Mobility scenarios and their impact on air quality in the city of Naples

Urban air quality in Naples is strongly influenced by emissions from both maritime traffic and road transport. This work uses the CAMx chemical transport model to quantify how selected mobility measures could improve air quality relative to a 2017 baseline. For the maritime sector, we examine shore‑side electrification of ships at berth in the Port of Naples, which removes exhaust emissions during hoteling. The scenario reduces annual emissions by about 18% for NO x , 7% for SO 2 and 12% for PM 10 . At the receptor level, decreases in ambient NO 2 reach roughly −2.3 ppbV near the docks (more than 10% locally), with smaller but noticeable reductions for SO 2 and PM 10 . Road traffic is investigated through two fleet‑renewal options: (i) targeted retirement of the highest‑emitting vehicles and (ii) a proportional downsizing of the entire fleet. The selective strategy is clearly more effective, lowering NO x , PM 10 , and PM 2.5 emissions by about 37%, 43%, and 49%, respectively. In densely trafficked areas, modeled NO 2 concentrations fall by more than −2.3 ppbV, with relative reductions up to 21%, while PM 10 and PM 2.5 decrease by as much as −0.6 and −0.5 µg/m 3 . An analysis of the temporal evolution of concentrations indicates that both the port and road interventions meaningfully ease compliance with current and forthcoming air‑quality standards. This effect is particularly evident for NO 2 , PM 10 , PM 2.5 and SO 2 . The results underscore the potential of coordinated sector‑specific mobility policies to deliver tangible public‑health benefits in complex urban environments.