New research suggests that brake pad dust is responsible for 20% of the particulate matter pollution, and as bad as diesel exhausts.
The study, led by scientists from King's College London, found that the metals contained in brake dust and diesel exhausts, although slightly different, had similar effects on the body's immune cells.
It is currently estimated that 7% of the traffic particulate matter (PM2.5) pollution comes from tailpipe exhaust fumes, while 28% can be attributed to brake, clutch, tyre and road wear. Brake dust itself represents around 20% of the total PM2.5 pollution.
Toxic dust harmful and responsible for "London throat"
The scientists behind the study have analysed the effects of these pollutants on immune cells in a lab, and concluded that these were as harmful as diesel fumes pollution.
Dr Liza Selley, MRC Centre for Environment and Health at King’s College London and Imperial College London, said: “Diesel fumes and brake dust appear to be as bad as each other in terms of toxicity in macrophages. Macrophages protect the lung from microbes and infections and regulate inflammation, but we found that when they’re exposed to brake dust they can no longer take up bacteria.”
“Worryingly, this means that brake dust could be contributing to what I call ‘London throat’ – the constant froggy feeling and string of coughs and colds that city dwellers endure – and more serious infections like pneumonia or bronchitis which we already know to be influenced by diesel exhaust exposure.”
She added that "concentrations of metallic traffic particles were 3 times higher on roads with speed bumps."
Could EVs solve the problem?
EVs, being equipped with regenerative braking, will help reduce brake-related emissions. However, as one of the scientists behind the study said, "there is no such thing as a zero-emission vehicle". Road traffic, as a whole (through brake, tyre and road surface wear), is responsible for harmful Non-Exhaust Emissions emissions (NEEs) - regardless of the type of vehicle used.