No individual or individuals shall cause, suffer or allow to be discharged in the atmosphere from any source other than ships, marine vessels, railroad locomotives, or air or land transport vehicles, smoke the shade or appearance of which is equivalent to, or greater than, that density described as No. 2 of the Ringelmann Chart, provided, however, that smoke, the shade or appearance of which is equivalent to, but not darker than, No. 2 of the Ringelmann Chart for a period or periods aggregating four minutes in any 30 minutes shall be permitted and provided further, that smoke, the shade or appearance of which is equivalent to, but not darker than, No. 3 of the Ringelmann Chart for a period or periods aggregating three minutes in any 15 minutes shall also be permitted when building new fire or when breakdown or malfunctioning of equipment occurs such as to make it evident that the emission was not reasonably preventable.
(Ord. 250-8-88, passed 8-15-88) Penalty, see § 90.99