http://www.legislation.gov.uk/ukpga/Eliz2/4-5/52/section/2/1991-02-01Clean Air Act 1956 (repealed 27.8.1993)An Act to make provision for abating the pollution of the air.1979-08-31texttext/xmlenStatute Law Database2011-05-261991-02-01 Dark Smoke2F1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .