"Opacity" means the property of a substance tending to obscure vision and measured in terms of percent obscuration. The relationship between opacity and Ringelmann number is approximately equal to the following in shades of white to gray.
Opacity | Ringelmann |
(Percent) | Number |
20................................... | 1 |
40................................. | 2 |
60................................. | 3 |
80................................. | 4 |
100................................. | 5 |
Nev. Admin. Code § 445B.121
NRS 445B.210