"Rydym wedi ymchwilio i'r holl fesurau posibl ar gyfer lleihau lefelau nitrogen deuocsid. Mae'n hastudiaethau cychwynnol yn dangos mai terfynau cyflymder 50 milltir yr awr ddylai fod fwyaf effeithiol i wella'r ansawdd aer ymhob lleoliad. Gall y camau rydym yn eu cymryd i wella ansawdd aer yng Nghymru ein helpu i sicrhau'r amodau cywir ar gyfer gwell iechyd a llesiant."
“We have been carrying out investigations into all potential measures for reducing nitrogen dioxide levels. Our initial studies tell us that 50 mph speed limits should have the greatest potential to improve air quality at each location. The actions we take to improve air quality in Wales have a key role in supporting the right conditions for better health and well-being.”