Air Quality in the Port of Chalki Island: Assessing the Role of Traffic and Atmospheric Circulation during the First Half of 2025

Traffic in insular tourist areas is one of the most significant factors which affects ambient air quality. This study investigates the influence of traffic emissions on PM2.5 concentration variability within the port area of Chalki Island (located in the southeastern Aegean Sea). The analysis was employed during the period from February 13 to June 17, 2025. For the analysis, the Air Quality Index (AQI) was calculated utilizing hourly average PM2.5 concentration records from a mobile calibrated air quality monitoring system (AQ-Mesh). To study the impact of low-tropospheric circulation on pollution variability, wind speed data from the ERA5 reanalysis dataset were employed. Furthermore, to evaluate the effect of traffic on air quality in the port area, a traffic index that expresses traffic density (considering daily-scale traffic variation) was calculated, incorporating the total number of vehicles, vessels, and passengers (as provided by local authorities). The results indicated that air quality at the beginning of summer period degrades by 45% compared to the winter period (January, 2025). During June, the monthly mean AQI was equal to 38.5±4.5 (classified as 'Good' air quality class). Correspondingly, the traffic index shows a relative increase of approximately 74% during the summer period (relative to winter, 2025). The calculation of the correlation coefficients between the AQI and wind speed (for each grid point over an extended area of the Aegean basin), shows that low atmospheric circulation acts as a driver for the variation of PM2.5 concentrations. The increased wind speed over southeastern Aegean is related to an improved air quality in Chalki’s port area. The results provide critical insights into the environmental pressures faced by small Mediterranean ports, highlighting the urgency for continuous monitoring and the development of sustainable transport frameworks for insular areas