Air Quality index, 28/12/2003 - 11/01/2004
| 28/12 | 29/12 | 30/12 | 31/12 | 01/01 | 02/01 | 03/01 | 04/01 | 05/01 | 06/01 | 07/01 | 08/01 | 09/01 | 10/01 | 11/01 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Conurbation | |||||||||||||||
| Brussels | 3 | 4 | 6 | 5 | 3 | 3 | 4 | 5 | 3 | 3 | 4 | 4 | 4 | 3 | 3 |
| Antwerp | 3 | 4 | 6 | 6 | 4 | 4 | 6 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 3 |
| Ghent | NA | 4 | 6 | 10 | 4 | 5 | 6 | 5 | 5 | 4 | NA | 3 | 4 | 4 | NA |
| Liège | 3 | 5 | 7 | 7 | 6 | 4 | 6 | 6 | 6 | 3 | 5 | NA | 4 | 5 | 4 |
| Charleroi | 4 | 3 | 7 | 6 | 3 | 4 | 6 | 7 | 4 | 4 | 3 | NA | 3 | 3 | 4 |
| Area | |||||||||||||||
| Coast | NA | NA | 4 | 4 | 4 | 4 | 6 | 4 | 4 | NA | NA | NA | 4 | 4 | NA |
| West-Vlaanderen (south) | 4 | 3 | 6 | 5 | 3 | 4 | 7 | 4 | 5 | 4 | 3 | 3 | 4 | 4 | 4 |
| Ghent canal area | NA | 4 | 7 | 6 | 5 | 5 | 6 | 5 | 5 | 5 | NA | 4 | 4 | 5 | 4 |
| Oost-Vlaanderen (south) | 3 | 3 | 6 | 6 | 2 | 3 | 6 | 5 | 4 | 2 | 3 | 3 | 4 | 3 | 4 |
| Antwerp harbour area | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Kempen - Vlaams-Brabant (east) | NA | NA | NA | NA | NA | NA | NA | NA | 4 | 3 | 3 | 3 | 3 | 3 | 4 |
| Limburg | 4 | 3 | 7 | 7 | 5 | 5 | 7 | 6 | 4 | 2 | 3 | 3 | 3 | 3 | 4 |
| Region | |||||||||||||||
| Brussels | 3 | 4 | 6 | 5 | 3 | 3 | 4 | 5 | 3 | 3 | 4 | 4 | 4 | 3 | 3 |
| Flanders | 3 | 4 | 6 | 6 | 4 | 4 | 6 | 5 | 4 | 3 | 3 | 3 | 3 | 4 | 4 |
| Wallonia | 4 | 4 | 7 | 7 | 4 | 4 | 6 | 7 | 5 | 3 | 4 | NA | 4 | 4 | 4 |
| Country | |||||||||||||||
| Belgium | 3 | 4 | 6 | 6 | 4 | 4 | 6 | 5 | 4 | 3 | 3 | 3 | 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 |