Brake Dust: A Hidden Pollutant In Our Environment?

Brake dust is a major component of air pollution, contributing up to 20% of roadside traffic pollution. It is caused by friction between the iron brake rotor grinding on the brake pads when a vehicle slows down. This dust contains several metals, including vanadium, copper, steel, brass, and potassium titanate, and has been found to induce significant markers of toxicity such as inflammation. While electric vehicles use regenerative braking, which reduces the amount of brake dust generated, they are not exempt from creating such pollution.

Brake dust is a major pollutant

Brake dust is a significant component of air pollution, contributing up to 20% of traffic-related particles. It has been found to cause respiratory issues and inflammation, with researchers from the University of Southampton suggesting that it could be more damaging to our respiratory systems than diesel car emissions. The problem is exacerbated by the fact that brake dust remains largely unregulated, with most efforts to curb pollution focusing solely on reducing exhaust emissions.

While electric vehicles have been touted as a solution, they are not exempt from the issue. Electric vehicles, like all vehicles, contain metallic components in their clutches, engines, and brakes, which contribute to the production of brake dust. Additionally, the heavy battery packs of electric vehicles can exacerbate tire wear, which is another source of particulate matter emissions.

To address the issue of brake dust pollution, several solutions have been proposed. One approach is to design technologies that are resistant to friction and wear, reducing the amount of brake dust generated. Another solution is to develop low-environmental-impact brake systems, such as the Greentive project as part of the European LOWBRASYS initiative, which aims to reduce particulate emissions by 50%. Additionally, California and Washington have passed laws to limit the use of copper in brake pads, recognizing the toxic effects of brake dust on public health.

In conclusion, brake dust is a significant pollutant that contributes to air pollution and poses risks to human health. Addressing this issue requires a combination of technological advancements, legislative actions, and a shift towards more sustainable transportation options. By reducing congestion and the strain on vehicle components, we can ultimately reduce the pollution burden on our lungs and the environment.

It can be more harmful than diesel exhaust fumes

While diesel exhaust emissions are often considered a key culprit of urban air pollution, research suggests that dust from brake pads could be more harmful to our lungs. This dust, known as "non-exhaust emissions", has now surpassed exhaust emissions in many European countries and is the major type of emission from road transport. Brake dust is often the main contributor to these non-exhaust emissions, but it is not yet subject to regulation.

A recent study published in the United Kingdom in February 2025 analyzed the impact of non-exhaust emissions like road particles, tire particles, and brake pad particles on the lungs. The study found that brake dust contributes up to 55% of non-exhaust emissions by mass and can be more harmful than diesel exhaust fumes. Researchers grew human lung cells in a lab and exposed them to dust from car brakes and diesel tailpipes, finding that brake dust caused greater injury to the cells.

The high copper content in brake dust has been identified as a defining characteristic of brake dust from NAO (non-asbestos organic) pads, which are commonly used in vehicles today. Copper can aggravate asthma when inhaled, and exposure to high concentrations of copper has been associated with impaired lung function and an overall risk of death. Treating brake dust with a chemical that neutralizes copper has been shown to minimize the harm caused by the dust.

The switch to electric vehicles (EVs) will eliminate exhaust emissions, but it will not eliminate brake dust. In fact, due to their heavier weight, electric vehicles can generate more non-exhaust dust than petrol or diesel vehicles. Upcoming emissions standards, such as the Euro 7 emissions regulations scheduled for November 2026, will place limits on brake dust emissions, which may spur the development of new brake materials or dust-trapping mechanisms.

It contributes to 20% of roadside pollution

Brake dust is a significant contributor to roadside pollution, accounting for up to 20% of the total pollution found in these areas. This dust is a fine powder that is produced as a result of the friction between the brake pads and the rotors or drums of a vehicle's braking system. The composition of brake pads includes a range of metals and other materials

Electric vehicles produce less brake dust

Electric vehicles (EVs) have been under scrutiny for their green credentials, with some claiming that they produce more pollution from brakes and tyres than petrol and diesel cars. However, research suggests that EVs produce less brake dust than their petrol and diesel counterparts.

One of the main reasons for this is the regenerative braking system found in EVs, which reduces the need for friction brakes to be applied as often. This results in less brake dust being generated and released into the environment. In fact, some electric vehicles, such as the rear-wheel-drive VW ID models, use drum brakes on the rear axles, which are enclosed and do not release dust even when used.

The weight of electric vehicles, due to their heavy battery packs, can lead to increased tyre wear and brake dust. However, this is mitigated by the regenerative braking system, and the overall impact on brake dust generation is reduced. Additionally, tyre manufacturers are developing special tyres for electric vehicles that provide greater efficiency, less wear, and improved grip.

While brake dust is a contributing factor to pollution, it is important to note that it is not the only source of particulate matter from vehicles. Tyre wear, for example, can also contribute significantly to pollution levels, and this is an area of focus for researchers and regulatory agencies alike.

In conclusion, while electric vehicles may face scrutiny for their green credentials, they produce less brake dust than petrol and diesel cars due to their regenerative braking systems and other design features. This contributes to a net reduction in particulate matter from exhausts, tyres, and brakes, leading to improved air quality in cities with a high uptake of electric vehicles.

Brake dust is largely unregulated

While brake dust is a well-known pollutant, it is currently largely unregulated. This is despite the fact that researchers from the University of Southampton have found that particulate matter (PM) from brake pads could be damaging our respiratory systems more than diesel cars.

Brake dust is a result of the friction between the iron brake rotor grinding on the brake pads when a vehicle slows down. This dust then becomes airborne and can be inhaled, causing potential harm to our lungs. In addition to iron, brake dust contains up to fourteen different metal species, including vanadium, copper, steel, brass, potassium titanate, and glass.

While electric vehicles are often seen as a solution to the problem of vehicle emissions, they too can produce brake dust. Electric vehicles use regenerative braking, which limits the need for conventional brake pads, but does not eliminate brake dust entirely. Heavy battery packs in electric vehicles can also exacerbate tire wear, which is another source of particulate emissions.

Despite the growing awareness of brake dust as a pollutant, it has not yet been adequately studied. Several questions remain unanswered regarding the physicochemical characteristics, emission factors, and possible adverse health effects of brake dust. This lack of understanding makes it difficult to effectively regulate brake dust.

However, some places, like California and Washington, have passed laws to limit the use of copper in brake pads, recognizing the potential harm of this particular material. These laws are a step towards addressing the issue of brake dust pollution and protecting public health.

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