Tyre particulate pollution has been a big deal in environmental circles for some time, but it seems to be only recently that it's had a lot of media attention. Is this good news that it's finally gaining some attention or bad news that it's being used to astroturf? I'm really not sure.
Tyre wear does release particulate matter, but it's mostly heavy, large particles that end up on the road and get washed away by weather.
With the exception of tunnels, where heavy particles are constantly being churned up from the road surface and re-circulated into the air, tyre and brake wear is a relatively minor contributor to urban air pollution.
The BBC's "More or Less" pointed out some of the claims about tyres being a major contributor to air pollution are exaggerated. One of the claims was based on the total amount of wear from tyres as weight, without considering that most of that wear is made of very large particles that remain on the ground.
Rubber tyres on asphalt produce a fair bit of very fine particulate matter, and are currently ubiquitous in vehicles - I imagine this is what fjfaase was referring to.
That said, the contribution is tiny - on the order of 2.5% of total roadside PM10.
When you drive, the tread of your tires becomes more and more shallow, and at some point, it's so shallow that they need to be replaced. It happens, because the tires get abraded as you drive, shedding some of their surface. Where do you think the surface goes? Tire pollution is very real. Nobody says that the pollution isn't caused by combustion: it's another major source of pollution.
Tire pollution is in some ways worse than combustion pollution these days. Modern gasoline-burning engines (and modern, properly maintained diesel ones) mostly emit volatile, gaseous pollution. However, tire pollution consists of solid microparticles, that contribute to significantly to airborne dust, which can be measured through PM2.5 and PM10.
My understanding was always that tires produce a lot of particulates but they are fairly large and heavy; most of them fall out of the air very quickly.
If that's true it could be true that cars emit lots of PM from tyre wear but must of it never reaches detectors and can reasonably be ignored. That doesn't necessarily invalidate the overall point: that we reduced PM from exhaust enough that other still unregulated sources are better targets for future reduction efforts.
"There is emerging evidence that tyre wear particles and other particulate matter may contribute to a range of negative health impacts including heart, lung, developmental, reproductive, and cancer outcomes."
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