According to this Flanders Today (a local Belgian newspaper) article
a new small car on petrol in the city creates less fine dust than an electric car of average size.
The researcher, Bruno Van Zeebroeck, claims that this is because
Fine dust is created not just by a car’s motor but also by the wearing out of tyres and braking. Those so-called non-exhaust emissions are higher in electric cars because most of them are heavier than other kinds of cars. These non-exhaust emissions are a particular problem in the city, where drivers brake often.
[...] Van Zeebroeck pointed out that the test didn’t examine the smallest particles of fine dust, which are the most harmful to human health. These particles are mostly emitted by diesel-fuelled cars.
However, I can’t find any research that backs up this claim. Is there any truth in this?
Note: to be clear I'm not interested in possible dust particle emissions from electricity generation, but only emissions that stem from using the car so from tyre wear and braking of electric cars.
They certainly do not create more particulate emissions, but they might not create that much less than a gasoline powered car, depending on the model of car considered.
First, what was previously thought? According to point IV.a.55 of this report the council of Europe's standing committee on Science and Technology, electric vehicles produce no fine particulate emissions. The report is dated 1998 however, so things may have changed since.
The new study (perhaps 'review' or 'article' would be better? It's a think tank's internal publication, not peer reviewed) can be read in full here, but you need to look at the Dutch version for the graphs.
The very first section already answers our question. The author never claims that electric cars produce more particulate emissions than ordinary cars. The title of the section says it all: "Electric cars produce almost as much particulate matter (PM) [as] modern petrol or diesel cars".
The first graph in this section solidifies this. The electric cars considered all have lower total PM emissions than any of the similarly sized cars that are not EVs, though only modestly lower for the most part. A small gasoline car produces slightly less emissions than a medium sized EV however.
Figures 3 and 4 suggest that the reason the advantage is so small now is because tighter emissions standards have dramatically reduced PM from cars over the last 25 years. So when the council of Europe report was written, it probably was fair to say that electric vehicles had no PM emissions at all (as compared to existing gasoline powered cars), but this is apparently no longer true.
The last part of the section concerned with emissions seems very badly done to me, and at best is educated speculation. The author tries to mathematically compute an estimate for the increase in PM emissions from the extra weight of an electric car, but uses an unsourced formula with very nice round numbers, that I believe is likely to have been made up on the spot (33.33% factors for everything?). Even this slipshod analysis finds that the electric version of a normal family car is no worse than the gasoline version for PM emissions, and smaller EVs are much better.
On the whole, I think the news story ought to have been: "Emissions Standards so Good that Gasoline Cars Now Competitive with EVs!" which is still exciting, but doesn't mislead the reader into thinking this was always the case, or that it's an argument against EVs in and of itself (remember, EVs are unchanged at the level of PMs that Council of Europe considered to be zero. It's that gasoline powered cars have dropped by > 75% for gasoline, and even more for diesel since the report was written).
(Edit: Some of the original links have rotted. The Dutch report's title was belang niet uitlaat fijn stof emissies, which translates to The Importance of Fine Dust Emissions. The author is Bruno Van Zeebroeck. There is currently a version up here. I cannot find the Council of Europe's Report now, because it was indexed by a doi that not longer points at anything.).
I compared vehicles that had an electric version and a non electric version of the same model. This is so that we can compare the differences in weight in cars that are the same in terms of size and componentry, except for the difference of being electric and being non electric. We don't want to compare a Tesla ModelX to a Smart ForTwo petrol car!
The 235 mile Kia e-Niro 64 kWh is a good fit for comparison - it weighs 1,812kg and the petrol versions are somewhere between 1,490kg & 1,594kg depending on model. So here the electric version would be 12% - 18% heavier.
The additional weight is just the extra weight of the battery; electric components weigh less and they are simpler (no clutch, combustion engines are heavy and related to engine size).
For small cars
The Smart EQ 79 mile range ForTwo coupe with 17.2kWh battery weighs 1,095kg. The older ForTwo petrol version weighed 880kg. So the electric version would be about 20% heavier. If it was possible to have a battery with a range of 235m you would need another battery of
((17.2kWh / 79m) x 235m) - 17.2kWh = 54kWh battery
which would weigh another 203kg. That would mean the small car would be 33% heavier at the same range as the Kia.
Weight in electric vehicles also compares strongly with range, the longer the range the bigger the battery the extra size. These are difficult comparisons but it seems like you could say electric vehicles are somewhere between 10 and 30% heavier for electric cars. It is also obvious that some vehicles are unnecessarily heavy.
Other benefits of Electric Cars regarding particulate emissions
Electric cars will have much less brake pad wear because they will have regenertive brakes. Brake pad wear can normally account for 30% (ish) of the particulate emissions from cars (although drum brakes would also reduce the amount of brake pad particulates and the car wouldn't need to be electric).
Electric vehicles have smoother acceleration so may not wear the tyres so much but...due to the extra torque in an electric motor, maybe there is no difference (please correct me here!). Also electric vehicles won't have a clutch which could add a little to wear.
If the amount of tyre and road particulate matter generated is proportional to the extra weight then I think generally there isn't going to be much difference in particulate emissions, especially if you factor in the regenerative breaking savings. However, battery weight needs to be factored in and the larger the battery the more particulates generated from tyre and road wear.
There are few regulations on materials and particulate emissions for brake pads, tyres, clutches and how roads are made and maintained. Also there are few reliable studies and many variables (a wet country wouldn't have so much redistribution of particulates as a dry country). Also, how do you compare? Do you compare a car with or without drum brakes.
I think the real problem is unnecessarily heavy cars, poor traffic management with many stop starts in a journey, poor regulations on compositions of tyres and other componentry and better driving behaviour that reduces unnecessary acceleration and braking. Electric vehicles have obvious other benefits like zero particulates from the exhaust, zero NO2 from the exhaust, much less CO2 emissions (50% including manufacture??? if using mostly renewables), they have longer lives too.
Longer ranges from EVs could also be gained from battery swap stations similar to those in China so that large heavy batteries are used less often or are only swapped in on longer journeys.
Overall, the research shows that electric cars are cleaner than those that rely on internal-combustion engines only if the power used to charge them is also clean. That is hardly a surprise, but the magnitude of the difference is. How green electric cars really are, then, will depend mainly on where they are driven. In France, which obtains more than half its power from nuclear stations, they look like a good bet. In China—which is keen on electric cars, but produces some 80% of its electricity from coal—rather less so.
It was pointing at a recent article "Life cycle air quality impacts of conventional and alternative light-duty transportation in the United States" by Christopher W. Tessuma,
Jason D. Hill, and Julian D. Marshall in PNAS vol. 111 no. 52, 18490–18495, doi: 10.1073/pnas.1406853111, which included the following chart
Fig. 2. Air quality health impacts in the United States for each scenario: attributable increases in annual mortality (upper scale) and the resulting monetized health impacts (lower scale).