The United Kingdom Department for Environment, Food and Rural Affairs (DEFRA, 2007) reported the most significant human-made sources of particulate matter are stationary fuel combustion and road transport. In urban streets, road transport emissions dominate. Ultra fine particles (UFPs, diameter<100nm) and other traffic-related pollutants have potential health impacts, in particular respiratory-related illnesses. This is largely due to the size of UFP’s (relative to their mass) and their ability to deposit deeply into the lung where the residence time can be several months. Previous studies have investigated the effects of different parameters, such as traffic flow, meteorological factors and pollutant concentrations of traffic-related PM10 and PM 2.5. Few studies have considered UFP. Presently there are no legislative standards or guidelines which exist for UFP in the United States, UKand the EU.
