The Roles of Air Pollutants in Freight Mode Selection: Water Transportation

Transportation is widely recognised as the main contributors to the air pollutants emission. However, the concern in freight mode selection is relatively low compared to that of greenhouse gas (GHGs)/CO
₂
emission. This study identifies the relationship between the air pollutants and GHGs through an illustrative case of transporting goods from Shanghai to Hong Kong. The transport option with low GHGs emission did not necessary an option with low air pollutants (SO
_x
, NO
_x
, Particulate Matter) emission. The contradict results are also reflected in the case of water transportation. The limitation of life cycle study (transporting and distribution stage) in evaluating the environmental footprint is also discussed by using the case of the food product. The available studies are either excluding the distribution stage (by ship) or only considering the GHGs emission in assessing the environmental component. This study highlights the role of air pollutants in freight mode selection and the need for a comprehensive system boundary for a better decision-making.