36. Giorgio Martini presented the interim status of the literature survey so far. A more comprehensive presentation will be available for discussion at the next meeting. Essentially there is a large body of work since 2000, but many issues in assessing the information due to non-standardised testing methods.

37. Preliminary findings:

• Non exhaust emissions (includes resuspension) currently estimated for 50% of traffic related PM emissions in urban env. relatively increasing because other sources are decreasing rather than because absolute levels increase.
• Brake wear in urban location 16-55%, approx. 50% by mass brake wear particles become airborne – the others expected to be too big to be airborne.
• In coarse particle fraction mean diameter 5-6 um, but found transition metals in fine fraction of airborne brake wear particles
• Tyre wear: 5-30 % generated tyre wear particles emitted as PM10 depending on the driving conditions. Non exhaust PM10 contains 11-20% tyre wear particles
• Coarse fraction >7um, but PN 30-60nm mode has been reported at non-steady state driving conditions with stops.
• Transitions metals Fe, Cu, Zn, have been found in tyre wear debris – also organic compounds PAH, benzothiazole etc.
• Emission factors – major gaps in knowledge found.