1.  These regulations may be cited as the Dark Smoke (Permitted Periods) Regulations, 1958, and shall come into operation on the 1st day of June, 1958.

2.—(1) The Interpretation Act, 1889, applies to the interpretation of these regulations as it applies to the interpretation of an Act of Parliament.

(2) In these regulations “the Act of 1956” means the Clean Air Act, 1956, and “black smoke” means smoke which, if compared in the appropriate manner with a chart of the type known at the date of the passing of the Act of 1956 as the Ringelmann Chart, would appear to be as dark as or darker than shade 4 on the chart.

(3) Where a single boiler or unit of industrial plant is fired by more than one furnace discharging to the same chimney those furnaces shall, for the purposes of these regulations, be deemed to be one furnace.

3.—(1) Subject to the provisions of these regulations, emissions of dark smoke from any chimney for not longer than 10 minutes in the aggregate in any period of 8 hours, or, if soot-blowing is carried out within any such period, for not longer than 14 minutes in the aggregate in that period, shall be left out of account for the purposes of section 1 of the Act of 1956.

(2) The said periods of 10 minutes and 14 minutes shall be increased in the case of a chimney serving 2 furnaces to 18 minutes and 25 minutes respectively, in the case of a chimney serving 3 furnaces to 24 minutes and 34 minutes respectively, and in the case of a chimney serving 4 or more furnaces to 29 minutes and 41 minutes respectively.

4.  Nothing in these regulations shall authorise—

(i)the continuous emission of dark smoke, caused otherwise than by soot-blowing, for a period exceeding 4 minutes; or

(ii)the emission of black smoke for more than 2 minutes in the aggregate in any period of 30 minutes.

5.  Nothing in these regulations shall apply to the emission of smoke from any vessel.

EXPLANATORY NOTE

Section 1 of the Clean Air Act, 1956, makes it an offence to emit dark smoke (as defined in the Act) from the chimney of a building, or of certain boilers or industrial plant, but provides that emissions of smoke lasting for not longer than such periods as may be specified by the Minister of Housing and Local Government by regulations shall, in such classes of case and subject to such limitations as may be so specified, be left out of account for the purposes of the section. These Regulations specify the permitted emissions of smoke, but do not apply to emissions of smoke from vessels.