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Classification of Igeo (Müller 1969)
| Class | Description | Igeo value |
|---|---|---|
| 0 | Unpolluted | Igeo ≤ 0 |
| 1 | Slightly polluted | 0 < Igeo ≤ 1 |
| 2 | Moderately polluted | 1 < Igeo ≤ 2 |
| 3 | Moderately/severely polluted | 2 < Igeo ≤ 3 |
| 4 | Severely polluted | 3 < Igeo ≤ 4 |
| 5 | Severely/extremely polluted | 4 < Igeo ≤ 5 |
| 6 | Extremely polluted | Igeo > 5 |
