MOJAVE DESERT AIR QUALITY MANAGEMENT DISTRICT
RULE 401 - VISIBLE EMISSIONS
(Adopted: May 7, 1976)
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 three minutes in any one hour which is:
(a) As dark or darker in shade as that designated No. 1 on the Ringelmann Chart, as published by the United States Bureau of Mines, or
(b) 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.