environment health transport

In defence of electric vehicles: roadside air pollution

Electric vehicles are a strangely contested technology. In some circles they are celebrated, many are supportive but hesistant, and some downright hate them. What I find interesting about the hatred is that it comes from completely opposing directions. Men who like their cars to go ‘vroom vroom’ hate them, with Jeremy Clarkson the iconic leader of that miserable band. But lots of environmentalists hate them too.

I constantly hear objections to electric cars from committed greens. In some circles you can’t mention them without adding a collection of caveats, because if you don’t, your audience will inevitably raise them for you. This reached an extreme recently when I saw a well-meaning tweet celebrating the cutting of the government grant for electric vehicles. They shouldn’t be any support for them at all, she argued, because “EVs are ecocidal.”

Scepticism from greens is really unhelpful, because net zero targets simply will not be reached without electric vehicles. They don’t solve everything. They’re not ‘the’ solution to sustainable transport. But they are an absolutely vital piece of the jigsaw, and so we really need to have a more grown up conversation about their role.

Prompted by this bizarre tweet, I thought I’d write a post or two in defence of EVs. You don’t need my caveats again – see this post on the ‘three R’s’ of travel, or the hierarchy of sustainable transport for where cars come in the list of priorities. Let’s look at some specific objections, starting today with roadside air pollution. That’s the pollution from traffic, rather than pollution from power stations to charge your electric cars, which I’ll deal with another time.

Let me give a specific example, in the form of Chris Woodford’s mostly excellent book on air pollution, Breathless. While castigating diesel fumes, he then adds this: “though electric cars sound marvellous… there are still emissions from brakes, tyres and road dust to worry about.”

Or here’s George Monbiot, writing about electric cars last year. “A switch to electric cars will reduce pollution. It won’t eliminate it, as a high proportion of the microscopic particles thrown into the air by cars, which are highly damaging to our health, arise from tyres grating on the surface of the road.”

This is a line I’ve heard many times now – electric cars produce pollution from their brakes and tyres. This is particulate pollution, the small particles that are especially harmful to health. But petrol and diesel cars also have brakes and tyres. Nobody talked about this until electric cars came along, and it is only ever mentioned with reference to electric cars. Apparently electric cars are seriously polluting after all, argue the tabloids gleefully. You might even get the impression that they’re not worth bothering with at all. “It’s hotly debated whether electric cars will end up spraying more particulates into the air than petrol and diesel ones” says Woodford.

What neither Woodford nor Monbiot do is say what percentage of overall traffic pollution comes from these dreaded tyres and brake pads.

So let’s take a look. The government ran a consultation on this very question in 2019. They found that ‘non exhaust’ emissions from traffic are around 8%.

I have a lot of respect for George Monbiot, but I’d want to challenge him over the question of whether 8% counts as a “high proportion”. Exhaust fumes are overwhelmingly the big issue. There is no question whatsoever that if we want to improve air quality, it’s diesels and then petrol cars that we should focus on first.

Non-exhaust pollution isn’t negligible, which is why the government are investigating it. It’s also under-studied and it isn’t consistently measured, because not enough people had thought to measure non-exhaust emissions until the question of EVs came up.

It’s also highly contextual, and that 8% cannot be applied across every road in the UK, let alone the world. A study in Spain found that half of air pollution is from exhausts and half from other things – mainly dust. So if you live in a dusty place, EVs will make less difference – though that’s still a halving of air pollution.

How do you reduce non-exhaust pollution? The weight of vehicles matters, and Heavy Goods Vehicles are the worst culprits. Smaller and more lightweight vehicles will cause less wear and tear on roads and rubber. Another factor is driving style, which accounts for a third of tyre wear. Eco-driving techniques would help, and I reckon electric car drivers would already be more likely to use them. Electric cars usually have regenerative braking, which also reduces brake pad wear. And of course, the biggest difference will come from reducing the amount of journeys and the number of cars on the roads in the first place.

This is, ultimately, why many people raise this issue about electric cars and pollution. They want to emphasise that the best solutions lie in active transport or public transport, not in perpetuating car culture with EVs. I agree 100%, but let’s make that point by presenting the case for those solutions, not exaggerating the flaws of electric vehicles.

12 comments

  1. Very sensible and balanced article. Thank you! With all cars, so much depends on how you drive them, as well as how much. Even diesels are not too bad if you do not drive them hard – maximum NOX etc is produced at full throttle, which is not how most family cars are driven!

  2. I understood most of the concerns with environmental impact of electric cars tended to do more with the production of batteries, and the fact the same batteries are not replacable without repalcing the entire car.

    I tend to agree though that electric cars have their uses as long as they are not the whole solution. The issue being they are hyped to the extent you almost imagine they are. I can see their particular value in reducing the harms of local, non-CO2 air pollution which causes health problems, whether they significantly reduce overall CO2 emissions or not. But as a non driver they are still dangerous and take up space, if nothing else! I think far more emphasis personally should be given to improving bus services first (availability, regularity, price and of course emissions!) and then “active travel”.

  3. Hi Jeremy… Good points – well made. I don’t disagree with anything you say. I’m not anti electric cars, but the idea that they’re “zero-emission vehicles” (as some are actually badged on the bodywork) is obviously misleading and wrong. As you say, it’s important not to take that argument too far, if we don’t want a world full of diesel engines, but I think it’s good to raise the issue and challenge the idea that electric cars are squeaky clean.

    >>> “But petrol and diesel cars also have brakes and tyres. Nobody talked about this until electric cars came along, and it is only ever mentioned with reference to electric cars.”

    Yes, but there are three further things to consider.

    1. Our understanding of the dangers of particulate pollution is relatively recent (within the last three decades – so relatively recent in the long history of air pollution science) and still evolving. And that applies even more to non-exhaust emissions. So one reason “nobody talked about this” is perhaps simply that it’s still quite a new thing? In other words, We might be talking about it now even if electric cars hadn’t come along?

    2. “But petrol and diesel cars also have brakes and tyres.” Absolutely, but it’s not necessarily a like-for-like comparison. One of the problems is that electric/hybrid cars can be heavier (maybe 30% heavier) so the non-exhaust emissions from e.g. braking/tyres are more significant than the non-exhaust emissions from “traditional” cars. However, if electric cars are using non-frictional brakes (regenerative brakes – like electric motors running backwards to charge the batteries), that argument doesn’t necessarily apply in such a simplistic way.

    See Prof Roy Harrison’s comments here:
    https://eandt.theiet.org/content/articles/2017/03/particle-pollution-from-electric-cars-could-be-worse-than-from-diesel-ones/

    3. Because people have tended to over-simplify this whole issue as “diesel cars are dirty” and “electric cars are clean/green zero-emission”, there’s (rightly, I think) been some push-back from green transport campaigners. The reality is “diesel cars are even dirtier than we’ve been led to believe (if you factor in non-exhaust emissions)” and “electric cars are also dirty in various ways”.

    I did take your point that I’d been too hard on electric cars in my book and you may well be right about that!

    1. Thanks for your comments Chris – yes, the ‘zero emissions’ on the back of all those Nissan Leafs is disingenous, as it turns out. ‘Zero CO2 at the point of use’ would be accurate, but that’s quite long to write in chrome.

      You may be right about it being a new thing, and ultimately it’s great that more attention on air quality is revealing more detail about where pollution comes from. It means we can focus on all aspects of the problem in future, and factor in brakes and tyres as we work towards cleaner air.

      The problem is that there is already a lot of resistance to electric cars. All downsides are seized upon and endlessly repeated, in part to balance out the EV boosterism from some quarters. These downsides then get drummed in and that does have an influence. I’ve had conversations with people who have thought about getting an electric car, but had heard that they were no better for the environment. So they’re still driving a diesel, and that’s a bit of a tragedy. It means a solution that would be 90% better has been rejected, at least by that person, because they had heard the claims that it was 100% better weren’t true.

      Of course, the fossil fuel companies, legacy car manufacturers and the media culture of ‘vroom vroom’ motoring are quite happy for electric cars to be delayed, so doubt and scepticism is actively encouraged in some circles. All the more reason for a grown up conversation.

      Thanks for your book, by the way, which I really enjoyed and which influenced my own forthcoming book Climate Change is Racist. We have an editor in common in Hanna Milner, and having just worked on your book, she encouraged me to add a bit more about air pollution and environmental justice to my draft.

      1. And thank you so much for your kind and thoughtful review a few weeks ago.

        Very much looking forward to your book, which I have on pre-order. It couldn’t be more timely. I hope it does really well.

  4. To me the key issue is the ‘all or nothing’ thinking we tend to fall into, in our society. This ends up getting us very misled, confused, paralysed. I’d love to see more work on developing thinking/evaluation skills so we realise there’s ‘no free lunch’ and ALL our actions need careful balanced assessment so we can keep picking the ‘least worst option’, remembering that this will keep shifting as knowledge and circumstances change, such is the nature of life…

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