Table 5.

Classification for contamination degree and PERI

Contamination factor (C i f)	Classification	Contamination degree (C d)	Classification
C i f < 1	Low	C d < 8	Low
1 ≤ C i f < 3	Moderate	8 ≤ C d < 16	Moderate
3 ≤ Ci f <6	Considerable	16 ≤ C d < 32	Considerable
Ci f ≥ 6	Very high	C d ≥ 32	Very high
Scope of potential of ecological risk index E i r for individual element	Classification	Scope of potential ecological risk index (PERI)	Classification
E r < 40	Low	PERI < 150	Low grade
40 ≤ E r < 80	Moderate	150 ≤ PERI < 300	Moderate
80 ≤ E r < 160	Higher	300 ≤ PERI < 600	Severe
160 ≤ E r < 320	Much higher	600 ≤ PERI	Serious
320 ≤ E r	Serious