Ar sail gwybodaeth oddi wrth yr Awdurdod Glo, mae Llywodraeth Cymru wedi amcangyfrif bod mwy na 40 y cant o holl domennydd glo'r DU yng Nghymru a bod tua un o bob saith ohonynt yn cael eu hystyried yn rhai risg uchel.
Based on information from the Coal Authority, the Welsh Government has estimated that more than 40 per cent of all the UK’s coal tips are located in Wales and around one in seven of these are classed as high risk.