The document authorizes development of a new UN GTR on brake PM and PN emissions from all types of light-duty vehicle brake systems, including validation of the developed novel WLTP-Brake test cycle, investigation and selection of instrumentation and sampling methodology for brake wear particles, definition of minimum requirements for sampling, validation through interlaboratory study, inclusion of regenerative braking, and preparation of the PMP Brake protocol. It also reports on Amendment 2 to UN GTR No. 24 covering laboratory measurement of brake emissions for light-duty vehicles, detailing hardware requirements, test cycle specifications, cooling air conditioning, bedding procedures, and emissions measurement methodologies for particulate matter and particle number.

Proposal to amend UN GTR No. 24 by modifying test procedures, definitions, and requirements for brake particle emissions measurement. The amendment introduces improvements including revised definitions (vehicle electrification type, material formulation, pad size), updated measurement tolerances and signal filtering requirements, provisions for brake filtering systems, enhanced specifications for drum and electromechanical brake systems, relaxed cooling airflow adjustment requirements, and a new test cycle for speed-limited vehicles. Documentation of calibration requirements and ongoing quality controls are clarified throughout.

Report on the third inter-laboratory study evaluating the repeatability and reproducibility of particulate emission factors using GTR 24 (1st amendment) across 14 laboratories worldwide. The study assessed laboratory proficiency in brake particulate matter and particle number emissions measurements for light-duty vehicles, testing two low-metallic brakes and one low-emitting NAO brake using the WLTP-Brake cycle. Inter-lab coefficient of variation for PM₁₀ was 10-15% for low-metallic brakes (4.5-8.5 mg/km emission levels) and 30% for the NAO brake (1.5 mg/km). Intra-lab repeatability for PM₁₀ was less than 5% for low-metallic brakes but higher for the NAO brake. A success rate of 94.8% was achieved after applying quality checks, confirming GTR 24 suitability for regulatory testing. The report provides recommendations for GTR 24 amendments including friction work calculation methodology, torque quality metrics, sampling probe setup standardization, and residual torque limits.

Overview of documents and working party activities for the 95th session of the Working Party on Pollution and Energy (GRPE). Documents address improvements to UN R179 (Laboratory Measurement of Brake Emissions for Light Duty Vehicles) including handling of vehicles with limited speed, brake replacement parts regulation, and GTR 24 (Measurement procedures for Brake corner emission factors). Related documents also cover a new regulation for heavy-duty brake emissions and a new global technical regulation for heavy-duty brakes. Working documents ECE/TRANS/WP.29/GRPE/2026/29, ECE/TRANS/WP.29/GRPE/2026/30, ECE/TRANS/WP.29/GRPE/2026/31, ECE/TRANS/WP.29/GRPE/2026/32, and ECE/TRANS/WP.29/GRPE/2026/53 are submitted.

Final status report on development of a new UN GTR for laboratory measurement of brake particle matter (PM) and particle number (PN) emissions from heavy-duty vehicles. The GTR introduces brake emissions groups based on fundamental design and performance characteristics, defines brake group nominal test parameters by disc or drum diameter, establishes friction braking share coefficients with c-factor = 1 for full-friction braking, specifies required test input parameters including brake system type and filtering systems, prescribes the Worldwide Harmonized Heavy-Duty Brake Cycle (WHBC) comprising 246 brake events over 5:39 hours across urban, rural, and motorway segments, defines PM and PN measurement methodologies using gravimetrical and particle number counter methods, specifies hardware requirements including brake dynamometer, enclosure dimensions of 1950 mm length × 1000 mm height × 700 mm depth with divider plate, sampling tunnel with 300 mm fixed inner diameter, and brake temperature measurement by embedded thermocouples, and includes results of preliminary interlaboratory study.

Proposal to establish a globally harmonised laboratory methodology for measuring brake particulate matter (PM) and particle number (PN) emissions from heavy-duty vehicles, including trucks and buses, using a Worldwide Harmonized Heavy Duty Vehicles Brake Cycle (WHBC) and brake dynamometer testing. The GTR specifies test system requirements, including brake enclosure design, sampling tunnel specifications, climatic conditioning with cooling air temperature maintained at 23°C±2°C and relative humidity at 50%±5%, cooling airflow at 2500 Nm/h±5%, test preparation procedures, brake bedding with six repetitions of the WHBC followed by emissions measurement during one WHBC cycle, requirements for PM10, PM2.5, TPN10, and SPN10 measurement systems, brake temperature measurement using embedded thermocouples, calibration and validation procedures, and reporting of emission factors. The regulation applies to vehicles of categories M₂, M₃, N₂, N₃ [and O₃, O₄] with friction braking systems.

Phase 2 of the DfT Brake and Tyre Programme investigated variables affecting particle emissions from brake and tyre wear. Testing compared three vehicles on the same Golf VII platform (ICE, PHEV, EV) at different masses using controlled chassis dynamometer cycles. Results showed regenerative braking in EV and PHEV reduced PM2.5 more effectively than a ~20% mass reduction, while PN10 emissions remained similar across vehicle types and were insensitive to mass or regenerative braking. Testing of brake pad and disc variants found ceramic and low-dust pads gave lowest emissions, while high-mileage pads reduced PM2.5 but not PN10. PM2.5 and PN10 appear governed by different mechanisms, with volatile chemistry of brake pads being critical for PM2.5 emissions.

This handbook provides testing and reporting procedures for the Third Inter-laboratory Study Phase 2, focusing on front brake testing for a Ford Puma vehicle per GTR No. 24. Testing comprises three emission cycles (Steps B and C with samples M₁ and M₂) followed by a fourth WLTP-Brake cycle (Step D) at 975 m³/h ± 10% airflow. Data must be reported using EBF, TBF, and MMF templates with specified formats and calculations. Post-test parts mass measurement occurs only after Step D completion. All values must be submitted as numerical values without formulae, with pre-test and post-test weighing procedures requiring buoyancy correction per GTR 24 specifications.

Document presents an overview of brake force distributions (BFD) installed on light commercial vehicles (LCV) across different OEM applications and vehicle categories, showing front axle and rear axle percentage distributions for vehicles of category N₁ and N₂ with various gross vehicle weights ranging from 3.5 to 5.5 tonnes.

The report describes the final status of Amendment 2 to UN GTR No. 24 covering laboratory measurement of brake emissions, including hardware requirements (brake dynamometer, enclosure design, fixtures, temperature measurement, sampling tunnel and plane), the WLTP Brake cycle test procedure with quality checks and temperature specifications, cooling air conditioning specifications, cooling adjustment section procedures for different brake categories, bedding and emissions measurement sections, and PM mass concentration measurement methodology validated through an Inter-laboratory Study across multiple testing facilities.

Proposal to amend GRPE/2026/31 revising the methodology for measuring brake particle emissions from light-duty vehicles.

Agenda items include review of meeting minutes, overview of amendments to Brakes GTR 24 and UN R179, HD brakes and inertia considerations, projects on tyres and brakes including brake emissions from Phase 2 of the DfT Brake and Tyre Emissions Programme and characterization of brake particle emissions from electric vehicles, preliminary results of CPC inter-laboratory exercise on calibration materials, and any other business.

Meeting minutes documenting PMP discussions on amendments to Brakes GTR 24 and UN R179, including TF3a layout and testing topics, TF3b vehicles limited speed work, TF3c brake replacement parts with a new UNR to be introduced, and TF4 electromechanical brakes with no further progress. GTR and UNR informal documents on HD brakes were presented with trailers removed from scope, open points on PM Emission Factor units, caliper position, test input parameters, and cooling air flow value addressed, and a 3-month delay in round robin testing reported.

Overview of working documents for the 95th session of GRPE, listing five working documents on new GTR for heavy-duty brake emission, UN R179 second supplement, GTR 24 third amendment, vehicles with limited speed for UN R179 and GTR 24, and new UNR on emissions covering brake replacement parts, with informal documents to follow from clean working documents.

Agenda for a PMP webex meeting on 29 September 2026 to review meeting minutes, overview amendments to GTR 24 and UN R179 on brakes across multiple task forces covering layout and testing topics, vehicles limited speed, brake replacement parts, and electromechanical brakes, discuss GTR and UN R heavy-duty brakes, and address any other business.

Proposal to establish a new UN Regulation transposing UN GTR No. 24 into uniform provisions concerning approval of non-original and identical replacement brake parts (brake pads, drum brake linings, brake discs, and brake drums) with regards to particle emissions. The regulation applies to vehicles of category M₁, N₁, and N₂ between 3.5 and 5 tonnes maximum mass. Replacement brake parts must comply with particle emission limits, with emission factors calculated using test wheel load and friction braking share coefficient for the brake emissions family parent. Approval marks must be affixed to approved parts, and conformity of production shall be verified through sampling and testing procedures.

Proposal to modify UN GTR No. 24 with respect to laboratory measurement procedures for brake emissions of light-duty vehicles. This amendment improves and corrects the testing procedure, including detailed requirements for test system setup, cooling air conditioning, brake dynamometer specifications, WLTP-Brake cycle execution, emissions measurements for particulate matter (PM2.5, PM10) and particle number (TPN10, SPN10), calibration protocols, and reporting of results. The regulation defines brake corner emissions families, friction braking share coefficients for different vehicle electrification types (ICE, HEV categories, PEV), and test procedures using fully-enclosed brake dynamometers with isokinetic sampling systems. A version with tracked changes is available.

Task Force 3b addresses vehicles with limited speed by introducing a new Appendix 3 in Annex 4 to calculate adjusted cycles when vehicle maximum speed is lower than the WLTC-Brake cycle. The proposal modifies brake corner emissions family testing to allow vehicles with limited speed to be included in families with standard vehicles, with emission factors calculated from parent family factors or measured on adjusted cycles. Amendments address c-factor measurement, cycle-adjusted brake events, kinetic energy dissipation tolerances, and report file specifications.

Task Force 4 has completed revisions to GTR 24 concerning electro-mechanical calipers and proposes to include them in Amendment 3.