The spatiotemporal variations of PM2.5 concentration and its relationship with meteorological parameters: A multi-scale analysis in Madrid and Valencia, Spain

Fine particulate matter (PM 2.5 ), as a principal air pollutant, stands as one of the key indicators in atmospheric quality monitoring. The spatiotemporal patterns of PM 2.5 concentration in Madrid and Valencia during 2013–2022 were obtained from satellite-derived PM 2.5 products and ground-based measurements. The peak PM 2.5 concentrations occurred in July, August and December in Madrid, showing a geographical trend of hotspots in the southeast and coldspots in the northwest. Similarly, the highest PM 2.5 concentration in Valencia was observed in December and summer months (June–August), with hotspots appearing along the coastline. At diurnal and monthly scales, PM 2.5 concentrations in Madrid positively correlated with air temperature (AT); the results of feature importance using XGBOOST-SHAP model reveal that high temperature-humidity enhances PM 2.5 at seasonal scale, while high wind speed (WS) weakens it. Therefore, to mitigate elevated PM 2.5 levels during summer and winter in Madrid, strategies should focus on increasing green spaces and pervious pavement. Additionally, since Valencia experiences the peak PM 2.5 during spring and winter, requiring measures of reducing emission. Moreover, excessive humidity contributes the most to PM 2.5 accumulation in Valencia. For both cities, potential urban ventilation corridors during winter align along southwest-northeast direction, which could serve as an effective strategy to facilitate the dispersion of PM 2.5 . • Investigated the spatiotemporal variations of PM 2.5 in Madrid and Valencia from 2013 to 2022 using satellite products. • Conducted a multi-scale analysis of correlations between meteorological parameters and PM 2.5 concentration. • Quantitative analyzed the feature contribution of meteorological factors to PM 2.5 on seasonal scale. • For both cities, the southwest-northeast direction has the potential to form ventilation corridors in December.