Heavy vehicles' non-exhaust exhibits competitive contribution to PM2.5 compared with exhaust in port and nearby areas

Heavy port transportation networks are increasingly considered as significant contributors of PM2.5 pollution compared to vessels in recent decades. In addition, evidence points to the non-exhaust emission of port traffic as the real driver. This study linked PM2.5 concentrations to varied locations and traffic fleet characteristics in port area through filter sampling. The coupled emission ratio-positive matrix factorisation (ER-PMF) method resolves source factors by avoiding direct overlap from collinear sources. In the port central and entrance areas, freight delivery activity emissions including vehicle exhaust and non-exhaust particles, as well as induced road dust resuspension, accounted for nearly half of the total contribution (42.5%-49.9%). In particular, the contribution of non-exhaust from denser traffic with high proportion of trucks was competitive and equivalent to 52.3% of that from exhaust. Backward trajectory statistical models further interpreted the notably larger-scale coverage of non-exhaust emissions in the port's central area. The distribution of PM2.5 were interpolated within the scope of the port and nearby urban areas, displaying the potential contribution of non-exhaust within 1.15 & mu;g/m3-4.68 & mu;g/m3, slightly higher than the urban detections reported nearby. This study may provide useful insights into the increasing percentage of non-exhaust from trucks in ports and nearby urban areas and facilitate supplementary data collection on Euro-VII type-approval limit settings.

Automated summary

Heavy port transportation networks are increasingly recognized as major contributors to PM2.5 pollution compared to vessels. The study reveals that non-exhaust emissions from port traffic play a significant role. By using filter sampling and the ER-PMF method, PM2.5 concentrations in different locations and traffic fleet characteristics were linked in the port area. The study shows that freight delivery activity emissions, including vehicle exhaust, non-exhaust particles, and road dust resuspension, accounted for nearly half of the total contribution. The contribution of non-exhaust emissions, especially from dense traffic with a high proportion of trucks, was comparable to exhaust emissions.