Persistent high PM pollution in the Eastern Mediterranean and Middle East: insights from long-term observations and source apportionment in Cyprus

Abstract. Long-term daily PM2.5 and PM10 chemical speciation data was collected continuously from 2015 to 2023 at an urban traffic and regional background site in Cyprus, offering a unique opportunity to quantify the influence and trends of (i) local emissions on urban PM concentration levels and sources, and (ii) regional PM emissions over the Eastern Mediterranean basin. Despite a statistically significant drop in PM2.5 and PM10 at both sites over the last 19 years (2005–2023), concentration levels remain high with no further significant improvements observed over the last 9 years; making PM concentration levels well above the new EU annual limits. To refine this analysis, long-term trends (2015–2023) were explored for individual PM chemical species and sources derived by PMF source apportionment. A decreasing trend in traffic-related PM10 of 35 % was observed at the traffic site, suggesting the effectiveness of the gradual shift of the vehicle fleet towards the latest EURO-standard vehicles. On the other hand, this reduction in tailpipe traffic emissions was completely offset by an increase of uncontrolled urban emissions, such as road dust re-suspension and biomass burning from domestic heating, calling for the rapid implementation of abatement measures. Based on cluster analysis of air mass origins, the Middle East region was identified as a major hotspot of PM10 over the Eastern Mediterranean; with both high concentration levels of dust from the Arabian desert and substantial anthropogenic pollution with continuously increasing trends in biomass burning and sulfate-rich emissions from fossil fuel combustion over the past decade.