Mae Llywodraeth Cymru wedi gosod Cyfarwyddyd ar Gyngor Caerdydd a Chyngor Caerffili i gynnal asesiad erbyn 30 Mehefin 2019 er mwyn pennu'r opsiwn gorau ar gyfer cyflawni terfynau statudol o ran NO2 o fewn y cyfnod byrraf posibl. &nbsp;Mae Llywodraeth Cymru hefyd wedi neilltuo £20 miliwn er mwyn cynorthwyo'r ddau awdurdod lleol i sicrhau cydymffurfiaeth.
The Welsh Government has placed a Direction on Cardiff and Caerphilly Councils to undertake an assessment by 30 June 2019 to identify the best option to achieve statutory NO2 limit values within the shortest possible time. The Welsh Government has also allocated £20 million towards supporting the two local authorities to achieve compliance.