Air pollution and the impact of meteorological factors in air quality of Chalki Island during a winter period of 2023-2024

Air quality and climate change are of the dominant challenges for Islandic ecosystems in Mediterranean region. This work studies the air quality and the impact of meteorological conditions in pollution levels of Chalki Island, a small island that is located in the climatic sensitive region of southeastern Aegean basin. The analysis was conducted during a low touristic activity period that covers the days from 24^th of November 2023 to 3^rd of March 2024. Hourly recording of PM2.5, O3 and SO2 as well as meteorological factors of temperature (T) and relative humidity (HR) from a mobile air quality monitoring system (Haz-Scanner™ Model HIM-6000) which is located in the center of city in combination with meteorological parameters (precipitation, planetary boundary height, atmospheric pressure, wind speed and direction) available from the last generation of ECMWF reanalysis dataset (ERA5) are used for the analysis. The calculation of Air Quality Index (AQI) for the studied pollutants shows that PM2.5 is the dominant factor that determines the air quality in the city center of Chalki. The majority of days is classified in “good” and “moderate” air quality classes (in terms of AQI). Additionally, the analysis shows that climate conditions significantly affect the concentration of pollutants. In particular, the higher height of planetary boundary layer (PBL) and increased ventilation coefficient (as a measure of the dispersive capability) are related to improved air quality conditions. The temperature and relative humidity conditions lead to improved climate sense for the mean population (in terms of Discomfort Index; DI<21). Finally, AQI is positive correlated to DI values (corr. Coef: 0.4) indicating a synergy of degraded air quality and discomfort conditions on human health.