Jarrupölyä

Jarrupölyä, a Finnish term, translates directly to "brake dust." It refers to the fine particulate matter that is generated from the friction between brake pads and brake rotors (discs) on vehicles. This dust is a byproduct of the braking process and is composed of material worn away from both the brake pads and the rotor surface.

The composition of jarrupölyä varies depending on the type of brake system and the materials used in its components. Generally, it includes metal particles (such as iron, copper, and steel), as well as binder materials and fillers present in the brake pads. Historically, asbestos was also a component in some brake pads, but its use has been largely phased out due to health concerns.

When brakes are applied, the friction causes microscopic particles to be released into the air. These particles can then settle on vehicle surfaces, including wheels, bodywork, and the surrounding environment. In addition to being aesthetically unappealing, accumulating on wheels, jarrupölyä has also been a subject of environmental and health research. While the term is specific to Finnish, the phenomenon of brake dust is universal to all vehicles equipped with friction braking systems.