GREAT BASIN UNIFIED AIR POLLUTION CONTROL DISTRICT

RULE 400 - RINGELMANN CHART
(Adopted 9/05/74; Revised 1/18/79)

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:

1. As dark or darker in shade as that designated as No. 1 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.

1. "An observer" is defined as either a human observer or a certified, calibrated, in-stack opacity monitoring system.