Earlier this year I wrote about “London Throat” which most people experience if you have stayed any amount of time in London England. It turns out that  vanadium found in brake dust and in diesel exhaust contributes to “London throat” and also has an adverse impact on human health and immunity.

A recent study showed that  55% of traffic pollution is from non-exhaust particles, and 20% of that is brake dust. The dust is caused by the friction of the brake rotor grinding on the brake pads when a vehicle is braked, and the dust becomes airborne. What this also means is that zero emission vehicles which have been vaunted as the environmental salvo to the internal combustion engines of 20th century vehicles are still going to contribute to brake dust.

Price Tags publisher Andrew Walsh also sent on this article by Thom Bennett in Air Quality News that found that it was not only brakes but also tires that were emitting particles.  The British Air Quality Expert Group (AQEG) noted that particle pollution from tires was completely unregulated, and with the trend to  heavier vehicles like SUVs and electric vehicles, emissions from tires (called non-exhaust emissions or NEE) was problematic.

The BBC’s Roger Harrabin writes that brake, tires and road surface wear “directly contribute to well over half of particle pollution from road transport.No legislation is currently in place specifically to limit or reduce [these] particles.”

While European legislation is driving down pollutants from exhaust, as more vehicles are used on the road pollutants will increase from other unregulated sources. A researcher with Emissions Analytics found that tire particle pollution was one thousand times worse than car exhaust emissions.

No one thought to check asphalt emissions either, which turn out to have a 300 percent increase in secondary organic aerosols (SOA) in hot weather and climates. As Rhi Storer with The Guardian observes

“Paved areas make up approximately 45% of surfaces in US cities, with building roofs making up another 20%, making asphalt a significant part of the urban landscape. The researchers compared their findings with formation of SOA in Los Angeles, a key city for urban air quality case studies.”

Their findings showed that sunnier hotter locations caused more emissions, and of course new asphalt is installed in the hotter months. Temperature and solar exposure were key to producing SOA emissions which previously were thought to be mainly in cleaning solvents and paint.

This speaks to doing more with less, by using public transit in cities as opposed to individual vehicles in high density areas that are subject to vehicular pollution. We simply can’t drive our way out of this, assuming that electric vehicles will solve pollution problems, much less congestion.

Dr. Gary Fuller, who lectures in air quality measurement at London’s Imperial College bluntly states  that while it was known that road surfaces would factor into being an air pollution source,  the concentration of testing and regulation has been on automobile exhaust.

“This has been the focus of policy and new vehicles have to be fitted with exhaust clean-up technologies.With heavier and heavier vehicles, the combined total of particle pollution from road surface, brake and tire wear is now greater than the particle emissions from vehicle exhaust but there are no policies to control this.”


  1. actually, electric vehicles are probably going to be worses, as they are usually heavier than their gas cousins … ugh

  2. While electric vehicles can be heavier than fossil fuel driven ones, regenerative braking (drag produced when the field generated by a rotating electric motor is captured as electricity) produces no particles. They also have traditional friction brakes, but they’re used far less than in vehicles without regenerative braking capability. Of course emissions from tires meeting the road remain the same as other vehicles and vary with weight, speed, temperature and other factors.
    To repeat what’s been said before, we can’t drive our way out of this problem.

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