It's true that brake dust is the primary PM2.5 emission from vehicles in an urban environment. However the PM2.5 component from tail pipes are still very significant, higher than the contribution from tires.

The order is:

1. brake dust 2. road dust 3. engine emissions 4. tire dust

https://www.sciencedirect.com/science/article/abs/pii/S00456...

https://electrek.co/2025/05/27/another-way-electric-cars-cle...

> though diesel engines spit out a bunch of bad stuff.

Exactly. The noxious tailpipe emissions in a city are usually from diesel trucks, small vehicles like motorcycles (small or absent catalytic converters), modified vehicles (catalytic converter removed or diesel reprogrammed to smoke), but not modern gasoline ICE vehicles.

The love for diesel engines in many European countries was always confusing to me.

PM2.5 is also a broad category of particulates that come from many sources. The PM2.5 levels in the air depend on many sources, with wind being a major factor in changing PM2.5 levels. It’s hard to draw conclusions when a number depends on the weather and a lot of other inputs.

"relatively clean" means 85% of PM2.5 is from non-exhaust sources, and 15% is from exhaust after catalytic conversion. In New York EV and ICE are pretty much on par when it comes to this category of pollution, as the additional weight increases non exhaust sources. Source: https://www.sciencedirect.com/science/article/abs/pii/S13522...

It is different in Africa, where catalytic converters are harvested for precious metals and cars are driven without them.

Is that true for slower moving vehicles? I can't imagine there's a lot of brake dust generated by stopping & starting in the 0-10 mph range.

How do EVs fare in this regard? Brakes are used significantly less, but the additional weight from the batteries chews through tires faster.

It always surprises me when people want stop signs in their neighborhood for traffic calming. The last thing I want is all of the noise and pollution of vehicles stopping and starting over and over again; surely various piece of road furniture like bulb-outs, roundabouts, etc, do a better job with fewer drawbacks. Other than cost, of course.

There are some early tyre and brake dust collection systems which might help, but that won't do much for the road dust.

I've been wondering whether, theoretically, if self driving cars become widely usable and deployed in cities, will they be able to safely operate with harder tyre compounds and harder road surfaces that shed less but don't grip as well?

If nothing else, less aggressive driving should lead to less shedding.

There’s also ammonia from farmland, it reacts to form secondary PM25

I wonder if it is the `congestion` itself that causes the PM2.5 spike. More stop and go traffic, more brake dust, more tire dust?

Congestion leads to more use of the brakes, which can have nonlinear effects.

Also, I thought tire particles tend to be larger.

co2, co, NO.

Nothing i would breath in a garage. Nothing i like to breath in while i'm driving.

This is actually a major nitpick. If this "study" is this sloppy, what else isn't quite true?

  Minor nitpick, but tailpipes aren't the primary source of emissions. 

And besides, even if lung cancer and heart attack may be the most common means of premature death, it does not entail that air pollution is the primary cause of them. I thought that smoking and bad dietary/exercise habits were the main factors. Please correct me if I'm wrong, I'd like to know.

It’s a national issue because as soon as one city tries it out and it turns out to be pretty good and none of the doom scenarios ensue, congestion-charge opponents all over America lose most of their talking points.

Best they can do now is, “Well, we’re not New York.”

Attention economy, the algorithm, rage-bait, maximizing engagement, doomscrolling - pick your buzzword. Individual people care about all sorts of weird things, but on average, this and no other reason is why a person in Idaho suddenly finds themselves caring about Manhattan congestion pricing. It's easy to point a finger and laugh/marvel when it's something so obviously absurd to you, but of course you and I both have entirely different blind spots where our attention is marshalled and our opinion is formed by the rage-bait engine. Ours must seem preposterous to those on the outside looking in, too.

Probably very clear-cut, right? "No parking, no business" never made sense, but it makes even less sense in a city where cars are involved in less than a third of all trips

Especially considering that

* Congestion is an opportunity cost in itself already, which is paid in wasted time by all road users, impacting mostly those who spend a long time on the road, which is busses, taxis, professionals and delivery drivers, as they spend the most amount of time actually driving in congested roads

* Congestion pricing forces trips to self-select on cost/benefits in actual dollars, instead of time, so you optimize for wealthier trip takers, short stays or high value trips, where before you would favor long stays (which make looking for parking forever not so bad), and people who don't value their time very much

* Car use remains heavily subsidized, as motorists do not come close to paying the full costs associated with their road usage

> The strength of conviction people have about this policy–almost either way, but certainly among those against–seems to scale with distance from the city.

Writing this from mid-town Manhattan. There are a lot of strong feelings about congestion pricing. It was a common topic in the local media. The stronger voices tend to be those who drive and are affected by it. For Manhattan that is a relatively low percent of the population.

There are some people who are pro-congestion pricing, but as often has with these things the benefits are distributed whereas the costs are concentrated, leading to certain behavior.

Feels like this is the curse of modern US politics. I'm convinced the majority of people that "want high speed rail in CA" don't live in CA. Further away they live, the stronger they will argue for why we should have it.

It's because everything is a culture war issue now, and anything remotely seen as helpful or benefitting society or taking even an inch from cars is "bad" for the people who live in places like Idaho (and Staten Island).

Fox news.

Cars are en extension of some Americans' identity and driving is something they feel utterly entitled to.

I've lived all over the world and in NYC for decades so it seems silly to me. Bust most Americans have never seen or ridden an effective form of public transport. So they view congestion pricing as an infringement on their rights and quality of life.

Because success would encourage it in other cities facing terrible traffic.

People say they hate socialism, but drivers love car-socialism.

You're curious how an issue where government listening to experts results in obvious good outcomes and no serious failures became a national culture war issue?

There are reliable ways to transform American rhetoric to collectivist vs. individualist.

"We should toll roads". This will reliably produce "we should all contribute through tax to the maintenance of roads and they should be considered a public good".

"We should have land value taxes". This will reliably produce "we should not have to pay rent to the government for something that we own".

A simple self-interest model will capture all participants in this discussion. This is why economically optimal policies have such opposition. People don't want to pay the price for their actions. They're ideally hoping to have someone else pay it. It is just as common for a position like funding for SF's Muni.

Propositions J and K made it clear. One said "let's raise Muni spending". The other said "if we raise sales tax, that will go to Muni spending. If we don't, the Muni spending proposition dies". People voted for the first and against the second. Pretty straightforward position: "We should spend more money but from a place that is not me".

The way welfare is organized in the US also shows this. Welfare is the largest sector of the US federal budget, and the ideal is to tax all productive capacity to pay for the aged. This aligns with the increased vote share from the aged. The classic two wolves and a sheep at dinner.

New York has long been an influential city. It was the Robert Mosses deputies that spread all over the US to drive highways threw every city center. If New York can do something, it might be copied everywhere.

That and right-wing politics where anything that harms the car as a religious symbol is seen as a 'values' based attack.

It's because Trump made it one of his obsessions for a period of time, putting it on the MAGA radar.

I think it's because it disproportionately impacts the people who can least afford it. It allows the wealthy to continue to enjoy the convenience (relative to alternatives) of driving into the city while polluting and causing traffic at a price that has zero impact on their lives while it punishes those who already have much less and whose lives will be impacted by the fines and the often significant amounts of time they'll have to spend arranging and taking alternative modes of transportation.

That's a very hard sell when people all around the country are feeling continuous downward pressure on their lifestyle and financial security while billionaires are seen getting massive tax breaks and pillaging everything they want while escaping accountability for the harms they cause everyone else. Taking a basic task like driving into the city, something many people are forced to do for work, and punishing them for it while once again giving the wealthy a pass was certain to upset people. in fact, by forcing more of the peasant class off the roads it makes driving into the city much more pleasant for the people with enough money to not care about the extra expense. Taking from the poor to improve things for the wealthy resonates with a lot of people.

It also doesn't help that in other contexts, congestion pricing has already hit people's wallets and is seen as an exploitative business model designed to extract as much money from the public as possible. The last thing most people want is seeing congestion pricing and other price-fuckery infesting another aspect of their daily lives, which is why the pushback against wendy's implementing it was so swift and severe that the company had to backpedal even after spending a small fortune on the digital menu boards they needed to enable it.

https://pmc.ncbi.nlm.nih.gov/articles/PMC7314691/figure/f002...

Take a look at their figure, especially in May 2020—the average appears lower, but, more significantly, there is much less variability in May 2020 compared to earlier years.

The authors' model quite strongly includes their preferred confound (secular decrease in PM2.5) but doesn't explore what other covariates could explain the differences between years.

It's fine to say that one should be skeptical, but one contrary report doesn't invalidate an antecedent report, and the structure of a linear model strongly influences an outcome.

"Not statistically significant" doesn't mean did not happen.

Given the physical mechanisms involved it is implausible that pollution did not decline. And if you look at their data you see a marked drop in 2020 at day 70

This is March 10 or thereabouts, I think. And there are ZERO high pm 2.5 days for a 20 day stretch or so. This isn't seen in other years. The vast bulk of days are below the trend.

And then for the rest of the year there are some days above the trend line but no high pm 2.5 days.

This fits with people being extra cautious in the early days and then relaxing a bit as things went on.

Now, I'm eyeballing this so I could be incorrect. But:

1. The effect was found in other cities

2. The physical mechanism makes it highly expected that there would be a drop

The study was about the slope of the regression modal, but if you had scrambled the years I'm fairly confident I could have picked 2020 out of the set.

That's a very surprising finding since the drop in traffic was very noticeable. I wonder where the PM2.5 is coming from?

We have fruit trees in our backyard. The year of the COVID lockdown they had so much fruit the branches broke from the weight. Most fruit I've seen in 20 years in the house, by a large margin.

There's a large (long time) movement to do this to lower Manhattan, the most public transit connected area in the US (probably North America, definitely up there in the world). It's getting pick up again.

This is already underway

Big agree. Times Square would be a great place to start.

> You could, at the extreme, ban all motor vehicles but the opportunity cost would outweigh the benefits

We did this in Times Square and on Broadway, and it's honestly been great. I say this as someone who takes cars far more frequently than most New Yorkers and has a place I lived at full time for over a decade off one of those closed-off sections of Broadway.

The point of congestion pricing is to let market mechanisms determine where the optimum is.

I wouldn't assume your last claim.

It could also be the case that making it viable to drive personal vehicles at all inside a dense city comes with opportunity costs (parking, roads that cut through infrastructure, pollution, noise) that aren't worth it.

And I'd wager that it is the case.

Since this is generating revenue for NYC, you can't consider whether this tax is good or bad in a vacuum though. The alternatives are a different tax with its own effects, or more debt, or less spending. (In this case, the revenue goes to the MTA.) Any opportunity costs due to less traffic are at least partially offset by opportunity costs you aren't having to pay somewhere else.

Dynamic pricing based on congestion would solve this. It would also almost certainly result in higher costs for drivers though.

Try things and ask the people in a year if they like the results, then do the good ones more and the bad ones less.

You take a walk along a 55-mph stretch of highway, and then you take a walk down Broadway, and you see which one makes you feel better as a human being.

It's called congestion pricing because you can measure the opportunity cost.

21 minutes faster.

https://www.tomtom.com/newsroom/explainers-and-insights/the-...

The city does it for the benefit of the public, the Corp does it for the benefit of the shareholders

https://portal.311.nyc.gov/article/?kanumber=KA-03612

> Some drivers can apply for Low-Income Discount or Low-Income Tax Credit for Residents.

> A 50% discount is available for low-income vehicle owners enrolled in the Low-Income Discount Plan (LIDP). This discount begins after the first 10 trips in a calendar month and applies to all peak period trips after that for the remainder of the calendar month.

The revenue also goes towards public transit, and the congestion charge applies mainly to the wealthiest part of the wealthiest borough.

> Truckers were using lower manhattan as a cut-through route to other places

Popular truck route from Queens->Bronx was 59th st bridge, left onto 2nd then immediate left onto 59th, and another left onto 1st and take 1st all the way to Willis Ave bridge to beat the RFK bridge (formerly the Triborough) tolls.

It's good to point this out but I don't think the snarkiness at the beginning is necessary to get your point across.

exactly. and the pandemic "lockdowns" showed those of us who actually live here that what we want is fewer cars in our neighborhoods.

that's great. because those cars trash the city.

Who's "they" here? I don't think it's the government forcing everyone at finance and tech companies to come into the office.

NYC has 8M people and 2M cars. Manhattan has like a 22% car ownership rate, and it's… not the poor people. https://www.hunterurban.org/wp-content/uploads/2024/06/Car-L...

A parking spot will cost you more than rent in some other cities.

Because that’s not true. Cars are expensive compared to transit everywhere, but especially so in NYC. This was studied a lot before congestion pricing was implemented and only something like 2% of poor people were going to pay congestion charges. This did not stop a bunch of rich suburbanites from using them as a prop to demand that the city subsidize their lifestyle at the expense of NYC taxpayers, of course.

https://www.cssny.org/news/entry/the-cost-of-killing-congest...

> curious why no one is discussing this but this is basically a middle finger for poor people

Because the poor don’t drive in New York, and to the extent they do, they likely qualify for an exemption.

I don't think poor people who lived in NYC were driving that often anyway? cars are expensive to begin with and parking is crazy in that part of the city

You are assuming a car is required.

The whole issue with car dependency is that it is a massive barrier for participating in society.

Public transit is orders of magnitude cheaper, and very viable and often the better option in the New York area.

Concern trolling.