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.

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 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.

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.

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.