Investigation of the particulate air pollution and the ratio of PM2.5 to PM10 concentrations in the atmosphere over the lignite mining and lignite-fired power plants region of Western Macedonia, Greece.

The lignite long-lasting exploitation has resulted in a series of negative impacts on the air quality of the lignite basin of Ptolemaida, Amynteo and Florina. The coal-fired plants in this region are the greatest sources of air pollutants, such as SO2, NOX, CO2, PM, heavy metals and fly ash. In this study, we investigate the air quality of Western Macedonia based on measurements of PM2.5 and PM10 in ten air quality monitoring stations (Filotas, Koilada, Oikismos, Petrana, Komi, Amyntaio, Florina, Vevi-Meliti, Pontokomi and Anargyroi) which are located in the broader area of the lignite power plants. The trends of PM time series over a 12-year period (2010-2021) show a gradual decrease of PM2.5 and PM10 concentrations following the decline of lignite production in Greece. In order to characterize the underlying atmospheric and anthropogenic processes affecting the PM concentrations we assessed the ratios of PM2.5 to PM10. The high ratios of PM2.5/PM10 indicate a major contribution of fine particles attributable to anthropogenic air pollution sources, while small ratios indicate that coarse particles are dominant, which might be related to natural sources of air pollution. We found that average PM2.5/PM10 ratios during the study period ranged between 0.48 in Oikismos and 0.70 in Florina and Vevi-Meliti. For Florina and Vevi-Meliti, the daily PM2.5/PM10 ratios were found to reach the value of 1.0, while the daily average ratios of PM2.5/PM10 were above 0.9 for almost the 15 % of the days in these sites. In the other sites high daily ratios of PM2.5/PM10 were found for a lesser number of days. The high ratios which have been found at these sites indicate the considerable contribution of energy combustion for heating purposes and other anthropogenic processes. Overall, we used the PM2.5/PM10 ratio to characterize the processes affecting the air quality within the local environment.