Smygu yw’r prif beth sy’n achosi salwch ataliadwy a marwolaethau cyn pryd yng Nghymru.  Yn y Deyrnas Unedig, mae'n achosi chwarter o'r holl farwolaethau canser, ac yn gyfrifol am 80,000 o farwolaethau y gellir eu hatal bob blwyddyn, gyda 5,600 o’r rhain yng Nghymru.
Smoking is the leading cause of preventable illness and premature death in Wales. It causes a quarter of all cancer deaths in the UK and is responsible for 80,000 preventable deaths in the UK of which around 5,600 are in Wales, each year.