No person shall cause or permit to be discharged into the atmosphere from any single source of emission an air contaminant of a density equal to or darker than No. 2 of the smoke chart except:
(A) Smoke of a density equal to but not darker than No. 2 of the smoke chart may be emitted for not more than three minutes in any 30-minute period; or
(B) Smoke of a density equal to but not darker than No. 3 of the smoke chart may be emitted for not more than three minutes in any 60-minute period, but such emission shall not be permitted on more than three occasions during any 24-hour period.
(Prior Code, § 9.204)