Air Quality index, 18/03/2011 - 01/04/2011
| 18/03 | 19/03 | 20/03 | 21/03 | 22/03 | 23/03 | 24/03 | 25/03 | 26/03 | 27/03 | 28/03 | 29/03 | 30/03 | 31/03 | 01/04 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Conurbation | |||||||||||||||
| Brussels | 6 | 4 | 5 | 6 | 7 | 5 | 6 | 6 | 4 | 4 | 5 | 7 | 4 | 3 | 3 |
| Antwerp | 6 | 5 | 5 | 6 | 6 | 4 | 4 | 5 | 4 | 4 | 4 | 6 | 6 | 3 | 3 |
| Ghent | 5 | 4 | 5 | 6 | 7 | 4 | 5 | 6 | 4 | 5 | 5 | 6 | 4 | 3 | 3 |
| Liège | 4 | 4 | 5 | 5 | 6 | 6 | 5 | 6 | 4 | 5 | 6 | 6 | 5 | 4 | 2 |
| Charleroi | 6 | 5 | 5 | 5 | 6 | 6 | 6 | 7 | 6 | 6 | 6 | 7 | 4 | 2 | 3 |
| Area | |||||||||||||||
| Coast | 4 | 2 | 5 | 6 | 5 | 4 | 4 | 5 | 6 | 5 | 4 | 6 | 4 | 3 | 3 |
| West-Vlaanderen (south) | 4 | 2 | 4 | 7 | 6 | 4 | 5 | 5 | 4 | 4 | 4 | 6 | 4 | 3 | 3 |
| Ghent canal area | 6 | 4 | 5 | 6 | 7 | 4 | 4 | 6 | 3 | 5 | 5 | 7 | 6 | 3 | 3 |
| Oost-Vlaanderen (south) | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| Antwerp harbour area | 4 | 4 | 5 | 6 | 6 | 4 | NA | NA | 4 | 4 | 4 | 6 | 5 | 3 | 3 |
| Kempen - Vlaams-Brabant (east) | 6 | 3 | 3 | 4 | 5 | 4 | 4 | 6 | 3 | 6 | 4 | 6 | 4 | 3 | 3 |
| Limburg | 6 | 4 | 4 | 4 | 5 | 3 | 4 | 5 | 2 | 4 | 5 | 6 | 5 | 3 | 3 |
| Region | |||||||||||||||
| Brussels | 6 | 4 | 5 | 6 | 7 | 5 | 6 | 6 | 4 | 4 | 5 | 7 | 4 | 3 | 3 |
| Flanders | 5 | 4 | 4 | 6 | 6 | 4 | 4 | 5 | 4 | 4 | 4 | 6 | 5 | 3 | 3 |
| Wallonia | 5 | 3 | 4 | 4 | 6 | 5 | 5 | 6 | 5 | 5 | 5 | 6 | 4 | 3 | 2 |
| Country | |||||||||||||||
| Belgium | 5 | 4 | 4 | 6 | 6 | 4 | 5 | 6 | 4 | 4 | 4 | 6 | 5 | 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 |