Giordan Lighthouse, located on the island of Gozo in the Malta-Sicily Channel within the central Mediterranean region, is ideally located to study the primary sources of atmospheric pollution. A total of 10 years of data have been accumulated from the reactive gas and greenhouse gas detectors and the aerosol analyzers found at this Global Atmosphere Watch (GAW) regional station. The data has been evaluated, resulting in trends in emissions from shipping recorded within the same region coming to the fore. The other source of emissions that was evident within the recorded data originated from Mt. Etna, located on the island of Sicily and representing the highest active volcano in Europe. The aim of this paper is to investigate the effect of ship emissions on trace gases and aerosol background measurements at Giordan Lighthouse, including the putative influence of COVID-19 on the same emissions. The model used to evaluate ship emissions was the Ship Traffic Emission Assessment Model (STEAM). From trace gas measurements at Giordan Lighthouse, a slowly decreasing trend in sulfur oxide (SO_x) and nitrogen oxide (NO_x) emissions was noted. To better understand the air quality results obtained, the STEAM model was fed, as an input, an Automatic Identification System (AIS) dataset to describe the vessel activity in the area concerned. This study also investigates the effects of the COVID19 pandemic on marine traffic patterns within the area and any corresponding changes in the air quality. Such an analysis was carried out through the use of SENTINEL 5 data.

Long-term data analysis of the hourly ozone volume fractions in the middle of the Mediterranean Seawas carried out covering a period of 22 years. It was noticed that the amount of ozone during this period very rarely exceeded the recommended upper limit value of 80 ppb and that the amount of tropospheric ozone in the area is rather low. Fourier data analysis shows the presence of only a seasonal cycle in ozone concentrations. Statistical analysis of the data is showing a slightly negative trend in ozone concentrations of −0.46 ± 0.08 ppb/year for average values and a slightly higher negative trend of −0.54 ± 0.11 ppb/year for the 95^th percentile values. These results obtained through simple linear regression were confirmed using the more appropriate Mann–Kendall test. The possible quadratic trend was not observed for the whole series of data. Air mass trajectories were calculated for those days in the year with the highest pollution, indicating that during those days horizontal air transfer, in most cases, brings the air mass from the North and from Sicily in Southern Italy.

Measurements of concentrations of nitrogen oxides (NO_x) were collected over a period of thirteen years (2011–2023). The data were collected at Giordan Lighthouse atmospheric monitoring and research station on the Island of Gozo, forming part of the Maltese Archipelago, in the Central Mediterranean. Trend analysis shows that NO_x concentrations are decreasing at an annual rate of 0.15 ppbv per year. This is in comparison to what has been recorded across Europe due to stricter regulations and improvements in vehicle technologies. Significant reductions were observed during the COVID-19 pandemic due to the implementation of lockdowns and restrictions on mobility. NO_x concentrations also exhibit an amplitude seasonal variability of 35% with a maximum in October and a minimum in December, while the nitric oxide (NO) component of NO_x presents a broad maximum in May/June and a minimum in February. NO_x concentrations also show a strong diurnal variability with a maximum in the morning and a minimum in the afternoon. The diurnal amplitude of NO_x and NO is 44% and 148%, respectively. With respect to wind direction, the NO_x concentrations exhibit a maximum when the prevailing wind is from the South-East sector and a minimum when the wind is blowing from the West sector.

This paper presents the findings of a 12-year study on radon conducted from January 2011 to December 2022 at the Giordan Lighthouse station on the island of Gozo, Malta. Located in the Central Mediterranean, Gozo’s strategic position enables effective monitoring of air mass movements between Africa and Europe (from south to north) and between Europe and Central Asia (from west to east). Our research involves an analysis of seasonal and diurnal variations in radon levels, alongside analysis of relevant meteorological variables, clustering of air mass back trajectories, and assessment of local and remote radon production. The findings provide critical insights into the dynamics of atmospheric radon, which are significant not only for the Maltese islands, but also for enhancing our understanding of transcontinental radon transport in the Central Mediterranean, a region that has remained largely unexplored.

Concentrations of oxides of nitrogen (NO_x), as the sum total of nitric oxide (NO) and nitrogen dioxide (NO₂), the individual parts, i.e., NO and NO₂, (NO_x = NO + NO₂), and wind speed and direction measurements were gathered over a thirteen-year period (2011–2023) at the Giordan Lighthouse Geosciences Observatory, located on the Island of Gozo, forming part of the Maltese Archipelago (Central Mediterranean). The atmospheric concentration measurements were recorded with a Thermo Scientific Model 42i NO_x analyser, which employs the chemiluminescence technique to detect atmospheric traces of NO_x concentrations. In this case study, an investigation was conducted to understand the wind and seasonal variabilities of the measured concentrations. The highest NO_x concentrations occurred when the prevailing wind originated from the SE, while a broad minimum was observed when the wind blew from the S–W sector. The maxima were primarily associated with land-based sources, predominantly vehicular emissions on the main island, i.e., Malta. The amplitudes for NO, NO₂, and NO_x in relation to wind direction were 63%, 125%, and 121%, respectively. Significant variabilities were observed during the autumn season. Regarding wind speed, the NO_x concentrations reached their peak during high-wind-speed events, which are associated with transboundary pollution. A secondary broad maximum was observed for wind forces between 2 and 4, while the lowest concentrations were recorded at wind force 9. The NO_x concentrations exhibited a seasonal maximum in spring and a minimum in winter, which contrasts with the findings from the Monte Cimone station in Italy. The seasonal amplitudes for NO, NO₂, and NO_x were 46%, 15%, and 17%, respectively. It is evident that NO concentrations exhibited a greater seasonal variability, whereas NO₂ concentrations demonstrated significant variability in relation to wind direction.