An electric car has become the ultimate status symbol for Hollywood’s eco-conscious elite.
But a new study suggests that electric vehicles (EVs) aren’t as environmentally friendly as they might appear.
Researchers from the University of Southampton found that brake pads commonly used in EVs produce emissions even more toxic than diesel exhaust fumes.
These particles are 30 times smaller than the diameter of a human hair and are capable of slipping through the airways deep into the lungs’ most sensitive tissues.
So, although EVs don’t release any gases from their exhaust, they can still contribute to deadly air pollution.
The researchers warn that this ‘non-exhaust pollution’ is now responsible for the majority of vehicle emissions in Europe.
Lead author Dr James Parkin says: ‘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.’
A new study has shown that electric cars are not as emissions-free as they seem since particles released by braking can be extremely toxic (stock image)
One of the main appeals of an electric vehicle, over a diesel or petrol alternative, is that driving doesn’t produce any emissions.
This is true insofar as all-electric car doesn’t burn fossil fuel, so it doesn’t emit any CO2, nitrous oxide, or other toxic compounds while driving.
However, while research typically focuses on exhaust emissions, particles are also released into the air by tyre, road, and brake wear.
These emissions are largely unregulated by legislation and are now the biggest contributor to ‘particulate matter’ pollution in the UK – with brake dust being the biggest source.
Whenever you apply the brakes, the car’s brake pads are forced against the disc brake which converts kinetic energy into heat through friction, slowing the car down.
The intense energy involved in this process also wears down the brake pad’s surface, kicking out a cloud of very fine particles.
Dr Parkin says: ‘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.’
In their study, the researchers carefully collected the particles produced by four different types of brake pads: low metallic, semi-metallic, non-asbestos organic and hybrid-ceramic.
Researchers found that particles released by the non-asbestos organic used in most modern cars were more toxic to the lungs than diesel fumes. While non-electric cars would produce these emissions as well, it shows that electric cars are not without their pollution risks (stock image)
In the lab, Dr Parkin and his co-authors then exposed cells taken from the lining of the lung to the various emissions to simulate what would happen if they were inhaled.
The researchers found that the exposed lung cells underwent oxidative stress, inflammation, and even death.
Were these cells in someone’s delicate air sacs, small structures in the lung that enable the transfer of gases from the blood, this could have caused serious health issues.
Fine particulate pollution, including from cars, has been linked to a range of conditions, such as asthma, chronic obstructive pulmonary disease (COPD), cardiovascular diseases, dementia and scarring of the lung.
The most harmful brake pads were non-asbestos organic pads which are made of copper fibre, glass fibre, rubber, graphite, and resin and come as standard on the majority of modern cars.
In tests, the researchers found the emissions produced by these pads to be more toxic than diesel exhaust fumes.
The second most toxic were ceramic pads which also contain a high level of copper.
In later tests in which the copper was removed, the researchers found that the particulate matter became significantly less toxic.
Previous research has shown that EV owners actually have a bigger carbon footprint than non-EV owners because of their more lavish lifestyles
On average, research has found that EV owners tended to be wealthier, more educated, drive their cars more often, and have a higher carbon footprint
This suggests that it might be the copper content in some brake pad designs which makes them particularly harmful.
Project supervisor Professor Matthew Loxham says: ‘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.’
A study published last year found that brakes and tyres wear out 30 per cent faster on heavier EVs, leading to a greater level of particulate pollution.
In the future, the researchers suggest that current pollution legislation could be expanded to cover non-emissions sources such as brake dust.
However, Professor Roy Harrison, an expert on environmental health from the University of Birmingham who was not involved in the study, says it might be too early to draw any major conclusions.
Professor Harrison says: ‘As yet, studies in human populations have not shown exceptional toxicity, just that normally associated with exposure to fine particles.
He adds: ‘The good news is that emissions of brake wear particles from an electric vehicle are much less than from conventional petrol and diesel vehicles due to regenerative braking.’
