It shall be unlawful to cause or permit the emission of dense smoke from any fire, chimney, engine, oil burner or any other agent in the village so as to cause annoyance or discomfort to the residents thereof. For the purpose of testing and grading the density of smoke, the "Ringelmann Smoke Chart" as published and used by the United States geological survey, shall be, and is hereby adopted, as a standard for such grading, and smoke shall be and is hereby defined as and declared to be "dense" when it is of a degree of density of number three (3) of the said chart, or greater, for more than six (6) minutes in any one hour; whether such period of time is consecutive or not. (1970 Code §480)