Index

Equation

Classification

References

CF

CF < 1 (low CF)

1 ≤ CF < 3 (moderate CF)

3 ≤ CF < 6 (considerable CF)

CF ≥ 6 (very high CF)

[18] [23]

PLI

PLI = 0 (perfection)

PLI = 1 (baseline levels of

pollutants present)

PLI > 1 (progressive deterioration of site)

[24]

CD

CD < 6 (low CD)

6 ≤ CD < 12 (moderate CD)

12 ≤ CD < 24 (considerable CD)

CD ≥ 24 (very high CD) indicating

alarming anthropogenic contamination

[23] [18]

EF

EF: 2 - 5 (moderate enrichment)

EF: 5 - 20 (significant enrichment)

EF: 20 - 40 (very high enrichment)

EF > 40 (extremely high enrichment)

[25] [26]

Igeo

Igeo < 0 Class 0 (uncontaminated)

0 < Igeo < 1 Class 1 (uncontaminated to

moderately contaminated)

1 < Igeo < 2 Class 2 (moderately

contaminated)

2 < Igeo < 3 Class 3 (moderately to heavily

contaminated)

3 < Igeo < 4 Class 4 (heavily contaminated)

4 < Igeo < 5 Class 5 (heavily to extremely

contaminated)

Igeo ≥ 5 Class 6 (extremely contaminated)

[3] [27] [28]

PERI

< 30 (low risk)

: 30 - 60 (moderate risk)

: 60 - 120 (considerable risk)

: 120 - 240 (high risk)

> 240 (significantly high risk)

PERI < 110 (low risk)

PERI: 110 - 220 (moderate risk)

PERI: 220 - 440 (high risk)

PERI > 440 (significantly high risk)

[29] [23]