Smoke

No emission at any point from any chimney or otherwise of visible gray smoke of a shade darker than No. 2 on the Ringelmann Smoke Chart, as published by the U.S. Bureau of Mines in August, 1955, as information circular 7718 (revision of i.c. 6888), is permitted, except that visible smoke of a shade darker than No. 2 on such chart may be emitted for not more than four minutes in any 30 minutes in a C-5 district or in an I-1 or I-2 district and not more than eight minutes in any 30 minutes in an I-3 district. These provisions applicable to visible gray smoke shall also apply to visible smoke of a different color, excluding steam and other nontoxic emissions, but with an equivalent apparent opacity.

(Rev. Ords. 1987, § 19-337)