Air Quality index, 28/04/2011 - 12/05/2011
| 28/04 | 29/04 | 30/04 | 01/05 | 02/05 | 03/05 | 04/05 | 05/05 | 06/05 | 07/05 | 08/05 | 09/05 | 10/05 | 11/05 | 12/05 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Conurbation | |||||||||||||||
| Brussels | 4 | 5 | 6 | 6 | 5 | 5 | 5 | 5 | 6 | 6 | 6 | 5 | 5 | 4 | 5 |
| Antwerp | 4 | 5 | 6 | 6 | 5 | 5 | 5 | 5 | 6 | 6 | 6 | 4 | 5 | 4 | 5 |
| Ghent | 5 | 6 | 6 | 6 | 5 | 5 | 5 | 6 | 6 | 6 | 6 | 5 | 4 | 5 | 5 |
| Liège | 4 | 5 | 5 | 5 | 5 | 4 | 5 | 6 | 7 | 7 | 7 | 5 | 6 | 5 | 5 |
| Charleroi | 5 | 6 | 6 | 6 | 5 | 4 | 5 | 6 | 7 | 6 | 6 | 4 | 6 | 4 | 4 |
| Area | |||||||||||||||
| Coast | 5 | 6 | 6 | 5 | 5 | 5 | 5 | 6 | 7 | 6 | 5 | 5 | 5 | 4 | 5 |
| West-Vlaanderen (south) | 5 | 6 | 6 | 6 | 5 | 4 | 4 | 5 | 6 | 6 | 5 | 5 | 4 | 5 | 5 |
| Ghent canal area | 7 | 6 | NA | NA | 5 | 5 | 5 | 5 | 7 | 6 | 6 | 5 | 4 | 4 | 5 |
| Oost-Vlaanderen (south) | 4 | 6 | 6 | 6 | 5 | 5 | 5 | 6 | 7 | 6 | 6 | 5 | 5 | 5 | 5 |
| Antwerp harbour area | 4 | 6 | 6 | 6 | 5 | 5 | 5 | 5 | 6 | 6 | 6 | 4 | 5 | 5 | 4 |
| Kempen - Vlaams-Brabant (east) | 4 | 6 | 6 | 6 | 5 | 5 | 5 | 6 | 7 | 7 | 6 | 5 | 6 | 5 | 5 |
| Limburg | 5 | 6 | 6 | 6 | 5 | 4 | 5 | 6 | 7 | 7 | 7 | 5 | 7 | 6 | 5 |
| Region | |||||||||||||||
| Brussels | 4 | 5 | 6 | 6 | 5 | 5 | 5 | 5 | 6 | 6 | 6 | 5 | 5 | 4 | 5 |
| Flanders | 5 | 5 | 6 | 6 | 5 | 5 | 5 | 6 | 6 | 7 | 6 | 4 | 5 | 5 | 5 |
| Wallonia | 4 | 6 | 6 | 6 | 5 | 5 | 5 | 6 | 7 | 7 | 6 | 5 | 5 | 5 | 5 |
| Country | |||||||||||||||
| Belgium | 5 | 5 | 6 | 6 | 5 | 5 | 5 | 6 | 6 | 7 | 6 | 4 | 5 | 5 | 5 |
| 1 | exellent |
| 2 | very good |
| 3 | good |
| 4 | fairly good |
| 5 | moderate |
| 6 | poor |
| 7 | very poor |
| 8 | bad |
| 9 | very bad |
| 10 | horrible |