Hacker News new | past | comments | ask | show | jobs | submit login
Drivers who keep their windows down are exposed to 80 percent more air pollution (surrey.ac.uk)
207 points by clouddrover 50 days ago | hide | past | favorite | 228 comments

You can smell car exhaust even when there's not many cars on the road; if it's bad enough you can virtually taste it. Sitting at the lights is the worst. All that shit going into your lungs. And I don't even live in India or Vietnam, where the air pollution is unbelievably bad (literally - I did not truly get how bad it is in Delhi until I went there, even having seen photos) and people are just living in it, day in and day out.

In 5-10 years one of the things that will be recognized as a marker of privilege will be breathing clean air. We're going to see a diaspora out of the city and into the countryside... for the people who can afford to do that (and where the countryside offers clean air)

Air pollution is arguably the biggest health crisis in the world, and it has been a problem for decades. We're only just realising it, and it's still taking too long. It's taken decades to get climate change into people's minds, but right now today air pollution is having much bigger effects.

>and it has been a problem for decades

try centuries. Cities used to be population sinks sustained by migration because people kept dying so fast. During the heyday of early industrialisation the life expectancy in Liverpool[1] fell to 25 years. London periodically experienced infamous smogs, the one in 1950 killed about 12000 people.[2] No matter how bad it is today, it was even worse in the past. Electrical vehicles and better public transport and much more awareness and historical trajectory if anything though suggest that things are getting better, not worse. There's not going to be anyone fleeing from the cities, economics opportunities are going to outweigh pollution, as it did in the past.



>We're going to see a diaspora out of the city and into the countryside

I think that instead we will see cleaner air in cities since the economics of electric/hybrid cars will win, especially in city traffic. This trend can already be seen in SF where zero-emission hybrids and electrics make up a decent percentage of the traffic.

You talk about these things like they are the future. But western cities are already much much cleaner than 40 years ago. The move to electric cars and more livable cities is just the continuation of a fight that has been going on at least since the industrial revolution and adoption of hygiene.

Long before the industrial revolution. Horse manure and slaughter runoff were huge sources of disease in cities even before coal smoke took over the air.

As others have mentioned, personal automobiles are the problem, not the fuel they run on. Modern engines run rather cleanly. Noise, safety, rubbers and other particulates are also ruining the local environment.

Come on, they run not clean at all. Have you smelled a brand new diesel engine during winter? Or even a bad self-polluting hybrid?

Personal automobiles are part of the problem. Perhaps not the biggest problem but a big one in cities.

I am not really disagreeing with you but one should add that bad smell is not necessarily a good indicator for what is unhealthy.. there are many poisonous gases without any smell (also emitted by cars).

Diesel is pretty bad, but a modern gas engine after warming up with leaner fuel mix and catalytic converter heated up has pretty tame emissions.

Breaks are the biggest source of pollution.

Regenerative braking helps with pollution, since you're not wearing a brake pad, just running the motor in reverse.

Or in China where they have nearly half a million electric buses - https://www.bloomberg.com/news/articles/2019-05-15/in-shift-...

Note that as much as 30 percent of car pollution is not from the fuel and would remain.

What is the cause of that ~30%?


it's nowhere close to true. otherwise you'd have to change your tires and brakes each time you visit a gas station.

It may be you who are mistaken: “...particles from brake wear, tyre wear and road surface wear directly contribute to well over half of particle pollution from road transport.”


Notice how they specified "particle" pollution. That's a subclass of the general pollution. Small subclass.

Particle pollution, if they are using it correctly, which I think they are, includes exhaust and pretty much every post-production pollutant produced by a car (before it is scrapped I guess). See: https://www.epa.gov/pmcourse/what-particle-pollution

Or you can use some basic math, and calculate how much tire/breaks wears(loses original matter) per 100 000 km and how mach of gas a car burns for the same distance and compare these numbers.

My understanding is that on average, a tire loses a molecule's worth of rubber thickness every time it goes around. I would imagine tires lose more with heavy breaking of fast starts. The other day I saw some idiot on a motorcycle purposely spinning his tire at the stop, leaving a black mark on the pavement and a lot of smoke, which I then had to drive through. Fortunately that's rare.

I would guess that gasoline must result in mostly heat and not particle pollution in PM10 and PM2.5.

What happens is you can never get fully complete combustion. Some of the gasoline gets cracked and recombines to form HC soot. Which is also very reactive. Thus likely really bad for you.


This gives actual figures for PM2.5 emissions from exhaust, brake wear, and tire wear per mile for both gasoline and diesel vehicles.

There is an argument about how much EV's would reduce PM2.5. The above shows things were a lot worse 20 years ago. And current gasoline cars produce 0.008gm/mile PM2.5 from exhaust and 0.003 and 0.001 from brakes and tire wear.

That says to me that EV would still reduce emissions a lot. One can assume that brake wear is half that of a gasoline powered car. So you go from 0.011gm/mile for gas. To probably 0.003 for EV's.

Electrifying diesel trucks is a huge win.

That does not tell us anything though. The fact is that “The largest part of most combustion gas is nitrogen (N2), water vapor (H2O) (except with pure-carbon fuels), and carbon dioxide (CO2) (except for fuels without carbon); these are not toxic or noxious (although water vapor and carbon dioxide are greenhouse gases that contribute to global warming). A relatively small part of combustion gas is undesirable, noxious, or toxic substances, such as carbon monoxide (CO) from incomplete combustion, hydrocarbons (properly indicated as CxHy, but typically shown simply as "HC" on emissions-test slips) from unburnt fuel, nitrogen oxides (NOx) from excessive combustion temperatures, and particulate matter (mostly soot).”

Emphasis added. https://en.m.wikipedia.org/wiki/Exhaust_gas

A lot of energy has gone into cleaning up engine pollution already. Not sure where the 30% number comes from, but Brakes probably will get cleaned up once they become the star of the show.

EVs already solve that problem by mostly eliminating use of brake pads with regenerative breaking.

I hope we will see cleaner air in cities! But the time it takes to replace a country’s vehicle fleet is sometimes measured in decades, and no-one is even starting on a project of massively reducing fleet emissions. I think / hope you are right in the long term, but I think I am right in the short-medium term :)

> I think that instead we will see cleaner air in cities since the economics of electric/hybrid cars will win

Citation needed. The whole economic and environment footprint of electric vehicles in relation to their efficieny is rather bad. The future would the CNG but something is holding it back.

To be fair traffic is not the only factor in Delhi's pollution. Another thing is crop burning in Punjab and Haryana, which some people even claim is the biggest cause for the pollution.

You can see it has an effect as Delhi's pollution drastically differs between different times of year, which generally correlate with the time of crop burning.

According to Wikipedia it's the biggest environmental health risk factor that may kill 8.8 million people annually (March 2019), which definitely puts it up there, but hypertension probably still kills more people (9.4 mil, 2010).

It's hard to compare an environmental risk factor with actual diseases, but I don't think you can really argue that it's the biggest "health crisis" by any metric. Anxiety for example is still the most debilitating disease worldwide. It's still pretty bad though, which I didn't realize before looking into it, but the usual suspects are still worse in terms of health.

Well air pollution causes pulmonary hypertension.

Delhi air truly is horrific, especially in the winter. I spent the first half my life there, but literally could not breathe without having migraines when I returned.

When I left, my health also improved.

Clean air truly is an underrated privilege.

There’s plenty of air pollution in the countryside too from eg muck spreading or turning industrial compost heaps. It’s not really clear how bad they are

Not to mention, in the US, a large amount of people "moving to the countryside", usually results in that countryside turning into polluted auto-dependent sprawl with 6 lane roads and a ton of traffic.

At least in the city you have constraints on how much traffic can fit and alternatives to driving.

It's not just the US. It's everywhere. I have seen quiet country roads perfect for relaxed cycling and walking turned into dangerous, loud irritations by people who claim to 'love the countryside' as they drive their mountain bikes and backpacking poles to ever dwindling quiet places.

Oh my god the poles.

I think if you go to just about any moderately popular walking spot in the uk with steep stony parts, you will see just about every rocky step is covered in the scratch marks from the feet of the poles. One wonders if they are really effective if they can’t get a good grip on the more difficult terrain people presumably get them for help with.

whoah! I didn't mean this to turn into a Brexit, get rid of the immigrants thing!

> We're going to see a diaspora out of the city

I’ve never seen “diaspora” used this way, and dictionaries at hand don’t support it.

Did you mean “migration” or “exodus”?

Diaspora comes from the Greek "διασπορά", which literally means dispersion of any kind, not necessarily ethnic or cultural. It may sound OK to native Greek speakers (like me), but the English meaning in a bit different.

I believe "dispersion" would better denote a natural consequence and "exodus" would put more emphasis on intent.

> literally - I did not truly get how bad it is in Delhi until I went there, even having seen photos

There's obviously no economic incentive to do this, but I'd love to see a travel-agency-alike business offer a sort of "atmosphere simulator" that sets up the same composition of air pressure, heat, humditiy, and VOCs that the destination is going to have. It'd be great as a pre-test for people with lung conditions, to see if they would truly be okay with spending a vacation there (without needing to buy a plane ticket and waste days going there just to find out and immediately turn around.)

> We're going to see a diaspora out of the city and into the countryside... for the people who can afford to do that

Or we'll see the development of new coastal cities, and the redevelopment of existing coastal cities, to favor clean air over industry or (non-EV) cars; with the expectation that the city will be able to make it up in taxes (incl. estate taxes) from a large residential tax base of people who still want to live in cities, but also want clean air.

Coastal cities that already have such policies (and so little pollution) are clearly seeing hypergrowth in residential real-estate speculation, above-and-beyond what you'd expect from current global market forces. Vancouver BC, for example, is getting its real-estate markets pumped way beyond those of neighbouring Seattle WA.

(I say coastal cities here, because being near an ocean means having access to trade winds to sweep some amount of produced pollution away. An inland city has to work a lot harder—i.e. to strangle its industrial capacity much more thoroughly—to achieve the same effect.)

You don't realize how adjusted to it you may be. I've had rural friends come to my small city and say the air quality is bad, and I in turn found my nose and throat burning when I visited New York City.

I live in a relatively unpolluted city, but often when I've been out walking, I notice what feels like a thin layer of very fine dust on my hands. It never happens when I'm in rural areas.

My friends don't have this problem and fail to understand why I feel a strong urge to wash my hands as I get inside. At first I thought it might be because they're adjusted to it, but as I type this I realise it might also be because my hands produce slightly more sweat than the average hand (not excessive amounts, just a tiny, but noticeable bit more) which maybe gets absorbed by this particulate and that's why I can feel it? No idea if the science checks out.

So maybe the ability to feel pollution in your airways is also something that might differ from person to person? I sure have never felt it, but then again, I live in a relatively unpolluted city.

I get that during alder and elm pollen seasons, but usually around eyes and mouth where I sweat a lot. I'm not allergic but I do feel a constant need to wash my face that I never feel. Elm and alder pollen range from 15-50µm, I do not know how much/big pollution particles there are compared to that, but they usually measure PM10 and that is under 10µm, and in really badly polluted areas it is probably alot worse than pollen.

Optimistically, we could flip this on its head and say that a marker of privilege will be driving an ICE vehicle. It'll become enthusiast-driven rather than necessity.

If you can smell exhaust with windows shut multiple times per week, please have your car's exhaust checked, it may be harming you daily.

the air is fairly clean, and improving every year. whatever you think will be realized in 5 years has had 100 years to be realized, and has not been.

there used to be no catalytic converters on cars. gas used to be leaded. factories woyld burn stuff and dump it into the air without a filter. diesel autos had no soot filter and ran lower temp for extra unburnt gas. we used to clean things with cfcs.

right now, today, in the western world, is the cleanest it has ever been.

in chicago, a hundred years ago, meat factories across the river where the irish lived simply burned leftover animal parts. it would rain ash, 24/7. when those living there crossed the river to the office area without the ash, they would throw up from the cleaner air.

i have a feeling you are a millenial, and are just discovering a world of huge problems. what you don't realize is they are tiny, very ild problemq, that were huge and have been greatly and continually improving. you want to make changes to feel important, when the reality is, people have been working in this for a hundred years before you were old enough to notice, and what we have been doing is working quite well on improving things.

right now, today's air pollution where you live is having the smallest effect in over a hundred years.

this is like new adults screaming how bad trump is. because they don't remember bush, or clinton, or reagan, or nixon. and when they read about it, they think it's a story and can't imagine living through it.

"we're literal nazis now!" yeah, cops used to kill people in a union on behalf of corporations. we locked americans in camos for having squinty eyes. we made weed illegal to stop white women from screwing black men. we had drafts for overseas wars where no one attacked us, forcing kids to go die for nothing. we had bush and mueller - the honest superstar trump-punisher lie to congress on tv saying he found weapons of mass destruction in iraq and start an insane war. billions of cash shipped there and not arriving. and that air problem in india? that used to be where you live now. it got better.

the premium market for clean air you talk about? it didn't come when things were 10x worse. it's not going to come now, or in a decade when things get even better, as they have been.

the cheap non-premium market with cleaner air is the suburbs. your problem was solved ages ago.

> “ According to the World Health Organisation (WHO), air pollution kills an estimated seven million people worldwide every year and nine out of 10 people breathe air with high levels of pollutants.”

This is approximately half the deaths we would expect worldwide if no country was to do anything and we’d let COVID-19 rage through our societies.

Why is our response to air pollution so drastically different then? We don’t even implement a single day lockdown to reduce pollution for a single day. I’m sure air pollution also disproportionately affects young children and damages their lungs as opposed to Coronavirus.

This world is so weird.

It gets better. The WHO puts ischaemic heart disease as claiming about 9 million lives a year world wide. Most of which is caused from unhealthy diet, not exercising and smoking. Summing up to piss poor life choices. Yet theres a movement that a doctor telling someone obese to eat right and start walking everyday so they can later jog is fat shaming.

Hypothetically speaking if we were visited by aliens... yea, I dont blame them for not making contact.

What? Since when do doctors not tell people to lose weight?

No, docs tell people to lose weight, but theres a movement where that's considered fat shaming and "wrong". You being epically confused is natural. I was too when I stumbled across an article about this, then found that theres more with a full fledge movement as devoted as flat earthers. I hate this planet.

The simple answer is that Covid-19 is equally threatening to rich and poor anywhere in the world, while death from pollution is a highly localized problem, both in terms of geography and socio-economic position. This obviously doesn't take into account the danger of climate change or other dangers caused by the same pollution that we simply overlook.

You can't really prevent pollution deaths easily. You'd need to retrofit thousands of factories, construction sites, billions of cars, etc.

The solutions for Covid are quite simple in principle but our lack of discipline in minor things is killing us.

GP's point is fair though. Many developed economies are spending literally hundreds of billions of dollars tackling COVID. Have we done proper cost/benefit analyses to verify whether that money could save or improve more lives in other areas?

Look at the response to things such as mass shootings which, statistically, represent a small fraction of the total murders committed. Terrorist attacks (in the west) receive a disproportionate amount of attention compared to other problems as well.

Perhaps it's because these things can disrupt anyone's daily life seemingly at random. Pollution on the other hand is just part of our daily lives. There are other things which fall into that category as well such as smoking, fast food, alcohol, etc.

Perhaps we as a species, rightly or wrongly, fear the unexpected more than we fear the status quo, even if the latter is more harmful than the former. So we allocate resources to fix the former but not the latter.

I mean, there's good reason for this. Air pollution is manageable because it's known, the market and people can take it into account and try and make informed decisions. Terrorists attacks do not have this property and the variance of the people they kill is quite high. This makes it hard to ignore.

Have you heard of the Ford Pinto?


I think a famous newspaper article at the time said something like: "Ford decided your life was worth $500". And it was after a cost benefit analysis.

Covid has a fatality rate of, at best, 0.3%. At worst, higher than 3%.

Nobody sane is going to sit still and let, say, 1% out of 8 billion people (80 million people!) die.

We can work on other issues in parallel, but prioritizing emergencies.

> “ Covid has a fatality rate of, at best, 0.3%. At worst, higher than 3%.”

The current fatality rate is 1% despite it is only measured by testing the most severe cases which end up in hospital. How did you come up with 3%?

> “ Nobody sane is going to sit still and let, say, 1% out of 8 billion people (80 million people!) die.”

Latest science claims that we need 42% of a population to be infected to create herd immunity. Only this week we learned that slums in India (e.g in Mumbai) have reached herd immunity and are now the least affected in India where the rest of the country is struggling. 0.5-1% of 42% of 8 billion people (the expected number of deaths) is only twice as much as the yearly deaths from pollution.

Additionally pollution kills 7 million every year. A novel virus is novel only once, so after 2-3 years COVID cannot even reach the deaths caused by pollution even if we tried hard.

So overall it’s completely illogical why we respond to coronavirus with such draconian measures and at the same time are so blasé about pollution which is evidently more damaging overall.

I can't imagine the pollution death numbers to be directly/trivially correlated to pollution: pollution in a single place varies, victims move between places and pollution kills slowly, so it's not psychologically considered an urgency. Covid19 kills quickly, so it is trivial to establish correlation and causation: I would say that the world's response to Covid was driven by the narrative on social media.

If you are asking why humans as a species are not smarter than they are to see through short/long term effects, well, beats me :) But I still don't want my close ones to contract coronavirus, so I am still largely social-distancing. But I only hope to get an electric car in a couple of years.

We aren't blasé about pollution... But to actually get rid of it as drastically as you seem to suggest would shrink our economies by 30% permanently, not for 6 months. Or at least until the alternative techs take over, which could be after decades.

Coal plants? Gone today. Electricity production reduced by 30-50% in most countries.

No ICE vehicles? I don't even know how many there are, but I'd imagine we're talking about 1 billion or more. Now that you're at it, goodbye trucking, taxis, 80% of public transportation, food delivery, ambulances, fire trucks, ...

No planes or helicopters? Goodbye emergency search and rescue, weather services, crop spraying, etc.

You haven't thought this through with your comparison ;-)

We've had the better part of a hundred years to fix this if we wanted to. The main reason nobody's doing anything about pollution deaths is that it mainly affects poor people. It also mainly affects people in poorer "non-western" countries, with the Western Pacific and the South-East Asia regions dwarfing all other regions. (2012) [1]

[1]: https://www.who.int/airpollution/data/AAP_BoD_results_March2...

According to figure 2, European regions are in 2nd and 4th places with most deaths per capita, with the value in high-income European countries almost as high as in South-East Asia.

So what? If there is a total lockdown for covid, then there should be a total ban on cars, except for travels that are vital to the economy. The air in cities was perfect during the most strict lockdown phase.

Cars have benefits, your comparison makes no sense to me.

Covid is purely negative.

The answer is money.

Preventing pollution is expensive, and upsets the status quo. And many companies stand to lose their entire livelihood if it were to succeed.

A day of lockdown would probably not have a measurable impact. The first result I got on scholar for atmospheric pollutant half-life claims 83.5 days:

[1]: https://hysz.nju.edu.cn/_upload/article/files/79/b2/159a6762...

Professor Prashant Kumar, Director of GCARE at the University of Surrey, said: “To be blunt, we need as many cars as possible off the road, or more green vehicles to reduce air pollution exposure.“

We need to stop using ICE vehicles. All the other people on the street are even worse off. The people driving the cars are also causing the very pollution this mentions.

Unfortunately, brake dust and tire rubber also represents a surprisingly large amount of particulate matter as well. I wish I had the source, but it was far more significant than I ever would have guessed.

(I have an EV, a gasoline powered sports car, and a diesel SUV (with particulate filter and urea injection))

EV regen braking partially helps with the brake dust, at least. May be counteracted by the tire rubber because EVs can be driven in a more “spirited” way.

Teslas are actually pretty bad in this sense, since they are fairly heavy and sporty. My car (a Nissan Leaf) makes me feel bad if I push it too hard (specifically, it has a deeply unsatisfying acceleration curve while in “Eco” mode) and is much lighter, and I think cars like that would be better for this kind of thing.

In the other hand I often do my commute without using the brakes at all, using regen braking only.

Great point.

I also find it humorous that the busybodies who insist that stop signs be installed every block of their neighborhood arterial have to suffer from the resulting air and noise pollution.

I drive 'spiritedly', but I suppose the tire wear due to hard cornering is not nearly offset by the saved brake pad and exhaust emissions!

I moved to the US from the UK, where yield ("give way") signs were the standard and stop signs an attention-getting rarity.

I've often wondered how much harm to health has been done by the increased emissions at excess of stop signs (at least in the parts of the US I've visited). Does it outweigh whatever reduction in accidents you get by forcing a stop at junctions which (to my untrained eye) could safely be controlled with a yield?

I would be surprised if it did. The way a lot of our roads have been designed doesn’t really make yield signs an option. Only recently has the US begun to embrace roundabouts over the basic 90 degree intersection. Unfortunately, it’s hard to retrofit existing intersections because roundabouts take more space.

Why aren’t yield signs an option? In Europe they’re ubiquitous, everywhere where a road or street lower in the road hierarchy crosses a higher-tier one. No roundabout needed. As far as I know they work just fine.

As you say, roundabouts take up more space, and they are not nice for pedestrians. They're good for major interchanges if you don't want to build an underpass and there's lots of land. If land is cheap though, where are all the cars coming from?

In the 90s, many roundabouts were removed especially in the northeast. I don’t think this is true. In New Jersey alone I can remember seven or more very large roundabouts that were removed.

Those that you’re thinking of were likely “rotaries” which have some major design, functional, and qualitative differences as compared to roundabouts. Size, travel speed, and enforeced entry angle are the main differences between rotaries and roundabouts.

And then to confuse matters further “traffic circles” are common as traffic calming devices on the west coast. These are also round, but are very small and do not have a splitter island preceding. They usually sit in the middle of small residential intersections.

Also, sometimes rotaries (the largest, fastest, and most dangerous of the trifecta of round traffic things) are sometimes called traffic circles, which are otherwise the smallest / slowest traffic device.

If all that is confusing, well, you’re not alone. My feeling is that roundabouts and traffic circles are good, but rotaries are just highway interchange supercolliders. Removing them from the northeast was very good.

you missed an important purpose of stop signs which is to make a route less appealing to motorists in the first place. ultimately this is necessary if the volume of traffic is ever to be reduced.

So you're getting mad at people who are reacting irrationally to you speeding through neighborhoods?

I think there's more than one problem here.

Stop signs are a pretty bad solution for traffic calming, though. The key to effective traffic calming is to shape drivers’ natural behaviors, not authoritatively demand it.

A stop sign that serves no purpose than to slow people down will piss off drivers more than anything, and lead to people speeding between signs or running them. It will make your street noisier as impatient people aggressively obey the signs.

A typical neighborhood would be much better off if traffic was calmed by adding kerb extensions or narrowing the lanes.

I think the above commenter might share my frustration that local politics is often full of people unknowingly demanding the wrong solution to their problem.

As someone who lives in a neighborhood full of stop signs (just about every other street is signed), I find that it actually does exactly what you're saying, i.e. shape drivers' natural behaviors.

Almost everyone elects to drive on one of the nearby "thoroughfares" rather than stop and start all the way through the neighborhood. So I see stop signs as the perfect solution.

I'd agree this wouldn't probably work on a road that sees heavy traffic already though.

Except where I live they also put stop signs on the thoroughfares. Some places just have messed up traffic.

Stop signs are not meant to calm traffic, they're safety features. When you have to stop, you're not blindly driving into traffic, that's the whole point. You stop, you need to start driving again, you have the time to look to the left and to the right.

You can look left and right while gently rolling through there is no need to come to a full stop in many cases.

You can, but few do. The Stop sign makes sure you've come to a halt and are focused on what happens next instead of "just cruising".

Interruptions reset focus (unless you're so distracted that you don't notice the sign).

No, you need to come to a full stop at a stop sign. That's why it says STOP on it with capital letters - so that even idiots know what to do.

The point is that other jurisdictions get away with using way fewer stop signs than in North America, while having much safer roads.

Yep, from driving in the States it is clear that they liberally use stop sign where you really want a yield sign.

Even with perfect visibility, ignoring stop signs can kill:


Slowing down to idle speed and ensuring the intersection is clear absolutely nothing like what’s being addressed in that video.

Congratulations, you just got an immediate fail on your driving exam!

The US is gradually coming around (heh) to roundabouts.

I hope so, the only one in my immediate area is about 30 feet in diameter... That's right, there is a single-lane for the roundabout itself!

In retrospect, saying that I drive spiritedly immediately after talking about neighborhoods, was unfortunate juxtaposition on my part. The two are not related!

Nope! I don't speed through neighborhoods; in fact, I drive more slowly than most people through them. I did, however, have a commute through a neighborhood, for 10 years. (There was a 30mph arterial off of which spur roads went into the neighborhoods; no houses fronted the road, just fences).

A number of 4-way stops existed on the route to the office complex for no valid reason whatsoever. The arterial traffic was the vast majority of traffic. I watched over the course of 10 years as more 4-way stops were installed to calm traffic, which is specifically contra-indicated by proper traffic engineering. In fact, I remember reporting on one community meeting, where the community hired a traffic engineer who specifically told them not to use stop signs for traffic calming; they did anyway.

The stop signs actually took away from the attention folks paid to cross streets. Eyes down, stare at stop line, come to a stop, go.. it was much easier to not notice cross traffic or pedestrians!

They all should have been roundabouts, frankly.

Anyway, my point is, 4 way stops are an environmental nightmare in every possible way, and rarely the correct solution.

> I drive 'spiritedly'

My recommendation is to consider getting into motorcycles (seriously!). People who push things in their car are largely externalizing risk to other people. Motorcycles largely internalize their risk.

You can get an inexpensive motorcycle that will likely thrash any car you’re likely to afford. Plus, the skill required to operate a motorcycle makes it a lot more engaging to ride. Lastly, motorcycling is just far more exhilarating than driving.

I don’t want to shame you for wanting to drive hard, but you can satisfy your desires more fully while reducing the chances of killing or disabling someone who doesn’t have your appetite for risk.

EDIT: I am a motorcyclist, but not a very spirited rider. It turns out riding safely is plenty of excitement for me. I have friends who love to push it however, and I only challenge them to wear better gear and learn more skills.

I'm also a motorcyclist, although I don't own one at the moment and haven't ridden much in the last few years. (and a cyclist, and a runner...)

I also know people who do the periodic track day in their performance cars, and then dial it back on city streets. It's another way to get your thrill on while still minimizing risks to others. It's apparently a blast—I'm not sure I'm ready for it, but I'm sure some day I'll work up the courage.

Yeah, I've got a dozen or so track days under my belt, and have done some car control/teen driver instruction as well.

I no longer feel the need/desire to "go for a spirited drive" on the weekends, or whatever. Part of that is age, part of it experience, I suppose. But I very much enjoy a good run at an on-ramp or particularly nice section of open road from time to time.

There is the problem though that riding a motorcycle makes it a lot more likely you're going to die in a crash (even if it's not your fault).

| I drive 'spiritedly'

please don't

> Unfortunately, brake dust and tire rubber also represents a surprisingly large amount of particulate matter as well.

That crap ruins clothes too. I cycle and the stuff that comes off the road is crazy sticky, oily, black and horrible. It doesn’t wash out and is even hard to get off clear coated bike.

Conservation of mass. Fuel turns into CO2, H2O, nitrous oxides and a couple of worse things. Out of that, only H2O isn't a pollutant. Every liter (or every gram) of fuel must fly out of the exhaust as one of these things, otherwise it would accumulate inside the car. Now compare how many liters (grams) of fuel you use per year, versus how many grams of break pads and tires. That figure simply cannot be true, it sounds like a convenient myth circulated by oil industry.

The claim isn’t that brakes and tires contribute the most pollutants, but the most particulate pollutants.

Specifically, PM10, hard particles below 10 micrometers. CO2, Nox, etc from a car are hot gasses which expand relatively quickly, so dumping kilograms and kilograms of them is required to raise ambient air measurements above unsafe zones (measured in ppbs usually, see [0] for the EPA standards for NOx, PM, lead, etc).

Particulate matter, being solid, doesn’t spread as quickly as gasses. Small enough particulate emissions can be ingested into the lungs, and from there into the bloodstream. Once there, they can scrape blood vessels, eventually leading to plague and various heart conditions. Very trace amounts of PM10, and specifically smaller PM2.5 that can slip through the lungs easier, can have terrible health outcomes. In the EPA standards I linked, ug/m^3 is roughly equal to ppb, so the standard for PM2.5 is about 1/5 the level of NO2.

ICE engines generally only develop PM10 particles from insufficiently high temp combustion. For modern cars it isn’t absurd to suspect that brakes and tires produce more PM10. Here’s a summary of research done on the matter [1].

If you live in Europe, the US, or Canada, indoor and outdoor PM2.5 emissions will shave a few months off lifespans. China’s lifespans may be cut by as much as 5 years from particulate matter. [2] (not a scholarly source but links to them)

[0] https://www.epa.gov/criteria-air-pollutants/naaqs-table [1] https://publications.jrc.ec.europa.eu/repository/bitstream/J... [2) https://qz.com/1071421/this-is-how-much-of-your-life-air-pol...

> The claim isn’t that brakes and tires contribute the most pollutants, but the most particulate pollutants.

Yes, but that's the "spin", the gaslighting. "Hey, don't look at the huge amount of other pollution our gas vehicles produce, instead look at this small portion where we are not the main villain. Repeat after me: Baaaad break pads, baaad!!" Fossil fuel industry is fighting for their survival. Even if I agree with the numbers and the research, I can't agree that we should focus on this. The greenhouse gases pollution is a much bigger problem, EVs solve that, so if their break pads still produce the same amount of particulates, what does it matter? Don't let them get away with "see those EVs are not as good as you were told".

Focusing on PM pollution tends to reduce CO2 emissions. Most PM 2.5 comes from burning fossil fuels, so insisting on lower levels means burning fewer fossil fuels.

PM studies are able to tie pollution directly to lives and thus dollars (through statistical lives). So, if reducing coal use costs $2.7B a year, but we extend enough lives, prevent asthma, etc., to equal at least $2.7B then as a country we should enact the regulation. The US starting doing exactly this from 1996-2003 and it reduced CO2 emissions by making coal plants, steel mills, etc., more expensive to operate. As a result, PM studies like the Harvard Six Cities study were highly controversial and fossil fuel companies lobbied hard against them. It is a lot harder to tie climate change to direct costs because the impacts are somewhat fuzzy and on a long timeframe.

In this case, discovering brake pads and tires cause PM2.5 means we can invest in less-emitting brake pads. But this isn’t likely to produce tires/brakes that dramatically reduce emissions. A more likely approach is investing in mass transit, which would reduce CO2 output.

I wouldn’t say greenhouse gasses are a larger problem but a rather a harder to coordinate long-term global problem. PM pollution caused 4.2 million premature deaths in 2016 [0]. It is hard to directly state how many deaths climate change caused in 2016 but conservative estimates [1] are for about 500,000 deaths a year by 2050. Most PM deaths stem from terrible industrial air in poorer countries which if combated would also dramatically cut CO2.

[0] https://www.who.int/news-room/fact-sheets/detail/ambient-(ou...

[1] https://www.cnn.com/2019/01/16/health/climate-change-health-...

Referencing conservation of mass doesn't make sense. While CO2 is technically a "pollutant", it's not in the same league as the others. Particulates affect air quality in a way that CO2 does not.

Don’t forget that EVs use regenerative braking heavily, which generates power instead of brake dust.

They still rely on friction brakes. Especially at low speeds and/or heavy braking, which is what most braking in cities is. Also because of the extra torque a more jerky driving style is possible. I'm really sceptical that current EVs make any real difference to brake and tyre particulates.

Drivers of manual petrol cars can already reduce their brake dust by using engine braking. If one drives very carefully it is possible to not use brakes at all. Indeed it should never be necessary. Any time you hit the brakes means you were going too fast. But how many people drive like this? Barely any. Instead people speed right until the last minute then slam on the brakes. Then as soon as the opportunity arises it's heavy acceleration until the next slam of brakes. Driving EVs like this will produce just as much brake dust.

When I had an EV, I had rusty brakes even after my commute. That’s how little I used my brakes. I used regeneration braking exclusively except for rare circumstances where something unexpected happened.

Eventually I had to brake on purpose a few times to keep my brake discs shiny, because the rusty discs looked awful

They still rely on friction brakes. Especially at low speeds and/or heavy braking, which is what most braking in cities is.

I've been driving hybrids for the past five years and in my experience even in heavy traffic friction brakes aren't used nearly as much as in regular ICEs.

There's a constant, thin layer of rust on my rotors that I just can't scratch off in any way short of braking on an off-ramp on a highway.

I imagine EVs, having overall better regenerative braking, rely even less on their rotors.


I've always owned at least one manual transmission vehicle, but the EV does an order of magnitude more regenerative braking than any passenger car internal combustion engine does.

No, most of EV braking in the cities is regenerative.

My understanding is that at least where I live most remotely reasonable people use engine braking in city driving almost exclusively. Indeed needless use of the brake pedal is regarded as a sign of a poor driver. But other countries may have different driving cultures…

Not that I've noticed here in Australia. Personally, my current car is an auto, and trying to engine break just isn't very effective without switching to manual in my car. Engine breaking can also be noisier, as may have to shift down gears in a way that means the engine revs relatively high, for a brief time - making it a more noticible noise.

Out in the country, and for me that often means the hills and mountains, then engine breaking is a much bigger part of my driving style, esp down hills!

Engine breaking also doesn't cause your break lights to come on, and they provide a quicker signal that a car is slowing, than relying on people to detect the change in speed.

Why 3 cars though? You did your research, you must be aware of the grey energy associated with manufacturing ~5 tons of extremely inefficient transportation vehicles.

Because I like cars.

They bought those vehicles used perhaps?

Does that change things?

Sounds like because that poster has options they don't have to drive the ice vehicles very often

I'm sure those who want to complain will always find a reason. I'm sure that my purchases and 'hoarding' drove up demand which increases prices and pushes people into newer cars or makes used cars less affordable to the poor, meaning they stick with older less safe, less efficient vehicles, or something.

FWIW, my wife and I carpooled in the EV to and from work, every work day, until covid hit; now I work from home and she drives solo to the hospital.

But again, it probably doesn't matter. The EV is too heavy and the rare earth materials were mined in unfriendly ways, and the weight of the car means it sheds lots of tire material, and not all of our electricity comes from the solar panels on the roof, and we should live closer to work and walk everywhere anyway, and the alcohol I consume has a negative impact on the water supply in a drought state, and....

(don't let anyone find out that sometimes I drive to the racetrack just to go around in circles and end up back where I started!)

You seem to clearly understand what's at stake and yet you still passive-aggressively attack me.

Everything that you said is true, and it should be evident by now that baby steps like a couple of people carpooling in an EV when it's convenient to do so will not cut it. For every couple like you there are 10 couples who don't have the means to purchase an EV and their situation won't change by 2050, when cheap energy (read petrol) will be on the way out.

While it's an honourable thing that you are using your excess hard-earned money to buy EVs and solar panels instead of SUVs and fracking stocks, please understand that you're living above the living standards of most people and not everyone can afford this, and for them, reducing footprint = self-restraint.

Whether used or not, if they own a car that they don't use, another car will be built and put on the market instead, as long as other people need them.

I have some very heavy doubts about the validity of their data. Look at their primary findings:

"Using a popular family hatchback running on brand new, correctly inflated tyres, we found that the car emitted 5.8 grams per kilometer of particles."

Most tires seem to be around 7kg, which means according to their data a car would have all 4 tires reduced to nothing after 4828km. With most tires going bald after ~50,000km (not fully vaporized mind you), there's clearly something wrong here.

My guess is they tested brand new tires which may shed particulate quickly at the start, similar to how a new carpet sheds exponentially more at the start.

There's more information here:


They said that all four tires combined lost 1.8kg, which implies they only drove 340km? Also, this is literally based on measuring the weight of the tires apparently, so how much of that became PM2.5 class particles is a mystery.

The article also mentions "track testing", which if used for the test, would easily explain the enormous material lost after a short time. Track racing is very different than highway driving...

It's also the material on the road being heated and ground up, not just the material from the tyres themselves.

I think you're right, new tires have a lot of flash and channel runners that are artifacts of the rubber molding process and are she'd very early in the tire's life.

Is the rubber oxidizing? Some of the mass might be coming from the air.

The other people on the street might very well be better off. Driving a car is a very sedentary activity. Most other forms of transport are at least contributing a little to your health too.

(And at least cycling -- for any amount of time -- is a net positive in terms of health everywhere but the few most polluted cities. But even in the most polluted city, brief cycling is a net positive.)

Physical activity makes you breath more polluted air though.

Yes, but the positive effects of physical activity increase your life expectancy more than the polluted air decreases it.


So the solution is to keep polluting?

I don’t understand your point here. If everyone makes the effort to walk/bike more there will be a reduction in pollution.

My point is that I prefer to just walk or be careful and not do too much effort when on bike when there are pollution events in my city. I try to make sure I only have to breath through my nose then.

I believe it's worse here in Europe than in the US as we have a large proportion of diesel cars (though where I live now, most pollution comes from the harbour) and during bad pollution events you don't just smell it but you feel the particle-polluted air aggressing your respiratory system.

Exactly. Every time I see someone jogging/running in the downtown part of the city, surrounded by idling cars, I shake my head.

Would you rather they drive 20 miles first to jog?

The reality for most people in a city is that to exercise they inevitably first need to escape 5 miles worth if clogged up car arteries.

Are you trying to argue that they are inhaling pollution at an extremely high rate by running downtown or do you just not like the fact that I pointed this out?

It's not just ICE vehicles. These are obviously the worst, but even the most modern, efficient EV causes a massive number of problems when chosen as personal transport:

  * It makes the streets dangerous for everyone else
  * It occupies a vast amount of physical and visual space
  * It facilitates the construction of centralized shopping spaces that are at awkward distances for anyone not also driving
Overall private automobile use ought to be restricted to those with a compelling need for it: emergency services, some tradespeople, those with serious physical disabilities.

The rest of the circa US$10,000/capita should be garnished by taxation and spent on comprehensive electric bus, light electric rail and long distance train infrastructure.

Neighborhoods need to be quiet, safe, green and relaxing. This cannot happen with personal automobile use.

This is a viewpoint that basically says everyone must live in cities except for farmers.

Not only is this not possible without probably half a century of building high density housing (and realistically, never, because it would require lots of eminent domain seizures and tons of lawsuits), but it’s also... not really desirable? Half the point of not living in a city is cleaner air, less light and sound pollution, and less people.

Yeah, I don't buy any of that.

Why would a programmer, artist, schoolteacher, hairdresser, restaurant owner need to travel any great distance from their village or town?

Most people in the world already live in cities... and they like them. They like looking at other people, smelling them, ranking and comparing them, copying them. They like the convenience of being able to get around easily, have other people cook food for them or play music for them.

The inevitable and obviously viewable consequence of people moving out of cities is that they create noisy, polluting, long-distance commuting sprawl: exactly the opposite of cleaner air and less light and sound pollution.

In order to move back away from the existing situation of an earth riven by roads the incursion of humans into ever smaller fragments of natural ecosystems we need to reduce the population and concentrate it in cities.

This¹ is mostly concentrating on tropical rainforest destruction but the same is true nearly everywhere: more and more roads are built in order to service human desires (cheap wood, grazing or (in EU and NA) solitude and privacy.

It can't go on.

1. https://e360.yale.edu/features/as_roads_spread_in_tropical_r...

while we're at it, we must also note that environmental footprint of private residencies (HVAC, water supply, trash collection, construction process itself) is pretty bad as well; so it follows that house ownership ought to be restricted to people who actually need it - farmers, and maybe party elite. Everyone else should live in maximum efficiency block housing, necessarily mass-produced from unfinished concrete, and placed as tall and dense as possible, to minimize transport costs. It also follows that intercity travel should be restricted, for the same reasons.

Oh wait! Cities should be sub-terran! Can be built very deep and dense, outside temp is fixed so no heating cost, electricity can be produced by compact nuclear reactors, air/water fully recycled. Only essential/important people will be allowed to go outside, to not pollute the environment. Right?

we must also note that environmental footprint of private residencies (HVAC, water supply, trash collection, construction process itself) is pretty bad as well;

Absolutely, this is another excellent argument against mindless sprawl.

unfinished concrete Concrete is not an ideal construction material if you are worried about reducing CO2 emissions.

It also follows that intercity travel should be restricted, for the same reasons. Yes, if you want to have a pleasant earth to live on then feckless, wasteful travel should be restricted. This does not have to be done by rules -- simply charging people the full cost of their trip would place it out of their ability.

outside temp is fixed so no heating cost, No, the outside temperature is rising, thanks to the freedom-loving, brave self-expression of car drivers crawling like ants to and from their places of consumption to their places of production.

In case you missed the memo: the party bosses are now the ones selling you the polluted suburban lifestyle while they cycle bicycles around clean, gated, low-traffic, tree-lined communities. So, keep living in the past... after all the future won't hold much for you.

Interesting compared to other study showing that cyclists are least exposed to pollution on their commute: https://www.theguardian.com/environment/2018/dec/13/cyclists...

...only because they spent less time commuting

>All the commuters set off at the same time, and the cyclists were by far the fastest, arriving in 11 minutes, half the time of bus and car travellers.

Buses and cars still do better when you're measuring pollution per minute

That Guardian article also mentions "green routes", taking side streets or pedestrian / bicycle walkways. There's a lot less pollution in those areas than on a busy road.

sounds like a win-win-win. Less time traveling, less pollution, better exercise.

Cruel irony that cyclists, part of the solution, inhale the worst of the problem.

But, crucially, this should not be taken as discouraging people from cycling. In almost all cases, the health benefits of active commuting outweigh the additional pollution consumed: https://www.sciencedirect.com/science/article/pii/S009174351...

Yea but that's different from saying that cycling is correlated with a reduction in, say, lung cancer. I'm not sure I'll be any more grateful to die of lung cancer at age 82 than 72; I'd really prefer not to die of lung cancer at all, even if that means dying of heart attack or stroke a few years earlier.

Right. That is a subjective personal decision, and absolutely understandable. To accomplish that, one has to stay at home, though. Even sedentary modes of transport expose their inhabitants to pollution, unfortunately.

This is why it would be only fair if there was regulation that said that a car's exhaust must end in the cabin.

Noise pollution is another thing that cars directly cause but protect their users from—and indeed partake in the vicious circle where people want to move to calmer areas away from the noise, which creates more traffic and thus more noise!

Generally, it is more important for all deliveries to reduce their emissions, so making deliveries pipe their exhausts into the products they deliver is the right way to go.

Here, enjoy your new couch! And let us get the air from the back of our truck into your apartment.

While we are at it, let's make sure that any toilet flush goes directly back into one's water supply and disposal of waste and trash takes place in the household's garden.

We used to have a system where people ejected sewage into the street, too. It’s telling that you equate air pollution to sewage, and then imply that pumping it into the street constitutes proper disposal.

I think you are missing GP's point: a parent post to theirs is suggesting piping exhaust gasses from cars into the very small space that cabin has. Our sewage does go to rivers, lakes or seas (a huge environmental issue as well), so GPs example is quite to the point, because that's the equivalent in water use (with the benefit that our apartments are bigger and we do not reuse the water right away so there is more time to filter waste out).

If you still don't get the parallel, let's move one step up: all greenhouse gasses produced from your energy use in your apartment have to stay in (including those from coal power plants, grocery production and delivery...). Sorry, no opening windows for you to get your own CO2 out to other people.

My point is that air is a shared resource, and thus a shared responsibility. But someone turning the narrative extreme does not help drive any solution forward (I am reminded of Stan's dad Randy getting a Prius in Southpark).

If the alternative were to dump the waste into the commons, like cars do, why not? These days we have better ways to deal with wastewater and garbage, but cars are still mostly allowed to externalize their negatives without a second thought. Although admittedly we have come a long way since the really crazy days.

I found that wearing an anti pollution mask really was a night and day difference.

I’d love to hear what you’re using and how you came to settle on that.

Respro masks were the only ones for which I could google studies showing that they actually filter fine particulates. They are quite expensive though.

Given my experience with masks while walking through a supermarket on a hot day, I can't say that doing anything vaguely sportlike with a mask seems extremely unappealing to me. I figured this was some special kind of mask but it sounds like one meant to catch extremely small particles rather than have some special airflow feature.

But perhaps it doesn't seem worth it to me because the smog here isn't as bad as where GP is? I've never really seen a haze in cities like Aachen or Eindhoven the way TV shows it is abroad (particularly China comes to mind, but probably car-oriented USA also?).

Yes. The nature of a filtering mask will mean that you will need to exert more energy to breathe through it.

I would say that initially I felt that I couldn't cycle as far with a mask. But as I did it more it became easier, effectively like exercise for your lungs.

And would say that if you have trouble with a mask walking then strenuous activity with one is probably not a good idea unless you work up to it.

In terms of the effect, I live in London which is so-so when it comes to pollution. But you really notice the difference, especially going behind the exhausts of diesel vehicles.

Breathing is a little harder with a respro mask, but it doesn't impede me by much on a bike. The filter is pretty large so the airflow is good and in has valves for breathing out. What kind of mask are you wearing in the supermarket? The Respro mask is a lot more like a N95 mask a contractor would wear while handling heavy tools than a surgical mask.

Yes and no. Riding a bike at your best speed isn’t going to happen with a mask, but I prefer not to work up a sweat while commuting, so I’m not using enough oxygen for the mask to make a difference. That said I might feel differently in a hotter climate.

Disposable N95 masks work fine. They're about five bucks.

I use the Respro ultralight [0], I got recommended it from someone at my local bike store.

Cycling behind a large lorry is less unpleasant. But of course it's not gonna block everything.

[0] https://respro.com/store/product/ultra-light

I'm concerned by the promo picture on that website[1], that mask really doesn't look tight, and it only has one strap. There's a reason most N95 masks have two straps[2] and that's because a tight fit is essential for filtering particles in the surrounding air. Even a small gap between your skin and the mask will mess with the negative pressure expected to happen within the mask to force the surrounding air to pass through the filter when you breathe in (which, in the case of [2] is the entire mask).

They might not look pretty but for anyone looking for a cheap and reliable mask, just get a regular N95 mask from a hardware store, it's used by carpenters etc. all the time to block particles and it works well for most car/truck pollutants. Of course it won't filter gases or whatever else cars emit that may damage your health.

[1]: https://respro.info/images/v3_product_background/_ProductBac... [2]: http://wasip.com/wp-content/uploads/2014/12/W795110-P

Back when Toronto regularly had smog alerts, I could only bike commute (on major arteries) with a mask on.

It requires some knowledge of the area, but I think it is possible to at least route around the worst air in polluted cities. I usually check local AQI and wind direction to pick a (possibly longer) route with less pollution[0] upwind before biking, using AirVisual for overall AQI and Windy to get a rough idea how wind is flowing.

[0] Busy roads, factories, plants or places with conspicuously high local AQI.

Cyclists are leading the way though. Maybe we could get a statue to honor them along some important (bike) path?

Seems like the focus should be on not poisoning the air in the first place.

My dad was telling us how, given that my spouse drives a lot of highway kilometers to work, we should totally get some air filter. A few days later I randomly realized: why don't we put that filter on the exhaust if it's so bad?!

It would only work if exhaust filters were mandatory for all cars, since the environment is "free" to ruin for anyone it doesn't make economical sense to install an exhaust filter unless you're legally obliged.

Sure, we already have a load of regulations to make cars less pollutive. Would this be unreasonable? People are already putting this in their car, just not on the business end.

It's also not just other drivers or the poor environment: a huge number of people (I'd speculate that it's the majority) live near busy roads. Adverse health effects from breathing near a busy road are common knowledge.

I cannot believe there isn’t a single filter for the exhaust. Is there really no air filter for the exhaust?

It affects the performance of the car which means it has less sales potential.

Not just the performance, I think the less efficient combustion (from backpressure?) would also lead to more CO and perhaps worse mileage so more CO2.

I don't know how the numbers stack up though, maybe you could make the filter really big, like a meter wide or something and the airflow would be good enough? The filter would need replacing/cleaning quite often as well, probably every 10,000km or so.

That is essentially what the catalytic converter does. However, it can have a small negative effect on engine efficiency, especially when exhaust backpressure isn't optimal.

> air pollution kills an estimated seven million people worldwide every year

But what the news has everyone scared of is fission power plants rather than the dirty ones burning stuff... I had a hard time believing this stat when I first read it.

Imagine if climate change is actually a liberal hoax, and the only thing that cleaning up the air would do is make it easier to see Starlink at night and save seven million souls a year. Still seems worth it.

Taking your situation at face value, in that case people would spend a lot on filters but keep carbon.

I was surprised to learn recently that there is a cheap and easy to take action that will reduce your exposure to air pollution while driving: Replace your passenger-compartment air filter with a HEPA filter! Most cars made in the last 15 years or so have an air filter right before the AC. You can, for slightly more money, replace this with a HEPA filter. I haven't tested, but this will probably be very effective, since the car is such a small space and there is so much pollution outside.

Replacing the filter is an incredibly easy job on most cars. You don't need any tools or even to open the hood. You just pull out your glove box, and then the filter slides in and out.

I honestly think that in terms of health, this might be the action that has the highest ROI. (Amount of health improvement per amount of time / money invested.)

"The study found that commuters who turn on the recirculation are exposed to around 80 percent less harmful particles than those who open their car windows."

Doesn't that mean they have 5 times more exposure, not 80% more?

It depends on how they calculated percent change, but looking at the journal article, you are correct. From the abstract...

> Compared with recirculation, PM2.5 and PM10 were higher by up to 589% (Blantyre) and 1020% (São Paulo), during windows-open and higher by up to 385% (São Paulo) and 390% (São Paulo) during fan-on, respectively.

The headline should read 400% more to reflect the 80% reduction. This is a massive failure of the university press office and I think your comment should be at the top.

And yet, now, city ride sharing vs. COVID.

Recirculated A/C! Fresh A/C! Windows closed! Windows open! Aggggghhh!

The article says “in-car air pollution” and does not once mention toxic emissions from BPA, flame retardants, lead, chromium and other materials used in automobile interior construction. Is that a solved problem?

I can't stand having my windows down, at least at any speed over like 30mph.

The pressure differential messes with my ears. I can't understand people who cruise around with the windows down.

It really depends on the profile of the car. Some have almost no bad pressure/sound effects.

My AC is broken and I’m a broke student so I either keep the windows down or die a heat death in these months. Though it’s also kinda chill once you get used to it. The only thing is that my left arm is now noticeably browner than my right arm.

Wind down a second window.


I drive an electric car charged by solar panels on my house.

Huh, the headline is very general, but they did the study in poor cities...

At least in the EU/US there are emission standards that have to be met for cars to be legally allowed on the road. I wonder how that affects things.

Then again, Dieselgate has shown that almost all car manufacturers make their engines to barely pass the imperfect test, but that real life driving is way worse than the pollution figures on paper.

The regulations are indeed shit. The conditions of the tests do not correspond to anything realistic.

Just look at the curve of the WLTP test on Wikipedia : https://en.m.wikipedia.org/wiki/Worldwide_Harmonised_Light_V...

Who drives like this? 1 minute to reach the high speed on the high speed test for example. The speed is never maintained, it's either accelerating or slowing down.

Today you see hybrids cars with tiny batteries that are close to useless just to meet regulations. In practice these hybrid cars smoke a lot, because it's cold and the battery is cold, because it's warm and you want AC, because you need to not drive too slow in the traffic, because the battery is already empty.

When the diesel gate happened, the French minister of the environment decided to test many cars on a track. They never published the results.

Cabin filters were invented for a reason.

Change them at regular intervals, or, in extra heavy traffic, put the recirculator on.

It'll make the air stuffy, but will keep it cleaner than it would have been otherwise. Don't keep it on for too long though, as the CO2 levels will start to rise and you might begin to lose concentration.

There also needs to be better emission standards on the other end of the vehicle as well. I've been riding a motorbike, and I hate getting stuck at red lights. I lost my fask mask with an N99, but should we be pumping that much pollution out in the first place?

>put the recirculator on

...and yet, the majority of cars (IME) default to recirc off.

What percentage of the air in the cabin actually passes through the cabin filter? Cabin filters are too small to filter the amount of air required for more than one human, let alone a packed car with 5 or more. Air gets in through seams and gaps and cars aren't very airtight.

Yes because of CO2 buildup. You need air from outside.

I haven’t seen this in the comments but its one reason I wonder why convertibles sell so well in the UK. I have a sun roof and i hardly ever use it because i hate the smell of exhaust. I may use the sunroof on a coastal road once in a while but not for long periods. I chose the car i drive because it has a hepa filtration system built into the climate control. I agree with comments about pollution but i must add that as a motorcyclist for a decade in London i blamed most pollution on short journeys like school runs. During school breaks the roads were much cleaner. So getting everyone to commute to work by bike won’t fix the problem when from experience most of the pollution is parents taking kids to school!

But if the window is up, nobody can listen to my music. Which is necessary for me to self-medicate my ADD ... :(

Am I the only one who noticed the headline and article say completely contradictory things?

I did, but I think that’s an English language issue. Apparently, by “keep windows down” they have meant “keep them shut down”. Completely counter-intuitive to me, vast majority of car windows move the other way, down to open, up to close.

I'm not sure I follow: in both the title and article, keeping windows down means allowing air from outside through the windows, no? Surely closing the windows cannot expose one to more air pollution than opening them?

Emissions Analytics found that emissions of particulate matter from tire wear can be 1,000 times worse than from tailpipes.


This is a rapidly increasing problem as more EVs, which are very heavy on tire wear, generate more pollution. Good idea to stay on top of alignment: https://teslamotorsclub.com/tmc/threads/unusual-tire-wear.10...

>The hatchback's tires emitted 5.8 grams of particulate matter per kilometer

This number seems incredibly suspect. It's far too high. That rate of loss cannot be sustained. Either their research is wrong or loss levels off dramatically and quickly. At that rate of loss the tires, across 4 tires at 27 lbs each, would evaporate in 8500km and realistically be unusable after under a thousand.

Particulate matter might not come entirely from the rubber of the tyre.

Parts of the road surface are also broken up into fine dust and sent airborne. Tar from asphalt doesn't sound great to have in lungs, nor does sillica dust from aggregate/concrete.

Looking how quickly potholes form, I could totally imagine 5 grams of loss of road surface per kilometre.

That might be right for an F1 car, they go through two sets of tires a race.

It says “hatchback”, so: no?

That study is utter nonsense:

> 5.8 grams of particulate matter per kilometer

Red flag. What kind of contrived conditions did they conspire to create that number?

And with regard to Tesla vehicles being heavy, that’s obviously fixed by using wider tyres or harder tyres, in order to get the requisite traction.

Is it EVs that are heavy on tyre wear, or Teslas specifically? I've not heard issues from the Outlander, Zoe, Prius and Leaf drivers I know, and we talk EVs regularly.

There's a lot of data about specifically Tesla being hard on tires, with owners recommending regular alignment to preserve. Doesn't matter if it's a diesel 18 wheeler or an ev though, tire wear is a v major contributor to air pollution, my primary point which was downvoted. I wonder if some sort of air ground effects might alleviate this, like a hovercraft when safe to apply?

I think when you have more torque under your control, you're more tempted to use it, and even a tiny amount of tyre skidding makes a lot of dust.

Also, EV's are heavier so will break up the road surface much faster - various studies have shown doubling the weight on a wheel far more than doubles road wear.

Sponsored by your friendly manufacturers of auto cabin air filters.

[In all honesty, my auto's cabin air filter is always far dirtier than the engine's air filter.]

It's a shame, because I like to keep my windows cracked every so slightly. It helps me hear where all of the cars are around me.

In pandemic times I only ride e-hailed taxies with the window opened at least 50%.

Guess it's a matter of picking my poison.

Another way in which the poor are disproportionately affected.

Driving a beater with no AC in the summer? All windows down.

Dang, not looking good for the convertible lifestyle.


"Heavily subsidised" is presumably locale-dependent.

In my country drivers are very heavily taxed and it's not obvious where the money goes; biggest infrastructure projects are rail.

Unfortunately cars are often the only pragmatic option for commute and other travel in non-urban areas.

Sounds like most non urban areas should be discouraged.

I don't understand what that means - how do you "discourage" social structures that have built up over hundreds and sometimes thousands of years?

Taxes, zoning, mandating higher density housing, apartments with large shared yards over houses with small individual yards, discouraging private transit ...

Encourage urban living, not suburban. You can go entirely rural, or high density urban.

Should we store the exhaust used to transport your food, clothes, etc. in your house also? Seems unfair to punish the delivery man for your consumption.

If I decide to wastefully and stupidly order a bunch of extra clothes and food when I can fulfill the same requirements by other means... then, yeah, sure.

Imagine walking around with an extra 1000Kg of clothes on me powered by fuel extracted from a dictatorship half-way across the world. I'd say the exhaust is only the beginning of the full cost I should fairly be charged.

I know people who live next to a busy highway. They are scientifically proven to die a few years before their high income peers living in a nice secluded villa. Not all animals are equal.

I always use 64x drivers for my windows 10. I don't use open source drivers but only proper ones from the manufacturers. I don't think this would expose me to more air pollution.

It might not, but your “proper” drivers may be of poor quality and expose you to other issues.

Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact