| Igeo Class | Igeo Class | Contamination level |
| 0 | Igeo ≤ 0 | Uncontaminated |
| 1 | 0 < Igeo < 1 | Uncontaminated/moderately contaminated |
| 2 | 1 < Igeo < 2 | Moderately contaminated |
| 3 | 2 < Igeo < 3 | Moderately/strongly contaminated |
| 4 | 3 < Igeo < 4 | Strongly contaminated |
| 5 | 4 < Igeo < 5 | Strongly/extremely contaminated |
| 6 | 5 < Igeo | Extremely contaminated |