!
(/s, just in case)
What if I live in CAnada?
For those concerned, you should be able to buy zero-copper brake pads at any auto parts store. California began regulating copper quantity in brake pads over a decade ago, due to fear of brake dust entering waterways and killing aquatic life, and many auto parts stores carry the pads required for California in other states – for those that don’t have them in-stock at the store, they can easily special order them. It is worth noting the zero-copper pads squeak like mad when cold.
Glad someone else is paying attention to aquatic life.
I just installed my first set of ceramic pads last year and wasn’t prepared for how squeaky they can be when cold (and/or with light pressure). It embarrasses my wife, but IDGAF, I know what I have, no lowballers, etc.
Half the dust and all the stopping power is a win for me. I haven’t heard of copper specifically included/excluded, at least not in the marketing.
The ones without copper look nearly identical to the normal ceramics, and typically only say something like “no copper” or “zero copper” or “copper free” on the box in small letters. While the normal ceramics do make noise when cold, the copper-less ones take a considerable amount more heat to get them to quiet down. My wife hated them, but she never complained about the lack of dust on the wheels.
How long before there becomes a new strain special little guy who wants to start a “brake rolling” trend?
āSpecial little guyā. Love that!
For the larger non-research science public, as they are assessing what it means for their health, it’s important to contextualize the risk this data is trying to quantify. This is one more data point for your personal exposure profile. You need to add it the larger spectrum of exposures your getting in your daily life. If I lived in an urban locale or worked in a garage, I’d be paying particular attention to this information. Do you smoke, or live in an area routinely impacted by wildfires? Then your lungs are taking a heavy particulate load already. Then layer on volatile or semi-volatile organic chemical exposures on top of that. Are you inadvertently huffing a lot of gas/parts cleaner for a few hours a day/week while you wrench? Lots of things to consider, but one way to tackle it is if you look at your total exposure profile, are there some “low hanging fruit” exposures you could reduce or eliminate with a small effort. There likely are.
If anything this data would suggest if you work in or own a brake shop, might be time to take another look at the HVAC system and maybe up your filtration factor.
. . . or wearing respirators or N90 face masks . . .
“Are you inadvertently huffing a lot of gas…”
Inadvertently? No.
Just joking. Great comment.
breathes in deeply “Ahhhhh! I love the smell of VOCs in the morning!”
Looking at the study just far enough to find the thing I was wondering about: the cultures were exposed to the same concentration of particulate matter, 32 ug/cm^2 for 24 h if short-term memory serves, with no calculation for how this would or would not correlate to actual production amounts per mile driven. If there isnāt any of that consideration further on in the study, then it would seem to be a study of āwhat do these pollutants do to lung tissueā rather than āwhat do these pollutants as caused by automobile driving do to lung tissue.ā
I’m sure particulate from brake pads is horrible for your lungs, but does the study account dosage and delivery?
One of the reasons emissions are bad for lungs (and the environment) is because they’re a gas that’s dissipated into the air where we can then breath it. Conversely, brake pad particulate is a somewhat solid mass. Yes it’s more akin to a dust that can be airborne… But if it’s typically settling on car surfaces or the ground before reaching our lungs, then there’s no/little delivery and the harm may be minimal.
As for dosage, again I’d like to know how much is needed to infiltrate to pose a threat. Cars constantly emit emissions while running. Unless you’re a grandma riding the brake, brake usage is much less frequent (and with electric one pedal driving becoming more popular…. Even less frequent).
Anyway, it would be interesting to know more.
“Brake wear particulate matter was generated using a wheel and brake assembly on a test rig which replicated typical braking activity across city, highway, and country driving conditions. Meanwhile, diesel particulate matter was collected from a 12.6-liter inline-six engine running on a test bench at 1,200 rpm to emulate highway driving conditions.”
Without knowing the exact details, it looks like it tries to replicate real-world production amounts. Whether that translates to real-world interactions (how much of that generated stuff actually makes it to where people breath) doesn’t seem clear.
Yeah for sure. I also wonder whether driving with windows open or closed would impact the results, and whether the particulate is captured by air filters.
I think you’re right for direct inhalation, but like with tire particle emissions there’s other problems once it gets washed off the vehicle/road surface and into the surrounding environment. As far as I can tell we don’t really know what it does once it’s free.
So true. The 3M “forever chemicals” is a good example. That junk was dumped into the environment for decades, is currently impossible to remove, and doesn’t break down naturally.
The assumption that something doesn’t have a harmful impact if it doesn’t kill us immediately is a human blind spot that comes from a biology evolved for a short life and immediate threats.
“None of us are getting out of here alive.” Wood and coal smoke used to be a lot more prevalent, so they were a big culprit. Tobacco is a known carcinogen, yet it’s (mostly) still legal. Sunlight causes skin cancer. Loud music causes tinnitus. Ultimately, it’s “pick your poison”.
If the framework of your argument could be used to undertake a real-life remake of a scene out of The Deer Hunter, it likely has been stretched beyond its breaking point.
The difference: in 1900, only 76M people were polluting America. Now, we have 325M doing it. Big difference.
Once it’s free, stormwater washes it all into the storm sewers, which lead to streams, creeks, and rivers. Over time, the pollutants concentrate because of flow patterns and can completely poison a waterway. No fish, no bugs, no birds.
You also have to factor in the tradeoffs between fewer particulate emissions and poorer brake performance leading to more direct crashes, injuries, and deaths. “Don’t let perfect be the enemy of better.”
We’ve had emission regulations for half a century so it should be no surprise that exhausts are cleaner. We haven’t had any real regulations for tires or brake pads.
Bring back drum brakes?
Drums still vent to atmosphere. Sure, it’s largely enclosed so I’d expect it to be lower, but the whole thing this study makes me question is how much is actually making it into people’s lungs, and what does brake type (drum/disc) impact that, as well as vehicle type, wheel style, and all that.
I agree. The amount of brake dust that settles and sticks to wheels alone makes me wonder how big a threat this actually is.
I could see some argument being made that it gets on the road and things like that; and thus every car driving over it kicks it up, and rain washes it in other places. But the idea it goes straight from the brakes into your lungs seems far harder for me to envision.
I support people figuring that stuff out though.
Figure about 1/3 of your dust gets stuck to the rims due to static electricity. The rest goes down the drain.