This paper focuses on the assessment of the air quality with regards to its effects on human health at 14 monitoring stations in 8 EU Countries through two different Air Quality Index methodologies. Specifically, hourly values of SO 2 , CO, NO 2 , O 3 and PM 10 are used to calculate the PI and API indices. The analysis reveals that, although CO and SO 2 do not form a public health hazard at the sites studied, in terms of NO 2 the percentages of “low pollution” days are more than 65%, while a number of stations present significant percentages of “moderate pollution” (up to 33%) and “unhealthy conditions for sensitive groups” (up to 1.5%). Regarding PM 10 , “moderate pollution” days reach 36.5%, whereas another 0.5% of the days are found to be “unhealthy for sensitive groups” in some areas. It is also found that when examining the combined effect of all 5 above-mentioned pollutants, roughly 50–75% of the days present moderate risk of increased mortality, whereas in some areas high risk is observed in more than 35% of the days. Furthermore, some areas present significant percentages (up to 9%) of days with very high risk of increased mortality (i.e. more than 15.3%). Finally, it is found that the CO and SO 2 contribution to the risk of increased total mortality is relatively low at all stations, while the O 3 and NO 2 contributions are quite variable (13–52% and 11–50%, respectively) depending mainly on the type of station. On the other hand, the PM 10 contribution is rather uniform at all stations (approximately 30%), suggesting that PM 10 forms a homogeneous air quality stressor in the EU.