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A new study has revealed that brake dust from vehicles may pose a greater risk to lung health than diesel exhaust emissions. The findings challenge the prevailing focus on tailpipe emissions in pollution regulations, suggesting that non-exhaust emissions deserve urgent attention.
The Hidden Danger of Brake Dust
Air pollution is responsible for approximately 7 million premature deaths globally each year, with urban pollution often attributed to diesel exhaust. However, recent research indicates that dust from braking systems could be significantly more harmful to human lungs.
Brake dust, a major component of non-exhaust emissions—along with tire and road wear particles—has surpassed exhaust emissions as the dominant source of pollution from road transport in several European countries. Despite its prevalence, brake dust remains largely unregulated.
Scientists grew lung-like cells in laboratory conditions and exposed them to both diesel exhaust and brake dust. Their observations revealed that brake dust was considerably more harmful across various health markers linked to respiratory diseases such as asthma and lung cancer. Notably, the removal of copper from the brake dust reduced its toxic effects.
Regulation Lagging Behind Science
While exhaust emissions are subject to stringent regulations, there are currently no such controls for non-exhaust emissions in the UK. The study underscores the need to reformulate brake pads to reduce the health risks associated with their use.
Historically, brake pads contained asbestos fibers to manage overheating. However, following asbestos’ ban in 1999 due to its link to lung disease, the automotive industry developed alternative linings, including non-asbestos organic (NAO) brake pads. Ironically, dust from NAO brake pads was found to be the most toxic when compared to other brake pad types and even diesel exhaust dust.
Further analysis of brake dust and diesel exhaust dust revealed that high copper content was a defining characteristic of brake dust from NAO pads. Researchers discovered that this copper could penetrate lung cells and cause cellular damage. However, neutralizing the copper in brake dust significantly reduced its harmful effects, indicating that copper plays a key role in the toxicity of these emissions.
Electric Vehicles Are Not a Perfect Solution
The shift to electric vehicles (EVs) is often touted as a means to reduce vehicle emissions, but this study highlights an overlooked issue—EVs still generate non-exhaust emissions. In fact, due to their heavier weight, EVs can produce even more brake and tire dust than petrol or diesel vehicles.
While regenerative braking systems in EVs reduce the use of traditional friction braking, they do not eliminate it entirely. This means that brake dust emissions will continue to be a problem unless new materials or dust-trapping technologies are introduced.
The Future of Brake Dust Regulation
The upcoming Euro 7 emissions standards, set to be implemented in November 2026, will introduce limits on brake dust emissions. This could encourage the development of innovative brake materials or mechanisms to capture dust before it is released into the air.
In the United States, California and Washington have already passed legislation to limit copper content in brake pads, primarily to protect aquatic ecosystems. However, this study suggests that reducing copper in brake pads could also have significant benefits for human health.
With non-exhaust emissions accounting for around 60% of vehicle-derived pollution in the UK, experts stress the importance of addressing all sources of air pollution, not just those from exhaust pipes.
Conclusion
As the world moves toward greener transportation, the conversation must expand beyond exhaust emissions to include the dangers of non-exhaust pollutants like brake dust. Science and regulation must work together to ensure that the push for cleaner vehicles does not overlook hidden health hazards.
Disclaimer: This article is based on the research findings published in Particle and Fibre Toxicology (2025) and is intended for informational purposes only. Readers are encouraged to refer to the original study for further details and consult health professionals for concerns related to air pollution exposure.
