Clean Air Act 1993

3 Meaning of “dark smoke”

(1) In this Act “dark smoke” means smoke which, if compared in the appropriate manner with a chart of the [1956 c. 52.] type known on 5th July 1956 (the date of the passing of the Clean Air Act 1956) as the Ringelmann Chart, would appear to be as dark as or darker than shade 2 on the chart.

(2) For the avoidance of doubt it is hereby declared that in proceedings—

(a) for an offence under section 1 or 2 (prohibition of emissions of dark smoke); or

(b) brought by virtue of section 17 (smoke nuisances in Scotland),

the court may be satisfied that smoke is or is not dark smoke as defined in subsection (1) notwithstanding that there has been no actual comparison of the smoke with a chart of the type mentioned in that subsection.

(3) Without prejudice to the generality of subsections (1) and (2), if the Secretary of State by regulations prescribes any method of ascertaining whether smoke is dark smoke as defined in subsection (1), proof in any such proceedings as are mentioned in subsection (2)—

(a) that that method was properly applied, and

(b) that the smoke was thereby ascertained to be or not to be dark smoke as so defined,

shall be accepted as sufficient.