Class

Class

Class

Class

<1, non-contamination

>−1, <2, light

>−2, <3, moderate

>−3, heavy

>8, low

>−8, <16, moderate

>16, <32, relatively high

>−32, very high

<40, low

>−40, <100, strong

>−100, <320, very strong

>−320, extremely strong

RI

<150, low

>150, <300, moderate

>−300, <600, strong

>−600, very strong