Assessing the air quality derived from marine traffic in the central Mediterranean and Malta

Abstract

This study focuses on air pollution resulting from marine vessels following routes within the the Central Mediterranean region. In particular, the concentrations of carbon monoxide (CO), nitrogen dioxide (NO2), and sulphur dioxide (SO2) are considered. The analysis is carried out on remotely-sensed data obtained through the high-resolution and state-of-the-art TROPOMI sensor on board the SENTINEL-5P satellite that forms part of the COPERNICUS constellation. The air pollution data is correlated with the density of passenger ships, fishing boats, as well as cargo and tanker vessels obtained from the official EMODnet Human Activities portal and which was recorded over the same time period and spatial extent. A total of 31 months between 2019 and 2021 are considered. Custom Matlab scripts are implimented and used to process the deluge of files that are then visualised by QGIS. The region considered is centred around an area with a high volume of cargo and tanker traffic and with minimal contamination from land-based sources. Statistical analysis and regression models are fitted to the data in order to quantify the relationship between vessel density and pollution concentration. As evident from the presented information, NO2 concentrations clearly follow the vessel route patterns. On the other hand, there is less confidence in the dependence of SO2 and CO levels. This could be attributed to the MARPOL Annex VI regulations that were recently introduced.