| Contamination Factor (CF) |
| Contamination Level | PLI value | Contamination Level |
| CF < 1 |
| Low | PLI < 5 | Low |
| 1 ≤ CF < 3 |
| Moderate | 5 < PLI < 50 | Moderate |
| 3 ≤ CF < 6 |
| Considerable | 50< PLI < 100 | Considerable |
| CF > 6 |
| Very high | PLI > 100 | Very high |