The air quality and the influence of Etesians on pollution levels in the Rhodes city, the case of July 2022

In July 2022 strong and high-frequency northern sector winds blew over the Aegean Sea. The low tropospheric circulation in combination with the air quality and human comfort are of great importance for the climate and human health. This study investigates the variation of pollutants’ concentrations (PM10, NO2, O3 and SO2), meteorological factors (temperature, relative humidity, wind speed and direction) and discomfort index in Rhodes city during July, 2022. Additionally, the impact of Etesians on pollution levels is studied. The strength of the Etesian flow is quantified by calculating a statistical index that takes under consideration the July pressure gradient (ΔP) over Aegean Sea. For the analysis, pollutants concentration recordings from a mobile air quality monitoring system during July 2022 and, mean sea level pressure (MSLP) data from ERA5 reanalysis during July for the period from 1980 to 2022 are analyzed. Results indicate that traffic affects the pollution level although the pollution limits, according to the European directive for air quality (2008/50/EC), are not exceeded. Findings also reveal an increase in ΔP, about 1.8hPa, during 2022 compared to the period from 1980 to 2022 and the dipole of high (over Balkans) and low (over eastern Mediterranean) pressure centers also strengthens, leading to stronger winds over Aegean Sea. The ΔP is strongly correlated (0.8) to the first principal component of MSLP over the eastern Mediterranean. Finally, study shows that the Etesian flow tends to reduce the concentration of PM10, NO2 and O3 improving the air quality in Rhodes city.