OECD Says Electric Cars Won’t Save Us From Pollution

The organization calls particulate matter ‘An ignored environmental policy challenge.’

Hummer on the rocks
Big trucks are a big problem.


The Organization for Economic Cooperation and Development (OECD) has issued a new report, "Non-exhaust Particulate Emissions from Road Transport: An Ignored Environmental Policy Challenge," which looks at the issue of the particulate matter (PM) emissions from tire, brake, clutch, and road wear, as well as the resuspension of road dust, basically stirring up all the PM that settled on the road previously. The report assumes that diesel and gasoline-powered cars are going to be replaced with electric vehicles, eliminating tailpipe emissions, but that problematic PM emissions will remain or even increase.

Treehugger recently covered the EPA's refusal to tighten up the regulation of PM, listing many of the health hazards. However, the OECD notes that the PM emissions from road traffic might even be worse for health than those from other sources, like burning coal, because they are concentrated in areas with the greatest population density and the most traffic. The PM problem is significant; the report notes that "globally, exposure to ambient PM has been ranked as the seventh most important risk factor for mortality, causing an estimated 4.2 million premature deaths in 2015."

They are not just particles of carbon, either, but include toxic metals and other materials. "Other elements, including iron, copper, zinc and sulphur have also shown associations with health impacts, such as cardio-pulmonary oxidative stress, heart-rate variability and tissue damage."

Emissions in California
Emissions in California.


They also note that as cars get cleaner, or even go from internal combustion engine vehicles (ICEV) to electric vehicles (EVs), "the proportion of PM emissions from non-exhaust sources has increased in recent years due to the significant reductions in PM from exhaust emissions over this period." A look at these projections for California out to 2035 shows the seriousness of the problem. It's already way cleaner than Europe because there are so few diesel vehicles, and the PM2.5 (PM with diameters that are generally 2.5 micrometers and smaller) exhaust emissions drop precipitously as the fleet is electrified. But the overall levels of PM2.5 keep rising with the number and weight of cars, and non-exhaust emissions rise to close to 100%.

Treehugger covered another study a few years ago that concluded that EVs actually emitted more PM than ICEV because they were heavier and that road and tire wear is directly proportional to the weight of the vehicle. This was hugely controversial at the time (fortunately for me, all the comments have disappeared) and I was accused of being a shill for the oil companies by claiming that EVs are no cleaner than ICEVs. This is not the case at all, as EVs emit no tailpipe emissions, and have overall lifecycle carbon emissions that are far less than ICEVs. The issue here is particulate matter only, the stuff that is bad for our immediate health, mostly in urban areas, and has nothing to do with greenhouse gas emissions. Also unlike the other study, the OECD report does not claim that EVs are as bad as ICEVs, with a big caveat:

"Electric vehicles are estimated to emit 5-19% less PM10 from non-exhaust sources per kilometer than internal combustion engine vehicles (ICEVs) across vehicle classes. However, EVs do not necessarily emit less PM2.5 than ICEVs. Although lightweight EVs emit an estimated 11-13% less PM2.5 than ICEV equivalents, heavier weight EVs emit an estimated 3-8% more PM2.5 than ICEVs."

The reason light EVs emit less non-exhaust PM than an ICEV is that they have regenerative braking and not nearly as much brake wear, so there are lower emissions. But as the long-range electric Hummers and Rivians and F-150s roll out, then the weight kicks in.

The OCED notes that if policies don't recognize the fact that size matters when it comes to PM emissions, then "consumer preferences for greater autonomy and larger vehicle size could therefore drive an increase in PM2.5 emissions in future years with the uptake of heavier EVs."

Should Resuspended Particles Even Count?

Also controversial in the earlier discussions was the inclusion of resuspended particles that previously were deposited on the road; readers considered it double-counting of the same emissions. The OECD faced the same complaint and responds:

"First, the concept of double-counting should not be confounded with the concept of re-emissions. Re-emissions occur at a different time than initial emissions...Second, recent evidence from PM source apportionment studies demonstrates that resuspension contributes significantly to PM levels even when direct wear emissions are excluded."

They also note that resuspension, where the particles are kicked up by the wind, means that people are breathing PM even when there aren't any vehicles on the road, and finally, the PM might have started as big, less dangerous PM10 and then got ground down by road traffic into smaller PM2.5.


Bring back tiny cars!
Bring back light, tiny, electric cars!.

Lloyd Alter

The OECD calls for policies to promote the "lightweighting of vehicles," promoting the use of smaller cars. Clearly, the trend to giant SUVs and pickups with bigger, heavier batteries is a problem, and the OECD calls for inclusion of vehicle weight in calculating taxes and fees, and calls for weight limitations in cities. (Treehugger noted after another study that we need fewer, smaller, lighter, and slower cars to deal with particulates.) But they also call for fewer cars and more promotion of alternatives.

"Vehicle-kilometres travelled in urban areas can be reduced using a variety of policies that disincentivise the use of private vehicles and incentivise the use of alternative modes such as public transport, cycling, and walking. As population exposure to PM from non-exhaust emissions is greatest in urban areas, urban vehicle access regulations (UVARs) such as low-emission zones and congestion pricing schemes can also be an effective means of reducing the social costs of non-exhaust emissions."

To reiterate: this is not an indictment of or a rant about electric cars. No matter how they are powered, we need fewer, lighter, and smaller cars, particularly in our cities.

We know that non-exhaust emissions are a serious problem for human health, and they are not being discussed as a serious issue. As the OECD notes, "given the magnitude of the aggregate social costs they entail, and the fact that the transition to electric vehicles will not lead to significant reductions in non-exhaust emissions," perhaps we should look at policies to deal with the number of cars in general, rather than what is under the hood.

Electric cars won't reduce congestion, they won't solve our parking problems, they will still kill people, especially when all the giant pickups and SUVs hit the streets, and now we are learning that they won't even significantly reduce pollution in cities. Maybe it's time to consider other ways to get people out of cars, and really make a difference.