A major step toward reducing vehicle-related air pollution has been taken as the United Nations Economic Commission for Europe (UNECE) adopted the world’s first global regulation to measure and limit brake particle emissions.
The regulation was approved under the World Forum for Harmonization of Vehicle Regulations (WP.29), the United Nations platform responsible for developing globally harmonized vehicle standards.
The regulation was adopted under the World Forum for Harmonization of Vehicle Regulations (WP.29) through:
- UN Global Technical Regulation No. 24 (GTR No. 24) – global test methodology
- UN Regulation No. 179 (UN R179) – enforceable emission limits
Together, these establish a harmonized global approach to tackle non-exhaust emissions from vehicles.
The new regulation introduces a standardized method to measure particulate emissions generated by vehicle braking systems, an increasingly significant contributor to non-exhaust vehicle emissions.
Entry Into Force and Affected Regions
- The regulation is expected to enter into force in 2026, aligning with upcoming emission frameworks.
- It will be adopted across UNECE contracting parties, including:
- European Union
- UK
- Other global markets following UNECE standards
This ensures global harmonization and reduces regulatory fragmentation.
A Science-Based, Harmonized Approach
The regulation, developed under the United Nations Economic Commission for Europe (UNECE) framework, establishes a globally harmonized methodology to measure brake particle emissions.
It applies primarily to:
- M1 category – passenger cars
- N1 category – light commercial vehicles
- With optional application to certain N2 vehicles (lights trucks)
Brake emissions are measured using a brake dynamometer, following a dedicated test cycle designed to simulate real-world braking conditions.
The regulation sets limits for PM10 emissions (particles ≤10 micrometers), expressed in milligrams per kilometer (mg/km).
Additionally, the framework incorporates Solid Particle Number (SPN) measurement procedures. While the methodology is defined, specific SPN limit values will be introduced in future amendments.
Why Brake particle emissions matter?
Over the past two decades, stricter environmental regulations have significantly reduced exhaust emissions from vehicles. However, a growing share of pollution now comes from non-exhaust sources, including:
- Brake wear
- Tyre wear
- Road surface abrasion
- Resuspended road dust
Research indicates that non-exhaust emissions now account for nearly 80% of particulate pollution from vehicles, compared with about 40% in 2000.
When drivers apply brakes, friction between the brake pads and discs generates heat and microscopic particles. These particles are released into the air as PM10 and PM2.5, two forms of fine particulate matter known to impact human health and air quality.
Even with the rise of electric vehicles, brake emissions remain relevant because all vehicles use braking systems, although regenerative braking can reduce friction-based particle release.
Features of the New UN Regulation
The newly adopted regulation introduces a global testing framework to ensure that brake emission measurements are consistent, reliable, and comparable across different regions.
1. Standardized Testing Methodology
The regulation establishes a harmonized laboratory procedure to measure particle emissions from braking systems under controlled conditions.
2. Real-World Driving Simulation
Testing cycles replicate common driving conditions, including different speeds, braking intensities, and temperature variations.
3. Measurement of Fine Particulate Matter
The regulation measures both particle mass and particle number, focusing on particulate pollutants such as PM10 and PM2.5.
4. Consistent Laboratory Conditions
Standardized test environments ensure repeatable results across manufacturers, laboratories, and regulatory authorities worldwide. This framework allows governments to establish clear emission limits for brake systems in future regulations.
Alignment with Future Emission Standards
The new UNECE methodology will support upcoming vehicle emission policies, particularly the Euro 7 Emission Standard in the European Union.
For the first time, Euro 7 will introduce limits on brake particulate emissions for passenger cars and vans, expanding regulatory control beyond traditional exhaust pollutants.
By creating a globally recognized testing standard, the UNECE regulation enables countries to align national emission policies with an international framework, reducing regulatory fragmentation and simplifying global vehicle trade.
Benefits for Air Quality and Public Health
Brake wear particles consist of metallic and mineral fragments produced by friction between brake components. These particles can:
- Enter the respiratory system
- Contribute to urban particulate pollution
- Impact ecosystems and biodiversity
The new global standard supports international efforts to reduce fine particulate pollution in cities, which is associated with respiratory and cardiovascular diseases.
Implications for the Automotive Industry
The regulation is expected to accelerate innovation in braking technologies and vehicle design.
Automotive manufacturers may need to develop:
- Low-emission brake materials
- Coated brake discs
- Alternative friction technologies
- Improved regenerative braking systems
- Brake particle capture technologies
These advancements will help manufacturers meet future emission limits while maintaining vehicle safety and braking performance.
Part of a Broader Strategy on Non-Exhaust Emissions
The brake emission regulation is part of a broader UNECE effort to address non-exhaust vehicle pollution.
Work is already underway to develop global testing methods for tyre abrasion, another major source of microscopic particles released during driving.
Together, these initiatives aim to build a comprehensive regulatory framework covering both exhaust and non-exhaust emissions from vehicles.
Global Impact
UNECE vehicle regulations are widely adopted by more than 50 countries, meaning the new brake emission standard could influence automotive regulations across multiple regions.
The regulation represents:
- The first global standard addressing brake particle emissions
- A major step toward cleaner transportation systems
- A foundation for future non-exhaust emission regulations
Conclusion
As exhaust emissions decline, non-exhaust pollution has become a critical environmental challenge. The adoption of a global standard for measuring brake particle emissions marks an important milestone in tackling this issue.
By enabling consistent measurement methods and supporting regulations such as Euro 7, the UNECE framework will help reduce particulate pollution and contribute to healthier urban environments and cleaner mobility worldwide.
Source: UN adopts global standard to measure and limit brake particle emissions | UNECE
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