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.