New research suggests that brake dust, a byproduct of friction braking in all vehicles, could pose a greater health risk than diesel exhaust emissions.
Despite the push for cleaner transport solutions, the study highlights a lesser-known but significant source of airborne pollution - one that affects internal combustion engine (ICE) cars and electric vehicles (EVs) alike.
Brake dust vs diesel emissions
Scientists from the University of Southampton in the UK examined the toxicity of brake pad emissions, comparing them to diesel exhaust particles.
The results were alarming: non-asbestos organic (NAO) brake pads were found to be more harmful to human lungs than diesel fumes.
These pads, commonly used in the US due to their low cost, quiet operation, and durability, triggered the highest levels of lung inflammation among the four brake pad types tested.
Historically, brake pads contained asbestos, which was phased out due to its well-documented health risks. In its place, manufacturers introduced copper fibres to enhance thermal conductivity.
However, the study found that copper dust from these modern pads is linked to respiratory conditions such as cancer, asthma, and chronic pulmonary disease.
The EV factor
While EVs use regenerative braking to reduce reliance on friction brakes, they are also significantly heavier than ICE vehicles.
This added mass means that when traditional brakes engage, they generate more dust per stop, potentially offsetting some of the environmental benefits of zero tailpipe emissions.
Calls for regulation
Brake dust is currently unregulated in most parts of the world. Some US states, including California and Washington, have introduced legislation to reduce copper content in brake pads - primarily to protect aquatic life rather than human health.
Meanwhile, Europe’s upcoming Euro 7 emissions regulations, set to take effect in 2026, will begin limiting brake dust emissions for new vehicles.
Proper brake maintenance is crucial in reducing brake dust emissions, especially for those looking to maximise braking efficiency and longevity.
Beyond brakes, tyres are another significant contributor to non-tailpipe vehicle emissions.
Given that EVs produce more tyre wear due to their added weight, concerns around particulate pollution remain a pressing issue for future vehicle regulation.
The road ahead
As governments and manufacturers push for cleaner air and sustainable transport, non-tailpipe emissions - including brake and tyre dust - must be addressed.
While EVs reduce exhaust emissions, their increased weight presents new challenges.
Stricter regulations and advancements in brake technology could play a crucial role in mitigating these hidden pollutants, ensuring cleaner air for future generations.