Table 4 Enriched factor (EF), contamination factor (CF), geo-accumulation index (Igeo) and pollution load index (PLI) range values and their environmental risk grades

Single Indices

EF

[32]

0 – 1

Background concentration or no enrichment

1 – 3

Minor enrichment

3 – 5

Moderate enrichment

5 – 10

Moderately severe enrichment

10 – 25

Severe enrichment

25 – 50

Very severe enrichment

 > 50

Extremely serve enrichment

CF

[34]

˂ 1

Minimum contamination

1 to 3

Moderate contamination

3 to 6

Considerable contamination

 > 6

Very high contamination

Igeo

[32]

0

Uncontaminated or background concentration

0–1

Uncontaminated

1–2

Moderately contaminated to uncontaminated

2–3

Moderately contaminated

3–4

Moderately to highly contaminated

4–5

Highly contaminated

 > 5

Very highly contaminated

Integrated Index

PLI

[37]

0

Perfection

1

Baseline

 > 1

Increasing contamination