Class

Value

Status

Class I

I_geo < 0

Unpolluted

Class II

0 < I_geo < 1

Unpolluted to moderately polluted

Class III

1 < I_geo < 2

Moderately polluted

Class IV

2 < I_geo < 3

Moderately to heavily polluted

Class V

3 < I_geo < 4

heavily polluted

Class VI

4 < I_geo < 5

heavily to extremely polluted

Class VII

I_geo > 5

Extremely polluted