Global brake emission rules adopted by UNECE

March 12, 2026

Although tailpipe emissions from vehicles have declined substantially over recent decades, non-exhaust emissions — particularly those generated by brake and tyre wear — are now emerging as a major contributor to particulate matter (PM) pollution in cities worldwide. As internal combustion engines become cleaner, these overlooked pollution sources are drawing increasing regulatory attention.

To address this growing environmental concern, the United Nations Economic Commission for Europe World Forum for Harmonization of Vehicle Regulations (WP.29) has formally adopted a landmark regulation establishing the first internationally harmonized laboratory standard for measuring and limiting brake particle emissions from light-duty vehicles.

First global standard for brake emission testing and limits

The new UN Regulation sets out uniform testing procedures and emission thresholds for particulate matter produced by vehicle braking systems. It builds upon the previously adopted UN Global Technical Regulation (GTR) No. 24, which introduced standardized methodologies to measure brake system emissions from passenger cars and vans.

According to Per Ohlund, Chair of the UNECE Working Party on Pollution and Energy (GRPE), this regulatory step represents a critical evolution in vehicle emission control policy. As exhaust emissions continue to decrease, tackling non-exhaust particulate pollution is essential to maintaining progress in urban air quality improvement.

Science-based and globally harmonized approach

The regulation primarily applies to:

• Passenger cars (M1 category)

• Light commercial vehicles (N1 category)

• Optional inclusion of certain light N2 vehicles

Brake particle emissions are measured using a brake dynamometer test bench, simulating real-world driving and braking conditions through a dedicated brake cycle. The regulation establishes limits for PM10 emissions (particulate matter with a diameter of 10 micrometers or less), expressed in milligrams per kilometer (mg/km).

Additionally, the framework introduces procedures for measuring Solid Particle Number (SPN) emissions. While numerical SPN limits are not yet defined, they are expected to be introduced through future amendments.

Addressing brake emissions in electric and hybrid vehicles

UN Regulation No. 179 is the first global regulation to explicitly consider electrified powertrains in brake emission assessments.

Battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs) rely heavily on regenerative braking, which reduces the use of conventional friction brakes. To ensure accurate emission accounting, the regulation incorporates a friction braking share coefficient. This mechanism adjusts emission calculations to reflect the actual proportion of braking performed by friction systems versus regenerative technology.

This ensures fairness and technical accuracy across conventional, hybrid, and fully electric vehicles.

Expanding vehicle emission policy beyond the tailpipe

The adoption of UN Regulation No. 179 marks a major shift in global vehicle regulation by extending emission standards beyond exhaust gases. As the automotive industry accelerates electrification and decarbonization, regulators are ensuring that climate gains are matched by improvements in air quality and public health protection.

By targeting brake-generated particulate matter, policymakers are closing a long-standing regulatory gap in modern vehicle environmental performance.

Implementation timeline and euro 7 integration

The regulation is expected to be implemented within the European Union under the upcoming Euro 7 standards, as well as in the United Kingdom. It is scheduled to enter into force by the end of 2026.

A complementary UN regulation addressing replacement brake systems is also nearing finalization. This measure will ensure that vehicles certified with low-emission braking systems maintain reduced particulate emissions throughout their entire operational lifespan — including after brake component replacement.

Why this matters for urban air quality

• Brake and tyre wear are becoming dominant sources of traffic-related PM pollution.

• Electric vehicles still produce non-exhaust emissions.

• Standardized global testing ensures regulatory consistency.

• Euro 7 will significantly expand emission control scope.

This regulation represents a decisive advancement in global efforts to combat particulate pollution and promote cleaner, healthier mobility worldwide.