Under the Clean Air Act 1993, it is an offence to emit visible smoke from a chimney and to buy or sell unauthorised fuels in a smoke control area.
O dan Ddeddf Aer Glân 1993, mae'n drosedd allyrru mwg gweladwy o simnai a phrynu neu werthu tanwydd anawdurdodedig mewn ardal rheoli mwg.