Air Quality index, 20/09/2021 - 04/10/2021
| 20/09 | 21/09 | 22/09 | 23/09 | 24/09 | 25/09 | 26/09 | 27/09 | 28/09 | 29/09 | 30/09 | 01/10 | 02/10 | 03/10 | 04/10 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Conurbation | |||||||||||||||
| Brussels | 3 | 4 | 4 | 4 | 3 | 4 | 3 | 3 | 4 | 3 | 2 | 3 | 3 | NA | 3 |
| Antwerp | 3 | NA | 5 | 4 | 3 | 4 | 3 | 3 | 3 | 3 | 2 | 3 | 3 | 3 | 3 |
| Ghent | 3 | NA | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 3 | 4 | 3 |
| Liège | 3 | 4 | 3 | 4 | 3 | 4 | 4 | 3 | 3 | 3 | 3 | 4 | 4 | 4 | 3 |
| Charleroi | 3 | 4 | 4 | 3 | 2 | 4 | 3 | 3 | 3 | 2 | 3 | 3 | 3 | 3 | 3 |
| Area | |||||||||||||||
| Coast | 4 | NA | 5 | 4 | 4 | 4 | 4 | 4 | 4 | 3 | 4 | 3 | 2 | 4 | 3 |
| West-Vlaanderen (south) | 4 | NA | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 3 | 1 | 2 |
| Ghent canal area | 4 | NA | 4 | 4 | 3 | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 2 | 1 | 2 |
| Oost-Vlaanderen (south) | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Antwerp harbour area | 4 | NA | 4 | 4 | 3 | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 3 | 10 | 3 |
| Kempen - Vlaams-Brabant (east) | 3 | NA | 4 | 4 | 3 | 4 | 3 | 3 | 4 | 3 | 3 | 4 | 3 | 3 | 4 |
| Limburg | 3 | NA | 4 | 4 | 3 | 4 | 4 | 3 | 3 | 3 | 3 | 4 | 3 | 4 | 3 |
| Region | |||||||||||||||
| Brussels | 3 | 4 | 4 | 4 | 3 | 4 | 3 | 3 | 4 | 3 | 2 | 3 | 3 | NA | 3 |
| Flanders | 3 | NA | 4 | 4 | 3 | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 3 | 9 | 3 |
| Wallonia | 3 | 4 | 4 | 4 | 3 | 4 | 3 | 3 | 3 | 3 | 3 | 4 | 3 | 4 | 3 |
| Country | |||||||||||||||
| Belgium | 3 | NA | 4 | 4 | 3 | 4 | 3 | 3 | 4 | 3 | 3 | 4 | 3 | 5 | 3 |
| 1 | exellent |
| 2 | very good |
| 3 | good |
| 4 | fairly good |
| 5 | moderate |
| 6 | poor |
| 7 | very poor |
| 8 | bad |
| 9 | very bad |
| 10 | horrible |