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