Brake pad emissions increase sharply during harsh braking
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Photo: Johan Bjurer, Mostphotos.com
As exhaust emissions decline, non-exhaust emissions from brakes are becoming increasingly important for urban air quality. The LIFE NEEVE project continues to generate new knowledge about non-exhaust emissions from road transport.
Life-NEEVE scientists Tawfiq Al Wasif-Ruiz, José Sanchez-Martin and late Carmen Barrios-Sánchez at CIEMAT, together with colleagues at Universidad Politécnica de Madrid (UPM) and European Commission, Joint Research Centre (JRC), recently published the scientific paper:
Particle emissions characterization from non-asbestos organic brake pads during on-road harsh braking
In the study published in Sustainability, the researchers examined particle emissions from non-asbestos organic brake pads during harsh braking and found a strong link between thermal stress and nanoparticle formation.
Key findings
Particle emissions remained close to background levels at speeds up to 100 km/h but emissions increased sharply during braking from 120 km/h.
Most emitted particles were ultrafine nanoparticles and contained metals such as iron and titanium. Overall, the results highlight that brake pad composition and thermal stress strongly influence nanoparticle formation.
A growing focus in transport emissions
The findings contribute to a better understanding of non-exhaust emissions, a growing focus area for vehicle manufacturers, regulators and air-quality researchers as transport emissions evolve.
What are non-exhaust emissions?
Non-exhaust emissions are particles released from road traffic that do not come from the exhaust pipe. They include fine particles (PM2.5 and PM10) and microplastics generated by tyre wear, brake wear, road surface wear, and road dust resuspension.
The LIFE NEEVE project studies how both tyre and brake systems contribute to these emissions under real driving conditions, and how material properties and friction influence particle formation.
As exhaust emissions decrease, non-exhaust sources are becoming a growing share of total traffic-related pollution, with increasing focus on tyres, brakes, and road surfaces.