YOLO-SOLANO AIR QUALITY MANAGEMENT DISTRICT

RULE 2.3 - RINGELMANN CHART

A person shall not discharge into the atmosphere from any single source of emission whatsoever, any air contaminant for a period or periods aggregating more than 3 minutes in any one hour which is:

  1. As dark or darker in shade as that designated as No. 2 on the Ringelmann Chart, as published by the United States Bureau of Mines; or
  2. Of such opacity as to obscure an observer's view to a degree equal to or greater than does smoke described in subsection a. of this rule.