1. 459 Factor 6 accounts for most of the mass of Cu 460 and Zn (89 and 46%, respectively) and a major part of 461 Pb mass (34%), while it is also characterized by high 462 levels of BC. This source is identified as Vehicular 463 traffic, including both exhaust and non-exhaust 464 emissions. Non exhaust emissions are comprised of 465 brake, tyre and road wear and road dust resuspension. 466 Zn is a metal that is generally used in rubber to 467 strengthen the tires and has been suggested for tyre 468 wear emissions;; Tajikistan;Zn and Pb are trace metals that have 438 been linked with waste incineration,2010