My Urban Car

A perplexing question- Why don’t UK air pollution experts like electric vehicles?

Air pollution from vehicles is a curse on the health of everyone around them including in other vehicles.


The mortality burden of air pollution in England is estimated to be between 26,000 and 38,000 a year, but in addition many people suffer avoidable chronic ill health as a result of it. Improvements in air quality have been associated with improved health outcomes – for example, reductions in air pollution in London have led to reduced childhood asthma hospital admissions

England: Chief Medical Officer’s annual report 2022: air pollution

There are 2 types of pollution – gases and particulate. Both damage cells throughout your body and trigger a range of conditions including asthma, heart disease and lung cancer.

The solution appears so straightforward. To simultaneously and rapidly limit catastrophic climate change and cut air pollution by phasing out fossil fuels and the vehicles that burn them. This would eliminate the CO2 , the toxic gases and the toxic particulate produced by fuel burning engines. So why does it feel like many of the biggest names in tackling air pollution in the UK are implacably opposed to the transition away from combustion to electric vehicles?

This article will explore

  • quotes by some influential UK air pollution experts
  • run through each of the arguments they raise and why I believe they incorrectly exaggerate pollution from electric vehicles while underplaying pollution from combustion vehicles with sources where applicable
  • explain why some of the quotes being used by those seeking to delay action on air pollution and global warming

My background in air pollution

I am an enthusiast and evangelist for electric cars and for clean air. I am not a scientist but I do have a good working knowledge of both subjects. MyUrbanCar was originally set up to provide an app to tell drivers about which cars produced the most and least toxic NOx pollution. While the app didn’t succeed in the end, I learned from reading research reports, talking to experts and reviewing data that showed which vehicles pollute far more than others out of their exhausts and why. I also learnt why some vehicles appeared clean in lab tests but turned out to be massively polluting on our roads.

My interest was in looking at and cutting traffic pollution on a “per vehicle, per model and per brand basis” because there were massive variations between cars. This is a little different from many UK campaign groups and academics studying measuring air pollution as an aggregate from many sources (including agriculture and wood burning) in the air we breathe. Both methods provide very different insights and have different limitations.

It’s personal too. When I discovered the diesel I drove in London was producing as much pollution as 25 petrol cars, I switched to a petrol and then later to a fully electric car. I’m very aware of pollution around me, I have a nose for NOx and can often smell it, even well after a single diesel vehicle has clattered off down the road. I also regularly notice the visible smoke even from many ULEZ exempt and supposedly “clean diesels”. When driving I rarely set the ventilation to suck in outside air, especially when diesel vehicles are present and when on foot I avoid heavily congested streets where possible.

It’s worth noting that the car industry successfully lobbied against the strictest Euro 7 rules necessary to reduce exhaust pollution. Euro 7 will come, but will have much less effect on air pollution from exhausts. Essentially the industry argued that with the switch to electric vehicles, replacing combustion cars anyway, there is no point of diverting investment to the outgoing technology.

My primary independent sources of information are Transport and Environment (T&E) and the International Council on Clean Transportation (ICCT) along with roadside testing in Scotland and other countries by the True Initiative. These are the leading Independent NGO’s researching and lobbying for lower emissions of pollutants and CO2 from vehicles at a European level.

Their particular focus is the environmental impact of different transport technology choices. Both have, as far as I can see, have come out unequivocally in finding that replacing Combustion vehicles with Battery Electric Vehicles provides the best, indeed only currently solution, to reduce CO2 global warming gas emissions by over 60% and dramatically cut air pollution.

A sample of influential UK pollution expert views

By contrast in the UK, the top search result from a well respected UK expert in a google search for “Frank Kelly Electric Cars” brings up his 2017 quote to the Guardian, from an article entitled Electric cars are not the answer to air pollution, says top UK adviser

Prof Frank Kelly said that while electric vehicles emit no exhaust fumes, they still produce large amounts of tiny pollution particles from brake and tyre dust, for which the government already accepts there is no safe limit

The Guardian 2017

This particular chestnut has been doing the rounds ever since Professor Kelly produced this quote in 2017. His original comments were more nuanced.. suggesting we needed to walk, cycle and take public transport more, as the shift to electric cars alone would not eliminate particulate emissions. That’s an old quote now, so what’s he saying on the 26th April 2023?

The benefit of moving to an electric vehicle, from an exhaust emission point of view, is actually pretty small, says Kelly. And since electric vehicles still produce pollution from their tyres, brakes and road wear, air pollution won’t fully go away. “We’re still going to have a pretty big problem in our cities,” says Kelly.

New Scientist “Electric Vehicles are rapidly taking off – but is that a good thing? APR 2023

This latest comment is very bizarre indeed. He says “from an exhaust emission point of view”, so is the suggestion that electric vehicles have a secret toxic exhaust pipe tucked away somewhere, or that petrol and diesel engines exhaust pollution is now so low it is practically zero emission? Whether it is Professor Kelly’s intention I think most people people skimming through his comments will take away the impression electric vehicles don’t cut air pollution (even from exhausts) noticeably, and might even make it worse. Indeed his comment appears to simultaneously be massively overplaying pollution from electric cars and at the same time massively underplaying the pollution from combustion vehicles.

How about another often quoted expert. Again, a google search on the term “electric cars Gary Fuller” brings up articles like “Electric Cars are not the solution” and quotes like

Will our streets be pollution free when the last petrol and diesel cars are sold in the UK in just over two decades time? Sadly not. This is for two main reasons. First, we will still have diesel lorries and buses. Second, electric cars still release particle pollution into the air from wearing tyres, brakes and road surfaces. Already more particle pollution comes from wear than from the exhausts of modern vehicles

Gary Fuller Writing in Environmental health news 2017

Further quotes in an article also from 2017 include phrases like “Electric cars move pollution from our cities to distant power plants”.

What narrative are these UK air pollution experts trying to get across?

So one question is why did some of the air pollution establishment seem to have come out as strongly against transition from fossil fuels as Exxon or BP and what are these experts trying to say? Well here is Gary again responding to a very on point question by Environmental Protection Scotland in November 2019.

“HOW DO YOU ENCOURAGE PEOPLE TO OWN ELECTRIC CARS IF THERE ARE SO MANY MIXED MESSAGES OVER THE POLLUTANTS THEY CREATE FROM BRAKE DUST AND TYRE WEAR?
GARY: Communication with the motorist has to be clear. A total of 40% of all car journeys in England are less than two miles, and 60% are less than four miles so there is a real opportunity to encourage active travel by getting people out of vehicles altogether for those trips at least. This creates a huge opportunity to encourage people to take part in active travel. If we can tackle the short-distance journeys we are also helping reduce urban noise and slow climate change. What we should not do is simply swap the streets congested with diesel cars for ones with electric vehicles. We also need to think about the design of our streets, to encourage walking, and cycling”

So that seems to clarify it. In answer to a question about how we encourage people to switch to electric cars, the only reference to electric cars is… don’t swap petrol or diesel cars for electric cars, while most of the answer is about active travel. Active travel is defined as “travel, especially commuting or movement in one’s local area, of a kind that involves physical exercise, such as walking or cycling”. It is worth noting the phrase “active travel” does not just exclude private cars, it also excludes buses, trains and tubes.

Essentially then, to paraphrase George Orwell, the message is that everything on 2 wheels or 2 feet is good, and everything on 4 wheels is bad. To cut air pollution they seek to rely entirely on persuading the whole of mainstream society to dump private cars and public transport and switch to bikes and walking. While they rightly highlight many short local journeys could be made without a car, they refuse to differentiate between zero emission or fossil fuel burning vehicles for all other journeys. We discuss this in more depth our article “Opinion : Are competing ideas slowing UK action on climate change?”

It is worth noting that their expectation of sharply falling exhaust emissions may actually be based on 3 assumptions

  1. That combustion vehicles are quickly replaced by electric ones
  2. that new combustion vehicles will comply with legal limits when new
  3. that combustion vehicles will continue to pollute only within legal limits as they get older

Satisfying assumption 1 requires the speedy adoption of electric vehicles.
Assumptions 2 and 3 require blind faith in something that has never happened in the past, and seems highly unlikely to happen in the future, especially number 3, which will depend on owners of older combustion cars spending hundreds or thousands of pounds maintaining and repairing complex and expensive pollution cleanup technology on their vehicles.

The big problem – How the media & the public perceive these quotes

I have no idea if there is some sort of miscommunication or misunderstanding here but the perception produced is crystal clear. If you want cut air pollution we all have to walk and cycle. Electric cars, despite having zero exhaust pollution could actually make things worse they suggest.

Now I don’t have any problem with encouraging active travel. It is good for people’s health and will indeed cut pollution and CO2. But I don’t ever come across these expert’s quotes in relation to “active travel” discussions on social media or comments from newspaper articles or readers comments. In fact, in my experience, these quotes almost exclusively used by owners of the most polluting diesel vehicles whose takeout is “your electric car is just as polluting as my diesel, maybe worse, that expert says so”. I’ve never heard one of these discussions mention active travel on a bicycle or walking. These quotes are continually used as a justification for continuing to ignore both air pollution and climate change. They are used interchangeably by the public with lines like “it’s all a con”.. “I’m driving a diesel because Gordon Brown told me to” (over 20 years ago) and “climate change is a myth” and “electric cars are just move the pollution to coal power stations” (also from Gary).

Until the arrival of the electric car, air pollution campaigning and research in the UK was focussed very much on the health impacts of toxic exhaust emissions from burning petrol and diesel fuel. Now it seems clear that the view of some UK experts is that removing 100% of all these exhaust emissions at a stroke will have a “pretty small” impact on public health. Not only does this seem to be to be utterly wrong, it also undermines the excellent scientific work at these same experts have done to cut air pollution. After all, if you’re effectively arguing that petrol and diesel cars produce no noticeable extra air pollution over that from an electric car producing none, then why would we need a ULEZ or any action on exhaust pollution.

It’s also worth noting it’s just not me that thinks this and the effect of slowing the switch away from burning fuel will disproportionately affect the health outcomes of poorest people in the UK. I think this view is both perverse and profoundly wrong and is contradicted by the expectations from other experts outside UK, like the American Lung Association.

This report finds that a national shift to 100 percent sales of zero-emission
passenger vehicles (by 2035) and medium- and heavy-duty trucks (by
2040), coupled with renewable electricity would generate over $1.2 trillion
in public health benefits between 2020 and 2050. These benefits would
take the form of avoiding up to 110,000 premature deaths, along with nearly
3 million asthma attacks and over 13 million workdays lost due to cleaner
air

Zeroing in on Healthy Air is a report by the American Lung Association 2023
  • To be clear, I agree that particulate pollution from tyres and brakes and road surfaces can be toxic and can be a threat to public health and that more research should be done to discover more about the problem and find solutions
  • I agree that encouraging walking and cycling is a good thing in especially in urban areas. Indeed I practice what I preach, having helped to set up a school street and a well used new pedestrian crossing and have worked to improve road and junction designs for people on foot and on their bikes in Wandsworth where I live. I walk, take electric Lime Bikes or public transport for the vast majority of my London journeys
  • I am also however of the opinion that the removal of toxic particulate and toxic gases from exhausts will provide massive benefits to our health
  • I disagree that the switch to electric vehicles will noticeably increase pollution from non exhaust sources and explain why below.

Misconceptions about why electric vehicles won’t deliver big cuts in urban air pollution?

1 Particulate emissions from the exhausts of petrol and diesel cars are now at safe levels?

The answer to that is no.

Diesel engines produce far more particulate than petrol engines. As a result diesels have had to use DPF filters to cut their emissions for around the last 2 decades, while petrol vehicles weren’t required to filter their exhaust till more recently. Diesel particulate filters are expensive to repair while petrol ones generally are cheap and easy.

Exhaust Particulate filters – pollution solved?

The fix for diesel particulate was the DPF or diesel particulate filter. This has the ability to cut particulate by about 98%, or does it?

DPF on dual carriageway
  • DPF’s store the particulate then burn off it off when the filter reaches higher temperatures when the engine is worked hard. Usually this means that urban cars burn off some of their particulate and dump the rest on a motorway journey or A road later on..
  • New research in London by the University of Birmingham has found that while DPF’s have reduced the amount of larger particulate pollution from diesels, the smaller more dangerous Ultra fine particles (UFPs) showed “no sign of improvement between 2014 and 2020”. These are particles that can enter the bloodstream and affect organs and cells throughout the body. Article by Gary Fuller on this!
  • if the DPF never gets driven fast enough outside urban areas, it can get blocked (like a vacuum cleaner that’s never emptied). Then it fails. This happens primarily in urban areas where cars drive slowly.
  • Once blocked a DPF is very expensive to replace. Many owners either leave the DPF faulty or remove it and don’t replace it. If Just 5% of diesels have non performing filters these vehicles can produce as much particulate as 95% of diesels with working filters. Fitting a replacement DPF can cost most of the value of an older diesel car.

Essentially then, in tests published in the media of diesel vehicles that were brand new or perfectly and expensively maintained and repaired, DPF’s do work for larger particulate. If you look at the effect of DPF’s on what people breath in cities they work less well because if a tiny percentage fail, the air remains highly polluted and dangerous smaller particles slip through the filter anyway. The only protection for public health is a newish MOT test requirement for “no visible smoke”. Judging by the number of diesel vehicles emitting visible smoke, some MOT stations are clearly passing vehicles without a working filter without any negative consequences.

This pollution occurs when a combustion car is moving, stopped in traffic or parked with the engine idling. Any time you hear a combustion engine it is polluting the air around it. Drivers of these vehicles keep polluting even while parked and on the phone, running a laptop, keeping the aircon running, eating a sandwich or even having a cigarette

Electric cars produce zero exhaust particulate whether, moving or stationary new or old, well maintained or not, for the life of the vehicle.

2 Toxic gas emissions from petrol and diesel cars are now at safe levels?

Again the answer to this is no.

Essentially this was a story about NOx (nitrogen oxides) with

  • petrol cars becoming much much less polluting after the introduction of catalytic converters in 2001 and
  • diesels remaining illegally polluting, culminating in the dieselgate scandal.

Diesel engines were not only far more polluting, they were also far more of a challenge to clean up. They remain so today and 35.8% of cars on our roads are still diesel (Source: SMMT 2022 Motorparc). In pollution terms they are more prominent than that because diesel drivers drive a higher average mileage than any other fuel type. In fact because sales of new diesels collapsed, only around 400,000 of the 12.58m diesel cars on our roads were built since 2019 when real world pollution testing was mandated. Even diesels produced since 2019 are allowed to emit illegal levels of air pollution because the car industry lobbied for a conformity factor over the limit. On average the NOx pollution from the 2019 and prior cars has been measured to be between 7 and 11 times more than a petrol car.

There are 2 primary toxic gases emitted by engines that burn fossil fuels

NOx

NOx is not visible but it’s very noticeable. It’s the “oily rag” smell and taste in the air after a diesel vehicle passes you in the street and remains in the air after it’s gone. Diesel engines emit vast amounts of NOx (up to 30 times more than petrol cars in the worst cases). Older equipment (NOx traps) failed to cut these emissions and so a new much more expensive set of “Adblue systems” were introduced.

Like diesel DPFs, Adblue systems work a lot less well in practice than they are meant to. Like DPF’s the technology is largely dependant on getting the exhaust hot enough. So driving like a maniac on a country A road or a regulatory test cycle on a track, an Adblue system could work perfectly. By contrast there are many scenarios where Adblue system don’t remove NOx at all effectively such as:

  • For the first 5 minutes of a journey
  • Anywhere where roads are slow moving or stationary due to congestion
  • Anywhere with traffic lights, pedestrian crossings or queues of stationary traffic
  • On any vehicle with a stop start system that shuts off the engine when stationary
  • On any road where average traffic speeds are under 30 mph
  • on cold days in winter
  • on hot days in summer
Fact check: Are diesel NOx emissions within legal limits yet? click to open

Majority of post-RDE Euro 6 diesel cars still over-emitting, shows new TRUE analysis from Scottish citiesLarge scale NOx testing taking 225,000 measurements from 95,000 unique vehicles in Edinburgh and Glasgow on behalf of the Scottish government published in 2023 found:
Early Euro 6 diesel vehicles up to 2019 remained highly polluting
“The nitrogen oxides (NOX) emission performance of measured diesel vehicles did not improve significantly until the introduction of Euro 6d-TEMP
standards. Euro 6d-TEMP vehicles sold since 2019 were found to emit, on average, 198mg/km, or 40% below the level of the preceding Euro 6 standard (498 mg/km) but remained way up the Euro 6 legal limit of 80 mg/km set in 2015.

“Taxi’s and private hire diesel vehicles are much more polluting than private cars
The remote sensing measurements show that taxis and private hires certified to Euro 4–6, or registered between 2006 and 2019, emit NOX emissions 41%–68% more on average than other private cars. Taxis were shown to emit significantly higher levels of NOX than private hire vehicles, with London Taxi Company black cabs as the highest emitting taxi brand that still circulate
the Scottish cities.”


With each year and every mile added to a diesel vehicle the more polluting diesels become when tested on the road.
“When emissions were investigated as a function of the registration year of
measured vehicles, there were positive correlations between the NOX emissions from diesel passenger cars certified to Euro 4–6 and how long they have
been registered, or in use. Similar trend was found for CO emissions from petrol passenger cars certified to Euro 4–6. The results allude to the possible
degradation of emission control systems of diesel vehicles that were previously not widely studied.

Link to full report below
Majority of post-RDE Euro 6 diesel cars still over-emitting, shows new TRUE analysis from Scottish cities

Essentially then Adblue works best in less populated areas like country lanes, and least well in any town or city. So it’s least effective where the most people will breath in the pollution and most effective at protecting the lungs of cows grazing in a remote country field.

There is another reason why adblue proved fairly ineffective. Even when hot enough, the adblue systems only work if fed with large amounts of adblue liquid, but diesel carmakers realised this would affect sales because it would be awkward and expensive to keep filling the required big tanks of Adblue which would also take up space and add weight in a diesel car. So instead they.. believe or not.. cheated…

  • Diesel carmakers starved adblue systems of liquid except when a test might take place and colluded to fit inadequately sized tanks for adblue on their cars. (VW and BMW were fined $1billion for this by the European commission). Mercedes were exempted because while they were equally guilty they blew the whistle.
  • Essentially most of the diesels on the road only switch on Adblue systems when outside temperatures are between 12C and 25C. The rest of the time NOx emissions may be up to 30 times above regulated levels. Even when working an Adblue system may be starved of the amount it needs to function fully. This is software controlled and the issue may apply to many pre 2019 Euro 6 diesels that remain exempt from UK clean air zones including in London. There is nothing an owner can do to make their diesel vehicle limit its pollution to legal levels.

Carbon Monoxide –

Combustion vehicles produce another toxic gas, this time one that petrol burning engines produce more of. While deadly in a short time period in a confined space, in outside air it dissipates quickly. This is why there is less focus on this extremely deadly pollutant.

Ozone

Ozone is created in the atmosphere through a cycle of reactions between nitrogen oxides and volatile organic compounds (VOC). Sunlight, stagnant air and higher temperatures increase the rates of reactions that generate ozone. Nitrogen oxides are produced by combustion engines.. and global warming generate more Ozone especially during heat waves. It is precisely during heatwaves (and cold weather) that diesel cars turn off the equipment that is meant to clean up nitrogen oxides from their exhaust.

Exhaust gas pollution occurs when a combustion car is moving, stopped in traffic or parked with the engine idling. Any time you hear a combustion engine it is polluting the air around it. Drivers of these vehicles keep polluting even while parked and on the phone, running a laptop, keeping the aircon running or even having a cigarette.

Electric cars produce zero exhaust toxic exhaust gasses. whether moving or stationary, new or old, well maintained or not, for the life of the vehicle.

3 Particulate from tyres and brakes will soar when we switch to electric vehicles?

Since electric vehicles produce no toxic exhaust emissions tyre emissions and brake emissions have for the first time become the focus of media pages devoted to preventing or delaying the transition away from fossil fuels.

Particulate from tyres and brakes is serious issue but some regularly used quotes in these stories suggest it is more important than all exhaust emissions combined and/or that particulate emissions from these 2 sources will soar as more electric cars replace petrol and diesel engine vehicles.

Fundamentally this theory hangs on the thread that Electric vehicles may not have an engine generating toxic gas and particulate but by golly they still have wheels and brakes and as EV’s are bit heavier (and obviously always will be!!!) well that’s it.. it will be a disaster.

Fact check: are Electric cars heavier? click to open


The brilliant thing about these 2 theories is, particulate from brakes and tyres is extremely hard to measure scientifically and compare between vehicles. So when air pollution experts warn of rising particulate levels from brakes and tyres when more people switch to electric cars, it is probably conjecture which can neither be confirmed nor contradicted by any solid evidence. What they and we can do is look at useful proxies for real pollution data.

Proxies for particulate from brakes and tyres

2 proxies are most clearly pertinent. How long do
1) brake pads and
2) tyres last before they wear out
The logic is for using these as proxies is pretty simple. Both brakes and tyres wear out as they are used. If they wear out faster on one vehicle type than another, then that vehicle type is almost certain to be emitting more mass or weight of particulate on the road. What the proxy won’t tell you is if there is a size and nature of the particulates. Smaller particles are lighter but also more toxic to humans.
There is strong anecdotal evidence looking at these proxies completely contradict the theory combustion car good, electric car bad mantra. This is explored with examples from fleets in this link below.
Report: Do electric vehicles produce more tyre and brake pollution than their petrol and diesel equivalents? by Dr Euan McTurk commissioned for the RAC

Pollution from brakes will soar?

The claim is that as a result of their extra weight the brake pads on EV’s will wear out more quickly and produce more brake dust particulate. Like most good stories it sounds plausible and very attractive to drivers already worrying about switching to an electric car. So how does it stack up?

Well not at all is the answer, as anyone who’s ever driven an electric car would know. Electric vehicles mostly use regenerative braking which involves using the electric motors to brake. “Regen braking” uses no friction and produces no particulate. It does vary by vehicle but on average brake pads last between twice and 4 times as long on EV’s than petrol or diesel vehicles. So the actual story here is people still buying petrol or diesel vehicles will create far more particulate from their brakes as well as exhaust pollution on top.

This has been backed up new Research from Imperial college which was glossed over in an article by Gary Fuller in a September 2023 article titled “Autobesity’ on course to worsen air pollution caused by motoring– trend for bigger, heavier cars means more particles get released from brakes, tyres and road surfaces”

The 2023 Imperial college study found

  • “despite electric and hybrid vehicles being heavier than ICE vehicles, the results show that (regenerative braking systems) would reduce brake wear by between 64% and 95%”
  • by 2035, we project that total UK brake wear PM emissions would reduce by up to 39% compared with 2020 levels (thanks to the switch to electric vehicles)
  • EVs produce negligible PM10 and PM2.5 emissions during rural and motorway driving
  • Reductions of 64% to 94% in any aspect of air pollution are extraordinary so it’s odd Gary Fuller chose to leave it off his headline and mention it only in paragraph 8 of his piece. If I was an air pollution scientist I can’t help feeling I would be rather more excited.

This has been backed by companies who run fleets of combustion and electric vehicles. It’s also reflected by the extraordinary mileages EV’s do without a change of brake pads and the advice to “use their friction brakes sometimes” to stop them corroding and seizing up though lack of use. None of this suggest more brake pollution from EV’s.

Pollution from Tyres will soar?

Again the theory is extra weight along with stronger torque will cause tyre particulate to soar. I think the reality is rather more nuanced.

  • If tyre life is a good proxy for particulate we really need large scale studies of tyre life across fleets to compare EV and combustion car tyre life. I believe this will give a much more accurate picture over the life of a tyre in the real world than tests set up using individual cars as the results vary enormously according to driving speed, especially when cornering.
  • I really don’t think the “shocking result” that an EV cornering at high speeds on a track in an Emissions Analytics test creates more tyre wear adds much to our knowledge. Anyone who has watched the regular tyre swaps in an F1 race wont find this much of a revelation.
  • Front tyres on most front wheel drive cars wear out sooner and front wheel drive EV’s are no exception but the rear tyres last as long as they do on combustion cars.
  • Driving style is likely to have more influence on tyre wear than just weight. Just as example tyres on my Tesla Model 3 Performance, one of the fastest accelerating cars on the market lasted 25,000 miles. By comparison some forums suggest owners of BMW 3 series and Audi A4 saloons have to do front or back tyre replacements at under 15,000 miles.
  • Perhaps I’m biased being an EV driver but I very rarely see many EV’s driven highly aggressively. Even BMW’s like an i4. Overall EV’s are less stressful and this may mean that even in performance models tyre wear will be less than you expect
  • EV owners may actually choose to corner slower than piston car drivers because the combination of regenerative braking before a bend and strong acceleration after makes it the natural and safer thing to do.
  • It’s worth noting while the EV acceleration is sometimes stronger, regenerative braking, especially by lifting off the accelerator pedal, encourages earlier and less sudden braking which reduces tyre wear when slowing.(something the Imperial brake study contradicts I think wrongly)
  • Many new EV’s are switching to rear wheel drive or 4 wheel drive. This reduces the chance of tyres losing grip during acceleration and should result in less particulate when accelerating.
  • While traction control and ESC systems used on some petrol and diesel cars to stop wheels slipping cut the engine and use brake pads to prevent wheels slipping, it is possible on electric cars to cut power to the motors, creating less particulate.
  • In any case tyre particulate from all vehicles whether electric or combustion should be falling fast in towns and cities as more an more roads adopt lower speed limits especially 20mph urban speed limits. Why? Well tyres wear out (and produce more particulate when cornering at speed and when accelerating or braking hard). While a slightly heavier EV might produce slightly more particulate in a village with a sharp bend and a 40-50mph limit, at 20mph tyre wear should be much much lower. To get very high levels of tyre wear on EV you would need to take it at very high speed as is discussed in the RAC link above when Emissions Analytics did just that.
  • there also needs to be work to ensure all car tyres are made of less toxic and longer lasting materials that cause less harm whether in air, soil or water. Some cheap tyres have a much shorter life and produce more particulate. The worst tyres that wear fastest should be removed from sale a recommendation from Emissions Analytics that should be endorsed.

Resuspension of particulate will soar with EV’s

The allegation this time is that the wheels of EV’s will throw more particulate from a road surface into the air. Resuspension is real. While it’s not usually visible from tarmac it is very obvious on unsurfaced tracks and car parks. Anyone who has spent a moment observing it, knows the higher the speed the more dust is thrown up, for example a car driving fast through a dusty car park. Yes a heavy lorry will throw up much more than a car (they have more tyres as well as more weight) but they are an order of magnitude larger than an EV.

Rudolf Koller - Die Gotthardpost (1874)

In reality suspension of dust and pollutants is not something unique to EVs, it is something that all moving objects and land animals produce (except snails perhaps). As this painting of the Gotthard postal coach in 1874 shows (without an electric car in sight) particulate is thrown up by the coach wheels, and the horses and the calf and the cows. On dirt surfaces visible particulate is thrown up by walkers, runners, cyclists and even passing a Dachshund. And of course a gust of wind will do exactly the same lifting grit large enough to make your eyes smart. So stopping resuspension of particulate isn’t possible unless you stop all movement and wind or we learn to levitate using an anti gravity device or on a snail like trail of slime.

So do we just have to resign ourselves to this? yes and no

Let me explain. The reason our air pollution experts are so concerned about the issue is they can see how toxic some of these resuspended particles are. So where do these toxic particles come from? Well largely from

  1. petrol and diesel vehicle exhausts
  2. brake dust
  3. particles from tyres and road surfaces.

Switching from combustion vehicles to electric will eliminate source 1 and drastically reduce source 2. Sadly though it won’t be quick. Back in 1999 the UK finally banned lead in petrol. Imperial College found that in 2021 London’s air is still contaminated with lead from petrol exhausts which has been banned since 1999
While levels of lead in the air fell sharply at first they have now stabilised and the air in London still contains particles of lead from vehicles driven over 21 years ago and are even measurable at rooftop height. I believe the correct conclusion then is the opposite, that the route to sharp drops in air pollution is to accelerate the replacement of combustion engines with electric vehicles, while at the same time working to ensure that future tyres produce fewer particles that are less toxic and more effectively regulated. We need to the same with road surfaces and also research whether the rougher poorer quality road surfaces in the UK are causing more particulate than the same vehicle using the same tyres on smoother road surfaces in other countries.

Air pollution is a major threat to health and we need to reduce it. I simply believe that the negative approach of some in the air pollution field in the UK is creating uncertainty and doubt, worsening public health and creating a dangerous delay in drivers transitioning from petrol and diesel to pure electric cars. Couching that (in my personal opinion) misinformation alongside exhortations to switch to active travel does not make it any less wrong or harmful.

With absolutely no sense of irony, another group at Imperial has just produced a report claiming electric vehicles won’t produce sufficient cuts in carbon emissions in London because there won’t be enough of them and too many petrol and diesel cars will still be on our roads after 2030. Their solution.. switching 80% of car journeys to active travel with a bit of public transport.

Noise – the forgotten pollutant

Environmental noise has a major effect on health as detailed below by the European Environment Agency report.

Fact check: Noise- What are specific health impacts? click to open

Environmental noise, and in particular road traffic noise, remains a major environmental problem affecting the health and well-being of millions of people in Europe. Twenty percent of Europe’s population are exposed to long-term noise levels that are harmful to their health. That corresponds to more than 100 million people within Europe.
Long-term exposure to noise can cause a variety of health effects including annoyance, sleep disturbance, negative effects on the cardiovascular and metabolic system, as well as cognitive impairment in children. Looking at the current data, we estimate that environmental noise contributes to 48,000 new cases of ischaemic heart disease a year as well as 12,000 premature deaths. In addition, we estimate that 22 million people suffer chronic high annoyance and 6.5 million people suffer chronic high sleep disturbance. As a result of aircraft noise we estimate that 12,500 school children suffer reading impairment in school.
European Environment Agency report 2020

Electric vehicles vastly reduce noise from road vehicles. from cars and taxies to vans and bin lorries to buses and trucks.

By far the noisiest vehicles on the road today are the smallest. Motorbikes especially those whose owners have paid to swap their exhausts to make them louder. Electric mopeds and motorbikes will make particularly big difference. According to research in Paris a single loud combustion bike can wake 11,000 people an hour when driving in the city at night. Some of these bikes can be heard from over a mile away or more. Currently the UK limit is 80db for a motorbike, much louder than a large jet at 2000 feet and there is no effective enforcement yet of noise limits.

As we switch to electric vehicles annoyance at combustion vehicle noise will stand out ever more and increase. People coming home late at night can probably already guess that taking a diesel cab home will wake their neighbours while an electric one won’t. We need to remember that noise leads, not just to disrupted sleep, (affecting performance at work and in education) but also to stress and negative health outcomes like cardiovascular disease.

What will cities with electric vehicles sound like? Much like this city in China.

https://x.com/theevuniverse/status/1663819228489609216?s=61

Where will you find a more balanced view

Here, Chris Whitty, UK chief medical officer for England in answers to UK Parliament Environmental Audit Committee on the 5th July, 2023.

emphasis added

Q92            Caroline Lucas: I want to ask some questions about transport. In the first instance, I have a very general question. What contribution do transport emissions make to the public health burden of air pollution in the UK?

Professor Whitty: “In urban areas—so this is talking about where people live rather than if you just spread it thinly across the country—they have a very significant contribution and, in particular, in areas of deprivation more widely.

Within that, the biggest relative contribution is in nitrogen oxides, NOx, which we have really the capacity now to significantly reduce. It has already gone down a very long way due to steady improvements in engineering. However, motor vehicles, whether private or large trucks, lorries and buses, still produce quite significant NOx. If we were to move over to electrification of the fleet, we would essentially eliminate those down to zero, but we would still have particulate matter.

Particles from transport also come from road surface, brakes and tyres. Electrification does not solve that problem at a stroke. It does reduce brake problems to quite a high degree because most electric cars do use regenerative braking, which is a mechanism that does not produce friction and, therefore, it doesn’t lead to particles.

Initially, in fact, because of battery size, electric cars would probably be slightly heavier. If anything, issues of tyres and road wear may slightly go up over that period and we will need to deal with that.

I don’t think we have thought about how to reduce air pollution from tyres previously, because it has been such a small proportion. Now that we are getting rid of many of the tailpipe or all of the tailpipe emissions, I think we need to start looking at these quite seriously

I believe Professor Whitty is correct.

Conclusion

I have nothing against Frank Kelly, Gary Fuller and the many teams doing great work at Imperial including Friederike Otto a climatologist providing rapid attribution of climate events across the world. I just find it odd that some teams Imperial College appear to be actively trying to dissuade drivers from moving away from burning fossil fuel and, with the full backing of the Guardian Newspaper, spreading misleading uncertainty and doubt about electric vehicles that is a gift to big oil lobbyists, wrong on air pollution and wrong on climate change. Saying they aimed for all drivers to get on their bicycle and failed is frankly naive and no defence if the result is to perpetuate the burning of oil and gas.

The human race can’t successfully address climate change without phasing out fossil fuels and powering transport and heating and the rest of our lives with zero carbon, primarily renewable electricity.

Each new combustion car put on the road today will on average burn 17,000 litres of fuel, resulting in 39.27 tons of CO2 for petrol or around 25 times the car’s own weight. For diesels it’s nearer 45 tons. Each combustion car sold takes us further from the 50% cut in emissions required by 2030. Active travel will assist but it can’t succeed on it’s own. I just hope that one day climate change deniers won’t be quoting some teams at Imperial as their reason to buy another new combustion vehicle and maintain their addiction to burning petrol and diesel. Is that really too much to ask?

David Nicholson

David Nicholson Is the founder of Rivergecko Ltd & MyUrbanCar which provide consultancy and advice for drivers and fleets to speed the transition from dirty fossil fuel transport to clean vehicles powered by renewable energy on land water and air.

The @MyUrbanCar twitter feed is a source of news & reviews of electric & plugin cars and vans in the UK.
The @rivergecko twitter feed & www.myurbancar.com websites bring news and opinion on cleantech transport including cars, vans, buses, trucks, shipping, rail & aviation as well as autonomous vehicles & renewable energy, air pollution & motor industry news.

David Nicholson has worked as an underwriter at Lloyd's of London since the 1980's. His interest in technology goes back many years including interactive mapping, apps, green tech, boats, solar and cars.

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