Minutes of a PMP hybrid session held 12 October 2026 at the Palais des Nations in Geneva. Discussion covered amendments to GTR 24 and UN R179 on heavy-duty brake emissions, including new limits for 2030, C-factor measurements, driving modes, brake functions, emission factor calculations, and compliance and conformity of production procedures. Topics included measurement setup, payload factor, test inertia determination methods, inter-laboratory study status with data from 5 labs, and removal of square brackets from GTR text. The group reviewed brake particle emission work from Phase 2 of the DfT programme and preliminary results from a calibration materials inter-laboratory exercise involving 8 labs, recommending continued use of emery oil for annual validation at 23 nm.

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.

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.

Final status report on development of a new UN Global Technical Regulation addressing particle matter (PM) and particle number (PN) emissions from heavy-duty vehicle brake systems. The GTR introduces brake emissions groups based on design and performance characteristics, establishes test parameters for disc and drum brakes across five diameter groups, defines the World Harmonized Heavy-Duty Brake Cycle (WHBC) comprising 246 brake events over 5:39 hours, specifies brake dynamometer hardware requirements with enclosure dimensions of 1950 mm length, 1000 mm height, and 700 mm depth, requires PM10 and PM2.5 gravimetric measurement and particle number counting, and prescribes a friction braking share coefficient (c-factor) of 1 pending availability of additional data. A preliminary interlaboratory study confirms test cycle reproducibility and particle measurement repeatability, with recommendations to specify fixed enclosure and duct dimensions for improved cross-laboratory consistency.

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.

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.

Presentation on brake inertia determination for potential amendment to heavy-duty brake emission protocol. Currently proposed protocol assumes test inertia determined based on UN R90, but comparison with C-factor from vehicle testing showed significant differences in inertia and actual load during dynamometer testing, with front and rear values differing by up to 2.3 times. Proposes retaining UN R90-based approach as default method while adding alternative inertia determination method considering vehicle mass and multi-axle configurations. Analysis of 43 Japanese market vehicle models showed UN R90-based approach can result in brake loads ranging from 0.1 to 5.7 times those of vehicle-based approach.

Round Robin exercise 2 evaluated detection efficiency and calibration variability of condensation particle counters (CPCs) at 23 nm and 10 nm across eight laboratories using multiple calibration materials including emery oil, soot, silver, and graphite particles. Measured variability was better than 5% at plateau and around 5% at 23 nm. Material differences from soot at 23 nm ranged from −0.04 to 0.41 units depending on the particle type. Preliminary recommendations include continuing with emery oil for continuity, applying generator/CPC type-specific correlation factors determined by manufacturers when different materials are used, and conducting annual validations with the same material.

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.

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.

Proposal to establish a new UN Regulation on laboratory measurement of brake emissions for heavy-duty vehicles of categories M₂, M₃, N₂ and N₃ using friction braking. The regulation defines test procedures, brake emissions groups, compliance requirements with emission limits for PM10 and SPN10, type approval processes, conformity of production requirements with statistical sampling procedures, and technical specifications for test systems including brake dynamometers, brake enclosures, sampling tunnels, and particle measurement instrumentation.

Proposal to amend GRPE/2026/29, establishing a globally harmonized laboratory methodology for measuring brake particulate matter (PM) and particle number (PN) emissions from heavy-duty vehicles of categories M₂, M₃, N₂, N₃, and O₃, O₄.

Proposal to amend GRPE/2026/53, establishing a new UN Regulation transposing UN GTR No. 24 for the approval of non-original and identical replacement brake parts (pads, linings, discs, drums) for vehicles of categories M₁, N₁, and N₂ with maximum mass between 3.5 and 5 tonnes.

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.

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.

Draft amendments to the proposal to include testing of vehicles with limited speed (GRPE/2026/32). The document provides specifications for brake emissions testing including test-system requirements, climatic conditioning, brake dynamometer setup, sampling procedures, and data analysis methods for measuring particulate matter and particle number emissions from friction brake systems on light-duty vehicles.

Draft amendments to the proposal to improve and correct the procedure for measuring laboratory brake emissions on light-duty vehicles (GRPE/2026/30). The document establishes scope and application for vehicles of category M₁ and N₁, defines abbreviations and symbols, sets compliance requirements with emission limits for PM10, and specifies test procedures including cooling adjustment, brake bedding, and emissions measurement sections using the WLTP-Brake cycle. It addresses brake corner emission families, type approval requirements, conformity of production testing at least once every 12 months with statistical pass/fail decision charts, and conformity assessment through verification procedures.

Editorial corrections to the Appendix and reference to Annex 4.