With the aim of promoting the spread of safe and environmentally friendly vehicles, regulations and standards have been established for vehicle type approval and quality control. The new emission regulation, Euro 7 (Regulation (EU) 2024/1257), not only regulates exhaust emissions, but also adds the measurement of particulate matter (brake emissions) from brake wear that is emitted into the atmosphere. In this study, we have measured brake emissions for over 30 types of brakes (mass, particle size, particle count, chemical composition), and we will give a lecture on the current situation and future issues.

In this study particles generated from non-asbestos organic brake pads (NAO) and so called low metallic brake pads (LM), as well as summer, winter and all-season tyres were characterized regarding their emitted particle mass (PM), particle numbers (PN), as well as their size and morphology. A newly developed custom-built dynamometer that is capable of individual and simultaneous measurement of brake and tyre wear, was employed. The chemical composition of emitted particles was further analyzed via LC-MS/MS, ICP-MS/MS and SEM/EDX and revealed a high contribution of brake disc wear based on elemental patterns.

We employed a protontransfer reaction time-of-flight mass spectrometer in combination with a fast mobility particle sizer to investigate the connection between the real-time emissions of volatile organic compounds (VOCs) and ultrafine particles from brake wear. Two commercially prevalent brake pad materials for light-duty vehicles were studied.

The formation of ultrafine particles was systematically preceded by an increase in gaseous emissions, and shows a classic nucleation and growth pattern. This supports the hypothesis that the ultrafine particles are formed from gaseous precursors, which has important implications for previously determined emission factors.

The transport sector is a major contributor to urban particulate pollution, with brake dust emissions increasing as vehicles become heavier. The Euro 7 standard introduces a PM₁₀ brake dust limit value of 7 mg/km, measured using a standardised test procedure (GTR No. 24) on an inertia dynamometer. However, these well-controlled conditions do not fully reflect real driving conditions. To address this, two in-vehicle sampling systems have been developed: a semi-closed system that closely mirrors GTR No. 24 but is miniaturised, and an open system that better represents natural cooling of the brake.

There is still relatively little knowledge about the chemistry and toxicity of air pollution from car brakes. Using a pin-on-disc setup, we successfully collected more than 100 mg of airborne brake wear particles from two different brake pads in two different size fractions (PM_1-2.5 and PM_2.5-10). The mass was sufficient for extensive chemical analysis, microscopy, and toxicity studies. In all cases, iron was found as the most abundant element, which was substantially or even predominantly emitted by the gray cast iron disc rather than the pads. Oxidative stress and DNA damage was observed in all cases at all tested concentrations.

Tire wear particles (TWP) impact environmental health when leaching associated chemicals. Yet, the atmospheric processes affecting their transport, aging, and deposition are only poorly understood to date. One reason for this is the challenge of detecting TWP in environmental samples. Here, we test the recently suggested approach of tracing TWP in the atmosphere via organic marker components. We developed a new method to quantify six selected markers (DPG, 6PPD, IPPD, DPPD, 6PPDq, IPPDq) in atmospheric samples. We tested five types of atmospheric TWP samples mimicking the lifecycle of TWP in the atmosphere, highlighting the variability of results.