Ozone changes in response to the heavy-duty diesel truck control in the Pearl River Delta

In recent years, restricting heavy-duty diesel trucks from driving within urban areas during the daytime is implemented in major PRD cities (e.g. Guangzhou and Shenzhen). Potential effects of this traffic control policy on spatial and temporal variations of O-3 concentrations are examined by CMAQ model system. Temporal profiles of mobile source emissions are modified to reflect the emission characteristics after the control. Our results show that: (1) with the updated mobile emission profile, there is a notable improvement in O-3 simulation performance for urban sites, with reductions in both the nighttime O-3 overestimation (up to 25 ppb) and the daytime underestimation on O-3 peak values (up to 20 ppb); (2) although the control policies are only applied in urban locations, their effects may extend to much larger downwind areas. The results from this study provide basic information that is useful in understanding the effects of mobile control policies on ambient O-3 in highly developing regions of China where similar strategies have been widely implemented. (C) 2013 Elsevier Ltd. All rights reserved.