This study investigates population exposure to multiple air pollutants and compound episodes in Europe from 2003 to 2019. It uses Quantile LightGBM (QLG) machine learning models to estimate daily concentrations of PM2.5, PM10, NO2, and O3 at a 0.1-degree resolution across 1426 NUTS3 regions in 35 European countries, representing 543 million people. The results show annual declines in PM10 (2.72%), NO2 (2.45%), and PM2.5 (1.72%), while O3 levels increased by 0.58% in southern Europe, leading to more unclean air days. Despite improvements in air quality, 86.3% of Europeans experience at least one compound event day per year, particularly for PM2.5-NO2 and PM2.5-O3. The study highlights the need for targeted measures to address specific pollutants and their compound events, especially with rising temperatures. It also emphasizes the importance of addressing ozone pollution, which has increased due to climate change and complex interactions between pollutants. The study provides comprehensive insights into the spatial and temporal patterns of air pollution exposure, contributing to the assessment of air quality in Europe under new WHO guidelines. The findings underscore the urgency for stronger control measures on pollutants like PM2.5 and O3, and the need for integrated approaches to manage air pollution and climate change. The study also identifies the need for more comprehensive solutions to address air quality and public health concerns in Europe.This study investigates population exposure to multiple air pollutants and compound episodes in Europe from 2003 to 2019. It uses Quantile LightGBM (QLG) machine learning models to estimate daily concentrations of PM2.5, PM10, NO2, and O3 at a 0.1-degree resolution across 1426 NUTS3 regions in 35 European countries, representing 543 million people. The results show annual declines in PM10 (2.72%), NO2 (2.45%), and PM2.5 (1.72%), while O3 levels increased by 0.58% in southern Europe, leading to more unclean air days. Despite improvements in air quality, 86.3% of Europeans experience at least one compound event day per year, particularly for PM2.5-NO2 and PM2.5-O3. The study highlights the need for targeted measures to address specific pollutants and their compound events, especially with rising temperatures. It also emphasizes the importance of addressing ozone pollution, which has increased due to climate change and complex interactions between pollutants. The study provides comprehensive insights into the spatial and temporal patterns of air pollution exposure, contributing to the assessment of air quality in Europe under new WHO guidelines. The findings underscore the urgency for stronger control measures on pollutants like PM2.5 and O3, and the need for integrated approaches to manage air pollution and climate change. The study also identifies the need for more comprehensive solutions to address air quality and public health concerns in Europe.