A new study commissioned by EIT Urban Mobility, TfL and the Greater London Authority has found that brake wear releases more particulate matter into the atmosphere than tyre wear and exhaust emissions combined. Studies in London, Milan and Barcelona found that overall, Non-Exhaust Emissions (NEE) make up between 68% and 88% of PM10 and up to 78% of PM2.5 generated by road traffic.
Brake wear is the largest source of NEE in cities, their emission being exacerbated by frequent stop-start driving. Significantly over 40% of these particles become airborne.
Tyre wear is the second-largest NEE, although only 1–5% of the particles become airborne, most settling in road dust, water systems, or soil. Good news for the air, less so for other areas of the environment.
