[kieranmaine]

A 2019 UK government report found tyre wear, brake wear and road surface wear to be problematic:

From "Report: Non-Exhaust Emissions from Road Traffic" (https://uk-air.defra.gov.uk/library/reports.php?report_id=99...)

"Data from the UK National Atmospheric Emissions Inventory indicate that particles from brake wear, tyre wear and road surface wear currently constitute 60% and 73% (by mass), respectively, of primary PM2.5 and PM10 emissions from road transport, and will become more dominant in the future. Currently they contribute 7.4% and 8.5% of all UK primary PM2.5 and PM10 emissions. Therefore to achieve further gains in PM2.5 and PM10 air quality in relation to road transport sources requires attention to reducing non- exhaust emissions, not solely a focus on lowering exhaust emissions.

The magnitudes of non-exhaust emissions are, however, highly uncertain, particularly when compared to data for exhaust emissions."

[xputer]

That's pretty scary, don't brakes contain asbestos?