Air Quality index, 04/07/2021 - 18/07/2021
| 04/07 | 05/07 | 06/07 | 07/07 | 08/07 | 09/07 | 10/07 | 11/07 | 12/07 | 13/07 | 14/07 | 15/07 | 16/07 | 17/07 | 18/07 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Conurbation | |||||||||||||||
| Brussels | 3 | 3 | 3 | 3 | 4 | 4 | 4 | 4 | 3 | 4 | 4 | 4 | 3 | 4 | 4 |
| Antwerp | 2 | 2 | 3 | 3 | 3 | 4 | 3 | 3 | 4 | 4 | 4 | 3 | 3 | 3 | 4 |
| Ghent | 2 | 3 | 4 | 3 | 3 | 4 | 3 | 4 | 3 | 4 | 4 | 4 | 4 | 3 | 4 |
| Liège | 3 | 2 | 4 | 3 | 3 | 4 | 4 | 3 | 3 | 3 | 4 | 4 | 3 | 4 | 4 |
| Charleroi | 3 | 2 | 3 | 3 | 4 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 5 |
| Area | |||||||||||||||
| Coast | 3 | 3 | 4 | 4 | 4 | 3 | 3 | 3 | 3 | 5 | 4 | 4 | 4 | 3 | 4 |
| West-Vlaanderen (south) | 3 | 3 | 4 | 4 | 4 | 4 | 3 | 4 | 3 | 4 | 4 | 4 | 3 | 3 | 4 |
| Ghent canal area | 3 | 3 | 3 | 3 | 3 | 4 | 3 | 4 | 3 | 4 | 4 | 4 | 3 | 3 | 4 |
| Oost-Vlaanderen (south) | 3 | 3 | 4 | 3 | 4 | 4 | 3 | 4 | 3 | 4 | 4 | 4 | 4 | 4 | 5 |
| Antwerp harbour area | 2 | 3 | 4 | 3 | 4 | 4 | 3 | 4 | 4 | 4 | 4 | 4 | 3 | 4 | 4 |
| Kempen - Vlaams-Brabant (east) | 3 | 3 | 3 | 3 | 4 | 4 | 4 | 3 | 4 | 3 | 3 | 3 | 3 | 4 | 4 |
| Limburg | 3 | 3 | 4 | 3 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 3 | 4 | 4 |
| Region | |||||||||||||||
| Brussels | 3 | 3 | 3 | 3 | 4 | 4 | 4 | 4 | 3 | 4 | 4 | 4 | 3 | 4 | 4 |
| Flanders | 3 | 3 | 3 | 3 | 4 | 4 | 3 | 4 | 3 | 4 | 4 | 4 | 3 | 4 | 4 |
| Wallonia | 3 | 2 | 3 | 3 | 3 | 4 | 4 | 3 | 3 | 3 | 4 | 4 | 3 | 4 | 4 |
| Country | |||||||||||||||
| Belgium | 3 | 3 | 3 | 3 | 4 | 4 | 3 | 3 | 3 | 3 | 4 | 4 | 3 | 4 | 4 |
| 1 | exellent |
| 2 | very good |
| 3 | good |
| 4 | fairly good |
| 5 | moderate |
| 6 | poor |
| 7 | very poor |
| 8 | bad |
| 9 | very bad |
| 10 | horrible |