Air Quality index, 31/08/2004 - 14/09/2004
| 31/08 | 01/09 | 02/09 | 03/09 | 04/09 | 05/09 | 06/09 | 07/09 | 08/09 | 09/09 | 10/09 | 11/09 | 12/09 | 13/09 | 14/09 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Conurbation | |||||||||||||||
| Brussels | 4 | 5 | 6 | 6 | 6 | 7 | 7 | 6 | 4 | 5 | 6 | 4 | 3 | 3 | 3 |
| Antwerp | 3 | 6 | 5 | 6 | 5 | 7 | 6 | 5 | 3 | 4 | 6 | 4 | 3 | 3 | 3 |
| Ghent | 4 | 5 | 5 | 6 | 5 | 7 | 6 | 5 | 4 | 4 | 6 | 4 | 3 | 2 | 3 |
| Liège | 5 | 5 | 6 | 7 | 9 | 6 | 6 | 6 | 6 | 5 | 7 | 4 | 3 | 6 | 5 |
| Charleroi | 4 | 5 | 6 | 6 | 7 | 7 | 6 | 6 | 5 | 5 | 6 | 4 | 3 | 3 | 3 |
| Area | |||||||||||||||
| Coast | 4 | 5 | 6 | 6 | 5 | 7 | 7 | 5 | 4 | 4 | 5 | 5 | 4 | 3 | 4 |
| West-Vlaanderen (south) | 4 | 5 | 6 | 7 | 6 | 7 | 7 | 6 | 5 | 6 | 6 | 5 | 4 | 3 | 4 |
| Ghent canal area | 4 | 4 | 5 | 6 | 6 | 8 | 6 | 5 | 5 | 5 | 5 | 4 | 3 | 4 | 4 |
| Oost-Vlaanderen (south) | 4 | 4 | 5 | 7 | 6 | 7 | 6 | 6 | 4 | 4 | 5 | 4 | 4 | 3 | 4 |
| Antwerp harbour area | 4 | 5 | 6 | 6 | 6 | 7 | 6 | 5 | 4 | 5 | 6 | 4 | 4 | 4 | 4 |
| Kempen - Vlaams-Brabant (east) | 4 | 4 | 6 | 7 | 6 | 7 | 7 | 6 | 5 | 5 | 6 | 4 | 3 | 4 | 3 |
| Limburg | 4 | 4 | 5 | 6 | 7 | 7 | 5 | 5 | 4 | 4 | 6 | 4 | 4 | 4 | 4 |
| Region | |||||||||||||||
| Brussels | 4 | 5 | 6 | 6 | 6 | 7 | 7 | 6 | 4 | 5 | 6 | 4 | 3 | 3 | 3 |
| Flanders | 4 | 4 | 5 | 6 | 6 | 7 | 6 | 5 | 4 | 4 | 5 | 4 | 4 | 3 | 3 |
| Wallonia | 4 | 5 | 6 | 7 | 7 | 7 | 6 | 6 | 5 | 5 | 6 | 4 | 3 | 4 | 4 |
| Country | |||||||||||||||
| Belgium | 3 | 4 | 5 | 6 | 6 | 7 | 6 | 5 | 4 | 4 | 5 | 4 | 3 | 3 | 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 |