Traffic emission scenarios in Lombardy region in 1998–2015

This study assesses and discusses the current and future contribution of road traffic to primary PM10 and PM10 main precursors (i.e. NOx, SO2, NH3, VOC) in the Lombardy region (Italy). It defines a coherent and updated set of input parameters (emission factors, mileage and fleet composition) for traffic emission estimation between 1998 and 2015. 1998–2004 emissions are assessed basing on historical data, while 2005–2015 rely on different hypothesis about mobility development and vehicular turnover rate. The work shows that road traffic emissions of PM10 and PM10 precursors are expected to decrease in the period 2005–2015, with a reduction greater than 70% in scenarios with a fast vehicle turnover and a decrease in fuel usage. Increase in fuel consumption could substantially lower the emission reduction expected, off-setting a substantial part of the new technology benefits. The introduction of DPF (diesel particulate filter) vehicles will determine a reduction of PM10 exhaust, however this could potentially be stalled by the increase in diesel usage in the vehicle fleet and an increase in mileage driven, as the latter causes a rise in the contribution of PM10 from abrasion. Concerning the total atmospheric emissions in Lombardy, SO2 (−6%) and NH3 (b−2%) emission will remain constant, while PM10, VOC and NOx emission will decrease, respectively by 2–30%, 6–15% and 2–32% in the period 2001–2015.