Percentage of the urban population exposed to air pollutants in the 28 European Union (EU) member states according to EU reference values for the main air pollutants and World Health Organization (WHO) air quality guidelines (AQGs) for 2014 [24]
| Estimated exposure according to EU reference values | Estimated exposure according to WHO AQGs | |
| PM2.5 | 12 | 91 |
| PM10 | 21 | 63 |
| NO2 | 17 | 98 |
| O3 | 9 | 9 |
| BaP | 24 | 91 |
| SO2 | <1 | 49 |
Data are presented as %. Concentrations of particles with a 50% cut-off aerodynamic diameter of x µm (PMx), nitrogen dioxide (NO2), ozone (O3) and sulfur dioxide (SO2) are measured in μg·m−3; concentrations of benzo[a]pyrene (BaP) are measured in ng·m−3. Data from [25].