A study by the University of Southampton has found that microscopic particles emitted from certain types of commonly fitted brake pads can be more toxic than those found in diesel vehicle exhausts.
The University says this research has important implications for health and future policy because, as we switch from diesel and petrol-powered cars to EVs, non-exhaust particle emissions will remain. And non-exhaust emissions could even increase over time due to EVs being heavier than combustion engine vehicles and creating greater friction.
The research revealed that a higher concentration of copper in some pads is associated with increased harmful effects on sensitive cells from people’s lungs, as a result of particles being breathed in.
Exposure to pollution generated by cars, vans and lorries has long been linked to an increased risk of lung and heart disease. However, while past attention has mainly concentrated on exhaust emissions, particles are also released into the air from tyre, road and brake pad wear – emissions which are largely unregulated by legislation.
These ‘non-exhaust’ pollution sources are now responsible for the majority of vehicle particulate matter (PM) emissions in the UK and parts of Europe, with brake dust being the main contributor.
Lead author of the study, Dr James Parking, says that a move to electric cars is bringing the problem into sharper focus: “People generally associate pollution from cars as being from exhaust pipes and think of EVs as having zero emissions. However, EVs still produce particulate matter due to friction and wear of the road, tyres, and brakes.
“We wanted to understand how different types of chemical composition of pads affect the toxicity of the particles emitted and what this might mean for the health of individuals.”
Researchers suggest that current legislation, which focuses on PM exhaust emissions, may be inadequate to fully mitigate the health effects of vehicles in the future.
The findings, published in the journal Particle and Fibre Toxicology, suggest that a reduction of copper content in brake pads could help mitigate some of the harmful effects of vehicle particulate matter.
