The researchers found the link between living near highways and future neurological disorders to be independent of income, education, ethnicity, comorbidity, and coexisting medical conditions associated with future neurological disorders (traumatic brain injury, diabetes, hypertension, stroke, coronary heart disease, congestive heart failure, and arrhythmia).
If is very, very, very difficult to control for all these factors. Apart from the data dredging problem, the difficulty of controlling for all confounding factors is what make so few association studies hold up when prospectively tested.
As a rough rule of thumb if the hazard ratio is not 3 or greater in an association study then it almost certainly won’t be replicated prospectively.
Living near a noisy highway is rarely prime real estate. How do we account forincome when there are so few in that subset?
I also wouldn't discount the effect of endless stress. That is, the drone of noise. I recently moved from to a street that's fairly busy. Only in the middle of the night is it quite. I don't like it.
It really depends on your building too. I live near a highway and getting around by car is really convenient as a result. Highway noise is not very audible due to the construction of the windows and the walls. My air quality meter says the PM1.0, PM2.5 & PM10 counts are 3-1 ug/m^3 inside and I don't have air filters on.
I have a handheld one by igeress that I got on amazon. It's basically a no name chinese one, so YMMV. They also have a pretty bad pollution problem too, so probably some of the better consumer ones are from there too.
Also, the neighborhoods tend to be safer and more inviting than those right next to the major freeways.
I was originally thinking air quality is the major reason, but Vancouver has really good air quality overall compared to where I live in Los Angeles. I would be interested in seeing this type of study be done across cities with different air quality.
Given that Vancouver has good air quality, the difference between living 150 meters from a highway vs. further might be more pronounced than if living in LA where the baseline pollution level is high enough that living next to a highway doesn't give meaningfully higher exposure.
I live in a house next to the highway. I can hear cars pass as I type this at 10pm. It’s irritating. Upper middle class homes, 250k-350k where median home price is $150k.
Anyone living near a busy road is swimming in particulate matter on the micrometre and nanometre scale, and particles on that scale bypass the normal defences, get into the blood stream and saturate the body. Small particles can even move down nerves, it’s really not surprising that long term exposure causes neurological problems.
And what many overlook is many of these particles have nothing to do with emissions. Brake pads and tires turn to dust. So too bits of the road surface are slowly converted to fine particulates. Converting everyone to autodrive teslas powered by fusion reactors wont stop rubber from meeting asphalt.
(Switching to manual transmissions would probably reduce the brake dust. Id like to see if european roads suffer as much. Between automatic transmissions, weight, and some traction control schemes, NA cars chew through brake pads.)
Additionally, roads can be designed in a way that calms vehicle movement instead of accelerate-brake cycle. For example, narrower roads with curves instead of wide straight roads with speed bumps near pedestrian crossings.
while switching to electric vehicles likely reduces break dust, such switch would simultaneously increase dust from tires, since increased acceleration. The latter being already 80% of urban "particulate matter" pollution.
Tyre wear does release particulate matter, but it's mostly heavy, large particles that end up on the road and get washed away by weather.
With the exception of tunnels, where heavy particles are constantly being churned up from the road surface and re-circulated into the air, tyre and brake wear is a relatively minor contributor to urban air pollution.
> tyre and brake wear is a relatively minor contributor to urban air pollution
Why do you say that? Would love to know more, but all the research I've read lists them as significant contributors, second only to resuspension, each now exceeding tailpipe emissions on both PM 10 and PM 2.5.
As an aside, we'd probably agree that vehicle weight is the mediating factor across all of these sources, regardless of the ratios from one type to the other. Massive load hauling trucks are generating a disproportionate share of emissions of all types, this is not really about making sedans a little more efficient.
Claims that tyre/brake particles exceed exhaust emissions are inevitably referring to particulate mass, not particulate count. One large particle can weigh as much as millions of nanoparticles, but is far less dangerous. Exhaust nanoparticles (sub-PM2.5) are small enough to penetrate the respiratory system, diffuse to the blood stream, and cross the blood-brain barrier.
Here in London, some of the most obviously polluted and stinking roads are those where the traffic barely moves at all - lots of slow moving or idling vehicles. There isn't a great deal of brake or tyre wear when vehicles are standing still!
> Claims that tyre/brake particles exceed exhaust emissions are inevitably referring to particulate mass, not particulate count
Huh, all the studies I've read and linked are comparing like with like within particle size categories. Idling considerations are addressed in the modeling too.
You seem fairly unshakable here, but the topic seems well researched and the results are pretty unambiguous to me.
Categorising particles into PM2.5 and PM10 is far too narrow. This doesn't adequately account for, and perhaps doesn't even measure, nano-scale combustion products. The 2.5 in PM2.5 refers to micrometers (μm), not nanometers (nm).
If you're only counting the largest particles, then yes, a lot of them are going to come from tyres.
I don’t think Nissan Leaf is particularly good at neck-breaking acceleration, and it probably outnumbers the drag-racing Teslas. Even then, a Tesla isn’t particularly speedy in traffic.
I often drive a Renault Zoe which also isn't a sports car. I frequently leave sports cars behind at the traffic light. From 0-30 kph even the small/cheap electric cars are sport cars. And it is terribly tempting to develop a pedal-to-the-metal habit. So I assume tire dust will increase significantly in the cities.
Rate of acceleration isnt the issue. You may make more dust per second but so long as you are getting to the same end speed, and not spinning tires, the total amount of acceleration is the same.
In my experience, over braking is the greater problem. Front tires degrade more quickly than rears. The average driver brakes far harder than they accelerate.
I think the heavier EVs hit a crossover point because of regenerative braking, but weight does set them back, that's one of the whole points of this study:
This is a curve though. We could almost simplify the problem and only look at what heavy trucks generate and ignore all the cars completely, it'd be a non-crazy approximation.
A set of pads typically lasts about as long as a set of tires (at the very least they're within a factor of two of each other). Compare relative volumes of materials. Brake dust is always going to be a much smaller source of particulate matter in the air than tire dust.
FWIW if the fumes/particulate from burning them are any indication tires are probably way nastier than brakes.
Second paragraph, though: I've never been around a brake pad fire, but I'd rather breathe vulcanized rubber than "metal shavings of copper, steel, graphite, and brass bonded with resin":
In my non-chemist, non-doctor opinion the circumstantial evidence points to brake dust being way less bad than tire dust.
Being inert in the presence of most common substances tends to correlate well with low toxicity. It's the stuff that chemically reacts to all sorts of things that tends to be the most poisonous.
Tires break down over time under "normal earthly conditions" which includes a lot of the same temperatures and molecules that are found inside the human body. To me this is a massive red flag for toxicity.
High temperature tends to make things react more readily. Most of the stuff in brakes has to be really stable at high temperatures and being stable at high temperatures tends to correlate well with being chemically inert.
The most reactive stuff in brakes are the long complex molecules used to bind it all together. These sorts of molecules are similiar to the molecules used in tires and all sorts of other plastic like things. So all else being equal tires probably have more of the chemically interesting things that cause problems in the human body.
Burning brakes smells way better than burning tires which seems to confirm this (remember, your nose has millions of years of incremental improvement when it comes to indicating what is and isn't suitable to ingest).
And before anyone thinks they're gonna get some easy internet points by saying "but asbestos", the amount of asbestos in brake pads is nonzero (to account for the sketchy unbranded stuff that may or may not use it) but still tiny enough that people working in proximity to it have mostly stopped dropping dead at 60 thanks to lung cancer so I think that however much asbestos is in brake pads it's low enough to not be an issue from a public health POV.
TL;DR I'll take my chances with brakes over tires.
Would have guessed the opposite, FWIW, on the grounds that the bad stuff is hard materials (like mine dust). But if anyone actually knows that would be interesting. How good a measure is total PM2.5 or whatever, without asking about what it's made of?
That said, as was pointed out below, changing the car's design to vacuum up brake dust would be much easier than getting away from rubber.
Yeah, you generally shouldn't be inhaling dust but inert dust (silica -> silicosis) is better than reactive dust (asbestos -> cancer).
I'm not well versed enough on the specifics to tell you whether or not PM2.5 is a good measure of pollution. The experts in the subject of air pollution routinely use it so it can't be thaaaat bad.
> Compare relative volumes of materials. Brake dust is always going to be a much smaller source of particulate matter in the air than tire dust.
It's not a fair comparison, because you don't wear through the entire tire material as extensively as a brake pad. Fortunately we don't have to back of the napkin this one, there's lots of research showing brakes are near peers or exceed tires in contribution to PM 2.5.
As to your second point that brake material might be less harmful -- there is some initial research on how composition mediates impact.
Aluminum, sulfate, nickel, arsenic, and silicon seem to have the strongest relations. Aluminum is a frequent abrasive in brake pads, they aren't merely contributing some form of benign 2.5.
I can't do a comparison, you might be right it's "less bad" than tires, which contain other heavy metals. But I do not think the research is powerful enough to precisely settle that question beyond the overwhelming academic consensus that both are bad and we should definitely try to reduce both.
I mean, you can still shift gears in an automatic car. I used to do it all the time when I lived in a snowy, hilly city. I've never in my life seen an automatic where the only options were drive, reverse, neutral, and park. There's always some amount of control, even if it's only 1/2/3.
Edit: Upon reflection, I assume your comment meant that newer cars will somehow use engine braking themselves. Since electric brake systems are rare in ice cars, would this be referring to cruise control features?
"Engine braking" isn't just letting the engine spin down at 0 throttle. Propper engine braking, aka "Jake brake", is letting the engine spin at 100% throttle but zero fuel input (and some valve trickery). This lets air in to be compressed, releasing it before the down stroke of the piston. No car does that. It is a separate installed system on trucks. It can be almost as powerful as the engine. In a car, it could handle all but emergency braking.
I have on my manual 15-year old diesel bmw very much an engine brake. It breaks quite well compared to neutral which seems to like to go on forever, and actually indicates proper consumption.
On highways and motorways, I rarely need to use brake at all. Of course, being a sensible driver helps (in contrary to what many people expect from me when they see the car and expect yet another immature aggressive driver)
Maybe not exactly the same, but the B mode on hybrid cars sound similar.
When you are driving down a large hill (e.g. on a mountain) eventually the battery will become fully charged, so you can't use regenerative braking anymore. To provide some resistance so you aren't effectively driving in neutral, the car will spin the engine at high RPM without supplying any fuel (I'm not sure how this works in terms of lubrication, as I understand the fuel provides this too?). You can also engage B mode which does this at an earlier stage, so have more control without having to use the brake when driving down steep hills (like engaging a lower gear).
London hybrid busses do the same thing, as they come to a stop you can hear the engine spinning at high RPMs.
> Engine braking occurs when the retarding forces within an engine are used to slow down a motor vehicle, as opposed to using additional external braking mechanisms such as friction brakes or magnetic brakes.
> The term is often confused with several other types of braking, most notably compression-release braking or "jake braking" which uses a different mechanism.
But when you see a sign saying "no engine braking" it refers to the jake brake, not down-shifting in a car. (It's a long trademark story over the use of "jake")
This doesn’t seem like a trivial improvement. Particulates are not the only toxic component of exhaust either; electric cars should produce no NOx, CO or O3 which is a big improvement. It’s also worth noting that brake wear particulates haven’t been a target because historically exhaust-related emissions were so much larger.
If we haven’t really tried to fix it, who’s to say we can’t?
Trains do use brake shoes on the wheels, and in some cases disc brakes. All trains have mechanical braking capability, as far as I know. Many also have electric braking, especially passenger trains with frequent stops, which is either regenerative or dissipated as heat via resistors. Freight trains tend to use mechanical breaking, but have infrequent stops and can plan a long slow-down. In any case, the braking force has to be transmitted somehow to the wheels before it is transmitted to the rails. There is only rarely wheel on rail sliding outside of emergency situations. But, particulates of steel on steel sliding should be relatively benign. A good train system is better utilized compared to cars as well.
All this is to say that yes, there are fine particulates from trains, but it should normally be much less than from living near a highway.
I remember from my days working for London Underground Ltd that whenever I'd blow my nose after a shift, my snot would have a concerning amount of black matter in it. The days I was off and not entering the subway, my snot didn't have this black particulate matter. I like to think it was my nose doing its job and keeping all that from entering my lungs, but I'll never know.
Yes but far fewer. The metal turns to dust, but orders of magnitude less quickly than rubber/pads/road surface. The stuff carried by the trains is probably more dangerous than the train itself.
Dumb question - how well would an attempt to suck in the particles work putting aside the obvious impracticality? There are currently tons of reasons not to do it today but could it theoretically be solved via clean and cheap energy to make the efficiency loss not a foregone self defeating act.
Quality of air definitely matters, but I wonder what actually has more negative effect - poor ppm levels or the stress from the noise.
People think that's not a big deal and you just get used to it, but the truth is, your brain is ALWAYS processing that noise in the background as a source of potential danger, taking a long-term tall on your mental state.
I work in an office with poor CO2 PPM levels, and constant noise. I've started enjoying working from home, even though I used to absolutely hate doing that.
Yes, I wonder about the noise issue too. In my personal experience, living near a busy road had a huge effect on sleep quality which in turn increases stress levels and reduces wellbeing.
The depth and breadth of neurological issues could not possibly be explained simply by noise. Humans lived in close quarters for most of our existence which would have included a lot of elevated noise levels.
there might be a different set of neurological effects caused difference between the noise spectra of natural sources, to include human generated noise, and the unnatural sources like car traffic. the color spectrum of natural scenes has been found to have different impacts than that of manmade urban scenes.
I'm curious how different living next to a highway is to living in a dense urban city though (like NYC) and if it's different why? In either case you have a lot of car traffic (probably closer to your place of residence than people that live close to a highway) Not to mention if you live in a dense urban city then you will spend more time walking directly next to traffic.
Whatever the effect, it's at least getting better. As someone who rides a bike to work every day on urban roads that are usually congested, the recent rise of hybrids, and even just cars with auto start-stop systems, has been a blessing. It used to be that driving next to a line of stopped cars was a nightmare, but now at least half of them have their engines off, if they have an engine at all.
Moving an automobile a couple miles in a dense urban environment at very slow speeds shouldn't require much energy, at least from a pure physics standpoint.
> Moving an automobile a couple miles in a dense urban environment at very slow speeds shouldn't require much energy, at least from a pure physics standpoint.
If the terrain is flat, I agree. In hilly cities, not so much.
If your "physics" don't include drag, rolling resistance, or conversion losses, I'm forced to agree.
However, regenerative braking (like any other energy conversion process) is not lossless, and it turns out that low-speed, high torque acceleration is where they're least efficient [1]: required torque increases with the incline you're trying to accelerate up. And if you're staying at low speed, you'll be stuck in this low-efficiency regime, and you won't recoup much going back downhill.
the one thing that strikes me as different, having lived in manhattan / queens / brooklyn for 25 years, is that by a highway there is high speed traffic, which is extremely loud and sudden, and a lot of it is heavy commercial traffic, heavier than what is feasible within an urban environment. the next time you're at a rest stop off of I95 just stand outside and listen to the noise of huge trucks blowing by at 80mph. I think those sudden blasts of sound and vibration are well above and beyond the stress when you're in a dense urban environment. City traffic, especially if you're on a side street as is more common for residential, you're looking at 10-20mph traffic for the most part and without 18-wheelers going by most of the time.
There is also the issue of subway noise, which is more like a constant stream of periodic vibrations. that is probably not good for one's nerves either but it is fairly subtle.
The most stressful thing about urban living for me was the constant light, ugly sodium colored light at all times, flashing lights, emergency lights, etc. I now live in a rural area and I will bundle up and sit outside on my deck at 1 am in 20 degree weather just to enjoy the darkness. There was never total or near total darkness in the city at any time, not even indoors unless you have blackout shades which we did not.
the worst of all worlds are those folks living in those apartments that overlook the BQE and stuff like that. They look like expensive places and I think whoever is choosing to live there is completely crazy, they get the most particulate matter (except that their windows are probably sealed shut, which is bad in itself), the most noise, the most light, etc.
I agree about light being an issue in cities, too. And it's gotten worse with the advent of LED streetlights.
But it's usually pretty easy to install blackout curtains if you want them. Or even just to buy a comfortable eye-mask for sleeping. Effective sound-proofing is much more difficult and expensive.
I live in a side street about 100 yards from a major avenue in my city. You can see on our front porch the impact of particulates... it’s covered in gross sticky dust once we do our spring cleaning.
Likewise being under a flight path to a major airport. The white deck on our boat at a marina on the approach to BWI gets all kinds of particulates on it from the exhaust of planes passing overhead.
According to this article[1], nanoparticles drop off quickly compared to larger particles:
"However, the highest averages were recorded inside the cars and buses: the closer to the source of the pollution, the exhaust pipes spewing out the fumes, the higher the total number of nanoparticles. The difference between walking by the kerbside of the road, and by the building side, on the same pavement – just a few short steps – was an average of 82,000 particles versus 69,000. The same readings registered no change in PM2.5."
If there's a confirmed link between neurological disorders and air quality and traffic, wouldn't this show up in major metropolitan cities as well? Someone who lives near a highway is probably exposed to the same if not more automobile pollutants as someone in a city? I guess I'm trying to make the point that if the conclusion that they're drawing (proximity to cars = neurological disorders) it should show up in contexts outside of just "highways."
Once I was talking to a retired real estate agent and they said they had noticed a disproportionate number clients who lived by the highway had lung cancer in their family.
I've always been fearful of the life outcomes endured by those raised in the Washington Bridge Apartments (they straddle the trans-Manhattan expressway, sort of like the western end of the Cross Bronx Expressway)
I live near a four lane road which is quite busy. I'm only about 50m away but there are two blocks of houses between me and lots of trees. The road speed is 60km/h but most vehicles travel 80km/h. I wonder if speed has some effect of whipping up the pollutants more?
The road is near the main hospital. My town is not a very big maybe 70,000 total spread out over a large area. But ambulances go by once or twice per hour more frequently in the summer. The noise from them bother me more than fumes although I can't smell fumes or see nano-scale sized particulates.
So if I start to act crazy...well, crazier, here in the comments you'll all know why. And before I do.
I wonder if they controlled for... why people choose to live where they live. I.e., this wasn’t an RCT; they could just assign people to live near highways or not. So the people who are living near highways are there for a reason.
Are residences near highways, perhaps farther from certain other things, like city centres? Such that a certain type of person (people with pre-existing [perhaps subclinical] mental issues of the type that might make them want to avoid people) would be drawn to live in these residences more than others?
To me, “living near a highway” sounds a lot like a euphemism for “living in the middle of nowhere”, since by definition all arterial roads connecting “somewhere” to “somewhere” through “nowhere” are highways. If you live somewhere isolated that’s accessible at all by road, and you don’t have the budget to build your own long stretch of lane out from the highway, then presumably you live on a highway.
> To me, “living near a highway” sounds a lot like a euphemism for “living in the middle of nowhere”
I would have thought the opposite. Essentially no-one lives directly adjacent to a rural highway in the sense of overlooking it in the UK, even say the M25 doesn't have flats lining it, generally arterial roads have setbacks so you might be able to hear the cars etc but you've probably got a buffer zone measured in the tens of meters.
The actual roads I'd be thinking of are things like the A406 (North Circular Road), A40, A4, etc, which do have houses and flats immediately next to it. The sort of 'inner-city' 40-50mph urban clearways. There are also a ton of 30mph roads which serve a similar purpose. Basically what one would call a 'main road' as opposed to a side street.
Example of a sort of middling neighbourhood: https://goo.gl/maps/o6oSRW84dx147TK48 (this bit of the A40 is either 40mph or 30mph but has an absolute ton of traffic almost all of the time).
> “living near a highway” sounds a lot like a euphemism for “living in the middle of nowhere”, since by definition all arterial roads connecting “somewhere” to “somewhere” through “nowhere” are highways.
The study uses a definition based on average vehicles per day that travel the road. I think you're interpreting "highway" like a road that connects two cities, which is one of the word's many meanings, but they are using a different definition.
By using a traffic-based definition, this study is roughly counting the number of (running) cars that you're near.
Also, with their definition, people in urban or rural areas can be either near or not near a highway. If you live in the middle of a city but you're removed from high-traffic roads by neighborhood streets with low traffic, you're not near a highway.
> To me, “living near a highway” sounds a lot like a euphemism for “living in the middle of nowhere”
In more (sub)urban settings, I read it as "poor." But either way, it does seem hard to properly control for, and my gut tells me socioeconomic factors drive this more than pollution.
Or just that being close to a highway is often unpleasant, so those who can afford more pleasant parts of town have already done so. Surely they tried to control for wealth but it's easy to do so imperfectly. (Haven't read the paper, though!)
There are multiple major highways in urban greater Vancouver. The Trans Canada is the big one, and Oak street is essentially highway 99 (which becomes the I5)
Is it not also likely proximity to green plants reduces stress, and blood pressure? And mood improvement might shave years off exposure of risk to Parkinson's insidious side effects on mood leading to later or post death (postmortem exam) diagnosis.
While green plants may reduce stress, I don't think their absence can explain the effect observed here. Exposure to aircraft noise during sleep has been documented to cause endothelial dysfunction [0], which increases oxidative stress [1]. I think it sounds very plausible that increased oxidative stress over a prolonged period can cause neurological problems.
Interstate highways are included in the category of “highways”, and are often just a road running through the middle of green space like forest. It wouldn’t really make sense to claim that “living near highways” does X unless it was still true even for living near such a forested interstate highway.
They approximated income, education, and ethnicity at the neighborhood-level (400-600 people) based on census data. That doesn't seem granular enough to me if the poorest families in each neighborhood live closest to the major roads.
I’ve seen similar studies done in the U.K., where in cities plenty of relatively affluent people live directly on very congested, polluted roads, and the findings were identical. IIRC they found the worst effects were on people who had been living there for 40+ years - and speculated that that was down to lead exposure until TEL was banned - however the impacts of contemporary pollutants was still significant.
With the way the Corona Virus is spreading we might all be wearing Face masks pretty soon.
This may seem like common sense after Flint, but at this point I think a home water filter is needed for most parts of the country. Can't blindly trust the municipalities.
A Home Air filter is probably needed too.
Here's a growing list of things Youtube told me things one should invest:
1. Home Water Purifier
2. Air Filter
3. Good Mattress / Pillow
4. Blackout Blinds for Windows (sleep)
5. Gym Membership
6. Standing Desk
7. Travel
8. Vegan/Plant Based Diet
Oh and Washing Hands regularly.
Yeah its a growing list, and getting kind of expensive. I'm surprised how much it starts resembling living in a 4 star hotel.
Not sure why you're getting downvoted, I would agree that most of these make a lot of sense if you can afford them. I wonder what the order of importance is - I had a doctor tell me it was sleep > diet > exercise, but where do e.g. air and water quality fit in?
I would modify vegan/plant based diet slightly - either add supplements for B12, or eat eggs. Also, I hadn't considered travel to be as important as the rest of the items. Do you know what need this fulfills?
> Living near a major road or highway was associated with a 14-per-cent risk for dementia, and seven per cent for Parkinson’s disease.
I love how the article completely misses the important data point: what are the actual risks for other categories not living next to highways? Without this information, an "increased risk" is meaningless speculation.
The researchers found the link between living near highways and future neurological disorders to be independent of income, education, ethnicity, comorbidity, and coexisting medical conditions associated with future neurological disorders (traumatic brain injury, diabetes, hypertension, stroke, coronary heart disease, congestive heart failure, and arrhythmia).