Type of Air Pollution from Electric Cars 'Worse than Petrol or Diesel'

February 19, 2025

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by Neil Shaw (Coventry Live) After a new study showing the impact on lung health, one expert said 'the zero-emission label is clearly not accurate.' -- Pollution from electric cars could be as bad or worse than that from petrol and diesel cars - according to new research. Exposure to air pollution is associated with around seven million premature deaths per year across the world, and the exhaust fumes from cars is often seen as a major part of that.

But research from the University of Southampton has found that dust from brake pads could be more harmful to our lungs. James Parkin, research fellow in air pollution at the University of Southampton, said: "Dust produced by wear of the road, tyres, and brakes, known as 'non-exhaust emissions', are now the major type of emissions from road transport, surpassing exhaust emissions across many European countries. Of these, brake dust is often the main contributor, but it’s not yet subject to regulation. There is much less known about the potential health effects of brake dust compared to diesel exhaust dust."

The team grew cells in the lab to mimic the lining of the lung, and exposed these cells to both brake dust and diesel exhaust dust. Brake dust proved significantly more harmful to these cells across different measures that are linked to lung diseases such as cancer and asthma

James told The Conversation: "Despite this, current vehicle regulations in the UK only target exhaust emissions. Our findings suggest there is an urgent need to consider regulation of non-exhaust emissions as well. Reformulating brake pads might be one way to reduce the potential health burden imposed by these emissions.

"Brake pads previously contained asbestos fibres to deal with overheating. However, asbestos was banned in the UK in 1999 because of links to lung disease. This resulted in the motor industry designing new brake pad linings, including non-asbestos organic (NAO) pads commonly used in vehicles today.

"We compared the harmfulness of dust from the wear of different pad types. Ironically, we found that dust from the NAO pads, designed to replace asbestos-containing pads, was the most toxic to lung cells compared not only to dust from other pad types, but also to diesel exhaust dust. Some of the effects on our exposed cells relate to diseases such as lung cancer, lung fibrosis (lung scarring), asthma, and chronic obstructive pulmonary disease."

He added: "Previous research has shown that metals in air pollution particles can have toxic effects. We measured the metal content in the different types of brake dust and diesel exhaust dust. AI techniques identified high copper content as the defining characteristic of brake dust from NAO pads.

"We also found that this copper could get inside exposed lung cells. Most interestingly, when we treated this brake dust with a chemical to neutralise copper, its toxic effects were diminished. This suggests that copper is causing at least some of the harmful properties of this dust.

"Almost half of all copper in the air we breathe comes from brake and tyre wear. Various studies conducted by other research groups have found that exposure to high concentrations of copper is associated with impaired lung function, and overall risk of death."

James said: "Unfortunately, while the switch to electric vehicles (EVs) will eliminate exhaust emissions, which include toxic gases as well as dust, it will not eliminate road, tyre and brake dust. Studies indicate that, because they tend to be heavier, electric vehicles can generate more non-exhaust dust than petrol or diesel vehicles – the zero-emission label is clearly not accurate. READ MORE

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Car brake dust can be more harmful than diesel exhaust – new study (The Conversation)
New study finds brake pad emissions can be more toxic than diesel exhaust (University of Southampton)
Copper-enriched automotive brake wear particles perturb human alveolar cellular homeostasis (Particle and Fibre Toxicology)
Brake pad dust can be more toxic than exhaust emissions, study says -- Research shows move to electric vehicles may not be enough to enable pollution from cars to be eradicated (The Guardian)
Brake dust is more harmful to lungs than exhaust gases, study finds (ITC)
Study finds brake dust more harmful to lungs than diesel exhaust -- Researchers found that brake-wear particulate matter has a greater detrimental effect on lung cells than diesel exhaust particles. (Jerusalem Post)
New study finds car brake dust can be more harmful than diesel exhaust Dust produced by wear of the road, tyres, and brakes, known as 'non-exhaust emissions', are now the major type of emissions from road transport, surpassing exhaust emissions across many European Countries (PTI/Deccan Herald)

Excerpt from University of Southampton: A study by the University of Southampton has found microscopic particles emitted from certain types of commonly fitted brake pads can be more toxic than those found in diesel vehicle exhaust.

The research shows 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 Parkin , explains 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 electric vehicles 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.”

The scientists undertook an in-depth study examining the effects on lung health of PM from four different types of brake pad with differing chemical compositions; low metallic, semi-metallic, non-asbestos organic and hybrid-ceramic. The researchers were particularly interested in the smallest particles, of PM2.5 and below (often referred to as fine PM) – 30 times smaller than the diameter of a human hair.

These tiny particles can make their way beyond the upper airways and deeper into the delicate lung air sacs, which enable the exchange of oxygen and carbon dioxide to and from the blood stream. Fine PM from a variety of different sources is associated with over four million premature deaths per year worldwide.

Brake pad particulate matter was collected using specialist equipment. In the laboratory, the Southampton team used samples of cells from the lining of the lung and exposed them to the fine particulate matter to measure its effects, such as oxidative stress, inflammation, or the death of cells.

Results showed that of the four types of brake pads, non-asbestos organic pads were the most potent in terms of inducing inflammation and other markers of toxicity, and more toxic to human lung cells than diesel exhaust particles. Ceramic pads were the second most toxic. Importantly, both non-asbestos organic and ceramic pads contain high concentrations of copper, and later experiments to remove this copper found the PM became less toxic.

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. Air pollution, including from cars, has been linked to a range of conditions, such as asthma, chronic obstructive pulmonary disease (COPD), cardiovascular diseases, dementia and idiopathic pulmonary fibrosis (scarring of the lung).

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 health effects from vehicle emissions won’t necessarily be completely removed once the fleet is fully electrified. They suggest that current legislation, which focuses on PM exhaust emissions, may be inadequate to fully mitigate the health effects of vehicles in the future. READ MORE