43. The representative from the EC, chair of the IWG on PMP, introduced GRPE-80-28, presenting a status report of the activities of the IWG on PMP since the last session of GRPE. The Chair requested more information on the new provision to measure sub-23 nm particulates and if those new provisions expected to be submitted as a working document for the next session of GRPE in June 2020 would be submitted as amendments to both UN GTR No. 15 and UN Regulation No. [XXX] on WLTP. The representative from EC clarified this was still being considered where those new provisions would be implemented.

44. Regarding tyre wear emissions, the representative from Russia asked whether the different types of tyres tested meant difference in purpose (summer versus winter tyres) and / or different brands. The Chair of the IWG on PMP clarified the focus was on different abrasion rates, and on particulate size distribution, as the correlation between abrasion rates, particulates number and particulate size is not linear and still needed to be further defined.

45. The representative from India required more information on the cut-off point to have effective 10 nm particulate size measurements, especially for natural gas vehicles, which in India, had peak particulate emission at around 10nm. He also wondered about any potential impact of sampling point position on PN measurement. The Chair of the IWG on PMP said the cut-off was to be set at around 7nm where a 50% efficiency had been measured. He said lowering this threshold implied high levels of artefacts measurements. For natural gas vehicles, further investigation were necessary to measure particulates below 10 nm with good efficiencies. He finally highlighted that there are three research programs going on under the H2020 funding scheme of the EU that might bring new information and confirmed that at this stage no impact had been noted on the sampling point location.

46. The representative from Russia introduced GRPE-80-13 showing the importance of tyre and road wear emissions into the non-exhaust particulate emission mix. The report of the Russian Federation presented the comparative results of PM emissions from various vehicle systems, which were characterized by the following correlation: 28% with exhaust gases, 7% from braking systems, 12% from tyres and 53% from roadway, according to the materials of the research conducted in the Russian Federation and the UK. On this basis, He expressed the necessity for the tyre manufacturers and road construction services to revise the existing production technologies for tyres and roadway and to consider new materials and technologies to minimize the use of materials containing highly hazardous cancerogenic substances to improve health of population in large cities and elsewhere.

47. The representative from the Netherlands asked if the sources of particulate emission from transport were compared with other sources. The representative from Russia said there is research underway to have a broader look at all sources of emissions and that national inventories were performed at the national level that are providing information about the source of particulate emissions for the main sectors.

48. The representative from Australia highlighted that tyre and road wear emissions also highly depended on road surface technology and wondered if the results presented by Russia had been shared with the World Road Association. The representative from Russia replied that this information was now shared with WP.29 and that road associations were also collaborating with the World Health Organization (WHO) on those issues. The Chair welcomed the emergence of those issues to better understand the importance of the various sources of emissions and encouraged to further share such outcomes and inform all relevant stakeholders.

49. The Chair of the IWG on PMP asked if the study from Russia also looked at the particulate size distribution, as some literature seemed to indicate road and tyre wear particulate size were quite large. The representative from Russia agreed road wear particulate size was typically above 100 nm, but that many studies including the one from Russia considered small particulates in their findings.

50. GRPE acknowledged the progress made by IWG on PMP and noted no room had been requested for the GRPE week in June 2020.