Contamination Factor^a

Enrichment Factor^b

CF indices

Degree of contamination

EF indices

Degree of enrichment

CF < 1

Low contamination,

EF < 2

Deficiency to minimal enrichment

1 ≤ CF ≤ 3

Moderate contamination

2 ≤ EF ≤ 5

Moderate enrichment

3 ≤ CF ≤ 6

Considerable contamination

5 ≤ EF ≤ 20

Significant enrichment

CF ≥ 6

Very high contamination

20 ≤ EF ≤ 40

Very high enrichment

EF > 40

Extremely high enrichment