We all know that diesel emissions are hazardous – many studies have proved it, regulators have agreed, and some countries are already moving to phase out vehicles running on diesel. However, brake dust, which has never received as much attention as tailpipe emissions, could be even worse.
Indeed, as regulators continue to target petrol and diesel engines as a main source of dangerous emissions in the automotive industry, brakes may produce even more harmful particulate matter than them, according to a recent study by scientists at the University of Southampton.
Ultrafine particulate matter with a diameter of less than 2.5 micrometers (PM2.5) can reach the alveolar regions of the lungs, where it accumulates and causes inflammation, and which scientists have attributed to over 4 million premature deaths annually from heart disease, stroke, lung cancer, chronic lung disease, and respiratory infections.
Car brakes’ deadly irony
Per the results of the research, copper‑enriched non‑asbestos organic and ceramic brake pads resulted in wear which caused “the greatest oxidative stress, inflammation, and pseudohypoxic HIF activation,” with the latter being “a pathway implicated in diseases associated with air pollution exposure, including cancer, and pulmonary fibrosis.”
The team also discovered that the PM from brake wear caused by these pads could cause “perturbation of metabolism, and metal homeostasis compared with brake wear PM from low- or semi-metallic pads.” These brake pad types are more likely to perturb cellular homeostasis than diesel exhaust PM.
In other words, they release particles that can disrupt the human body’s balance of chemicals and metals, and may actually be more disruptive to cells in the organism than the particles from diesel exhaust, making it a bigger contributor to PM2.5-associated health risks than previously thought.
That said, the research group didn’t specify what type of brake disc (or rotor) it used as a baseline for the tests.
Lack of brake dust regulation
Meanwhile, as the study’s authors pointed out, there’s a glaring lack of regulation regarding the emissions through brake wear, and with it, any methods or technologies to effectively reduce them:
“Currently, non-exhaust emissions are largely unregulated by legislation, meaning that there is a lack of established technologies to mitigate their release. (…) They also tend to be more chemically heterogeneous than exhaust emissions, meaning they may have the potential to elicit different biological effects depending on the source material. Together this points to an urgent and unmet need to better understand the source-specific biological effects of non-exhaust emissions, and more specifically – brake wear.”
They also warned that the proliferation of electric vehicles (EVs) would lead to more emissions from brakes, tires, and the road because of the increased weight of battery-powered cars, and would get worse over time due to a shift towards heavier battery EVs, “which generate more of these friction-derived, non-exhaust emissions.”
Ultimately, despite being something that aims to save lives, car brakes seem to be quietly contributing to 4 million early deaths around the world, being a health emergency just as much, and perhaps even more than diesel and petrol engine emissions, reflecting a dire need for action in this area.
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