UNECE adopts new regulation for brake generated PM and proposes limits for tire abrasion
26 March 2026
The UNECE World Forum for Harmonization of Vehicle Regulations (WP.29) has adopted a new regulation that establishes the world’s first internationally harmonized laboratory procedure for measuring and limiting brake particle emissions from light-duty vehicles.
The new UN Regulation No. 179 introduces standardized test methods and emission limits for brake-generated PM and follows the earlier adoption of the UN Global Technical Regulation No. 24 to measure emissions from braking systems of cars and vans.
Regulation 179 applies primarily to passenger cars (M1 category) and light commercial vehicles (N1 category), with optional application to certain light N2 vehicles. Brake emissions are measured on a brake dynamometer using a dedicated brake test cycle that reflects real-world braking patterns. The regulation sets limits for PM10 emissions. Solid particle number (SPN) measurement procedures are included in the framework, with numerical limits to be specified in future amendments.
UN Regulation No. 179 is the first global brake emission regulation to explicitly account for electrified powertrains and incorporates a friction braking share coefficient that reflects the proportion of braking energy handled by friction brakes versus regenerative systems.
The regulation is expected to be deployed in the European Union as part of Euro 7 and in the United Kingdom. It will enter into force by the end of 2026. The European Commission has subsequently proposed a change to the Euro 7 regulation to replace UN Regulation No. 24 with UN Regulation No. 179.
UN Regulation No. 179 represents an evolution of the pre-existing UN Global Technical Regulation No. 24 and reflects the latest progress in this field. It is supported by the most recent results produced by the Particle Measurement Programme (PMP) when testing ‘Euro 7’ brakes. The regulation incorporates further harmonization and improvement of the testing environment; high-precision measurement of PM10, PM2.5, and particle numbers; testing of new technologies such as brakes equipped with passive or active emission-reduction filters and calculation of brake emissions for the entire vehicle.
A similar UN regulation for replacement braking system is being finalized.
In a related development, abrasion limits for C1 light-duty vehicle tires, prepared by the Task Force on Tyre Abrasion (TF TA), were endorsed by the Working Party on Noise and Tyres. An abrasion index (AICT) of 1.00 has been proposed for normal tires and snow tires. The AICT is a dimensionless value that expresses the abrasion of a test tire relative to a standard reference tire. The TF TA estimates that these limits could reduce overall abrasion from tires by more than 10%, and lead to the exclusion of around 30% of the high abrasion tires sold today in the European and Japanese markets. The proposal will be submitted for adoption to the World Forum for Harmonization of Vehicle Regulations (WP.29) at its session in June 2026. If adopted, the new regulation will enter into force in January of 2027.
Source: UNECE