| Index Value | Degree of Pollution |
| MPI > 2 | Not impacted |
| 2 < MPI < 5 | Very low contamination |
| 5 < MPI < 10 | Low contamination |
| 10 < MPI< 20 | Medium contamination |
| 20 < MPI < 50 | High contamination |
| 50 < MPI < 100 | Very high contamination |
| MPI > 100 | Extreme contamination |