Quote:
Originally Posted by OldDartmouthMark
Good post, though I'm curious about your assertion about particulate in brake dust:
1) Is the amount of brake dust in the air significant enough to create a major health issue? It's understandable that it would be considered a hazard, but I would think that it is order of magnitudes smaller than the amount of particulate in the air from other sources.
2) How much particulate is reduced by regenerative braking? I haven't seen data on it, but I believe that regenerative braking mostly occurs during times when a light brake application would be used to regulate the speed of the vehicle, rather than coming to a full stop, or heavier braking situations, when conventional brakes do the the work.
3) I am aware of environmental issues caused by brake pad material, however, though the govt seems to be dealing with it through a change in requirements for the friction materials used.
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Yes, according to a 2015 meta study titled "Brake wear particle emissions: a review" (published in the journal Environmental Science and Pollution Research) brake dust is often the largest source of non-exhaust particulate (or NEP) which also includes particles from tires, the road, and other mechanical components. However, the exact proportions depends on the stretch of road. Brake dust makes up the majority of the NEP near roads with more stopping due to intersections or congestion or with downhill sections, while it's a smaller percentage near flat, free-flowing roads. However, there tends to be a lot of stopping in urban areas and obviously urban areas is also where the population is concentrated.
Grigoratos, T., Martini, G. Brake wear particle emissions: a review. Environ Sci Pollut Res 22, 2491–2504 (2015).
https://doi.org/10.1007/s11356-014-3696-8
Another study from this year published in the same journal found significant health risks involved in NEP, with the biggest risk area being the cardiovascular system. (below)
Stojanovic, N., Glisovic, J., Abdullah, O.I. et al. Particle formation due to brake wear, influence on the people health and measures for their reduction: a review. Environ Sci Pollut Res 29, 9606–9625 (2022).
https://doi.org/10.1007/s11356-021-17907-3
There's also a 2021 study from the Journal of Hazardous Materials titled "Comparative analysis of non-exhaust airborne particles from electric and internal combustion engine vehicles" It specifically compares ICE vehicles to EVs in terms of NEPs and found that while EVs without regenerative braking actually produce more NEPs due to their greater weight (about 20% more for an otherwise equivalent vehicle), regen reduces that significantly to the point that large EVs actually produce fewer NEP than not only equivalent ICE vehicles but even some that are significantly smaller ICE vehicles. You can see one of the graphics they included in the study showing how gasoline ICE vehicles (or petrol as they call them since it was a British study) compared to EVs with different levels of regen capability. It should be noted that there are virtually no EVs on the market in NA that lack regenerative braking. While the regen is stronger in some vehicles than in others, the majority of braking can usually be done through regen. That is basically the whole reason for the existence of hybrids. If regen braking wasn't able to consistently recover the majority of the energy in a car's momentum, they wouldn't be able to offer such impressive fuel savings.
Click for full size image
Liu, Ye, Haibo Chen, Jianbing Gao, Ying Li, Kaushali Dave, Junyan Chen, Matteo Federici, and Guido Perricone. "Comparative Analysis of Non-exhaust Airborne Particles from Electric and Internal Combustion Engine Vehicles." Journal of Hazardous Materials 420 (2021): 126626.