A University of Southampton study found microscopic particles from specific brake pads can be more toxic than diesel exhaust. Researchers linked high copper content in some pads to increased lung toxicity. While vehicle pollution has been mainly associated with exhaust emissions, brake, tire, and road wear now contribute the majority of particulate matter emissions in the UK and Europe.
The study tested four types of brake pads, finding that non-asbestos organic and ceramic pads—high in copper—were the most toxic. Removing copper reduced toxicity, suggesting a potential way to mitigate harm. The research underscores that even electric vehicles still produce particulate pollution, which may increase due to their heavier weight. The findings highlight the need for updated regulations to address non-exhaust emissions.
The study’s lead author, Dr James Parkin, explains that the move to electric cars is bringing the problem into sharper focus: “People generally associate pollution from cars with exhaust pipes and think of electric vehicles as having zero emissions. However, EVs still produce particulate matter due to friction and wear of the road, tires, and brakes.
Project supervisor Professor Matthew Loxham comments: “This research has important implications for health and future policy because as we switch from diesel and petrol-powered cars to electric vehicles, non-exhaust particle emissions will remain. Non-exhaust emissions could increase over time due to electric vehicles being heavier than combustion engine vehicles and creating greater friction.”
The researchers highlight that while electric vehicles emit no exhaust emissions, they aren’t emission-free and that vehicle emissions’ health effects won’t be removed entirely once the fleet is fully electrified. They suggest that current legislation, which focuses on PM exhaust emissions, may be inadequate to mitigate the health effects of vehicles in the future entirely.