Smoke and air contaminants—Standards—Definitions.
Seattle Mun. Code § 11.84.100
in effect11.84.100 - Smoke and air contaminants—Standards—Definitions.
A. No motor vehicle first sold and registered as a new motor vehicle on or after January 1, 1971, shall discharge into the atmosphere at elevations of less than three thousand feet (3,000') any air contaminant for a period of more than ten (10) seconds which is:
1. As dark as or darker than the shade 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 A1.
B. No motor vehicle first sold and registered prior to January 1, 1971 shall discharge into the atmosphere at elevations of less than three thousand feet (3,000') any air contaminant for a period of more than ten (10) seconds which is:
1. As dark or darker than the shade designated as No. 2 of 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 B2.
C. For the purposes of this subsection the following definitions shall apply:
1. "Opacity" means the degree to which an emission reduces the transmission of light and obscures the view of an object in the background.
2. "Ringelmann chart" means the Ringelmann smoke chart with instructions for use as published by the United States Bureau of Mines in May, 1967, and as thereafter amended, information circular 7718, which is adopted by reference and three (3) copies of which are placed on file with the City Clerk. (RCW 46.37.390(2))
(Ord. 108200, § 2(11.84.100), 1979.)
Source: City of Seattle, Seattle Municipal Code and City Charter (Municode Library, library.municode.com)URL: https://library.municode.com/wa/seattle/codes/municipal_code?nodeId=TIT11VETR_SUBTITLE_ITRCO_PT8EQRE_CH11.84BRMIEQ_11.84.100SMAICOTAEFFetched: 11/1/2026