Dyma’r cam olaf fel rhan o nifer o gamau y mae Llywodraeth Cymru wedi’u rhoi ar waith er mwyn gwella ansawdd aer ar rai o’r ffyrdd sy’n creu’r llygredd mwyaf ledled Cymru, yn ogystal â lleihau tagfeydd a gwella diogelwch ar hyd y rhan hon o’r M4.
This is the final stage of a phased approach that the Welsh Government has taken to improve air quality on some of the most polluted roads across Wales, as well as reduce congestion and improve safety along this section of the M4.